From 9219d1b764d9ce765012a933d4c19eb23968387f Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Tue, 27 Nov 2012 21:31:01 +0000
Subject: [PATCH] Allow an ASTConsumer to selectively skip function bodies
 while parsing. Patch by Olivier Goffart!

llvm-svn: 168726
---
 clang/include/clang/AST/ASTConsumer.h   |  9 +++++++++
 clang/lib/Sema/SemaDecl.cpp             |  3 +++
 clang/unittests/Tooling/ToolingTest.cpp | 24 ++++++++++++++++++++++++
 3 files changed, 36 insertions(+)

diff --git a/clang/include/clang/AST/ASTConsumer.h b/clang/include/clang/AST/ASTConsumer.h
index 37b0740..4ce5852 100644
--- a/clang/include/clang/AST/ASTConsumer.h
+++ b/clang/include/clang/AST/ASTConsumer.h
@@ -17,6 +17,7 @@
 namespace clang {
   class ASTContext;
   class CXXRecordDecl;
+  class Decl;
   class DeclGroupRef;
   class HandleTagDeclDefinition;
   class PPMutationListener;
@@ -130,6 +131,14 @@ public:
 
   /// PrintStats - If desired, print any statistics.
   virtual void PrintStats() {}
+
+  /// \brief This callback is called for each function if the Parser was
+  /// initialized with \c SkipFunctionBodies set to \c true.
+  ///
+  /// \return \c true if the function's body should be skipped. The function
+  /// body may be parsed anyway if it is needed (for instance, if it contains
+  /// the code completion point or is constexpr).
+  virtual bool shouldSkipFunctionBody(Decl *D) { return true; }
 };
 
 } // end namespace clang.
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 6a9065e..edf50d2 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -7993,6 +7993,9 @@ void Sema::computeNRVO(Stmt *Body, FunctionScopeInfo *Scope) {
 }
 
 bool Sema::canSkipFunctionBody(Decl *D) {
+  if (!Consumer.shouldSkipFunctionBody(D))
+    return false;
+
   if (isa<ObjCMethodDecl>(D))
     return true;
 
diff --git a/clang/unittests/Tooling/ToolingTest.cpp b/clang/unittests/Tooling/ToolingTest.cpp
index d40c613..a45935d 100644
--- a/clang/unittests/Tooling/ToolingTest.cpp
+++ b/clang/unittests/Tooling/ToolingTest.cpp
@@ -10,6 +10,7 @@
 #include "clang/AST/ASTConsumer.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclGroup.h"
+#include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendAction.h"
 #include "clang/Frontend/FrontendActions.h"
 #include "clang/Tooling/CompilationDatabase.h"
@@ -162,5 +163,28 @@ TEST(newFrontendActionFactory, InjectsEndOfSourceFileCallback) {
 }
 #endif
 
+struct SkipBodyConsumer : public clang::ASTConsumer {
+  /// Skip the 'skipMe' function.
+  virtual bool shouldSkipFunctionBody(Decl *D) {
+    FunctionDecl *F = dyn_cast<FunctionDecl>(D);
+    return F && F->getNameAsString() == "skipMe";
+  }
+};
+
+struct SkipBodyAction : public clang::ASTFrontendAction {
+  virtual ASTConsumer *CreateASTConsumer(CompilerInstance &Compiler,
+                                         StringRef) {
+    Compiler.getFrontendOpts().SkipFunctionBodies = true;
+    return new SkipBodyConsumer;
+  }
+};
+
+TEST(runToolOnCode, TestSkipFunctionBoddy) {
+  EXPECT_TRUE(runToolOnCode(new SkipBodyAction,
+                            "int skipMe() { an_error_here }"));
+  EXPECT_FALSE(runToolOnCode(new SkipBodyAction,
+                             "int skipMeNot() { an_error_here }"));
+}
+
 } // end namespace tooling
 } // end namespace clang
-- 
2.7.4