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

clang/include/clang/Basic/DiagnosticLexKinds.td

@@ -505,17 +505,12 @@ def warn_pragma_message : Warning<"%0">,
 def err_pragma_message : Error<"%0">;
 def warn_pragma_ignored : Warning<"unknown pragma ignored">,
    InGroup<UnknownPragmas>, DefaultIgnore;
-def ext_stdc_pragma_ignored : ExtWarn<"unknown pragma in STDC namespace">,
-   InGroup<UnknownPragmas>;
 def ext_on_off_switch_syntax :
    ExtWarn<"expected 'ON' or 'OFF' or 'DEFAULT' in pragma">,
    InGroup<UnknownPragmas>;
 def ext_pragma_syntax_eod :
    ExtWarn<"expected end of directive in pragma">,
    InGroup<UnknownPragmas>;
-def warn_stdc_fenv_access_not_supported :
-   Warning<"pragma STDC FENV_ACCESS ON is not supported, ignoring pragma">,
-   InGroup<UnknownPragmas>;
 def warn_pragma_diagnostic_invalid :
    ExtWarn<"pragma diagnostic expected 'error', 'warning', 'ignored', 'fatal',"
             " 'push', or 'pop'">,

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -973,6 +973,12 @@ def warn_pragma_init_seg_unsupported_target : Warning<
 def err_pragma_fp_contract_scope : Error<
   "'#pragma fp_contract' can only appear at file scope or at the start of a "
   "compound statement">; 
+// - #pragma stdc unknown
+def ext_stdc_pragma_ignored : ExtWarn<"unknown pragma in STDC namespace">,
+   InGroup<UnknownPragmas>;
+def warn_stdc_fenv_access_not_supported :
+   Warning<"pragma STDC FENV_ACCESS ON is not supported, ignoring pragma">,
+   InGroup<UnknownPragmas>;
 // - #pragma comment
 def err_pragma_comment_malformed : Error<
   "pragma comment requires parenthesized identifier and optional string">;

clang/include/clang/Parse/Parser.h

@@ -185,6 +185,9 @@ class Parser : public CodeCompletionHandler {
   std::unique_ptr<PragmaHandler> UnrollHintHandler;
   std::unique_ptr<PragmaHandler> NoUnrollHintHandler;
   std::unique_ptr<PragmaHandler> FPHandler;
+  std::unique_ptr<PragmaHandler> STDCFENVHandler;
+  std::unique_ptr<PragmaHandler> STDCCXLIMITHandler;
+  std::unique_ptr<PragmaHandler> STDCUnknownHandler;
   std::unique_ptr<PragmaHandler> AttributePragmaHandler;
 
   std::unique_ptr<CommentHandler> CommentSemaHandler;

clang/lib/Lex/Pragma.cpp

@@ -1601,44 +1601,6 @@ struct PragmaPopMacroHandler : public PragmaHandler {
   }
 };
 
-// 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);
-  }
-};
-
 /// PragmaARCCFCodeAuditedHandler - 
 ///   \#pragma clang arc_cf_code_audited begin/end
 struct PragmaARCCFCodeAuditedHandler : public PragmaHandler {
@@ -1815,10 +1777,6 @@ void Preprocessor::RegisterBuiltinPragmas() {
   ModuleHandler->AddPragma(new PragmaModuleBuildHandler());
   ModuleHandler->AddPragma(new PragmaModuleLoadHandler());
 
-  AddPragmaHandler("STDC", new PragmaSTDC_FENV_ACCESSHandler());
-  AddPragmaHandler("STDC", new PragmaSTDC_CX_LIMITED_RANGEHandler());
-  AddPragmaHandler("STDC", new PragmaSTDC_UnknownHandler());
-
   // MS extensions.
   if (LangOpts.MicrosoftExt) {
     AddPragmaHandler(new PragmaWarningHandler());
@@ -1843,17 +1801,4 @@ void Preprocessor::IgnorePragmas() {
   // in Preprocessor::RegisterBuiltinPragmas().
   AddPragmaHandler("GCC", new EmptyPragmaHandler());
   AddPragmaHandler("clang", new EmptyPragmaHandler());
-  if (PragmaHandler *NS = PragmaHandlers->FindHandler("STDC")) {
-    // Preprocessor::RegisterBuiltinPragmas() already registers
-    // PragmaSTDC_UnknownHandler as the empty handler, so remove it first,
-    // otherwise there will be an assert about a duplicate handler.
-    PragmaNamespace *STDCNamespace = NS->getIfNamespace();
-    assert(STDCNamespace &&
-           "Invalid namespace, registered as a regular pragma handler!");
-    if (PragmaHandler *Existing = STDCNamespace->FindHandler("", false)) {
-      RemovePragmaHandler("STDC", Existing);
-      delete Existing;
-    }
-  }
-  AddPragmaHandler("STDC", new EmptyPragmaHandler());
 }

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();
 

clang/test/Preprocessor/pragma_unknown.c

@@ -1,29 +1,45 @@
 // RUN: %clang_cc1 -fsyntax-only -Wunknown-pragmas -verify %s
-// RUN: %clang_cc1 -E %s | FileCheck --strict-whitespace %s
+// RUN: %clang_cc1 -E %s 2>&1 | FileCheck --strict-whitespace %s
 
 // GCC doesn't expand macro args for unrecognized pragmas.
 #define bar xX
 #pragma foo bar   // expected-warning {{unknown pragma ignored}}
+// CHECK-NOT: unknown pragma in STDC namespace
 // CHECK: {{^}}#pragma foo bar{{$}}
 
 #pragma STDC FP_CONTRACT ON
 #pragma STDC FP_CONTRACT OFF
 #pragma STDC FP_CONTRACT DEFAULT
 #pragma STDC FP_CONTRACT IN_BETWEEN  // expected-warning {{expected 'ON' or 'OFF' or 'DEFAULT' in pragma}}
+// CHECK: {{^}}#pragma STDC FP_CONTRACT ON{{$}}
+// CHECK: {{^}}#pragma STDC FP_CONTRACT OFF{{$}}
+// CHECK: {{^}}#pragma STDC FP_CONTRACT DEFAULT{{$}}
+// CHECK: {{^}}#pragma STDC FP_CONTRACT IN_BETWEEN{{$}}
 
 #pragma STDC FENV_ACCESS ON          // expected-warning {{pragma STDC FENV_ACCESS ON is not supported, ignoring pragma}}
 #pragma STDC FENV_ACCESS OFF
 #pragma STDC FENV_ACCESS DEFAULT
 #pragma STDC FENV_ACCESS IN_BETWEEN   // expected-warning {{expected 'ON' or 'OFF' or 'DEFAULT' in pragma}}
+// CHECK: {{^}}#pragma STDC FENV_ACCESS ON{{$}}
+// CHECK: {{^}}#pragma STDC FENV_ACCESS OFF{{$}}
+// CHECK: {{^}}#pragma STDC FENV_ACCESS DEFAULT{{$}}
+// CHECK: {{^}}#pragma STDC FENV_ACCESS IN_BETWEEN{{$}}
 
 #pragma STDC CX_LIMITED_RANGE ON
 #pragma STDC CX_LIMITED_RANGE OFF
 #pragma STDC CX_LIMITED_RANGE DEFAULT 
 #pragma STDC CX_LIMITED_RANGE IN_BETWEEN   // expected-warning {{expected 'ON' or 'OFF' or 'DEFAULT' in pragma}}
+// CHECK: {{^}}#pragma STDC CX_LIMITED_RANGE ON{{$}}
+// CHECK: {{^}}#pragma STDC CX_LIMITED_RANGE OFF{{$}}
+// CHECK: {{^}}#pragma STDC CX_LIMITED_RANGE DEFAULT{{$}}
+// CHECK: {{^}}#pragma STDC CX_LIMITED_RANGE IN_BETWEEN{{$}}
 
 #pragma STDC CX_LIMITED_RANGE    // expected-warning {{expected 'ON' or 'OFF' or 'DEFAULT' in pragma}}
 #pragma STDC CX_LIMITED_RANGE ON FULL POWER  // expected-warning {{expected end of directive in pragma}}
+// CHECK: {{^}}#pragma STDC CX_LIMITED_RANGE{{$}}
+// CHECK: {{^}}#pragma STDC CX_LIMITED_RANGE ON FULL POWER{{$}}
 
 #pragma STDC SO_GREAT  // expected-warning {{unknown pragma in STDC namespace}}
 #pragma STDC   // expected-warning {{unknown pragma in STDC namespace}}
-
+// CHECK: {{^}}#pragma STDC SO_GREAT{{$}}
+// CHECK: {{^}}#pragma STDC{{$}}