Always allow "#pragma region".

[mattd]

Summary

Both MS and PS4 targets are capable of recognizing the
existence of: #pragma region, #pragma endregion.

Since this pragma is only a hint for certain editors, and has no logic,
it seems helpful to permit this pragma in all cases, not just MS compatibility mode.

[majnemer]

Why not always support the pragma regardless of the compiler mode? Our "support" for it just ignores it anyway...

[mattd]

In D42248#980541, @majnemer wrote:

Why not always support the pragma regardless of the compiler mode? Our "support" for it just ignores it anyway...

Thanks for the reply @majnemer.

I am not opposed to that idea. My change just operates similar to the existing behavior. The only reservation I had against not always accepting the pragma is that it might mislead devs who are not using PS4/VS based environments.

[probinson]

Well, my understanding is that the pragma is a complete no-op even for MSVC, and is used only as a marker for editors such as Visual Studio's.
So, unconditionally ignoring it would seem to be fine.

[mattd]

I'm certainly fine with always allowing this pragma. I can see it useful for other editors that might wish to utilize the hint.

[mattd]

Ping.

[• Quuxplusone]

FWIW, I would also like this patch, because it would mean that I could build with -Werror even when the project includes headers written by MSVC-using people. Given that we know what "#pragma region" does, it hardly deserves an "unknown pragma" diagnostic! So this patch is great IMHO. :)

[majnemer]

LGTM

[mattd]

Thanks @majnemer! Would you mind committing this on my behalf? I do not have commit access, thanks.

include/clang/Basic/LangOptions.def

 LANGOPT(C17               , 1, 0, "C17")
 LANGOPT(MSVCCompat        , 1, 0, "Microsoft Visual C++ full compatibility mode")
 LANGOPT(MicrosoftExt      , 1, 0, "Microsoft C++ extensions")
+BENIGN_LANGOPT(MicrosoftPragmaRegion, 1, 0, "region pragma support")
 LANGOPT(AsmBlocks         , 1, 0, "Microsoft inline asm blocks")
 LANGOPT(Borland           , 1, 0, "Borland extensions")
 LANGOPT(CPlusPlus         , 1, 0, "C++")

lib/Frontend/CompilerInvocation.cpp

 
   Opts.MSVCCompat = Args.hasArg(OPT_fms_compatibility);
   Opts.MicrosoftExt = Opts.MSVCCompat || Args.hasArg(OPT_fms_extensions);
+  Opts.MicrosoftPragmaRegion = Opts.MicrosoftExt || T.isPS4();
   Opts.AsmBlocks = Args.hasArg(OPT_fasm_blocks) || Opts.MicrosoftExt;
   Opts.MSCompatibilityVersion = 0;
   if (const Arg *A = Args.getLastArg(OPT_fms_compatibility_version)) {

lib/Lex/Pragma.cpp

   if (LangOpts.MicrosoftExt) {
     AddPragmaHandler(new PragmaWarningHandler());
     AddPragmaHandler(new PragmaIncludeAliasHandler());
+  }
+
+  // Region support.
+  if (LangOpts.MicrosoftPragmaRegion) {
     AddPragmaHandler(new PragmaRegionHandler("region"));
     AddPragmaHandler(new PragmaRegionHandler("endregion"));
   }

test/Frontend/region-pragmas.c

+// RUN: %clang_cc1 -triple x86_64-scei-ps4 -Wall -verify %s
+// RUN: %clang_cc1 -fms-compatibility -Wall -verify %s
+// RUN: %clang_cc1 -Wall -Wno-unknown-pragmas -verify %s
+// expected-no-diagnostics
+
+#pragma region foo
+#pragma endregion foo