Emit used/dllexport inline method definitions in nested classes (PR19743, PR11170)

The previous code that was supposed to handle this didn't work
since parsing of inline method definitions is delayed to the end
of the outer class definition. Thus, when HandleTagDeclDefinition()
got called for the inner class, the inline functions in that class
had not been parsed yet.

Richard suggested that the way to do this is by handling inline
method definitions through a new ASTConsumer callback.

I really wanted to call ASTContext::DeclMustBeEmitted() instead of
checking for attributes, but doing that causes us to compute linkage,
and then we fail with "error: unsupported: typedef changes linkage
of anonymous type, but linkage was already computed" on tests like
this: (from SemaCXX/undefined-internal.cpp) :-/

  namespace test7 {
    typedef struct {
      void bar();
      void foo() { bar(); }
    } A;
  }

Differential Revision: http://reviews.llvm.org/D3809

llvm-svn: 209549

clang/include/clang/AST/ASTConsumer.h

@@ -18,6 +18,7 @@
 
 namespace clang {
   class ASTContext;
+  class CXXMethodDecl;
   class CXXRecordDecl;
   class Decl;
   class DeclGroupRef;
@@ -56,6 +57,10 @@ public:
   /// \returns true to continue parsing, or false to abort parsing.
   virtual bool HandleTopLevelDecl(DeclGroupRef D);
 
+  /// \brief This callback is invoked each time an inline method definition is
+  /// completed.
+  virtual void HandleInlineMethodDefinition(CXXMethodDecl *D) {}
+
   /// HandleInterestingDecl - Handle the specified interesting declaration. This
   /// is called by the AST reader when deserializing things that might interest
   /// the consumer. The default implementation forwards to HandleTopLevelDecl.

clang/include/clang/Frontend/MultiplexConsumer.h

@@ -36,6 +36,7 @@ public:
   void Initialize(ASTContext &Context) override;
   void HandleCXXStaticMemberVarInstantiation(VarDecl *VD) override;
   bool HandleTopLevelDecl(DeclGroupRef D) override;
+  void HandleInlineMethodDefinition(CXXMethodDecl *D) override;
   void HandleInterestingDecl(DeclGroupRef D) override;
   void HandleTranslationUnit(ASTContext &Ctx) override;
   void HandleTagDeclDefinition(TagDecl *D) override;

clang/include/clang/Sema/Sema.h

@@ -1670,6 +1670,7 @@ public:
   Decl *ActOnFinishFunctionBody(Decl *Decl, Stmt *Body);
   Decl *ActOnFinishFunctionBody(Decl *Decl, Stmt *Body, bool IsInstantiation);
   Decl *ActOnSkippedFunctionBody(Decl *Decl);
+  void ActOnFinishInlineMethodDef(CXXMethodDecl *D);
 
   /// ActOnFinishDelayedAttribute - Invoked when we have finished parsing an
   /// attribute for which parsing is delayed.

clang/lib/CodeGen/CodeGenAction.cpp

@@ -11,6 +11,7 @@
 #include "clang/AST/ASTConsumer.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/DeclGroup.h"
+#include "clang/AST/DeclCXX.h"
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/TargetInfo.h"
@@ -104,6 +105,19 @@ namespace clang {
       return true;
     }
 
+    void HandleInlineMethodDefinition(CXXMethodDecl *D) override {
+      PrettyStackTraceDecl CrashInfo(D, SourceLocation(),
+                                     Context->getSourceManager(),
+                                     "LLVM IR generation of inline method");
+      if (llvm::TimePassesIsEnabled)
+        LLVMIRGeneration.startTimer();
+
+      Gen->HandleInlineMethodDefinition(D);
+
+      if (llvm::TimePassesIsEnabled)
+        LLVMIRGeneration.stopTimer();
+    }
+
     void HandleTranslationUnit(ASTContext &C) override {
       {
         PrettyStackTraceString CrashInfo("Per-file LLVM IR generation");

clang/lib/CodeGen/ModuleBuilder.cpp

@@ -81,6 +81,20 @@ namespace {
       return true;
     }
 
+    void HandleInlineMethodDefinition(CXXMethodDecl *D) override {
+      if (Diags.hasErrorOccurred())
+        return;
+
+      assert(D->doesThisDeclarationHaveABody());
+
+      // We may have member functions that need to be emitted at this point.
+      if (!D->isDependentContext() &&
+          (D->hasAttr<UsedAttr>() || D->hasAttr<ConstructorAttr>() ||
+           D->hasAttr<DLLExportAttr>())) {
+        Builder->EmitTopLevelDecl(D);
+      }
+    }
+
     /// HandleTagDeclDefinition - This callback is invoked each time a TagDecl
     /// to (e.g. struct, union, enum, class) is completed. This allows the
     /// client hack on the type, which can occur at any point in the file
@@ -90,17 +104,6 @@ namespace {
         return;
 
       Builder->UpdateCompletedType(D);
-      
-      // In C++, we may have member functions that need to be emitted at this 
-      // point.
-      if (Ctx->getLangOpts().CPlusPlus && !D->isDependentContext()) {
-        for (auto *M : D->decls())
-          if (auto *Method = dyn_cast<CXXMethodDecl>(M))
-            if (Method->doesThisDeclarationHaveABody() &&
-                (Method->hasAttr<UsedAttr>() || 
-                 Method->hasAttr<ConstructorAttr>()))
-              Builder->EmitTopLevelDecl(Method);
-      }
     }
 
     void HandleTagDeclRequiredDefinition(const TagDecl *D) override {

clang/lib/Frontend/MultiplexConsumer.cpp

@@ -226,6 +226,11 @@ bool MultiplexConsumer::HandleTopLevelDecl(DeclGroupRef D) {
   return Continue;
 }
 
+void MultiplexConsumer::HandleInlineMethodDefinition(CXXMethodDecl *D) {
+  for (size_t i = 0, e = Consumers.size(); i != e; ++i)
+    Consumers[i]->HandleInlineMethodDefinition(D);
+}
+
 void  MultiplexConsumer::HandleCXXStaticMemberVarInstantiation(VarDecl *VD) {
   for (size_t i = 0, e = Consumers.size(); i != e; ++i)
     Consumers[i]->HandleCXXStaticMemberVarInstantiation(VD);

clang/lib/Parse/ParseCXXInlineMethods.cpp

@@ -467,6 +467,9 @@ void Parser::ParseLexedMethodDef(LexedMethod &LM) {
       while (Tok.getLocation() != origLoc && Tok.isNot(tok::eof))
         ConsumeAnyToken();
   }
+
+  if (CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(LM.D))
+    Actions.ActOnFinishInlineMethodDef(MD);
 }
 
 /// ParseLexedMemberInitializers - We finished parsing the member specification

clang/lib/Sema/SemaDecl.cpp

@@ -9515,6 +9515,10 @@ Decl *Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Declarator &D) {
   return ActOnStartOfFunctionDef(FnBodyScope, DP);
 }
 
+void Sema::ActOnFinishInlineMethodDef(CXXMethodDecl *D) {
+  Consumer.HandleInlineMethodDefinition(D);
+}
+
 static bool ShouldWarnAboutMissingPrototype(const FunctionDecl *FD, 
                              const FunctionDecl*& PossibleZeroParamPrototype) {
   // Don't warn about invalid declarations.

clang/test/CodeGenCXX/attr-used.cpp

@@ -7,3 +7,11 @@ struct X0 {
   // CHECK: define linkonce_odr {{.*}} @_ZN2X0D1Ev
   __attribute__((used)) ~X0() {}
 };
+
+// PR19743: not emitting __attribute__((used)) inline methods in nested classes.
+struct X1 {
+  struct Nested {
+    // CHECK: define linkonce_odr {{.*}} @_ZN2X16Nested1fEv
+    void __attribute__((used)) f() {}
+  };
+};

clang/test/CodeGenCXX/dllexport.cpp

@@ -15,10 +15,14 @@ template void DLLEXPORT c<int>();
 struct S {
   void DLLEXPORT a() {}
   // CHECK-DAG: define weak_odr dllexport x86_thiscallcc void @"\01?a@S@@QAEXXZ"
+
+  struct T {
+    void DLLEXPORT a() {}
+    // CHECK-DAG: define weak_odr dllexport x86_thiscallcc void @"\01?a@T@S@@QAEXXZ"
+  };
 };
 
+
 void user() {
   a();
-  // FIXME: dllexported methods must be emitted even if they're not referenced in this TU.
-  &S::a;
 }