[Preprocessor] Do not expand macros if the input is already preprocessed

clang/include/clang/Frontend/FrontendAction.h

@@ -84,6 +84,8 @@ class FrontendAction {
   /// \return True on success; on failure ExecutionAction() and
   /// EndSourceFileAction() will not be called.
   virtual bool BeginSourceFileAction(CompilerInstance &CI) {
+    if (CurrentInput.isPreprocessed())
+      CI.getPreprocessor().SetEnableMacroExpansion(false);
     return true;
   }
 
@@ -98,7 +100,11 @@ class FrontendAction {
   ///
   /// This is guaranteed to only be called following a successful call to
   /// BeginSourceFileAction (and BeginSourceFile).
-  virtual void EndSourceFileAction() {}
+  virtual void EndSourceFileAction() {
+    if (CurrentInput.isPreprocessed())
+      // reset the preprocessor macro expansion to the default
+      getCompilerInstance().getPreprocessor().SetEnableMacroExpansion(true);
+  }
 
   /// Callback at the end of processing a single input, to determine
   /// if the output files should be erased or not.

clang/include/clang/Lex/Preprocessor.h

@@ -1831,6 +1831,8 @@ class Preprocessor {
     MacroExpansionInDirectivesOverride = true;
   }
 
+  void SetEnableMacroExpansion(bool Enable) { DisableMacroExpansion = !Enable; }
+
   /// Peeks ahead N tokens and returns that token without consuming any
   /// tokens.
   ///

clang/lib/CodeGen/CodeGenAction.cpp

@@ -908,6 +908,8 @@ bool CodeGenAction::loadLinkModules(CompilerInstance &CI) {
 bool CodeGenAction::hasIRSupport() const { return true; }
 
 void CodeGenAction::EndSourceFileAction() {
+  ASTFrontendAction::EndSourceFileAction();
+
   // If the consumer creation failed, do nothing.
   if (!getCompilerInstance().hasASTConsumer())
     return;
@@ -932,7 +934,7 @@ CodeGenerator *CodeGenAction::getCodeGenerator() const {
 bool CodeGenAction::BeginSourceFileAction(CompilerInstance &CI) {
   if (CI.getFrontendOpts().GenReducedBMI)
     CI.getLangOpts().setCompilingModule(LangOptions::CMK_ModuleInterface);
-  return true;
+  return ASTFrontendAction::BeginSourceFileAction(CI);
 }
 
 static std::unique_ptr<raw_pwrite_stream>

clang/lib/Frontend/FrontendActions.cpp

@@ -182,7 +182,7 @@ bool GeneratePCHAction::shouldEraseOutputFiles() {
 
 bool GeneratePCHAction::BeginSourceFileAction(CompilerInstance &CI) {
   CI.getLangOpts().CompilingPCH = true;
-  return true;
+  return ASTFrontendAction::BeginSourceFileAction(CI);
 }
 
 std::vector<std::unique_ptr<ASTConsumer>>

clang/lib/Frontend/Rewrite/FrontendActions.cpp

@@ -104,12 +104,13 @@ bool FixItAction::BeginSourceFileAction(CompilerInstance &CI) {
   }
   Rewriter.reset(new FixItRewriter(CI.getDiagnostics(), CI.getSourceManager(),
                                    CI.getLangOpts(), FixItOpts.get()));
-  return true;
+  return ASTFrontendAction::BeginSourceFileAction(CI);
 }
 
 void FixItAction::EndSourceFileAction() {
   // Otherwise rewrite all files.
   Rewriter->WriteFixedFiles();
+  ASTFrontendAction::EndSourceFileAction();
 }
 
 bool FixItRecompile::BeginInvocation(CompilerInstance &CI) {
@@ -299,7 +300,7 @@ bool RewriteIncludesAction::BeginSourceFileAction(CompilerInstance &CI) {
         std::make_unique<RewriteImportsListener>(CI, OutputStream));
   }
 
-  return true;
+  return PreprocessorFrontendAction::BeginSourceFileAction(CI);
 }
 
 void RewriteIncludesAction::ExecuteAction() {

clang/test/Modules/initializers.cpp

@@ -48,6 +48,7 @@
 // instantiation for v<int> in one of the two headers, because we will only
 // parse one of the two get() functions.
 
+#ifdef NS
 #pragma clang module build m
 module m {
   module a {
@@ -60,9 +61,7 @@ module m {
 #pragma clang module begin m.a
 inline int non_trivial() { return 3; }
 
-#ifdef NS
 namespace ns {
-#endif
 
 int a = non_trivial();
 inline int b = non_trivial();
@@ -102,12 +101,64 @@ inline void use(bool b, ...) {
       X<int>::e<int>, X<int>::f<int>, X<int>::g<int>, X<int>::h<int>);
 }
 
-#ifdef NS
 }
-#endif
 
 #pragma clang module end
 #pragma clang module endbuild
+#else
+#pragma clang module build m
+module m {
+  module a {
+    header "foo.h" { size 123 mtime 456789 }
+  }
+  module b {}
+}
+
+#pragma clang module contents
+#pragma clang module begin m.a
+inline int non_trivial() { return 3; }
+
+int a = non_trivial();
+inline int b = non_trivial();
+thread_local int c = non_trivial();
+inline thread_local int d = non_trivial();
+
+template<typename U> int e = non_trivial();
+template<typename U> inline int f = non_trivial();
+template<typename U> thread_local int g = non_trivial();
+template<typename U> inline thread_local int h = non_trivial();
+
+inline int unused = 123; // should not be emitted
+
+template<typename T> struct X {
+  static int a;
+  static inline int b = non_trivial();
+  static thread_local int c;
+  static inline thread_local int d = non_trivial();
+
+  template<typename U> static int e;
+  template<typename U> static inline int f = non_trivial();
+  template<typename U> static thread_local int g;
+  template<typename U> static inline thread_local int h = non_trivial();
+
+  static inline int unused = 123; // should not be emitted
+};
+
+template<typename T> int X<T>::a = non_trivial();
+template<typename T> thread_local int X<T>::c = non_trivial();
+template<typename T> template<typename U> int X<T>::e = non_trivial();
+template<typename T> template<typename U> thread_local int X<T>::g = non_trivial();
+
+inline void use(bool b, ...) {
+  if (b) return;
+  use(true, e<int>, f<int>, g<int>, h<int>,
+      X<int>::a, X<int>::b, X<int>::c, X<int>::d,
+      X<int>::e<int>, X<int>::f<int>, X<int>::g<int>, X<int>::h<int>);
+}
+
+#pragma clang module end
+#pragma clang module endbuild
+#endif
 
 #if IMPORT == 1
 // Import the module and the m.a submodule; runs the ordered initializers and

clang/test/Preprocessor/preprocess-cpp-output.c

@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -E -x c %s | FileCheck %s --check-prefixes=EXPANDED
+// RUN: %clang_cc1 -E -x cpp-output %s | FileCheck %s --check-prefixes=NOT-EXPANDED
+
+// EXPANDED: void __attribute__((__attribute__((always_inline)))) foo()
+// NOT-EXPANDED: void __attribute__((always_inline)) foo()
+
+#define always_inline __attribute__((always_inline))
+void __attribute__((always_inline)) foo() {
+    return 4;
+}