Fix Clang's __DEPRECATED define to be controled by -Wdeprecated. This

matches GCC behavior which libstdc++ uses to limit #warning-based
messages about deprecation.

The machinery involves threading this through a new '-fdeprecated-macro'
flag for CC1. The flag defaults to "on", similarly to -Wdeprecated. We
turn the flag off in the driver when the warning is turned off (modulo
matching some GCC bugs). We record this as a language option, and key
the preprocessor on the option when introducing the define.

A separate flag rather than a '-D' flag allows us to properly represent
the difference between C and C++ builds (only C++ receives the define),
and it allows the specific behavior of following -Wdeprecated without
potentially impacting the set of user-provided macro flags.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130055 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 436a2a42a4..f5dacfa6cf 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -1362,6 +1362,17 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("-fconst-strings");
   }
 
+  // GCC provides a macro definition '__DEPRECATED' when -Wdeprecated is active
+  // during C++ compilation. CC1 uses '-fdeprecated-macro' to control this.
+  // Both '-Wdeprecated' and '-fdeprecated-macro' default to on, so the flag
+  // logic here is inverted.
+  if (Args.hasFlag(options::OPT_Wno_deprecated, options::OPT_Wdeprecated,
+                   false)) {
+    // GCC keeps this define even in the presence of '-w', match this behavior
+    // bug-for-bug.
+    CmdArgs.push_back("-fno-deprecated-macro");
+  }
+
   // Translate GCC's misnamer '-fasm' arguments to '-fgnu-keywords'.
   if (Arg *Asm = Args.getLastArg(options::OPT_fasm, options::OPT_fno_asm)) {
     if (Asm->getOption().matches(options::OPT_fasm))