Preprocessor: Ignore unknown pragmas in -E -dM and -Eonly modes.

llvm-svn: 105830

clang/include/clang/Lex/Pragma.h

@@ -46,6 +46,15 @@ public:
   virtual PragmaNamespace *getIfNamespace() { return 0; }
 };
 
+/// EmptyPragmaHandler - A pragma handler which takes no action, which can be
+/// used to ignore particular pragmas.
+class EmptyPragmaHandler : public PragmaHandler {
+public:
+  EmptyPragmaHandler();
+
+  virtual void HandlePragma(Preprocessor &PP, Token &FirstToken);
+};
+
 /// PragmaNamespace - This PragmaHandler subdivides the namespace of pragmas,
 /// allowing hierarchical pragmas to be defined.  Common examples of namespaces
 /// are "#pragma GCC", "#pragma STDC", and "#pragma omp", but any namespaces may

clang/lib/Frontend/FrontendActions.cpp

@@ -9,6 +9,7 @@
 
 #include "clang/Frontend/FrontendActions.h"
 #include "clang/AST/ASTConsumer.h"
+#include "clang/Lex/Pragma.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Parse/Parser.h"
 #include "clang/Basic/FileManager.h"
@@ -223,6 +224,9 @@ void ParseOnlyAction::ExecuteAction() {
 void PreprocessOnlyAction::ExecuteAction() {
   Preprocessor &PP = getCompilerInstance().getPreprocessor();
 
+  // Ignore unknown pragmas.
+  PP.AddPragmaHandler(0, new EmptyPragmaHandler());
+
   Token Tok;
   // Start parsing the specified input file.
   PP.EnterMainSourceFile();

clang/lib/Frontend/PrintPreprocessedOutput.cpp

@@ -454,6 +454,9 @@ static int MacroIDCompare(const void* a, const void* b) {
 }
 
 static void DoPrintMacros(Preprocessor &PP, llvm::raw_ostream *OS) {
+  // Ignore unknown pragmas.
+  PP.AddPragmaHandler(0, new EmptyPragmaHandler());
+
   // -dM mode just scans and ignores all tokens in the files, then dumps out
   // the macro table at the end.
   PP.EnterMainSourceFile();

clang/lib/Lex/Pragma.cpp

@@ -26,6 +26,14 @@ using namespace clang;
 PragmaHandler::~PragmaHandler() {
 }
 
+//===----------------------------------------------------------------------===//
+// EmptyPragmaHandler Implementation.
+//===----------------------------------------------------------------------===//
+
+EmptyPragmaHandler::EmptyPragmaHandler() : PragmaHandler(0) {}
+
+void EmptyPragmaHandler::HandlePragma(Preprocessor &PP, Token &FirstToken) {}
+
 //===----------------------------------------------------------------------===//
 // PragmaNamespace Implementation.
 //===----------------------------------------------------------------------===//

clang/test/Frontend/unknown-pragmas.c

+// RUN: %clang_cc1 -Eonly -Wall -verify %s
+// RUN: %clang_cc1 -E -dM -Wall -verify %s
+
+#pragma adgohweopihweotnwet