Bug 1512504 - Remove support for MSVC. r=froydnj

Consequently, this removes: - MOZ_LIBPRIO, which is now always enabled. - non_msvc_compiler, which is now always true. - The cl.py wrapper, since it's not used anymore. - CL_INCLUDES_PREFIX, which was only used for the cl.py wrapper. - NONASCII, which was only there to ensure CL_INCLUDES_PREFIX still worked in non-ASCII cases. This however keeps a large part of detecting and configuring for MSVC, because we still do need it for at least headers, libraries, and midl. Depends on D19614 Differential Revision: https://phabricator.services.mozilla.com/D19615 --HG-- extra : moz-landing-system : lando
2019-02-14 21:45:27 +00:00 · 2019-02-14 21:45:27 +00:00 · ef3ad686ee
--- a/Makefile.in
+++ b/Makefile.in
@ -272,22 +272,15 @@ update-packaging:
 package-generated-sources:
 	$(call py_action,package_generated_sources,'$(DIST)/$(PKG_PATH)$(GENERATED_SOURCE_FILE_PACKAGE)')

-#XXX: this is a hack, since we don't want to clobber for MSVC
 # PGO support, but we can't do this test in client.mk
 # No point in clobbering if PGO has been explicitly disabled.
 ifdef NO_PROFILE_GUIDED_OPTIMIZE
 maybe_clobber_profiledbuild:
 else
-ifneq ($(CC_TYPE),msvc)
 maybe_clobber_profiledbuild: clean
 ifneq (,$(findstring clang,$(CC_TYPE)))
 	$(LLVM_PROFDATA) merge -o $(DEPTH)/merged.profdata $(DEPTH)/*.profraw
 endif
-else
-maybe_clobber_profiledbuild:
-	$(RM) $(DIST)/bin/*.pgc
-	find $(DIST)/$(MOZ_APP_NAME) -name '*.pgc' -exec mv {} $(DIST)/bin \;
-endif # msvc
 endif # NO_PROFILE_GUIDED_OPTIMIZE

 .PHONY: maybe_clobber_profiledbuild
--- a/browser/app/moz.build
+++ b/browser/app/moz.build
@ -62,7 +62,7 @@ if CONFIG['LIBFUZZER']:
 if CONFIG['ENABLE_GECKODRIVER']:
    DEFINES['MOZ_GECKODRIVER'] = True

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # Always enter a Windows program through wmain, whether or not we're
    # a console application.
    WIN32_EXE_LDFLAGS += ['-ENTRY:wmainCRTStartup']
--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@ -1791,16 +1791,14 @@ pref("browser.fission.simulate", false);
 // On platforms that do not build libprio, do not set these prefs at all, which gives us a way to detect support.

 // Curve25519 public keys for Prio servers
-#ifdef MOZ_LIBPRIO
 pref("prio.publicKeyA", "35AC1C7576C7C6EDD7FED6BCFC337B34D48CB4EE45C86BEEFB40BD8875707733");
 pref("prio.publicKeyB", "26E6674E65425B823F1F1D5F96E3BB3EF9E406EC7FBA7DEF8B08A35DD135AF50");
-#endif

 // Coverage ping is disabled by default.
 pref("toolkit.coverage.enabled", false);
 pref("toolkit.coverage.endpoint.base", "https://coverage.mozilla.org");
 // Whether or not Prio-encoded Telemetry will be sent along with the main ping.
-#if defined(NIGHTLY_BUILD) && defined(MOZ_LIBPRIO)
+#if defined(NIGHTLY_BUILD)
 pref("prio.enabled", true);
 #endif

--- a/browser/moz.build
+++ b/browser/moz.build
@ -45,9 +45,6 @@ for cdm in CONFIG['MOZ_EME_MODULES']:
 if CONFIG['MOZ_GPSD']:
    DEFINES['MOZ_GPSD'] = True

-if CONFIG['MOZ_LIBPRIO']:
-    DEFINES['MOZ_LIBPRIO'] = True
-
 # These files are specified in this moz.build to pick up DIST_SUBDIR as set in
 # this directory, which is un-set in browser/app.
 JS_PREFERENCE_PP_FILES += [
--- a/build/autoconf/expandlibs.m4
+++ b/build/autoconf/expandlibs.m4
@ -20,7 +20,7 @@ AC_CACHE_CHECK(what kind of list files are supported by the linker,
     dnl https://sourceware.org/bugzilla/show_bug.cgi?id=23600
     if AC_TRY_COMMAND(${CC-cc} -o conftest.${OBJ_SUFFIX} -c $MOZ_LTO_CFLAGS $CFLAGS $CPPFLAGS conftest.${ac_ext} 1>&5) && test -s conftest.${OBJ_SUFFIX}; then
         echo "INPUT(conftest.${OBJ_SUFFIX})" > conftest.list
-         if test "$CC_TYPE" = "msvc" -o "$CC_TYPE" = "clang-cl"; then
+         if test "$CC_TYPE" = "clang-cl"; then
             link="$LINKER -OUT:conftest${ac_exeext}"
         else
             link="${CC-cc} -o conftest${ac_exeext}"
--- a/build/moz.configure/bindgen.configure
+++ b/build/moz.configure/bindgen.configure
@ -273,7 +273,7 @@ def basic_bindgen_cflags(target, is_unix, compiler_info, android_cflags, clang_p
        ],
    }.get(target.os, [])

-    if compiler_info.type in ('msvc', 'clang-cl'):
+    if compiler_info.type == 'clang-cl':
        args += [
            # To enable the builtin __builtin_offsetof so that CRT wouldn't
            # use reinterpret_cast in offsetof() which is not allowed inside
--- a/build/moz.configure/headers.configure
+++ b/build/moz.configure/headers.configure
@ -27,7 +27,6 @@ check_headers(
    'unistd.h',
    'nl_types.h',
    'cpuid.h',
-    when=non_msvc_compiler,
 )

 # These are all the places some variant of statfs can be hiding.
@ -36,7 +35,6 @@ check_headers(
    'sys/statfs.h',
    'sys/vfs.h',
    'sys/mount.h',
-    when=non_msvc_compiler,
 )

 # Quota support
@ -45,7 +43,6 @@ check_headers(
 set_define('HAVE_SYS_QUOTA_H',
           try_compile(includes=['sys/quota.h'],
                       body='quotactl(0, nullptr, 0, (caddr_t)nullptr);',
-                       when=non_msvc_compiler,
                       check_msg='for sys/quota.h'))
 check_header('linux/quota.h',
             includes=['sys/socket.h'],
@ -59,14 +56,12 @@ check_headers(
    when=building_linux,
 )

-check_header('sys/queue.h',
-             when=non_msvc_compiler)
+check_header('sys/queue.h')

 check_headers(
    'sys/types.h',
    'netinet/in.h',
    'byteswap.h',
-    when=non_msvc_compiler,
 )

 # TODO: Move these checks to file specific to --enable-project=js.
--- a/build/moz.configure/rust.configure
+++ b/build/moz.configure/rust.configure
@ -321,7 +321,7 @@ set_config('WIN64_CARGO_LINKER_CONFIG', win64_cargo_linker_config)
@depends(target, c_compiler, rustc)
@imports('os')
 def rustc_natvis_ldflags(target, compiler_info, rustc):
-    if target.kernel == 'WINNT' and compiler_info.type in ('msvc', 'clang-cl'):
+    if target.kernel == 'WINNT' and compiler_info.type == 'clang-cl':
        sysroot = check_cmd_output(rustc, '--print', 'sysroot').strip()
        etc = os.path.join(sysroot, 'lib/rustlib/etc')
        ldflags = []
--- a/build/moz.configure/toolchain.configure
+++ b/build/moz.configure/toolchain.configure
@ -448,14 +448,11 @@ def get_compiler_info(compiler, language):
    form of a list or tuple), in the given `language`.

    The returned information includes:
-    - the compiler type (msvc, clang-cl, clang or gcc)
+    - the compiler type (clang-cl, clang or gcc)
    - the compiler version
    - the compiler supported language
    - the compiler supported language version
    '''
-    # Note: MSVC doesn't expose __STDC_VERSION__. It does expose __STDC__,
-    # but only when given the -Za option, which disables compiler
-    # extensions.
    # Note: We'd normally do a version check for clang, but versions of clang
    # in Xcode have a completely different versioning scheme despite exposing
    # the version with the same defines.
@ -469,9 +466,6 @@ def get_compiler_info(compiler, language):
        #if defined(__clang__)
        %COMPILER "clang-cl"
        %VERSION __clang_major__.__clang_minor__.__clang_patchlevel__
-        #else
-        %COMPILER "msvc"
-        %VERSION _MSC_FULL_VER
        #endif
        #elif defined(__clang__)
        %COMPILER "clang"
@ -487,8 +481,6 @@ def get_compiler_info(compiler, language):
        %cplusplus __cplusplus
        #elif __STDC_VERSION__
        %STDC_VERSION __STDC_VERSION__
-        #elif __STDC__
-        %STDC_VERSION 198900L
        #endif
    ''')

@ -514,9 +506,9 @@ def get_compiler_info(compiler, language):

    # Also check for endianness. The advantage of living in modern times is
    # that all the modern compilers we support now have __BYTE_ORDER__ defined
-    # by the preprocessor, except MSVC, which only supports little endian.
+    # by the preprocessor.
    check += dedent('''\
-        #if _MSC_VER || __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+        #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
        %ENDIANNESS "little"
        #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
        %ENDIANNESS "big"
@ -549,14 +541,6 @@ def get_compiler_info(compiler, language):
    stdc_version = int(data.get('STDC_VERSION', '0L').rstrip('L'))

    version = data.get('VERSION')
-    if version and type == 'msvc':
-        msc_ver = version
-        version = msc_ver[0:2]
-        if len(msc_ver) > 2:
-            version += '.' + msc_ver[2:4]
-        if len(msc_ver) > 4:
-            version += '.' + msc_ver[4:]
-
    if version:
        version = Version(version)

@ -604,7 +588,6 @@ def check_compiler(compiler, language, target):
                flags.append('-Xclang')
            flags.append('-std=gnu99')

-    # Note: MSVC, while supporting C++14, still reports 199711L for __cplusplus.
    # Note: this is a strict version check because we used to always add
    # -std=gnu++14.
    cxx14_version = 201402
@ -634,7 +617,7 @@ def check_compiler(compiler, language, target):
            flags.append('--target=%s' % target.toolchain)
            has_target = True

-    if not has_target and (not info.cpu or info.cpu != target.cpu and info.type != 'msvc'):
+    if not has_target and (not info.cpu or info.cpu != target.cpu):
        same_arch = same_arch_different_bits()
        if (target.cpu, info.cpu) in same_arch:
            flags.append('-m32')
@ -853,7 +836,7 @@ def default_c_compilers(host_or_target, other_c_compiler=None):
    def default_c_compilers(host_or_target, target, toolchain_prefix,
                            android_clang_compiler, *other_c_compiler):
        if host_or_target.kernel == 'WINNT':
-            supported = types = ('clang-cl', 'msvc', 'gcc', 'clang')
+            supported = types = ('clang-cl', 'gcc', 'clang')
        elif host_or_target.kernel == 'Darwin':
            types = ('clang',)
            supported = ('clang', 'gcc')
@ -878,10 +861,6 @@ def default_c_compilers(host_or_target, other_c_compiler=None):
                # Android NDK clangs do not function as host compiler, so
                # prioritize a raw 'clang' instead.
                prioritized = info.type
-            elif info.type == 'msvc' and target.cpu != host_or_target.cpu:
-                # MSVC compilers only support one architecture, so we'll
-                # want a cl in another (detected) path.
-                prioritized = 'cl'

            types = [prioritized] + [t for t in types if t != info.type]

@ -898,8 +877,6 @@ def default_c_compilers(host_or_target, other_c_compiler=None):
                result.append(android_clang_compiler)
            elif type == 'gcc':
                result.extend(gcc)
-            elif type == 'msvc':
-                result.append('cl')
            else:
                result.append(type)

@ -1119,16 +1096,6 @@ def compiler(language, host_or_target, c_compiler=None, other_compiler=None,
            raise FatalCheckError(
                'Only clang/llvm 3.9 or newer is supported.')

-        if info.type == 'msvc':
-            if info.version < '19.15.26726':
-                raise FatalCheckError(
-                    'This version (%s) of the MSVC compiler is not '
-                    'supported.\n'
-                    'You must install Visual C++ 2017 Update 8 or '
-                    'later in order to build.\n'
-                    'See https://developer.mozilla.org/en/'
-                    'Windows_Build_Prerequisites' % info.version)
-
        if info.flags:
            raise FatalCheckError(
                'Unknown compiler or compiler not supported.')
@ -1234,19 +1201,12 @@ def compiler(language, host_or_target, c_compiler=None, other_compiler=None,
            if value:
                return value[0]

-        @depends(valid_compiler, linker)
-        def unused_linker(compiler, linker):
-            if linker and compiler.type != 'msvc':
+        @depends(linker)
+        def unused_linker(linker):
+            if linker:
                log.warning('The value of %s is not used by this build system.'
                            % linker_var)

-        if host_or_target is target:
-            @depends(valid_compiler)
-            def is_msvc(compiler):
-                return compiler.type == 'msvc'
-
-            imply_option('LINKER', linker, reason='LD', when=is_msvc)
-
    return valid_compiler


@ -1258,7 +1218,6 @@ host_cxx_compiler = compiler('C++', host, c_compiler=host_c_compiler,
                             other_c_compiler=c_compiler)

 # Generic compiler-based conditions.
-non_msvc_compiler = depends(c_compiler)(lambda info: info.type != 'msvc')
 building_with_gcc = depends(c_compiler)(lambda info: info.type == 'gcc')


@ -1266,7 +1225,7 @@ building_with_gcc = depends(c_compiler)(lambda info: info.type == 'gcc')
 def msvs_version(info):
    # clang-cl emulates the same version scheme as cl. And MSVS_VERSION needs to
    # be set for GYP on Windows.
-    if info.type in ('clang-cl', 'msvc'):
+    if info.type == 'clang-cl':
        return '2017'

    return ''
@ -1289,7 +1248,7 @@ def check_have_64_bit(have_64_bit, compiler_have_64_bit):
@depends(c_compiler, target)
 def default_debug_flags(compiler_info, target):
    # Debug info is ON by default.
-    if compiler_info.type in ('msvc', 'clang-cl'):
+    if compiler_info.type == 'clang-cl':
        return '-Z7'
    elif target.kernel == 'WINNT' and compiler_info.type == 'clang':
        return '-g -gcodeview'
@ -1427,11 +1386,11 @@ set_config('WRAP_SYSTEM_INCLUDES', wrap_system_includes)
 set_config('VISIBILITY_FLAGS', visibility_flags)


-@depends(c_compiler, using_sccache)
-def depend_cflags(info, using_sccache):
-    if info.type not in ('clang-cl', 'msvc'):
+@depends(c_compiler)
+def depend_cflags(info):
+    if info.type != 'clang-cl':
        return ['-MD', '-MP', '-MF $(MDDEPDIR)/$(@F).pp']
-    elif info.type == 'clang-cl':
+    else:
        # clang-cl doesn't accept the normal -MD -MP -MF options that clang
        # does, but the underlying cc1 binary understands how to generate
        # dependency files.  These options are based on analyzing what the
@ -1444,10 +1403,6 @@ def depend_cflags(info, using_sccache):
            '-Xclang', '-MT',
            '-Xclang', '$@'
        ]
-    elif using_sccache:
-        # sccache supports a special flag to create depfiles
-        # by parsing MSVC's -showIncludes output.
-        return ['-deps$(MDDEPDIR)/$(@F).pp']


 set_config('_DEPEND_CFLAGS', depend_cflags)
@ -1492,29 +1447,6 @@ def pgo_flags(compiler, build_env, target):
                use_ldflags=[],
            )

-    if compiler.type == 'msvc':
-        num_cores = min(8, multiprocessing.cpu_count())
-        cgthreads = '-CGTHREADS:%s' % num_cores
-
-        return namespace(
-            gen_cflags=['-GL'],
-            gen_ldflags=['-LTCG:PGINSTRUMENT', '-PogoSafeMode', cgthreads],
-            # XXX: PGO builds can fail with warnings treated as errors,
-            # specifically "no profile data available" appears to be
-            # treated as an error sometimes. This might be a consequence
-            # of using WARNINGS_AS_ERRORS in some modules, combined
-            # with the linker doing most of the work in the whole-program
-            # optimization/PGO case. I think it's probably a compiler bug,
-            # but we work around it here.
-            use_cflags=['-GL', '-wd4624', '-wd4952'],
-            # XXX: should be -LTCG:PGOPTIMIZE, but that fails on libxul.
-            # Probably also a compiler bug, but what can you do?
-            # /d2:-cgsummary prints a summary of what is happening during
-            # code generation. How long individual functions are optimized,
-            # which functions are optimized, etc.
-            use_ldflags=['-LTCG:PGUPDATE', cgthreads, '-d2:-cgsummary'],
-        )
-

 set_config('PROFILE_GEN_CFLAGS', pgo_flags.gen_cflags)
 set_config('PROFILE_GEN_LDFLAGS', pgo_flags.gen_ldflags)
@ -2069,7 +2001,7 @@ js_option(env='AS', nargs=1, help='Path to the assembler')

@depends(target, c_compiler)
 def as_info(target, c_compiler):
-    if c_compiler.type in ('msvc', 'clang-cl'):
+    if c_compiler.type == 'clang-cl':
        ml = {
            'x86': 'ml',
            'x86_64': 'ml64',
@ -2079,7 +2011,7 @@ def as_info(target, c_compiler):
            type='masm',
            names=(ml, )
        )
-    # When building with anything but MSVC, we just use the C compiler as the assembler.
+    # When building with anything but clang-cl, we just use the C compiler as the assembler.
    return namespace(
        type='gcc',
        names=(c_compiler.compiler, )
--- a/build/moz.configure/windows.configure
+++ b/build/moz.configure/windows.configure
@ -251,13 +251,10 @@ def valid_ucrt_sdk_dir(windows_sdk_dir, windows_sdk_dir_env, c_compiler):
@depends(c_compiler, toolchain_search_path)
@imports('os')
 def vc_path(c_compiler, toolchain_search_path):
-    if c_compiler.type not in ('msvc', 'clang-cl'):
+    if c_compiler.type != 'clang-cl':
        return

-    vc_program = c_compiler.compiler
-
-    # In clang-cl builds, we use the headers and libraries from an MSVC installation.
-    if c_compiler.type == 'clang-cl':
+    # In clang-cl builds, we need the headers and libraries from an MSVC installation.
    vc_program = find_program('cl.exe', paths=toolchain_search_path)
    if not vc_program:
        die('Cannot find a Visual C++ install for e.g. ATL headers.')
@ -487,65 +484,17 @@ def valid_mt(path):

 set_config('MSMANIFEST_TOOL', depends(valid_mt)(lambda x: bool(x)))

-
-@template
-def linker_progs_for(host_or_target):
-    compiler = {
-        host: host_c_compiler,
-        target: c_compiler,
-    }[host_or_target]
-
-    @depends(compiler)
-    def linker_progs(compiler):
-        if compiler.type == 'msvc':
-            return ('link', 'lld-link')
-        if compiler.type == 'clang-cl':
-            return ('lld-link', 'link')
-    return linker_progs
-
-
 js_option(env='LINKER', nargs=1, help='Path to the linker')

-link = check_prog('LINKER', linker_progs_for(target), input='LINKER',
+link = check_prog('LINKER', ('lld-link',), input='LINKER',
                  paths=toolchain_search_path)

 js_option(env='HOST_LINKER', nargs=1, help='Path to the host linker')

-host_link = check_prog('HOST_LINKER', linker_progs_for(host),
-                       input='HOST_LINKER',
+host_link = check_prog('HOST_LINKER', ('lld-link',), input='HOST_LINKER',
                       paths=host_toolchain_search_path)

 add_old_configure_assignment('LINKER', link)


 check_prog('MAKECAB', ('makecab.exe',))
-
-
-@depends(c_compiler, using_sccache)
-def need_showincludes_prefix(info, using_sccache):
-    # sccache does its own -showIncludes prefix checking.
-    # clang-cl uses a gcc-style dependency scheme, see toolchain.configure.
-    if info.type == 'msvc' and not using_sccache:
-        return True
-
-
-@depends(c_compiler, when=need_showincludes_prefix)
-@imports(_from='re', _import='compile', _as='re_compile')
-def msvc_showincludes_prefix(c_compiler):
-    pattern = re_compile(br'^([^:]*:.*[ :] )(.*\\stdio.h)$')
-    output = try_invoke_compiler([c_compiler.compiler], 'C', '#include <stdio.h>\n',
-                                 ['-nologo', '-c', '-Fonul', '-showIncludes'])
-    for line in output.splitlines():
-        if line.endswith(b'\\stdio.h'):
-            m = pattern.match(line)
-            if m:
-                return m.group(1)
-    # We should have found the prefix and returned earlier
-    die('Cannot find cl -showIncludes prefix.')
-
-
-set_config('CL_INCLUDES_PREFIX', msvc_showincludes_prefix)
-
-# Make sure that the build system can handle non-ASCII characters in
-# environment variables to prevent silent breakage on non-English systems.
-set_config('NONASCII', b'\241\241')
--- a/build/templates.mozbuild
+++ b/build/templates.mozbuild
@ -159,7 +159,7 @@ def NoVisibilityFlags():
@template
 def ForceInclude(*headers):
    """Force includes a set of header files in C++ compilations"""
-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        include_flag = '-FI'
    else:
        include_flag = '-include'
--- a/config/config.mk
+++ b/config/config.mk
@ -106,14 +106,6 @@ VERSION_NUMBER		= 50
 CONFIG_TOOLS	= $(MOZ_BUILD_ROOT)/config
 AUTOCONF_TOOLS	= $(MOZILLA_DIR)/build/autoconf

-ifeq (msvc,$(CC_TYPE))
-# clang-cl is smart enough to generate dependencies directly.
-ifeq (,$(MOZ_USING_SCCACHE))
-CC_WRAPPER ?= $(call py_action,cl)
-CXX_WRAPPER ?= $(call py_action,cl)
-endif # MOZ_USING_SCCACHE
-endif # CC_TYPE
-
 CC := $(CC_WRAPPER) $(CC)
 CXX := $(CXX_WRAPPER) $(CXX)
 MKDIR ?= mkdir
@ -441,9 +433,3 @@ endif
 endif

 PLY_INCLUDE = -I$(MOZILLA_DIR)/other-licenses/ply
-
-export CL_INCLUDES_PREFIX
-# Make sure that the build system can handle non-ASCII characters
-# in environment variables to prevent it from breking silently on
-# non-English systems.
-export NONASCII
--- a/config/external/icu/defs.mozbuild
+++ b/config/external/icu/defs.mozbuild
@ -49,14 +49,3 @@ if CONFIG['CC_TYPE'] == 'clang-cl':
        '-Wno-macro-redefined',
        '-Wno-microsoft-include',
    ]
-
-if CONFIG['CC_TYPE'] == 'msvc':
-    CFLAGS += [
-        '-wd4005', # 'WIN32_LEAN_AND_MEAN' : macro redefinition
-        '-wd4996', # The compiler encountered a deprecated declaration.
-    ]
-    CXXFLAGS += [
-        '-wd4005', # 'WIN32_LEAN_AND_MEAN' : macro redefinition
-        '-wd4333', # '>>' : right shift by too large amount, data loss
-        '-wd4996', # The compiler encountered a deprecated declaration.
-    ]
--- a/config/external/moz.build
+++ b/config/external/moz.build
@ -13,7 +13,6 @@ DIRS += [
 if not CONFIG['MOZ_SYSTEM_JPEG']:
    external_dirs += ['media/libjpeg']

-if CONFIG['MOZ_LIBPRIO']:
 DIRS += [
    'prio',
 ]
--- a/config/external/msgpack/moz.build
+++ b/config/external/msgpack/moz.build
@ -4,6 +4,4 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.

-if CONFIG['MOZ_LIBPRIO']:
 DIRS += ['/third_party/msgpack']
-
--- a/config/moz.build
+++ b/config/moz.build
@ -43,7 +43,7 @@ if CONFIG['WRAP_STL_INCLUDES']:
    stl_compiler = None
    if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
        stl_compiler = 'gcc'
-    elif CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    elif CONFIG['CC_TYPE'] == 'clang-cl':
        stl_compiler = 'msvc'

    if stl_compiler:
--- a/config/rules.mk
+++ b/config/rules.mk
@ -359,7 +359,7 @@ else
 # Windows-to-Windows cross compiles should always use MSVC-style options for
 # host compiles.
 ifeq (WINNT_WINNT,$(HOST_OS_ARCH)_$(OS_ARCH))
-ifneq (,$(filter-out msvc clang-cl,$(HOST_CC_TYPE)))
+ifneq (,$(filter-out clang-cl,$(HOST_CC_TYPE)))
 $(error MSVC-style compilers should be used for host compilations!)
 endif
 HOST_OUTOPTION = -Fo# eol
@ -517,13 +517,6 @@ define EXPAND_CC_OR_CXX
 $(if $(PROG_IS_C_ONLY_$(1)),$(CC),$(CCC))
 endef

-# Workaround a bug of MSVC 2017 Update 8 (see bug 1485224)
-ifeq ($(CC_TYPE)_$(HOST_OS_ARCH)_$(MOZ_PROFILE_GENERATE),msvc_WINNT_1)
-LINKER_OUT=$(subst /,\,$1)
-else
-LINKER_OUT=$1
-endif
-
 #
 # PROGRAM = Foo
 # creates OBJS, links with LIBS to create Foo
@ -532,7 +525,7 @@ $(PROGRAM): $(PROGOBJS) $(STATIC_LIBS) $(RUST_STATIC_LIB) $(EXTRA_DEPS) $(RESFIL
 	$(REPORT_BUILD)
 	@$(RM) $@.manifest
 ifeq (_WINNT,$(GNU_CC)_$(OS_ARCH))
-	$(LINKER) -NOLOGO -OUT:$(call LINKER_OUT,$@) -PDB:$(LINK_PDBFILE) -IMPLIB:$(basename $(@F)).lib $(WIN32_EXE_LDFLAGS) $(LDFLAGS) $(MOZ_PROGRAM_LDFLAGS) $($(notdir $@)_$(OBJS_VAR_SUFFIX)) $(RESFILE) $(STATIC_LIBS) $(RUST_STATIC_LIB) $(SHARED_LIBS) $(OS_LIBS)
+	$(LINKER) -NOLOGO -OUT:$@ -PDB:$(LINK_PDBFILE) -IMPLIB:$(basename $(@F)).lib $(WIN32_EXE_LDFLAGS) $(LDFLAGS) $(MOZ_PROGRAM_LDFLAGS) $($(notdir $@)_$(OBJS_VAR_SUFFIX)) $(RESFILE) $(STATIC_LIBS) $(RUST_STATIC_LIB) $(SHARED_LIBS) $(OS_LIBS)
 ifdef MSMANIFEST_TOOL
 	@if test -f $@.manifest; then \
 		if test -f '$(srcdir)/$(notdir $@).manifest'; then \
@ -659,7 +652,7 @@ endif
 $(HOST_SHARED_LIBRARY): Makefile
 	$(REPORT_BUILD)
 	$(RM) $@
-ifneq (,$(filter msvc clang-cl,$(HOST_CC_TYPE)))
+ifneq (,$(filter clang-cl,$(HOST_CC_TYPE)))
 	$(HOST_LINKER) -NOLOGO -DLL -OUT:$@ $($(notdir $@)_OBJS) $(HOST_CXX_LDFLAGS) $(HOST_LDFLAGS) $(HOST_LINKER_LIBPATHS) $(HOST_LIBS) $(HOST_EXTRA_LIBS)
 else
 	$(HOST_CXX) $(HOST_OUTOPTION)$@ $($(notdir $@)_OBJS) $(HOST_CXX_LDFLAGS) $(HOST_LDFLAGS) $(HOST_LIBS) $(HOST_EXTRA_LIBS)
--- a/dom/bindings/moz.build
+++ b/dom/bindings/moz.build
@ -7,9 +7,6 @@
 with Files("**"):
    BUG_COMPONENT = ("Core", "DOM")

-if CONFIG['CC_TYPE'] == 'msvc':
-    CXXFLAGS += ['-bigobj']
-
 TEST_DIRS += ['test']

 XPIDL_SOURCES += [
@ -98,7 +95,6 @@ LOCAL_INCLUDES += [
    '/media/webrtc/trunk/',
 ]

-if CONFIG['MOZ_LIBPRIO']:
 LOCAL_INCLUDES += ['/third_party/msgpack/include']

 DEFINES['GOOGLE_PROTOBUF_NO_RTTI'] = True
--- a/dom/chrome-webidl/moz.build
+++ b/dom/chrome-webidl/moz.build
@ -69,7 +69,6 @@ if CONFIG['MOZ_PLACES']:
        'PlacesObservers.webidl',
    ]

-if CONFIG['MOZ_LIBPRIO']:
 WEBIDL_FILES += [
    'PrioEncoder.webidl',
 ]
--- a/dom/media/moz.build
+++ b/dom/media/moz.build
@ -304,7 +304,6 @@ SOURCES += [

 # Some codec-related code uses multi-character constants, which GCC and clang
 # warn about. Suppress turning this warning into an error.
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 SOURCES['DecoderTraits.cpp'].flags += ['-Wno-error=multichar']

 EXTRA_COMPONENTS += [
--- a/dom/media/mp4/moz.build
+++ b/dom/media/mp4/moz.build
@ -41,7 +41,7 @@ SOURCES += [
 FINAL_LIBRARY = 'xul'

 # Supress warnnings for now.
-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    CFLAGS += [
        '-wd4013', # 'function' undefined; assuming extern returning int
        '-wd4101', # unreferenced local variable
--- a/dom/media/platforms/agnostic/bytestreams/moz.build
+++ b/dom/media/platforms/agnostic/bytestreams/moz.build
@ -26,7 +26,7 @@ LOCAL_INCLUDES += [
 FINAL_LIBRARY = 'xul'

 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    CFLAGS += [
        '-wd4013', # 'function' undefined; assuming extern returning int
        '-wd4101', # unreferenced local variable
--- a/dom/media/platforms/ffmpeg/ffvpx/moz.build
+++ b/dom/media/platforms/ffmpeg/ffvpx/moz.build
@ -34,7 +34,7 @@ if CONFIG['CC_TYPE'] == 'clang':
  CXXFLAGS += [
    '-Wno-unknown-attributes',
  ]
-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
  CXXFLAGS += [
    '-wd4996', # deprecated declaration
  ]
--- a/dom/media/platforms/omx/moz.build
+++ b/dom/media/platforms/omx/moz.build
@ -31,9 +31,6 @@ FINAL_LIBRARY = 'xul'
 if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
    CXXFLAGS += ['-Wno-error=shadow']

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
 # Avoid warnings from third-party code that we can not modify.
 if CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += ['-Wno-invalid-source-encoding']
-    else:
-        CXXFLAGS += ['-validate-charset-']
--- a/dom/media/systemservices/moz.build
+++ b/dom/media/systemservices/moz.build
@ -48,7 +48,7 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
  UNIFIED_SOURCES += ['OSXRunLoopSingleton.cpp']
  EXPORTS += ['OSXRunLoopSingleton.h']

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    DEFINES['__PRETTY_FUNCTION__'] = '__FUNCSIG__'

    # This is intended as a temporary workaround to enable building with VS2015.
--- a/dom/media/webrtc/moz.build
+++ b/dom/media/webrtc/moz.build
@ -77,7 +77,6 @@ include('/ipc/chromium/chromium-config.mozbuild')
 #  - about attributes on forward declarations for types that are already
 #    defined, which complains about important MOZ_EXPORT attributes for
 #    android API types
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CXXFLAGS += [
    '-Wno-error=attributes',
    '-Wno-error=shadow',
@ -86,7 +85,7 @@ if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 DEFINES['TRACING'] = True
 FINAL_LIBRARY = 'xul'

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += [
        '-wd4275', # non dll-interface class used as base for dll-interface class
        '-wd4312', # This is intended as a temporary hack to support building with VS2015
--- a/dom/moz.build
+++ b/dom/moz.build
@ -104,11 +104,9 @@ DIRS += [
    'simpledb',
    'reporting',
    'localstorage',
+    'prio',
 ]

-if CONFIG['MOZ_LIBPRIO']:
-    DIRS += ['prio']
-
 if CONFIG['OS_ARCH'] == 'WINNT':
    DIRS += ['plugins/ipc/hangui']

--- a/dom/plugins/ipc/moz.build
+++ b/dom/plugins/ipc/moz.build
@ -148,7 +148,7 @@ CXXFLAGS += CONFIG['MOZ_CAIRO_CFLAGS']
 if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
    CXXFLAGS += ['-Wno-error=shadow']

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # This is intended as a temporary hack to support building with VS2015.
    # conversion from 'X' to 'Y' requires a narrowing conversion
    CXXFLAGS += ['-wd4838']
--- a/dom/plugins/test/testplugin/testplugin.mozbuild
+++ b/dom/plugins/test/testplugin/testplugin.mozbuild
@ -55,7 +55,7 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'gtk3':
    OS_LIBS += CONFIG['XLIBS']
    OS_LIBS += CONFIG['XEXT_LIBS']

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # This is intended as a temporary hack to support building with VS2015.
    # conversion from 'X' to 'Y' requires a narrowing conversion
    CXXFLAGS += ['-wd4838']
--- a/gfx/cairo/cairo/src/moz.build
+++ b/gfx/cairo/cairo/src/moz.build
@ -210,7 +210,6 @@ if CONFIG['MOZ_TREE_FREETYPE']:
    DEFINES['FT_LCD_FILTER_H'] = '%s/modules/freetype2/include/freetype/ftlcdfil.h' % TOPSRCDIR

 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CFLAGS += [
    '-Wno-enum-compare',
    '-Wno-int-to-pointer-cast',
@ -240,26 +239,6 @@ if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 else:
    CFLAGS += ['-Wno-unused-but-set-variable']

-if CONFIG['CC_TYPE'] == 'msvc':
-    CFLAGS += [
-        '-wd4005', # 'WIN32_LEAN_AND_MEAN' : macro redefinition
-        '-wd4018', # '>' : signed/unsigned mismatch
-        '-wd4047', # different levels of indirection
-        '-wd4101', # unreferenced local variable
-        '-wd4133', # 'function' : incompatible types
-        '-wd4146', # unary minus operator applied to unsigned type
-        '-wd4311', # 'variable' : pointer truncation from 'type' to 'type'
-        '-wd4477', # format string '%s' requires an argument of type 'type'
-        '-wd4996', # The compiler encountered a deprecated declaration.
-    ]
-    CXXFLAGS += [
-        '-wd4005', # 'WIN32_LEAN_AND_MEAN' : macro redefinition
-        '-wd4018', # '>' : signed/unsigned mismatch
-        '-wd4146', # unary minus operator applied to unsigned type
-        '-wd4828', # illegal in the current source character set
-        '-wd4838', # requires a narrowing conversion
-    ]
-
 # See bug 386897.
 if CONFIG['CC_TYPE'] in ('clang', 'gcc') and CONFIG['OS_TARGET'] == 'Android' and CONFIG['MOZ_OPTIMIZE']:
    CFLAGS += ['-O2']
--- a/gfx/cairo/libpixman/src/moz.build
+++ b/gfx/cairo/libpixman/src/moz.build
@ -85,7 +85,7 @@ use_arm_neon_gcc = False
 if CONFIG['INTEL_ARCHITECTURE']:
    use_sse2 = True
    if CONFIG['CPU_ARCH'] == 'x86':
-        if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+        if CONFIG['CC_TYPE'] == 'clang-cl':
            use_mmx = True
    if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
        use_mmx = True
@ -150,7 +150,6 @@ if CONFIG['OS_TARGET'] == 'Android' and (use_arm_neon_gcc or use_arm_simd_gcc):
    ]

 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CFLAGS += [
    '-Wno-address',
    '-Wno-missing-field-initializers',
@ -168,14 +167,6 @@ if CONFIG['CC_TYPE'] == 'clang-cl':
    CFLAGS += [
        '-Wno-unused-variable',
    ]
-if CONFIG['CC_TYPE'] == 'msvc':
-    CFLAGS += [
-        '-wd4047', # different levels of indirection
-        '-wd4101', # unreferenced local variable
-        '-wd4133', # 'function' : incompatible types
-        '-wd4146', # unary minus operator applied to unsigned type
-        '-wd4311', # 'variable' : pointer truncation from 'type' to 'type'
-    ]

 # See bug 386897.
 if CONFIG['OS_TARGET'] == 'Android' and CONFIG['MOZ_OPTIMIZE']:
--- a/gfx/qcms/moz.build
+++ b/gfx/qcms/moz.build
@ -27,7 +27,7 @@ use_sse2 = False
 use_altivec = False
 if CONFIG['INTEL_ARCHITECTURE']:
    use_sse2 = True
-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        if CONFIG['OS_ARCH'] != 'WINNT' or CONFIG['CPU_ARCH'] != 'x86_64':
            use_sse1 = True
    else:
--- a/gfx/skia/generate_mozbuild.py
+++ b/gfx/skia/generate_mozbuild.py
@ -24,7 +24,7 @@ header = """
 skia_opt_flags = []

 if CONFIG['MOZ_OPTIMIZE']:
-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        skia_opt_flags += ['-O2']
    elif CONFIG['CC_TYPE'] in ('clang', 'gcc'):
        skia_opt_flags += ['-O3']
@ -79,7 +79,7 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'windows':

 # We should autogenerate these SSE related flags.

-if CONFIG['INTEL_ARCHITECTURE'] and (CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc')):
+if CONFIG['INTEL_ARCHITECTURE']:
    SOURCES['skia/src/opts/SkBitmapProcState_opts_SSE2.cpp'].flags += CONFIG['SSE2_FLAGS']
    SOURCES['skia/src/opts/SkBitmapProcState_opts_SSSE3.cpp'].flags += ['-mssse3']
    SOURCES['skia/src/opts/SkBlitRow_opts_SSE2.cpp'].flags += CONFIG['SSE2_FLAGS']
@ -88,17 +88,6 @@ if CONFIG['INTEL_ARCHITECTURE'] and (CONFIG['CC_TYPE'] in ('clang', 'clang-cl',
    SOURCES['skia/src/opts/SkOpts_sse42.cpp'].flags += ['-msse4.2']
    SOURCES['skia/src/opts/SkOpts_avx.cpp'].flags += ['-mavx']
    SOURCES['skia/src/opts/SkOpts_hsw.cpp'].flags += ['-mavx2', '-mf16c', '-mfma']
-elif CONFIG['CC_TYPE'] in ('msvc', 'clang-cl') and CONFIG['INTEL_ARCHITECTURE']:
-    # MSVC doesn't need special compiler flags, but Skia needs to be told that these files should
-    # be built with the required SSE level or it will simply compile in stubs and cause runtime crashes
-    SOURCES['skia/src/opts/SkBitmapProcState_opts_SSE2.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=20']
-    SOURCES['skia/src/opts/SkBitmapProcState_opts_SSSE3.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=31']
-    SOURCES['skia/src/opts/SkBlitRow_opts_SSE2.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=20']
-    SOURCES['skia/src/opts/SkOpts_ssse3.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=31']
-    SOURCES['skia/src/opts/SkOpts_sse41.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=41']
-    SOURCES['skia/src/opts/SkOpts_sse42.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=42']
-    SOURCES['skia/src/opts/SkOpts_avx.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=51']
-    SOURCES['skia/src/opts/SkOpts_hsw.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=52']
 elif CONFIG['CPU_ARCH'] == 'arm' and CONFIG['CC_TYPE'] in ('clang', 'gcc'):
    CXXFLAGS += CONFIG['NEON_FLAGS']
 elif CONFIG['CPU_ARCH'] == 'aarch64' and CONFIG['CC_TYPE'] in ('clang', 'gcc'):
@ -116,7 +105,6 @@ if CONFIG['MOZ_TREE_FREETYPE']:
    DEFINES['SK_CAN_USE_DLOPEN'] = 0

 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CXXFLAGS += [
    '-Wno-deprecated-declarations',
    '-Wno-overloaded-virtual',
@ -456,7 +444,7 @@ def write_mozbuild(sources):
  write_sources(f, sources['arm'], 4)
  write_cflags(f, sources['arm'], opt_whitelist, 'skia_opt_flags', 4)

-  f.write("elif CONFIG['CPU_ARCH'] == 'aarch64' and CONFIG['CC_TYPE'] in ('clang-cl', 'clang', 'gcc'):\n")
+  f.write("elif CONFIG['CPU_ARCH'] == 'aarch64':\n")
  write_sources(f, sources['arm64'], 4)
  write_cflags(f, sources['arm64'], opt_whitelist, 'skia_opt_flags', 4)

--- a/gfx/skia/moz.build
+++ b/gfx/skia/moz.build
@ -17,7 +17,7 @@
 skia_opt_flags = []

 if CONFIG['MOZ_OPTIMIZE']:
-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        skia_opt_flags += ['-O2']
    elif CONFIG['CC_TYPE'] in ('clang', 'gcc'):
        skia_opt_flags += ['-O3']
@ -686,7 +686,7 @@ elif CONFIG['CPU_ARCH'] == 'arm' and CONFIG['CC_TYPE'] in ('clang', 'gcc'):
    SOURCES['skia/src/opts/SkBlitMask_opts_arm_neon.cpp'].flags += skia_opt_flags
    SOURCES['skia/src/opts/SkBlitRow_opts_arm.cpp'].flags += skia_opt_flags
    SOURCES['skia/src/opts/SkBlitRow_opts_arm_neon.cpp'].flags += skia_opt_flags
-elif CONFIG['CPU_ARCH'] == 'aarch64' and CONFIG['CC_TYPE'] in ('clang-cl', 'clang', 'gcc'):
+elif CONFIG['CPU_ARCH'] == 'aarch64':
    SOURCES += [
        'skia/src/opts/SkBitmapProcState_arm_neon.cpp',
        'skia/src/opts/SkBitmapProcState_matrixProcs_neon.cpp',
@ -759,7 +759,7 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'windows':

 # We should autogenerate these SSE related flags.

-if CONFIG['INTEL_ARCHITECTURE'] and (CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc')):
+if CONFIG['INTEL_ARCHITECTURE']:
    SOURCES['skia/src/opts/SkBitmapProcState_opts_SSE2.cpp'].flags += CONFIG['SSE2_FLAGS']
    SOURCES['skia/src/opts/SkBitmapProcState_opts_SSSE3.cpp'].flags += ['-mssse3']
    SOURCES['skia/src/opts/SkBlitRow_opts_SSE2.cpp'].flags += CONFIG['SSE2_FLAGS']
@ -768,17 +768,6 @@ if CONFIG['INTEL_ARCHITECTURE'] and (CONFIG['CC_TYPE'] in ('clang', 'clang-cl',
    SOURCES['skia/src/opts/SkOpts_sse42.cpp'].flags += ['-msse4.2']
    SOURCES['skia/src/opts/SkOpts_avx.cpp'].flags += ['-mavx']
    SOURCES['skia/src/opts/SkOpts_hsw.cpp'].flags += ['-mavx2', '-mf16c', '-mfma']
-elif CONFIG['CC_TYPE'] in ('msvc', 'clang-cl') and CONFIG['INTEL_ARCHITECTURE']:
-    # MSVC doesn't need special compiler flags, but Skia needs to be told that these files should
-    # be built with the required SSE level or it will simply compile in stubs and cause runtime crashes
-    SOURCES['skia/src/opts/SkBitmapProcState_opts_SSE2.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=20']
-    SOURCES['skia/src/opts/SkBitmapProcState_opts_SSSE3.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=31']
-    SOURCES['skia/src/opts/SkBlitRow_opts_SSE2.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=20']
-    SOURCES['skia/src/opts/SkOpts_ssse3.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=31']
-    SOURCES['skia/src/opts/SkOpts_sse41.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=41']
-    SOURCES['skia/src/opts/SkOpts_sse42.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=42']
-    SOURCES['skia/src/opts/SkOpts_avx.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=51']
-    SOURCES['skia/src/opts/SkOpts_hsw.cpp'].flags += ['-DSK_CPU_SSE_LEVEL=52']
 elif CONFIG['CPU_ARCH'] == 'arm' and CONFIG['CC_TYPE'] in ('clang', 'gcc'):
    CXXFLAGS += CONFIG['NEON_FLAGS']
 elif CONFIG['CPU_ARCH'] == 'aarch64' and CONFIG['CC_TYPE'] in ('clang', 'gcc'):
@ -796,7 +785,6 @@ if CONFIG['MOZ_TREE_FREETYPE']:
    DEFINES['SK_CAN_USE_DLOPEN'] = 0

 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CXXFLAGS += [
    '-Wno-deprecated-declarations',
    '-Wno-overloaded-virtual',
--- a/gfx/vr/service/moz.build
+++ b/gfx/vr/service/moz.build
@ -40,7 +40,7 @@ if CONFIG['OS_TARGET'] in ('WINNT', 'Linux', 'Darwin'):
 FINAL_LIBRARY = 'xul'

 # This is intended as a temporary hack to enable VS2015 builds.
-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # ovr_capi_dynamic.h '<unnamed-tag>': Alignment specifier is less than
    # actual alignment (8), and will be ignored
    CXXFLAGS += ['-wd4359']
--- a/gfx/ycbcr/moz.build
+++ b/gfx/ycbcr/moz.build
@ -24,7 +24,7 @@ if CONFIG['INTEL_ARCHITECTURE']:
    SOURCES['yuv_convert_sse2.cpp'].flags += CONFIG['SSE2_FLAGS']

    # MSVC doesn't support MMX when targeting AMD64.
-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        if CONFIG['CPU_ARCH'] == 'x86':
            SOURCES += [
                'yuv_convert_mmx.cpp',
@ -33,7 +33,7 @@ if CONFIG['INTEL_ARCHITECTURE']:
        SOURCES += ['yuv_convert_mmx.cpp']
        SOURCES['yuv_convert_mmx.cpp'].flags += CONFIG['MMX_FLAGS']

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    if CONFIG['CPU_ARCH'] == 'x86_64' or \
       (CONFIG['CPU_ARCH'] == 'x86' and CONFIG['CC_TYPE'] == 'clang-cl'):
        SOURCES += [
--- a/ipc/app/moz.build
+++ b/ipc/app/moz.build
@ -59,7 +59,7 @@ if CONFIG['MOZ_SANDBOX'] and CONFIG['OS_TARGET'] == 'Darwin':
        'mozsandbox',
    ]

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # Always enter a Windows program through wmain, whether or not we're
    # a console application.
    WIN32_EXE_LDFLAGS += ['-ENTRY:wmainCRTStartup']
--- a/ipc/chromium/chromium-config.mozbuild
+++ b/ipc/chromium/chromium-config.mozbuild
@ -31,7 +31,7 @@ if CONFIG['OS_ARCH'] == 'WINNT':
        'WIN32_LEAN_AND_MEAN': True,
    })

-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        DEFINES['COMPILER_MSVC'] = True

 else:
--- a/ipc/glue/moz.build
+++ b/ipc/glue/moz.build
@ -189,7 +189,7 @@ else:
        'GeckoChildProcessHost.cpp',
    ]

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # This is intended as a temporary hack to support building with VS2015.
    # 'reinterpret_cast': conversion from 'DWORD' to 'HANDLE' of greater size
    SOURCES['BackgroundChildImpl.cpp'].flags += ['-wd4312']
--- a/ipc/ipdl/test/cxx/app/moz.build
+++ b/ipc/ipdl/test/cxx/app/moz.build
@ -16,5 +16,5 @@ LOCAL_INCLUDES += [
    '/xpcom/base',
 ]

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    WIN32_EXE_LDFLAGS += ['-ENTRY:wmainCRTStartup']
--- a/js/src/js-cxxflags.mozbuild
+++ b/js/src/js-cxxflags.mozbuild
@ -7,7 +7,7 @@
 # ICU pkg-config flags
 CXXFLAGS += CONFIG['MOZ_ICU_CFLAGS']

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # C4805 warns mixing bool with other integral types in computation.
    # But given the conversion from bool is specified, and this is a
    # pattern widely used in code in js/src, suppress this warning here.
--- a/js/src/moz.build
+++ b/js/src/moz.build
@ -393,7 +393,6 @@ if CONFIG['MOZ_VTUNE']:
        'vtune/jitprofiling.c',
        'vtune/VTuneWrapper.cpp',
    ]
-    if CONFIG['CC_TYPE'] != 'msvc':
    SOURCES['vtune/ittnotify_static.c'].flags += ['-Wno-varargs', '-Wno-unknown-pragmas']

 if CONFIG['HAVE_LINUX_PERF_EVENT_H']:
--- a/js/src/shell/moz.build
+++ b/js/src/shell/moz.build
@ -26,12 +26,6 @@ UNIFIED_SOURCES += [

 DEFINES['EXPORT_JS_API'] = True

-if CONFIG['CC_TYPE'] == 'msvc':
-    # PGO is unnecessary for the js shell, but clang/gcc cannot turn off PGO
-    # because we need to resolve symbols from PGO runtime library when our
-    # object files have been compiled for PGO.
-    NO_PGO = True
-
 LOCAL_INCLUDES += [
    '!..',
    '..',
--- a/js/xpconnect/shell/moz.build
+++ b/js/xpconnect/shell/moz.build
@ -21,7 +21,7 @@ LOCAL_INCLUDES += [
    '/toolkit/xre',
 ]

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # Always enter a Windows program through wmain, whether or not we're
    # a console application.
    WIN32_EXE_LDFLAGS += ['-ENTRY:wmainCRTStartup']
--- a/js/xpconnect/wrappers/moz.build
+++ b/js/xpconnect/wrappers/moz.build
@ -22,7 +22,7 @@ SOURCES += [
 ]

 # warning C4661 for FilteringWrapper
-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += [
        '-wd4661', # no suitable definition provided for explicit template instantiation request
    ]
--- a/layout/base/moz.build
+++ b/layout/base/moz.build
@ -165,7 +165,7 @@ MARIONETTE_LAYOUT_MANIFESTS += ['tests/marionette/manifest.ini']
 MOCHITEST_MANIFESTS += ['tests/mochitest.ini']
 MOCHITEST_CHROME_MANIFESTS += ['tests/chrome/chrome.ini']

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # This is intended as a temporary hack to support building with VS2015.
    # 'type cast': conversion from 'unsigned int' to 'void *' of greater size
    CXXFLAGS += ['-wd4312']
--- a/layout/painting/moz.build
+++ b/layout/painting/moz.build
@ -68,7 +68,7 @@ FINAL_LIBRARY = 'xul'

 CXXFLAGS += CONFIG['MOZ_CAIRO_CFLAGS']

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # This is intended as a temporary hack to support building with VS2015.
    # 'type cast': conversion from 'unsigned int' to 'void *' of greater size
    CXXFLAGS += ['-wd4312']
--- a/layout/style/moz.build
+++ b/layout/style/moz.build
@ -227,11 +227,6 @@ SOURCES += [
    # windows.h.
    'nsLayoutStylesheetCache.cpp',
 ]
-if CONFIG['CC_TYPE'] == 'msvc':
-    # Needed for gCSSAnonBoxAtoms.
-    SOURCES['nsCSSAnonBoxes.cpp'].flags += ['-Zc:externConstexpr']
-    # Needed for gCSSPseudoElementAtoms.
-    SOURCES['nsCSSPseudoElements.cpp'].flags += ['-Zc:externConstexpr']

 include('/ipc/chromium/chromium-config.mozbuild')

--- a/media/ffvpx/ffvpxcommon.mozbuild
+++ b/media/ffvpx/ffvpxcommon.mozbuild
@ -29,7 +29,6 @@ LOCAL_INCLUDES += ['/media/ffvpx']
 AllowCompilerWarnings()

 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CFLAGS += [
    '-Wno-parentheses',
    '-Wno-pointer-sign',
@ -65,35 +64,7 @@ if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
    # Force visibility of cpu and av_log symbols.
    CFLAGS += ['-include', 'libavutil_visibility.h']
-elif CONFIG['CC_TYPE'] == 'msvc':
-    CFLAGS += [
-        '-wd4090', # 'return' : different 'const' qualifiers
-        '-wd4018', # '>' : signed/unsigned mismatch
-        '-wd4305', # 'initializing' : truncation from '__int64' to 'double'
-        '-wd4554', # '>>' : check operator precedence for possible error
-        '-wd4307', # '+' : integral constant overflow'
-        '-wd4028', # formal parameter 1 different from declaration
-        '-wd4056', # overflow in floating-point constant arithmetic
-        '-wd4756', # overflow in constant arithmetic
-        '-wd4005', #'WIN32_LEAN_AND_MEAN' : macro redefinition
-        '-wd4054', # 'type cast' : from function pointer 'FARPROC' to data pointer 'void *'
-        '-wd4189', # local variable is initialized but not referenced
-        '-wd4133', # 'function' : incompatible types - from 'AVSampleFormat *' to 'int *'
-        '-wd4221', # nonstandard extension used
-        '-wd4206', # nonstandard extension used
-        '-wd4702', # unreachable code
-        '-wd4101', # unreferenced local variable
-        '-wd4245', # conversion from 'int' to 'uint32_t', signed/unsigned mismatch
-        '-wd4703', # potentially uninitialized local pointer
-        '-wd4293', # '<<' : shift count negative or too big, undefined behavior
-        '-wd4334', # '<<' : result of 32-bit shift implicitly converted to 64 bits
-        '-wd4996', # The compiler encountered a deprecated declaration.
-        # from FFmpeg configure
-        '-wd4244', '-wd4127', '-wd4018', '-wd4389', '-wd4146', '-wd4701',
-        '-wd4057', '-wd4204', '-wd4706', '-wd4305', '-wd4152', '-wd4324',
-        '-we4013', '-wd4100', '-wd4214', '-wd4307', '-wd4273', '-wd4554',
-    ]
-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    LOCAL_INCLUDES += ['/media/ffvpx/compat/atomics/win32']
 DEFINES['HAVE_AV_CONFIG_H'] = True

--- a/media/gmp-clearkey/0.1/moz.build
+++ b/media/gmp-clearkey/0.1/moz.build
@ -58,23 +58,18 @@ DEFINES['MOZ_NO_MOZALLOC'] = True
 USE_LIBS += ['psshparser']

 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CFLAGS += [
    '-Wno-missing-braces',
    '-Wno-pointer-to-int-cast',
    '-Wno-sign-compare',
 ]
-elif CONFIG['CC_TYPE'] == 'msvc':
-    CFLAGS += [
-        '-wd4090',                  # '=' : different 'const' qualifiers
-    ]

 if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
    CFLAGS += [
        '-include', 'stdio.h',      # for sprintf() prototype
        '-include', 'unistd.h',     # for getpid() prototype
    ]
-elif CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+elif CONFIG['CC_TYPE'] == 'clang-cl':
    CFLAGS += [
        '-FI', 'stdio.h',           # for sprintf() prototype
    ]
--- a/media/libaom/moz.build
+++ b/media/libaom/moz.build
@ -99,7 +99,6 @@ if CONFIG['OS_TARGET'] == 'Android':
            '%%%s/sources/android/cpufeatures/cpu-features.c' % CONFIG['ANDROID_NDK'],
        ]

-if CONFIG['CC_TYPE'] != 'msvc':
 for f in SOURCES:
    if f.endswith('sse2.c'):
        SOURCES[f].flags += CONFIG['SSE2_FLAGS']
@ -114,15 +113,7 @@ if CONFIG['CC_TYPE'] != 'msvc':
    elif f.endswith('avx2.c'):
        SOURCES[f].flags += ['-mavx2']

-if CONFIG['CC_TYPE'] == 'msvc' and CONFIG['INTEL_ARCHITECTURE']:
-    for f in SOURCES:
-        if f.endswith('avx.c'):
-            SOURCES[f].flags += ['-arch:AVX']
-        if f.endswith('avx2.c'):
-            SOURCES[f].flags += ['-arch:AVX2']
-
 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CFLAGS += [
    '-Wno-sign-compare',
    '-Wno-unused-function', # so many of these warnings; just ignore them
--- a/media/libcubeb/src/moz.build
+++ b/media/libcubeb/src/moz.build
@ -72,7 +72,7 @@ if CONFIG['OS_TARGET'] == 'WINNT':
    OS_LIBS += [
      "avrt",
    ]
-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        CXXFLAGS += ['-wd4005'] # C4005: '_USE_MATH_DEFINES' : macro redefinition

 if CONFIG['OS_TARGET'] == 'Android':
--- a/media/libdav1d/moz.build
+++ b/media/libdav1d/moz.build
@ -159,11 +159,6 @@ if CONFIG['OS_TARGET'] == 'WINNT':
        '../../third_party/dav1d/src/win32/thread.c'
    ]

-if CONFIG['CC_TYPE'] == 'msvc':
-    LOCAL_INCLUDES += ['../../third_party/dav1d/include/compat/msvc/']
-    EXPORTS.dav1d += ['../../third_party/dav1d/include/compat/msvc/stdatomic.h']
-    CFLAGS += ['-wd4028']
-
 if CONFIG['CC_TYPE'] == 'gcc':
    LOCAL_INCLUDES += ['../../third_party/dav1d/include/compat/gcc/']
    EXPORTS.dav1d += ['../../third_party/dav1d/include/compat/gcc/stdatomic.h']
--- a/media/libopus/moz.build
+++ b/media/libopus/moz.build
@ -99,7 +99,6 @@ if CONFIG['CPU_ARCH'] in ('x86', 'x86_64'):
    SOURCES += silk_sources_sse4_1
    if not CONFIG['MOZ_SAMPLE_TYPE_FLOAT32']:
        SOURCES += silk_sources_fixed_sse4_1
-    if CONFIG['CC_TYPE'] != 'msvc':
    for f in SOURCES:
        if f in celt_sources_sse:
            SOURCES[f].flags += CONFIG['SSE_FLAGS']
--- a/media/libspeex_resampler/src/moz.build
+++ b/media/libspeex_resampler/src/moz.build
@ -49,9 +49,3 @@ if CONFIG['CPU_ARCH'] == 'arm' and CONFIG['BUILD_ARM_NEON']:
 # Suppress warnings in third-party code.
 if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
    CFLAGS += ['-Wno-sign-compare']
-
-if CONFIG['CC_TYPE'] == 'msvc':
-    CFLAGS += [
-        '-wd4018', # '<' : signed/unsigned mismatch
-        '-wd4101', # unreferenced local variable
-    ]
--- a/media/libtheora/moz.build
+++ b/media/libtheora/moz.build
@ -22,7 +22,6 @@ FINAL_LIBRARY = 'gkmedias'
 DEFINES['THEORA_DISABLE_ENCODE'] = True

 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CFLAGS += ['-Wno-type-limits']
 if CONFIG['CC_TYPE'] in ('clang', 'clang-cl'):
    CFLAGS += ['-Wno-tautological-compare']
@ -58,18 +57,16 @@ if CONFIG['INTEL_ARCHITECTURE']:
            DEFINES['OC_X86_ASM'] = True
            if CONFIG['CPU_ARCH'] == 'x86_64':
                DEFINES['OC_X86_64_ASM'] = True
-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
    if CONFIG['CC_TYPE'] == 'clang-cl':
        # clang-cl can't handle libtheora's inline asm.
        pass
-        elif CONFIG['CPU_ARCH'] == 'x86':
-            SOURCES += [
-                'lib/x86_vc/mmxfrag.c',
-                'lib/x86_vc/mmxidct.c',
-                'lib/x86_vc/mmxstate.c',
-                'lib/x86_vc/x86cpu.c',
-                'lib/x86_vc/x86state.c',
-            ]
+        #SOURCES += [
+        #    'lib/x86_vc/mmxfrag.c',
+        #    'lib/x86_vc/mmxidct.c',
+        #    'lib/x86_vc/mmxstate.c',
+        #    'lib/x86_vc/x86cpu.c',
+        #    'lib/x86_vc/x86state.c',
+        #]
    else:
        SOURCES += [
            'lib/x86/mmxfrag.c',
--- a/media/libvpx/moz.build
+++ b/media/libvpx/moz.build
@ -109,7 +109,6 @@ if CONFIG['OS_TARGET'] == 'Android':
        '%%%s/sources/android/cpufeatures/cpu-features.c' % CONFIG['ANDROID_NDK'],
    ]

-if CONFIG['CC_TYPE'] != 'msvc':
 for f in SOURCES:
    if f.endswith('.c'):
        if 'sse2.c' in f:
@ -123,16 +122,7 @@ if CONFIG['CC_TYPE'] != 'msvc':
        if 'avx2.c' in f:
            SOURCES[f].flags += ['-mavx2']

-if CONFIG['CC_TYPE'] == 'msvc' and CONFIG['INTEL_ARCHITECTURE']:
-    for f in SOURCES:
-        if f.endswith('.c'):
-            if 'avx.c' in f:
-                SOURCES[f].flags += ['-arch:AVX']
-            if 'avx2.c' in f:
-                SOURCES[f].flags += ['-arch:AVX2']
-
 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CFLAGS += [
    '-Wno-sign-compare',
    '-Wno-unused-function', # so many of these warnings; just ignore them
--- a/media/libwebp/src/dsp/moz.build
+++ b/media/libwebp/src/dsp/moz.build
@ -36,7 +36,7 @@ if CONFIG['CPU_ARCH'] == 'arm' and CONFIG['BUILD_ARM_NEON']:
    for f in SOURCES:
      if f.endswith('neon.c'):
        SOURCES[f].flags += CONFIG['NEON_FLAGS']
-elif CONFIG['CPU_ARCH'] == 'aarch64' and CONFIG['CC_TYPE'] != 'msvc':
+elif CONFIG['CPU_ARCH'] == 'aarch64':
    SOURCES += [
        'alpha_processing_neon.c',
        'dec_neon.c',
--- a/media/webrtc/moz.build
+++ b/media/webrtc/moz.build
@ -101,15 +101,9 @@ if CONFIG['MOZ_WEBRTC_SIGNALING']:
    GYP_DIRS['trunk/third_party/gflags'].variables = gyp_vars_copy
    GYP_DIRS['trunk/third_party/gflags'].sandbox_vars['COMPILE_FLAGS'] = {'WARNINGS_AS_ERRORS': []}

-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
    # Avoid warnings from third-party code that we can not modify.
    if CONFIG['CC_TYPE'] == 'clang-cl':
        CXXFLAGS += ['-Wno-invalid-source-encoding']
-        else:
-            CXXFLAGS += [
-                '-validate-charset-',
-                '-wd5038', # C5038 initializer list order warnings
-            ]

    if CONFIG['ENABLE_TESTS']:
        TEST_DIRS += [
--- a/media/webrtc/signaling/gtest/moz.build
+++ b/media/webrtc/signaling/gtest/moz.build
@ -42,7 +42,7 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] != 'uikit' and CONFIG['OS_TARGET'] != 'Android':

    FINAL_LIBRARY = 'xul-gtest'

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # This is intended as a temporary workaround to enable warning free building
    # with VS2015.
    # reinterpret_cast': conversion from 'DWORD' to 'HANDLE' of greater size
--- a/media/webrtc/trunk/gtest/moz.build
+++ b/media/webrtc/trunk/gtest/moz.build
@ -481,7 +481,7 @@ if CONFIG['OS_TARGET'] in ['Darwin', 'Linux', 'WINNT']:
        if CONFIG['CC_TYPE'] == 'clang':
            CXXFLAGS += ['-Wno-comma']

-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        # This is intended as a temporary workaround to enable warning free building
        # with VS2015.
        # reinterpret_cast': conversion from 'DWORD' to 'HANDLE' of greater size
--- a/media/webrtc/webrtc.mozbuild
+++ b/media/webrtc/webrtc.mozbuild
@ -22,7 +22,7 @@ if CONFIG['MOZ_WEBRTC']:
    elif CONFIG['OS_TARGET'] == 'Android':
        DEFINES['WEBRTC_ANDROID'] = True

-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        DEFINES['__PRETTY_FUNCTION__'] = '__FUNCSIG__'

    if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
--- a/memory/build/moz.build
+++ b/memory/build/moz.build
@ -46,7 +46,7 @@ if CONFIG['OS_TARGET'] == 'Android' and CONFIG['CC_TYPE'] == 'clang':
 if CONFIG['MOZ_BUILD_APP'] != 'memory':
    FINAL_LIBRARY = 'mozglue'

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += ['-wd4273'] # inconsistent dll linkage (bug 558163)

 if CONFIG['MOZ_REPLACE_MALLOC_STATIC']:
--- a/memory/mozalloc/moz.build
+++ b/memory/mozalloc/moz.build
@ -14,7 +14,7 @@ EXPORTS.mozilla += [
 if CONFIG['WRAP_STL_INCLUDES']:
    if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
        EXPORTS.mozilla += ['throw_gcc.h']
-    elif CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    elif CONFIG['CC_TYPE'] == 'clang-cl':
        DEFINES['_HAS_EXCEPTIONS'] = 0
        SOURCES += [
            'msvc_raise_wrappers.cpp',
--- a/mfbt/tests/moz.build
+++ b/mfbt/tests/moz.build
@ -81,7 +81,7 @@ DEFINES['IMPL_MFBT'] = True

 DisableStlWrapping()

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
  CXXFLAGS += [
    '-wd4275', # non dll-interface class used as base for dll-interface class
    '-wd4530', # C++ exception handler used, but unwind semantics are not enabled
--- a/modules/brotli/moz.build
+++ b/modules/brotli/moz.build
@ -56,7 +56,7 @@ HOST_SOURCES += [
    'tools/brotli.c',
 ]

-if CONFIG['HOST_CC_TYPE'] not in ('msvc', 'clang-cl'):
+if CONFIG['HOST_CC_TYPE'] != 'clang-cl':
    HOST_OS_LIBS += [
        'm' # for log2() function used by Brotli encoder
    ]
--- a/modules/fdlibm/src/moz.build
+++ b/modules/fdlibm/src/moz.build
@ -21,7 +21,7 @@ if CONFIG['CC_TYPE'] == 'clang':
        '-Wno-dangling-else',
    ]

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += [
        '-wd4018', # signed/unsigned mismatch
        '-wd4146', # unary minus operator applied to unsigned type
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@ -5998,9 +5998,7 @@ pref("dom.datatransfer.mozAtAPIs", true);
 #endif

 // Whether or not Prio is supported on this platform.
-#ifdef MOZ_LIBPRIO
 pref("prio.enabled", false);
-#endif

 // External.AddSearchProvider is deprecated and it will be removed in the next
 // cycles.
--- a/moz.configure
+++ b/moz.configure
@ -180,7 +180,7 @@ def library_name_info_template(host_or_target):
        if host_or_target.kernel == 'WINNT':
            # There aren't artifacts for mingw builds, so it's OK that the
            # results are inaccurate in that case.
-            if compiler and compiler.type not in ('msvc', 'clang-cl'):
+            if compiler and compiler.type != 'clang-cl':
                return namespace(
                    dll=namespace(prefix='', suffix='.dll'),
                    lib=namespace(prefix='lib', suffix='a'),
--- a/mozglue/build/moz.build
+++ b/mozglue/build/moz.build
@ -58,8 +58,6 @@ if CONFIG['MOZ_WIDGET_TOOLKIT']:
            '/memory/build',
        ]

-        if CONFIG['CC_TYPE'] == "msvc":
-            SOURCES += ['WindowsCFGStatus.cpp']
        SOURCES += [
            'Authenticode.cpp',
            'UntrustedDllsHandler.cpp',
--- a/python/mozbuild/mozbuild/action/check_binary.py
+++ b/python/mozbuild/mozbuild/action/check_binary.py
@ -247,7 +247,7 @@ def check_nsmodules(target, binary):
    # MSVC linker, when doing incremental linking, adds padding when
    # merging sections. Allow there to be more space between the NSModule
    # symbols, as long as they are in the right order.
-    test_msvc = (buildconfig.substs.get('CC_TYPE') in ('msvc', 'clang-cl') and \
+    test_msvc = (buildconfig.substs.get('CC_TYPE') == 'clang-cl' and \
        buildconfig.substs.get('DEVELOPER_OPTIONS'))
    test_clang = (buildconfig.substs.get('CC_TYPE') == 'clang' and \
        buildconfig.substs.get('OS_ARCH') == 'WINNT')
--- a/python/mozbuild/mozbuild/action/cl.py
+++ b/python/mozbuild/mozbuild/action/cl.py
@ -1,127 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-from __future__ import absolute_import
-
-import ctypes
-import os
-import sys
-
-from mozprocess.processhandler import ProcessHandlerMixin
-from mozbuild.makeutil import Makefile
-
-CL_INCLUDES_PREFIX = os.environ.get("CL_INCLUDES_PREFIX", "Note: including file:")
-
-GetShortPathName = ctypes.windll.kernel32.GetShortPathNameW
-GetLongPathName = ctypes.windll.kernel32.GetLongPathNameW
-
-
-# cl.exe likes to print inconsistent paths in the showIncludes output
-# (some lowercased, some not, with different directions of slashes),
-# and we need the original file case for make/pymake to be happy.
-# As this is slow and needs to be called a lot of times, use a cache
-# to speed things up.
-_normcase_cache = {}
-
-def normcase(path):
-    # Get*PathName want paths with backslashes
-    path = path.replace('/', os.sep)
-    dir = os.path.dirname(path)
-    # name is fortunately always going to have the right case,
-    # so we can use a cache for the directory part only.
-    name = os.path.basename(path)
-    if dir in _normcase_cache:
-        result = _normcase_cache[dir]
-    else:
-        path = ctypes.create_unicode_buffer(dir)
-        length = GetShortPathName(path, None, 0)
-        shortpath = ctypes.create_unicode_buffer(length)
-        GetShortPathName(path, shortpath, length)
-        length = GetLongPathName(shortpath, None, 0)
-        if length > len(path):
-            path = ctypes.create_unicode_buffer(length)
-        GetLongPathName(shortpath, path, length)
-        result = _normcase_cache[dir] = path.value
-    return os.path.join(result, name)
-
-
-def InvokeClWithDependencyGeneration(cmdline):
-    target = ""
-    # Figure out what the target is
-    for arg in cmdline:
-        if arg.startswith("-Fo"):
-            target = arg[3:]
-            break
-
-    if target is None:
-        print >>sys.stderr, "No target set"
-        return 1
-
-    # Assume the source file is the last argument
-    source = cmdline[-1]
-    assert not source.startswith('-')
-
-    # The deps target lives here
-    depstarget = os.path.basename(target) + ".pp"
-
-    showincludes = '-showIncludes' in cmdline
-    cmdline += ['-showIncludes']
-
-    mk = Makefile()
-    rule = mk.create_rule([target])
-    rule.add_dependencies([normcase(source)])
-
-    def on_line(line):
-        # cl -showIncludes prefixes every header with "Note: including file:"
-        # and an indentation corresponding to the depth (which we don't need)
-        if line.startswith(CL_INCLUDES_PREFIX):
-            dep = line[len(CL_INCLUDES_PREFIX):].strip()
-            # We can't handle pathes with spaces properly in mddepend.pl, but
-            # we can assume that anything in a path with spaces is a system
-            # header and throw it away.
-            dep = normcase(dep)
-            if ' ' not in dep:
-                rule.add_dependencies([dep])
-            # Hide the line by returning early
-            if not showincludes:
-                return
-        # Make sure we preserve the relevant output from cl. mozprocess
-        # swallows the newline delimiter, so we need to re-add it.
-        sys.stdout.write(line)
-        sys.stdout.write('\n')
-
-    # We need to ignore children because MSVC can fire up a background process
-    # during compilation. This process is cleaned up on its own. If we kill it,
-    # we can run into weird compilation issues.
-    p = ProcessHandlerMixin(cmdline, processOutputLine=[on_line],
-        ignore_children=True)
-    p.run()
-    p.processOutput()
-    ret = p.wait()
-
-    if ret != 0 or target == "":
-        # p.wait() returns a long. Somehow sys.exit(long(0)) is like
-        # sys.exit(1). Don't ask why.
-        return int(ret)
-
-    depsdir = os.path.normpath(os.path.join(os.curdir, ".deps"))
-    depstarget = os.path.join(depsdir, depstarget)
-    if not os.path.isdir(depsdir):
-        try:
-            os.makedirs(depsdir)
-        except OSError:
-            pass # This suppresses the error we get when the dir exists, at the
-                 # cost of masking failure to create the directory.  We'll just
-                 # die on the next line though, so it's not that much of a loss.
-
-    with open(depstarget, "w") as f:
-        mk.dump(f)
-
-    return 0
-
-def main(args):
-    return InvokeClWithDependencyGeneration(args)
-
-if __name__ == "__main__":
-    sys.exit(main(sys.argv[1:]))
--- a/python/mozbuild/mozbuild/frontend/context.py
+++ b/python/mozbuild/mozbuild/frontend/context.py
@ -484,12 +484,6 @@ class CompileFlags(BaseCompileFlags):

    def _warnings_as_errors(self):
        warnings_as_errors = self._context.config.substs.get('WARNINGS_AS_ERRORS')
-        if self._context.config.substs.get('MOZ_PGO'):
-            # Don't use warnings-as-errors in MSVC PGO builds because it is suspected of
-            # causing problems in that situation. (See bug 437002.)
-            if self._context.config.substs.get('CC_TYPE') == 'msvc':
-                warnings_as_errors = None
-
        if warnings_as_errors:
            return [warnings_as_errors]

--- a/python/mozbuild/mozbuild/frontend/gyp_reader.py
+++ b/python/mozbuild/mozbuild/frontend/gyp_reader.py
@ -243,7 +243,7 @@ def process_gyp_result(gyp_result, gyp_dir_attrs, path, config, output,
            context['UNIFIED_SOURCES'] = alphabetical_sorted(unified_sources)

            defines = target_conf.get('defines', [])
-            if config.substs['CC_TYPE'] in ('msvc', 'clang-cl') and no_chromium:
+            if config.substs['CC_TYPE'] == 'clang-cl' and no_chromium:
                msvs_settings = gyp.msvs_emulation.MsvsSettings(spec, {})
                defines.extend(msvs_settings.GetComputedDefines(c))
            for define in defines:
@ -380,7 +380,7 @@ class GypProcessor(object):
        # gyp expects plain str instead of unicode. The frontend code gives us
        # unicode strings, so convert them.
        path = encode(path)
-        if config.substs['CC_TYPE'] in ('msvc', 'clang-cl'):
+        if config.substs['CC_TYPE'] == 'clang-cl':
            # This isn't actually used anywhere in this generator, but it's needed
            # to override the registry detection of VC++ in gyp.
            os.environ['GYP_MSVS_OVERRIDE_PATH'] = 'fake_path'
--- a/python/mozbuild/mozbuild/test/configure/test_toolchain_configure.py
+++ b/python/mozbuild/mozbuild/test/configure/test_toolchain_configure.py
@ -70,8 +70,6 @@ def GCC_BASE(version):
        '__GNUC_MINOR__': version.minor,
        '__GNUC_PATCHLEVEL__': version.patch,
        '__STDC__': 1,
-        '__ORDER_LITTLE_ENDIAN__': 1234,
-        '__ORDER_BIG_ENDIAN__': 4321,
    })


@ -102,10 +100,14 @@ DEFAULT_GCC = GCC_6
 DEFAULT_GXX = GXX_6

 GCC_PLATFORM_LITTLE_ENDIAN = {
+    '__ORDER_LITTLE_ENDIAN__': 1234,
+    '__ORDER_BIG_ENDIAN__': 4321,
    '__BYTE_ORDER__': 1234,
 }

 GCC_PLATFORM_BIG_ENDIAN = {
+    '__ORDER_LITTLE_ENDIAN__': 1234,
+    '__ORDER_BIG_ENDIAN__': 4321,
    '__BYTE_ORDER__': 4321,
 }

@ -234,14 +236,6 @@ def VS(version):
    })


-VS_2013u2 = VS('18.00.30501')
-VS_2013u3 = VS('18.00.30723')
-VS_2015 = VS('19.00.23026')
-VS_2015u1 = VS('19.00.23506')
-VS_2015u2 = VS('19.00.23918')
-VS_2015u3 = VS('19.00.24213')
-VS_2017u4 = VS('19.11.25547')
-VS_2017u6 = VS('19.13.26128')
 VS_2017u8 = VS('19.15.26726')

 VS_PLATFORM_X86 = {
@ -265,8 +259,10 @@ CLANG_CL_3_9 = (CLANG_BASE('3.9.0') + VS('18.00.00000') + DEFAULT_C11 +
    },
 }

-CLANG_CL_PLATFORM_X86 = FakeCompiler(VS_PLATFORM_X86, GCC_PLATFORM_X86[None])
-CLANG_CL_PLATFORM_X86_64 = FakeCompiler(VS_PLATFORM_X86_64, GCC_PLATFORM_X86_64[None])
+CLANG_CL_PLATFORM_X86 = FakeCompiler(
+    VS_PLATFORM_X86, GCC_PLATFORM_X86[None], GCC_PLATFORM_LITTLE_ENDIAN)
+CLANG_CL_PLATFORM_X86_64 = FakeCompiler(
+    VS_PLATFORM_X86_64, GCC_PLATFORM_X86_64[None], GCC_PLATFORM_LITTLE_ENDIAN)

 LIBRARY_NAME_INFOS = {
    'linux-gnu': {
@ -385,7 +381,7 @@ class BaseToolchainTest(BaseConfigureTest):
        target_os = getattr(self, 'TARGET', self.HOST).split('-', 2)[2]
        if target_os == 'mingw32':
            compiler_type = sandbox._value_for(sandbox['c_compiler']).type
-            if compiler_type in ('msvc', 'clang-cl'):
+            if compiler_type == 'clang-cl':
                target_os = 'msvc'
        elif target_os == 'linux-gnuabi64':
            target_os = 'linux-gnu'
@ -874,14 +870,6 @@ class WindowsToolchainTest(BaseToolchainTest):
    # For the purpose of this test, it doesn't matter that the paths are not
    # real Windows paths.
    PATHS = {
-        '/opt/VS_2013u2/bin/cl': VS_2013u2 + VS_PLATFORM_X86,
-        '/opt/VS_2013u3/bin/cl': VS_2013u3 + VS_PLATFORM_X86,
-        '/opt/VS_2015/bin/cl': VS_2015 + VS_PLATFORM_X86,
-        '/opt/VS_2015u1/bin/cl': VS_2015u1 + VS_PLATFORM_X86,
-        '/opt/VS_2015u2/bin/cl': VS_2015u2 + VS_PLATFORM_X86,
-        '/opt/VS_2015u3/bin/cl': VS_2015u3 + VS_PLATFORM_X86,
-        '/opt/VS_2017u4/bin/cl': VS_2017u4 + VS_PLATFORM_X86,
-        '/opt/VS_2017u6/bin/cl': VS_2017u6 + VS_PLATFORM_X86,
        '/usr/bin/cl': VS_2017u8 + VS_PLATFORM_X86,
        '/usr/bin/clang-cl': CLANG_CL_3_9 + CLANG_CL_PLATFORM_X86,
        '/usr/bin/gcc': DEFAULT_GCC + GCC_PLATFORM_X86_WIN,
@ -900,32 +888,6 @@ class WindowsToolchainTest(BaseToolchainTest):
        '/usr/bin/clang++-3.3': CLANGXX_3_3 + CLANG_PLATFORM_X86_WIN,
    }

-    VS_FAILURE_MESSAGE = (
-        'This version (%s) of the MSVC compiler is not supported.\nYou must'
-        ' install Visual C++ 2017 Update 8 or later in order to build.\n'
-        'See https://developer.mozilla.org/en/Windows_Build_Prerequisites')
-    VS_2013u2_RESULT = VS_FAILURE_MESSAGE % '18.00.30501'
-    VS_2013u3_RESULT = VS_FAILURE_MESSAGE % '18.00.30723'
-    VS_2015_RESULT = VS_FAILURE_MESSAGE % '19.00.23026'
-    VS_2015u1_RESULT = VS_FAILURE_MESSAGE % '19.00.23506'
-    VS_2015u2_RESULT = VS_FAILURE_MESSAGE % '19.00.23918'
-    VS_2015u3_RESULT = VS_FAILURE_MESSAGE % '19.00.24213'
-    VS_2017u4_RESULT = VS_FAILURE_MESSAGE % '19.11.25547'
-    VS_2017u6_RESULT = VS_FAILURE_MESSAGE % '19.13.26128'
-    VS_2017u8_RESULT = CompilerResult(
-        flags=[],
-        version='19.15.26726',
-        type='msvc',
-        compiler='/usr/bin/cl',
-        language='C',
-    )
-    VSXX_2017u8_RESULT = CompilerResult(
-        flags=[],
-        version='19.15.26726',
-        type='msvc',
-        compiler='/usr/bin/cl',
-        language='C++',
-    )
    CLANG_CL_3_9_RESULT = CompilerResult(
        version='3.9.0',
        flags=['-Xclang', '-std=gnu99'],
@ -953,65 +915,11 @@ class WindowsToolchainTest(BaseToolchainTest):
    DEFAULT_GCC_RESULT = LinuxToolchainTest.DEFAULT_GCC_RESULT
    DEFAULT_GXX_RESULT = LinuxToolchainTest.DEFAULT_GXX_RESULT

-    # VS2017u6 or greater is required.
-    def test_msvc(self):
-        # We'll pick msvc if clang-cl can't be found.
-        paths = {
-            k: v for k, v in self.PATHS.iteritems()
-            if os.path.basename(k) != 'clang-cl'
-        }
-        self.do_toolchain_test(paths, {
-            'c_compiler': self.VS_2017u8_RESULT,
-            'cxx_compiler': self.VSXX_2017u8_RESULT,
-        })
-
    def test_unsupported_msvc(self):
        self.do_toolchain_test(self.PATHS, {
-            'c_compiler': self.VS_2017u6_RESULT,
+            'c_compiler': 'Unknown compiler or compiler not supported.'
        }, environ={
-            'CC': '/opt/VS_2017u6/bin/cl',
-        })
-
-        self.do_toolchain_test(self.PATHS, {
-            'c_compiler': self.VS_2017u4_RESULT,
-        }, environ={
-            'CC': '/opt/VS_2017u4/bin/cl',
-        })
-
-        self.do_toolchain_test(self.PATHS, {
-            'c_compiler': self.VS_2015u3_RESULT,
-        }, environ={
-            'CC': '/opt/VS_2015u3/bin/cl',
-        })
-
-        self.do_toolchain_test(self.PATHS, {
-            'c_compiler': self.VS_2015u2_RESULT,
-        }, environ={
-            'CC': '/opt/VS_2015u2/bin/cl',
-        })
-
-        self.do_toolchain_test(self.PATHS, {
-            'c_compiler': self.VS_2015u1_RESULT,
-        }, environ={
-            'CC': '/opt/VS_2015u1/bin/cl',
-        })
-
-        self.do_toolchain_test(self.PATHS, {
-            'c_compiler': self.VS_2015_RESULT,
-        }, environ={
-            'CC': '/opt/VS_2015/bin/cl',
-        })
-
-        self.do_toolchain_test(self.PATHS, {
-            'c_compiler': self.VS_2013u3_RESULT,
-        }, environ={
-            'CC': '/opt/VS_2013u3/bin/cl',
-        })
-
-        self.do_toolchain_test(self.PATHS, {
-            'c_compiler': self.VS_2013u2_RESULT,
-        }, environ={
-            'CC': '/opt/VS_2013u2/bin/cl',
+            'CC': '/usr/bin/cl',
        })

    def test_clang_cl(self):
@ -1060,15 +968,6 @@ class WindowsToolchainTest(BaseToolchainTest):
            'CXX': 'clang++-3.3',
        })

-    def test_cannot_cross(self):
-        paths = {
-            '/usr/bin/cl': VS_2017u8 + VS_PLATFORM_X86_64,
-        }
-        self.do_toolchain_test(paths, {
-            'c_compiler': ('Target C compiler target CPU (x86_64) '
-                           'does not match --target CPU (i686)'),
-        })
-

 class Windows64ToolchainTest(WindowsToolchainTest):
    HOST = 'x86_64-pc-mingw32'
@ -1076,14 +975,6 @@ class Windows64ToolchainTest(WindowsToolchainTest):
    # For the purpose of this test, it doesn't matter that the paths are not
    # real Windows paths.
    PATHS = {
-        '/opt/VS_2013u2/bin/cl': VS_2013u2 + VS_PLATFORM_X86_64,
-        '/opt/VS_2013u3/bin/cl': VS_2013u3 + VS_PLATFORM_X86_64,
-        '/opt/VS_2015/bin/cl': VS_2015 + VS_PLATFORM_X86_64,
-        '/opt/VS_2015u1/bin/cl': VS_2015u1 + VS_PLATFORM_X86_64,
-        '/opt/VS_2015u2/bin/cl': VS_2015u2 + VS_PLATFORM_X86_64,
-        '/opt/VS_2015u3/bin/cl': VS_2015u3 + VS_PLATFORM_X86_64,
-        '/opt/VS_2017u4/bin/cl': VS_2017u4 + VS_PLATFORM_X86_64,
-        '/opt/VS_2017u6/bin/cl': VS_2017u6 + VS_PLATFORM_X86_64,
        '/usr/bin/cl': VS_2017u8 + VS_PLATFORM_X86_64,
        '/usr/bin/clang-cl': CLANG_CL_3_9 + CLANG_CL_PLATFORM_X86_64,
        '/usr/bin/gcc': DEFAULT_GCC + GCC_PLATFORM_X86_64_WIN,
@ -1104,15 +995,6 @@ class Windows64ToolchainTest(WindowsToolchainTest):
        '/usr/bin/clang++-3.3': CLANGXX_3_3 + CLANG_PLATFORM_X86_64_WIN,
    }

-    def test_cannot_cross(self):
-        paths = {
-            '/usr/bin/cl': VS_2017u8 + VS_PLATFORM_X86,
-        }
-        self.do_toolchain_test(paths, {
-            'c_compiler': ('Target C compiler target CPU (x86) '
-                           'does not match --target CPU (x86_64)'),
-        })
-

 class LinuxCrossCompileToolchainTest(BaseToolchainTest):
    TARGET = 'arm-unknown-linux-gnu'
@ -1454,18 +1336,6 @@ class WindowsCrossToolchainTest(BaseToolchainTest):
    DEFAULT_CLANG_RESULT = LinuxToolchainTest.DEFAULT_CLANG_RESULT
    DEFAULT_CLANGXX_RESULT = LinuxToolchainTest.DEFAULT_CLANGXX_RESULT

-    def test_wsl_cross(self):
-        paths = {
-            '/usr/bin/cl': VS_2017u8 + VS_PLATFORM_X86_64,
-        }
-        paths.update(LinuxToolchainTest.PATHS)
-        self.do_toolchain_test(paths, {
-            'c_compiler': WindowsToolchainTest.VS_2017u8_RESULT,
-            'cxx_compiler': WindowsToolchainTest.VSXX_2017u8_RESULT,
-            'host_c_compiler': self.DEFAULT_CLANG_RESULT,
-            'host_cxx_compiler': self.DEFAULT_CLANGXX_RESULT,
-        })
-
    def test_clang_cl_cross(self):
        paths = {
            '/usr/bin/clang-cl': CLANG_CL_3_9 + CLANG_CL_PLATFORM_X86_64,
--- a/python/mozbuild/mozbuild/test/test_util.py
+++ b/python/mozbuild/mozbuild/test/test_util.py
@ -868,15 +868,14 @@ class TestMisc(unittest.TestCase):

 class TestEnumString(unittest.TestCase):
    def test_string(self):
-        CompilerType = EnumString.subclass('msvc', 'gcc', 'clang', 'clang-cl')
+        CompilerType = EnumString.subclass('gcc', 'clang', 'clang-cl')

-        type = CompilerType('msvc')
-        self.assertEquals(type, 'msvc')
-        self.assertNotEquals(type, 'gcc')
+        type = CompilerType('gcc')
+        self.assertEquals(type, 'gcc')
        self.assertNotEquals(type, 'clang')
        self.assertNotEquals(type, 'clang-cl')
-        self.assertIn(type, ('msvc', 'clang-cl'))
-        self.assertNotIn(type, ('gcc', 'clang'))
+        self.assertIn(type, ('gcc', 'clang-cl'))
+        self.assertNotIn(type, ('clang', 'clang-cl'))

        with self.assertRaises(EnumStringComparisonError):
            self.assertEquals(type, 'foo')
--- a/security/certverifier/moz.build
+++ b/security/certverifier/moz.build
@ -45,79 +45,6 @@ if CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += ['-Xclang']
 CXXFLAGS += ['-Wall']

-if CONFIG['CC_TYPE'] == 'msvc':
-    # -Wall with Visual C++ enables too many problematic warnings
-    CXXFLAGS += [
-        '-wd4324', # structure was padded due to __declspec(align())
-        '-wd4355', # 'this' used in base member initializer list
-        '-wd4464', # relative include path contains '..'
-        '-wd4480', # nonstandard extension used: specifying underlying type for
-                   # enum 'enum'
-        '-wd4481', # nonstandard extension used: override specifier 'keyword'
-        '-wd4510', # default constructor could not be generated
-        '-wd4512', # assignment operator could not be generated
-        '-wd4514', # 'function': unreferenced inline function has been removed
-        '-wd4610', # struct 'symbol' can never be instantiated - user defined
-                   # constructor required
-        '-wd4619', # pragma warning: there is no warning 'warning'
-        '-wd4623', # default constructor could not be generated because a base
-                   # class default constructor is inaccessible or deleted
-        '-wd4625', # copy constructor could not be generated because a base
-                   # class copy constructor is inaccessible or deleted
-        '-wd4626', # assignment operator could not be generated because a base
-                   # class assignment operator is inaccessible or deleted
-        '-wd4628', # digraphs not supported with -Ze (nsThreadUtils.h includes
-                   # what would be the digraph "<:" in the expression
-                   # "mozilla::EnableIf<::detail::...". Since we don't want it
-                   # interpreted as a digraph anyway, we can disable the
-                   # warning.)
-        '-wd4640', # construction of local static object is not thread-safe
-        '-wd4710', # 'function': function not inlined
-        '-wd4711', # function 'function' selected for inline expansion
-        '-wd4820', # 'bytes' bytes padding added after construct 'member_name'
-    ]
-
-    # Disable Spectre diagnostics only if optimization is disabled.
-    # AArch64 MSVC apparently warns about Spectre even if optimization is
-    # enabled, so disable the diagnostic there too.
-    if not CONFIG['MOZ_OPTIMIZE'] or CONFIG['CPU_ARCH'] == 'aarch64':
-        CXXFLAGS += [
-            '-wd5045', # Compiler will insert Spectre mitigation for memory
-                       # load if /Qspectre switch specified
-        ]
-
-    # MSVC 2010's headers trigger these
-    CXXFLAGS += [
-        '-wd4548', # expression before comma has no effect; ...
-        '-wd4668', # 'symbol' is not defined as a preprocessor macro...
-        '-wd4987', # nonstandard extension used
-    ]
-
-    # MSVC 2015 triggers these
-    CXXFLAGS += [
-        '-wd4456', # declaration of 'rv' hides previous local declaration
-        '-wd4458', # declaration of 'input' hides class member
-    ]
-
-    # The following warnings are disabled because MSVC 2017 headers aren't
-    # warning free at the -Wall level.
-    CXXFLAGS += [
-        '-wd4061', # enumerator 'identifier' in switch of enum 'enumeration' is
-                   # not explicitly handled by a case label
-        '-wd4365', # 'action' : conversion from 'type_1' to 'type_2',
-                   # signed/unsigned mismatch
-        '-wd4774', # '<function>' : format string expected in argument
-                   # <position> is not a string literal
-    ]
-
-    # Gecko headers aren't warning-free enough for us to enable these warnings
-    CXXFLAGS += [
-        '-wd4100', # 'symbol' : unreferenced formal parameter
-        '-wd4127', # conditional expression is constant
-        '-wd4946', # reinterpret_cast used between related types
-    ]
-
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CXXFLAGS += [
    '-Wextra',
    '-Wunreachable-code',
--- a/security/ct/moz.build
+++ b/security/ct/moz.build
@ -43,72 +43,6 @@ if CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += ['-Xclang']
 CXXFLAGS += ['-Wall']

-if CONFIG['CC_TYPE'] == 'msvc':
-    # -Wall with Visual C++ enables too many problematic warnings
-    CXXFLAGS += [
-        '-wd4324', # structure was padded due to __declspec(align())
-        '-wd4355', # 'this' used in base member initializer list
-        '-wd4464', # relative include path contains '..'
-        '-wd4480', # nonstandard extension used: specifying underlying type for
-                   # enum 'enum'
-        '-wd4481', # nonstandard extension used: override specifier 'keyword'
-        '-wd4510', # default constructor could not be generated
-        '-wd4512', # assignment operator could not be generated
-        '-wd4514', # 'function': unreferenced inline function has been removed
-        '-wd4610', # struct 'symbol' can never be instantiated - user defined
-                   # constructor required
-        '-wd4619', # pragma warning: there is no warning 'warning'
-        '-wd4623', # default constructor could not be generated because a base
-                   # class default constructor is inaccessible or deleted
-        '-wd4625', # copy constructor could not be generated because a base
-                   # class copy constructor is inaccessible or deleted
-        '-wd4626', # assignment operator could not be generated because a base
-                   # class assignment operator is inaccessible or deleted
-        '-wd4640', # construction of local static object is not thread-safe
-        '-wd4710', # 'function': function not inlined
-        '-wd4711', # function 'function' selected for inline expansion
-        '-wd4820', # 'bytes' bytes padding added after construct 'member_name'
-    ]
-
-    # Disable Spectre diagnostics only if optimization is disabled.
-    if not CONFIG['MOZ_OPTIMIZE']:
-        CXXFLAGS += [
-            '-wd5045', # Compiler will insert Spectre mitigation for memory
-                       # load if /Qspectre switch specified
-        ]
-
-    # MSVC 2010's headers trigger these
-    CXXFLAGS += [
-        '-wd4548', # expression before comma has no effect; ...
-        '-wd4668', # 'symbol' is not defined as a preprocessor macro...
-        '-wd4987', # nonstandard extension used
-    ]
-
-    # MSVC 2015 triggers these
-    CXXFLAGS += [
-        '-wd4456', # declaration of 'rv' hides previous local declaration
-        '-wd4458', # declaration of 'input' hides class member
-    ]
-
-    # The following warnings are disabled because MSVC 2017 headers aren't
-    # warning free at the -Wall level.
-    CXXFLAGS += [
-        '-wd4061', # enumerator 'identifier' in switch of enum 'enumeration' is
-                   # not explicitly handled by a case label
-        '-wd4365', # 'action' : conversion from 'type_1' to 'type_2',
-                   # signed/unsigned mismatch
-        '-wd4774', # '<function>' : format string expected in argument
-                   # <position> is not a string literal
-    ]
-
-    # Gecko headers aren't warning-free enough for us to enable these warnings
-    CXXFLAGS += [
-        '-wd4100', # 'symbol' : unreferenced formal parameter
-        '-wd4127', # conditional expression is constant
-        '-wd4946', # reinterpret_cast used between related types
-    ]
-
-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CXXFLAGS += [
    '-Wextra',
    '-Wunreachable-code',
--- a/security/sandbox/moz.build
+++ b/security/sandbox/moz.build
@ -169,7 +169,7 @@ elif CONFIG['OS_ARCH'] == 'WINNT':
    DisableStlWrapping()

    # Suppress warnings in third-party code.
-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        CXXFLAGS += [
            '-wd4275', # non dll-interface class exception used as base for dll-interface class
            '-wd4717', # recursive on all control paths, function will cause runtime stack overflow
--- a/toolkit/components/jsoncpp/src/lib_json/moz.build
+++ b/toolkit/components/jsoncpp/src/lib_json/moz.build
@ -21,7 +21,7 @@ if CONFIG['CC_TYPE'] == 'clang-cl':
        '-Xclang',
        '-fcxx-exceptions',
    ]
-elif CONFIG['CC_TYPE'] not in ('msvc', 'clang-cl'):
+elif CONFIG['CC_TYPE'] != 'clang-cl':
    CXXFLAGS += [
        '-fexceptions',
    ]
@ -32,7 +32,7 @@ DisableStlWrapping()
 Library('jsoncpp')

 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += [
        '-wd4005', # macro redefinition
    ]
@ -47,7 +47,6 @@ if CONFIG['CC_TYPE'] in ('clang', 'clang-cl'):
        '-Wno-c++11-narrowing',
    ]

-if CONFIG['CC_TYPE'] in ('clang', 'clang-cl', 'gcc'):
 CXXFLAGS += [
    '-Wno-implicit-fallthrough',
 ]
--- a/toolkit/components/maintenanceservice/moz.build
+++ b/toolkit/components/maintenanceservice/moz.build
@ -34,7 +34,7 @@ LOCAL_INCLUDES += [

 USE_STATIC_LIBS = True

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    WIN32_EXE_LDFLAGS += ['-ENTRY:wmainCRTStartup']

 RCINCLUDE = 'maintenanceservice.rc'
--- a/toolkit/components/protobuf/moz.build
+++ b/toolkit/components/protobuf/moz.build
@ -136,7 +136,7 @@ if CONFIG['CC_TYPE'] in ('clang', 'gcc'):
            '-Wno-null-conversion',
            '-Wno-unused-local-typedef',
        ]
-elif CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+elif CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += [
        '-wd4005',  # 'WIN32_LEAN_AND_MEAN' : macro redefinition
        '-wd4018',  # '<' : signed/unsigned mismatch
--- a/toolkit/crashreporter/crashreporter.mozbuild
+++ b/toolkit/crashreporter/crashreporter.mozbuild
@ -10,7 +10,7 @@ LOCAL_INCLUDES += [
 ]

 # Suppress warnings in third-party code.
-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += [
        '-wd4005', # macro redefinition
        '-wd4146', # negative unsigned
@ -34,7 +34,7 @@ if CONFIG['CC_TYPE'] in ('clang', 'clang-cl'):
         '-Wno-c++11-narrowing',
     ]

-if CONFIG['CC_TYPE'] not in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] != 'clang-cl':
     CXXFLAGS += [
         '-Wno-implicit-fallthrough',
     ]
--- a/toolkit/crashreporter/google-breakpad/src/tools/windows/dump_syms/moz.build
+++ b/toolkit/crashreporter/google-breakpad/src/tools/windows/dump_syms/moz.build
@ -19,7 +19,7 @@ HOST_CXXFLAGS += [
    '-O2',
 ]

-if CONFIG['HOST_CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['HOST_CC_TYPE'] == 'clang-cl':
    HOST_CXXFLAGS += [
        '-EHsc',
        '-MD'
--- a/toolkit/crashreporter/test/moz.build
+++ b/toolkit/crashreporter/test/moz.build
@ -36,7 +36,7 @@ if CONFIG['CC_TYPE'] == 'clang-cl':
        '-Xclang',
        '-fcxx-exceptions',
    ]
-elif CONFIG['CC_TYPE'] not in ('msvc', 'clang-cl'):
+else:
    SOURCES['ExceptionThrower.cpp'].flags += [
        '-fexceptions',
    ]
@ -57,5 +57,5 @@ include('/toolkit/crashreporter/crashreporter.mozbuild')
 NO_PGO = True

 # Temporary workaround for an issue in upstream breakpad
-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    CXXFLAGS += ['-wd4334']
--- a/toolkit/library/moz.build
+++ b/toolkit/library/moz.build
@ -85,7 +85,7 @@ def Libxul(name, output_category=None):
        LDFLAGS += ['-Wl,-U,_OBJC_CLASS_$_NSCustomTouchBarItem']
        LDFLAGS += ['-lresolv']

-    if CONFIG['MOZ_DEBUG_SYMBOLS'] and CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['MOZ_DEBUG_SYMBOLS'] and CONFIG['CC_TYPE'] == 'clang-cl':
        LDFLAGS += ['-NATVIS:%s/toolkit/library/gecko.natvis' % TOPSRCDIR]
    if CONFIG['RUSTC_NATVIS_LDFLAGS']:
        LDFLAGS += CONFIG['RUSTC_NATVIS_LDFLAGS']
@ -323,7 +323,7 @@ if CONFIG['OS_ARCH'] == 'WINNT':
        'dhcpcsvc',
    ]

-    if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+    if CONFIG['CC_TYPE'] == 'clang-cl':
        OS_LIBS += [
            'runtimeobject',
        ]
--- a/toolkit/moz.configure
+++ b/toolkit/moz.configure
@ -425,16 +425,9 @@ imply_option('--enable-fmp4', ffmpeg, '--enable-ffmpeg')
 option('--disable-av1',
        help='Disable av1 video support')

-@depends('--enable-av1', target, c_compiler)
-def av1(value, target, c_compiler):
-    enabled = bool(value)
-    if value.origin == 'default':
-        if target.os == 'WINNT' and target.cpu == 'x86' and \
-                c_compiler and c_compiler.type == 'msvc':
-            enabled = False
-        else:
-            enabled = True
-    if enabled:
+@depends('--enable-av1')
+def av1(value):
+    if value:
        return True

@depends(target, nasm_version, when=av1 & compile_environment)
@ -1141,17 +1134,14 @@ midl = check_prog('MIDL', midl_names, when=check_for_midl, allow_missing=True,
         when=depends(midl, target)(lambda m, t: m and t.kernel == 'WINNT'))
@imports(_from='mozbuild.shellutil', _import='quote')
 def midl_flags(c_compiler, target, toolchain_search_path):
-    if c_compiler and c_compiler.type in ('msvc', 'clang-cl'):
+    if c_compiler and c_compiler.type == 'clang-cl':
        env = {
            'x86': 'win32',
            'x86_64': 'x64',
            'aarch64': 'arm64',
        }[target.cpu]
        flags = ['-env', env]
-        if c_compiler.type == 'msvc':
-            flags += ['-cpp_cmd', c_compiler.compiler]
-        else:
-            # Ideally, we'd use the same flags setup as for msvc, but clang-cl
+        # Ideally, we'd use ['-cpp_cmd', c_compiler.compiler], but clang-cl
        # currently doesn't work as a preprocessor for midl, so we need to
        # find cl. https://bugs.llvm.org/show_bug.cgi?id=40140
        cl = find_program('cl', paths=toolchain_search_path)
@ -1243,18 +1233,6 @@ def launcher(value, target):
 set_config('MOZ_LAUNCHER_PROCESS', launcher)
 set_define('MOZ_LAUNCHER_PROCESS', launcher)

-# Prio
-# ==============================================================
-@depends(c_compiler)
-def libprio(info):
-    if info:
-      # MSVC is not supported by libprio.
-      if info.type in ('msvc',):
-        return None
-    return True
-
-set_config('MOZ_LIBPRIO', libprio)
-
 # Maintenance service (Windows only)
 # ==============================================================

--- a/toolkit/mozapps/update/updater/updater-common.build
+++ b/toolkit/mozapps/update/updater/updater-common.build
@ -101,7 +101,7 @@ DELAYLOAD_DLLS += [
    'wsock32.dll',
 ]

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    WIN32_EXE_LDFLAGS += ['-ENTRY:wmainCRTStartup']
 elif CONFIG['OS_ARCH'] == 'WINNT':
    WIN32_EXE_LDFLAGS += ['-municode']
--- a/widget/windows/moz.build
+++ b/widget/windows/moz.build
@ -151,7 +151,7 @@ OS_LIBS += [
    'rpcrt4',
 ]

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    SOURCES += [
        'ToastNotification.cpp',
        'ToastNotificationHandler.cpp',
--- a/xpcom/ds/moz.build
+++ b/xpcom/ds/moz.build
@ -133,12 +133,6 @@ UNIFIED_SOURCES += [
 SOURCES += [
    'nsGkAtoms.cpp',
 ]
-if CONFIG['CC_TYPE'] == 'msvc':
-    # Needed for gGkAtoms.
-    SOURCES['nsGkAtoms.cpp'].flags += [
-        '-constexpr:steps300000',
-        '-Zc:externConstexpr',
-    ]

 LOCAL_INCLUDES += [
    '../io',
--- a/xpcom/glue/standalone/moz.build
+++ b/xpcom/glue/standalone/moz.build
@ -13,7 +13,7 @@ Library('xpcomglue')

 FORCE_STATIC_LIB = True

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    DEFINES['_USE_ANSI_CPP'] = True
    # Don't include directives about which CRT to use
    CFLAGS += ['-Zl']
--- a/xpcom/io/moz.build
+++ b/xpcom/io/moz.build
@ -135,9 +135,6 @@ UNIFIED_SOURCES += [
 SOURCES += [
    'nsDirectoryService.cpp',
 ]
-if CONFIG['CC_TYPE'] == 'msvc':
-    # Needed for gDirectoryAtoms.
-    SOURCES['nsDirectoryService.cpp'].flags += ['-Zc:externConstexpr']

 if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
    SOURCES += [
@ -156,7 +153,7 @@ LOCAL_INCLUDES += [
    '../build',
 ]

-if CONFIG['CC_TYPE'] in ('msvc', 'clang-cl'):
+if CONFIG['CC_TYPE'] == 'clang-cl':
    # This is intended as a temporary hack to support building with VS2015.
    # '_snwprintf' : format string '%s' requires an argument of type 'wchar_t *',
    # but variadic argument 3 has type 'char16ptr_t'