Preserve unknown STDC pragma through preprocessor

Summary:
#pragma STDC FP_CONTRACT handler is only registered in parser so we
should keep the unknown STDC pragma through preprocessor and we also
should not emit warning for unknown STDC pragma during preprocessor.

rdar://problem/35724351

Reviewers: efriedma, rsmith, arphaman

Reviewed By: efriedma

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D41780

llvm-svn: 321909

1 files changed, 56 insertions, 0 deletions

diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index 198d5c6e9cb..8152176484d 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -95,6 +95,44 @@ struct PragmaFPContractHandler : public PragmaHandler {
                     Token &FirstToken) override;
 };
 
+// Pragma STDC implementations.
+
+/// PragmaSTDC_FENV_ACCESSHandler - "\#pragma STDC FENV_ACCESS ...".
+struct PragmaSTDC_FENV_ACCESSHandler : public PragmaHandler {
+  PragmaSTDC_FENV_ACCESSHandler() : PragmaHandler("FENV_ACCESS") {}
+
+  void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
+                    Token &Tok) override {
+    tok::OnOffSwitch OOS;
+    if (PP.LexOnOffSwitch(OOS))
+     return;
+    if (OOS == tok::OOS_ON)
+      PP.Diag(Tok, diag::warn_stdc_fenv_access_not_supported);
+  }
+};
+
+/// PragmaSTDC_CX_LIMITED_RANGEHandler - "\#pragma STDC CX_LIMITED_RANGE ...".
+struct PragmaSTDC_CX_LIMITED_RANGEHandler : public PragmaHandler {
+  PragmaSTDC_CX_LIMITED_RANGEHandler() : PragmaHandler("CX_LIMITED_RANGE") {}
+
+  void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
+                    Token &Tok) override {
+    tok::OnOffSwitch OOS;
+    PP.LexOnOffSwitch(OOS);
+  }
+};
+
+/// PragmaSTDC_UnknownHandler - "\#pragma STDC ...".
+struct PragmaSTDC_UnknownHandler : public PragmaHandler {
+  PragmaSTDC_UnknownHandler() = default;
+
+  void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
+                    Token &UnknownTok) override {
+    // C99 6.10.6p2, unknown forms are not allowed.
+    PP.Diag(UnknownTok, diag::ext_stdc_pragma_ignored);
+  }
+};
+
 struct PragmaFPHandler : public PragmaHandler {
   PragmaFPHandler() : PragmaHandler("fp") {}
   void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
@@ -233,6 +271,15 @@ void Parser::initializePragmaHandlers() {
   FPContractHandler.reset(new PragmaFPContractHandler());
   PP.AddPragmaHandler("STDC", FPContractHandler.get());
 
+  STDCFENVHandler.reset(new PragmaSTDC_FENV_ACCESSHandler());
+  PP.AddPragmaHandler("STDC", STDCFENVHandler.get());
+
+  STDCCXLIMITHandler.reset(new PragmaSTDC_CX_LIMITED_RANGEHandler());
+  PP.AddPragmaHandler("STDC", STDCCXLIMITHandler.get());
+
+  STDCUnknownHandler.reset(new PragmaSTDC_UnknownHandler());
+  PP.AddPragmaHandler("STDC", STDCUnknownHandler.get());
+
   PCSectionHandler.reset(new PragmaClangSectionHandler(Actions));
   PP.AddPragmaHandler("clang", PCSectionHandler.get());
 
@@ -371,6 +418,15 @@ void Parser::resetPragmaHandlers() {
   PP.RemovePragmaHandler("STDC", FPContractHandler.get());
   FPContractHandler.reset();
 
+  PP.RemovePragmaHandler("STDC", STDCFENVHandler.get());
+  STDCFENVHandler.reset();
+
+  PP.RemovePragmaHandler("STDC", STDCCXLIMITHandler.get());
+  STDCCXLIMITHandler.reset();
+
+  PP.RemovePragmaHandler("STDC", STDCUnknownHandler.get());
+  STDCUnknownHandler.reset();
+
   PP.RemovePragmaHandler("clang", OptimizeHandler.get());
   OptimizeHandler.reset();