Bug 1834955 - Upgrade minimum supported Clang-cl version to 9. r=firefox-build-system-reviewers,sergesanspaille

We have less constraints on the minimum supported clang-cl version, and
it would unlock C++17 inline variables (which had a bug on Windows
targets in clang up-to 8.x).

Differential Revision: https://phabricator.services.mozilla.com/D179037

build/moz.configure/toolchain.configure

@@ -1379,9 +1379,9 @@ def compiler(
                     flags.extend(("-isystem", os.path.join(sysroot.path, path)))
 
         if info.type == "clang-cl":
-            if info.version < "8.0.0":
+            if info.version < "9.0.0":
                 raise FatalCheckError(
-                    "Only clang-cl 8.0 or newer is supported (found version %s)"
+                    "Only clang-cl 9.0 or newer is supported (found version %s)"
                     % info.version
                 )
             if winsysroot and host.os != "WINNT":

docs/code-quality/coding-style/using_cxx_in_firefox_code.rst

@@ -249,7 +249,7 @@ list of acceptable features is given below:
    * - Inline variables (C++17)
      - 7.0
      - 3.9
-     - **No** (clang 5 has bugs with inline variables)
+     - Yes
    * - constexpr_if (C++17)
      - 7.0
      - 3.9

python/mozbuild/mozbuild/test/configure/test_toolchain_configure.py

@@ -249,8 +249,8 @@ CLANG_CL_3_9 = (
     + SUPPORTS_GNUXX11
     + SUPPORTS_CXX14
 ) + {"*.cpp": {"__STDC_VERSION__": False, "__cplusplus": "201103L"}}
-CLANG_CL_8_0 = (
-    CLANG_BASE("8.0.0")
+CLANG_CL_9_0 = (
+    CLANG_BASE("9.0.0")
     + VS("18.00.00000")
     + DEFAULT_C11
     + SUPPORTS_GNU99
@@ -966,7 +966,7 @@ class MingwToolchainTest(BaseToolchainTest):
     PATHS = {
         "/usr/bin/cl": VS_2017u8 + VS_PLATFORM_X86,
         "/usr/bin/clang-cl-3.9": CLANG_CL_3_9 + CLANG_CL_PLATFORM_X86,
-        "/usr/bin/clang-cl": CLANG_CL_8_0 + CLANG_CL_PLATFORM_X86,
+        "/usr/bin/clang-cl": CLANG_CL_9_0 + CLANG_CL_PLATFORM_X86,
         "/usr/bin/gcc": DEFAULT_GCC + GCC_PLATFORM_X86_WIN + MINGW32,
         "/usr/bin/g++": DEFAULT_GXX + GCC_PLATFORM_X86_WIN + MINGW32,
         "/usr/bin/gcc-4.9": GCC_4_9 + GCC_PLATFORM_X86_WIN + MINGW32,
@@ -988,20 +988,20 @@ class MingwToolchainTest(BaseToolchainTest):
     }
 
     CLANG_CL_3_9_RESULT = (
-        "Only clang-cl 8.0 or newer is supported (found version 3.9.0)"
+        "Only clang-cl 9.0 or newer is supported (found version 3.9.0)"
     )
-    CLANG_CL_8_0_RESULT = CompilerResult(
-        version="8.0.0",
+    CLANG_CL_9_0_RESULT = CompilerResult(
+        version="9.0.0",
         flags=["-Xclang", "-std=gnu99"],
         type="clang-cl",
         compiler="/usr/bin/clang-cl",
         language="C",
     )
     CLANGXX_CL_3_9_RESULT = (
-        "Only clang-cl 8.0 or newer is supported (found version 3.9.0)"
+        "Only clang-cl 9.0 or newer is supported (found version 3.9.0)"
     )
-    CLANGXX_CL_8_0_RESULT = CompilerResult(
-        version="8.0.0",
+    CLANGXX_CL_9_0_RESULT = CompilerResult(
+        version="9.0.0",
         flags=["-Xclang", "-std=c++17"],
         type="clang-cl",
         compiler="/usr/bin/clang-cl",
@@ -1032,8 +1032,8 @@ class MingwToolchainTest(BaseToolchainTest):
         self.do_toolchain_test(
             self.PATHS,
             {
-                "c_compiler": self.CLANG_CL_8_0_RESULT,
-                "cxx_compiler": self.CLANGXX_CL_8_0_RESULT,
+                "c_compiler": self.CLANG_CL_9_0_RESULT,
+                "cxx_compiler": self.CLANGXX_CL_9_0_RESULT,
             },
         )
 
@@ -1103,7 +1103,7 @@ class Mingw64ToolchainTest(MingwToolchainTest):
     # real Windows paths.
     PATHS = {
         "/usr/bin/cl": VS_2017u8 + VS_PLATFORM_X86_64,
-        "/usr/bin/clang-cl": CLANG_CL_8_0 + CLANG_CL_PLATFORM_X86_64,
+        "/usr/bin/clang-cl": CLANG_CL_9_0 + CLANG_CL_PLATFORM_X86_64,
         "/usr/bin/clang-cl-3.9": CLANG_CL_3_9 + CLANG_CL_PLATFORM_X86_64,
         "/usr/bin/gcc": DEFAULT_GCC + GCC_PLATFORM_X86_64_WIN + MINGW32,
         "/usr/bin/g++": DEFAULT_GXX + GCC_PLATFORM_X86_64_WIN + MINGW32,
@@ -1149,8 +1149,8 @@ class WindowsToolchainTest(BaseToolchainTest):
         self.do_toolchain_test(
             self.PATHS,
             {
-                "c_compiler": MingwToolchainTest.CLANG_CL_8_0_RESULT,
-                "cxx_compiler": MingwToolchainTest.CLANGXX_CL_8_0_RESULT,
+                "c_compiler": MingwToolchainTest.CLANG_CL_9_0_RESULT,
+                "cxx_compiler": MingwToolchainTest.CLANGXX_CL_9_0_RESULT,
             },
         )
 
@@ -1626,13 +1626,13 @@ class WindowsCrossToolchainTest(BaseToolchainTest):
     DEFAULT_CLANGXX_RESULT = LinuxToolchainTest.DEFAULT_CLANGXX_RESULT
 
     def test_clang_cl_cross(self):
-        paths = {"/usr/bin/clang-cl": CLANG_CL_8_0 + CLANG_CL_PLATFORM_X86_64}
+        paths = {"/usr/bin/clang-cl": CLANG_CL_9_0 + CLANG_CL_PLATFORM_X86_64}
         paths.update(LinuxToolchainTest.PATHS)
         self.do_toolchain_test(
             paths,
             {
-                "c_compiler": MingwToolchainTest.CLANG_CL_8_0_RESULT,
-                "cxx_compiler": MingwToolchainTest.CLANGXX_CL_8_0_RESULT,
+                "c_compiler": MingwToolchainTest.CLANG_CL_9_0_RESULT,
+                "cxx_compiler": MingwToolchainTest.CLANGXX_CL_9_0_RESULT,
                 "host_c_compiler": self.DEFAULT_CLANG_RESULT,
                 "host_cxx_compiler": self.DEFAULT_CLANGXX_RESULT,
             },