[clang/mac] Make -mmacos-version-min the canonical spelling over -mmacosx-version-min

[thakis]

Summary

This was promised 5 years ago in https://reviews.llvm.org/D32796,
let's do it.

Both flags are still accepted. No behavior change except for which
form shows up in --help output and in dumps of internal state
(such as with RC_DEBUG_OPTIONS).

[hans]

lgtm, but maybe wait a few more days in case the apple folks want to chime in

[dexonsmith]

LGTM too, but I’m not at Apple these days.

@akyrtzi, can you help find someone appropriate to take a quick look since @arphaman seems busy?

clang/include/clang/Driver/Options.td

 def mllvm : Separate<["-"], "mllvm">,Flags<[CC1Option,CC1AsOption,CoreOption,FC1Option,FlangOption]>,
   HelpText<"Additional arguments to forward to LLVM's option processing">,
   MarshallingInfoStringVector<FrontendOpts<"LLVMArgs">>;
 def mmlir : Separate<["-"], "mmlir">, Flags<[CoreOption,FC1Option,FlangOption]>,
   HelpText<"Additional arguments to forward to MLIR's option processing">;
 def ffuchsia_api_level_EQ : Joined<["-"], "ffuchsia-api-level=">,
   Group<m_Group>, Flags<[CC1Option]>, HelpText<"Set Fuchsia API level">,
   MarshallingInfoInt<LangOpts<"FuchsiaAPILevel">>;
-def mmacosx_version_min_EQ : Joined<["-"], "mmacosx-version-min=">,
-  Group<m_Group>, HelpText<"Set Mac OS X deployment target">;
 def mmacos_version_min_EQ : Joined<["-"], "mmacos-version-min=">,
-  Group<m_Group>, Alias<mmacosx_version_min_EQ>;
+  Group<m_Group>, HelpText<"Set macOS deployment target">;
+def : Joined<["-"], "mmacosx-version-min=">,
+  Group<m_Group>, Alias<mmacos_version_min_EQ>;
 def mms_bitfields : Flag<["-"], "mms-bitfields">, Group<m_Group>, Flags<[CC1Option]>,
   HelpText<"Set the default structure layout to be compatible with the Microsoft compiler standard">,
   MarshallingInfoFlag<LangOpts<"MSBitfields">>;
 def moutline : Flag<["-"], "moutline">, Group<f_clang_Group>, Flags<[CC1Option]>,
     HelpText<"Enable function outlining (AArch64 only)">;
 def mno_outline : Flag<["-"], "mno-outline">, Group<f_clang_Group>, Flags<[CC1Option]>,
     HelpText<"Disable function outlining (AArch64 only)">;
 def mno_ms_bitfields : Flag<["-"], "mno-ms-bitfields">, Group<m_Group>,

clang/lib/Driver/ToolChains/Darwin.cpp

struct DarwinPlatform {
   void addOSVersionMinArgument(DerivedArgList &Args, const OptTable &Opts) {
     if (Argument)
       return;
     assert(Kind != TargetArg && Kind != MTargetOSArg && Kind != OSVersionArg &&
            "Invalid kind");
     options::ID Opt;
     switch (Platform) {
     case DarwinPlatformKind::MacOS:
-      Opt = options::OPT_mmacosx_version_min_EQ;
+      Opt = options::OPT_mmacos_version_min_EQ;
       break;
     case DarwinPlatformKind::IPhoneOS:
       Opt = options::OPT_miphoneos_version_min_EQ;
       break;
     case DarwinPlatformKind::TvOS:
       Opt = options::OPT_mtvos_version_min_EQ;
       break;
     case DarwinPlatformKind::WatchOS:
private:
   Optional<llvm::Triple> TargetVariantTriple;
 };
 
 /// Returns the deployment target that's specified using the -m<os>-version-min
 /// argument.
 Optional<DarwinPlatform>
 getDeploymentTargetFromOSVersionArg(DerivedArgList &Args,
                                     const Driver &TheDriver) {
-  Arg *OSXVersion = Args.getLastArg(options::OPT_mmacosx_version_min_EQ);
+  Arg *macOSVersion = Args.getLastArg(options::OPT_mmacos_version_min_EQ);
   Arg *iOSVersion = Args.getLastArg(options::OPT_miphoneos_version_min_EQ,
                                     options::OPT_mios_simulator_version_min_EQ);
   Arg *TvOSVersion =
       Args.getLastArg(options::OPT_mtvos_version_min_EQ,
                       options::OPT_mtvos_simulator_version_min_EQ);
   Arg *WatchOSVersion =
       Args.getLastArg(options::OPT_mwatchos_version_min_EQ,
                       options::OPT_mwatchos_simulator_version_min_EQ);
-  if (OSXVersion) {
+  if (macOSVersion) {
     if (iOSVersion || TvOSVersion || WatchOSVersion) {
       TheDriver.Diag(diag::err_drv_argument_not_allowed_with)
-          << OSXVersion->getAsString(Args)
+          << macOSVersion->getAsString(Args)
           << (iOSVersion ? iOSVersion
                          : TvOSVersion ? TvOSVersion : WatchOSVersion)
                  ->getAsString(Args);
     }
-    return DarwinPlatform::createOSVersionArg(Darwin::MacOS, OSXVersion);
+    return DarwinPlatform::createOSVersionArg(Darwin::MacOS, macOSVersion);
   } else if (iOSVersion) {
     if (TvOSVersion || WatchOSVersion) {
       TheDriver.Diag(diag::err_drv_argument_not_allowed_with)
           << iOSVersion->getAsString(Args)
           << (TvOSVersion ? TvOSVersion : WatchOSVersion)->getAsString(Args);
     }
     return DarwinPlatform::createOSVersionArg(Darwin::IPhoneOS, iOSVersion);
   } else if (TvOSVersion) {

clang/test/Driver/darwin-debug-flags.c

 // RUN: env RC_DEBUG_OPTIONS=1 %clang -target i386-apple-darwin9 -I "path with \spaces" -g -Os %s  -emit-llvm -S -o - | FileCheck %s
 // <rdar://problem/7256886>
 // RUN: touch %t.s
 // RUN: env RC_DEBUG_OPTIONS=1 %clang -### -target i386-apple-darwin9 -c -g %t.s 2>&1 | FileCheck -check-prefix=S %s
 // <rdar://problem/12955296>
 // RUN: %clang -### -target i386-apple-darwin9 -c -g %t.s 2>&1 | FileCheck -check-prefix=P %s
 
 // CHECK: distinct !DICompileUnit(
 // CHECK-SAME:                flags:
 // CHECK-SAME:                -I path\\ with\\ \\\\spaces
 // CHECK-SAME:                -g -Os
-// CHECK-SAME:                -mmacosx-version-min=10.5.0
+// CHECK-SAME:                -mmacos-version-min=10.5.0
 
 int x;
 
 // S: "-dwarf-debug-flags"
 
 // P: "-dwarf-debug-producer"