Bug 1724606 - Replace uses of MACOSX_DEPLOYMENT_TARGET env variable with -mmacosx-version-min flag. r=firefox-build-system-reviewers,andi

They are equivalent, except for the fact that MACOSX_DEPLOYMENT_TARGET
may apply to more processes in a normal build. In practice, all the
processes that matter are covered through compiler flags.

On the opposite end, MACOSX_DEPLOYMENT_TARGET isn't necessary passed in
all cases (like clangd, mach static-analysis, etc.), while compiler
flags are.

Differential Revision: https://phabricator.services.mozilla.com/D122145

build/clang-plugin/Makefile.in

@@ -12,8 +12,3 @@ HOST_LDFLAGS += -brepro
 else
 HOST_LDFLAGS += -shared
 endif
-
-# Use the default OS X deployment target to enable using the libc++ headers
-# correctly.  Note that the binary produced here is a host tool and doesn't need
-# to be distributed.
-MACOSX_DEPLOYMENT_TARGET :=

build/moz.configure/toolchain.configure

@@ -56,16 +56,9 @@ with only_when(target_is_osx):
         help="Set the minimum MacOS version needed at runtime{|}",
     )
 
-    @depends("--enable-macos-target")
-    @imports(_from="os", _import="environ")
+    @depends_if("--enable-macos-target")
     def macos_target(value):
-        if value:
-            # Ensure every compiler process we spawn uses this value.
-            environ["MACOSX_DEPLOYMENT_TARGET"] = value[0]
-            return value[0]
-
-    set_config("MACOSX_DEPLOYMENT_TARGET", macos_target)
-    add_old_configure_assignment("MACOSX_DEPLOYMENT_TARGET", macos_target)
+        return value[0]
 
 
 @depends(host)
@@ -1102,15 +1095,27 @@ def compiler(
     )
 
     @depends(
-        compiler, provided_compiler, compiler_wrapper, host_or_target, sysroot_flags
+        compiler,
+        provided_compiler,
+        compiler_wrapper,
+        host_or_target,
+        sysroot_flags,
+        macos_target,
     )
     @checking("whether %s can be used" % what, lambda x: bool(x))
     @imports(_from="mozbuild.shellutil", _import="quote")
     def valid_compiler(
-        compiler, provided_compiler, compiler_wrapper, host_or_target, sysroot_flags
+        compiler,
+        provided_compiler,
+        compiler_wrapper,
+        host_or_target,
+        sysroot_flags,
+        macos_target,
     ):
         wrapper = list(compiler_wrapper or ())
         flags = list(sysroot_flags or ())
+        if host_or_target.os == "OSX" and macos_target:
+            flags.append("-mmacosx-version-min=%s" % macos_target)
         if provided_compiler:
             wrapper.extend(provided_compiler.wrapper)
             flags.extend(provided_compiler.flags)

config/config.mk

@@ -249,10 +249,6 @@ endif
 
 DEPENDENCIES	= .md
 
-ifdef MACOSX_DEPLOYMENT_TARGET
-export MACOSX_DEPLOYMENT_TARGET
-endif # MACOSX_DEPLOYMENT_TARGET
-
 # Export to propagate to cl and submake for third-party code.
 # Eventually, we'll want to just use -I.
 ifdef INCLUDE

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

@@ -885,7 +885,13 @@ class OSXToolchainTest(BaseToolchainTest):
     GCC_7_RESULT = LinuxToolchainTest.GCC_7_RESULT
     GXX_7_RESULT = LinuxToolchainTest.GXX_7_RESULT
     SYSROOT_FLAGS = {
-        "flags": PrependFlags(["-isysroot", xcrun("", ("--show-sdk-path",))[1]])
+        "flags": PrependFlags(
+            [
+                "-isysroot",
+                xcrun("", ("--show-sdk-path",))[1],
+                "-mmacosx-version-min=10.12",
+            ]
+        )
     }
 
     def test_clang(self):
@@ -1755,10 +1761,11 @@ class RustTest(BaseConfigureTest):
         )
         # Same for the arm_target checks.
         dep = sandbox._depends[sandbox["arm_target"]]
-        getattr(sandbox, "__value_for_depends")[
-            (dep,)
-        ] = arm_target or ReadOnlyNamespace(
-            arm_arch=7, thumb2=False, fpu="vfpv2", float_abi="softfp"
+        getattr(sandbox, "__value_for_depends")[(dep,)] = (
+            arm_target
+            or ReadOnlyNamespace(
+                arm_arch=7, thumb2=False, fpu="vfpv2", float_abi="softfp"
+            )
         )
         return sandbox._value_for(sandbox["rust_target_triple"])