On Darwin, the linker removes functions in CommentDumper.o (Comment::dump())
despite __attribute__(__used__).  As explained by Argyrios,
> .a archive files do some stripping of their own and they remove .o files that
> contain functions that are not referenced by any other .o file.

The fix is to use these functions from another .o file.

Thanks, Argyrios!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160437 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/Comment.h b/include/clang/AST/Comment.h
index 05ad33f..39753cf 100644
--- a/include/clang/AST/Comment.h
+++ b/include/clang/AST/Comment.h
@@ -115,6 +115,7 @@
 
   LLVM_ATTRIBUTE_USED void dump() const;
   LLVM_ATTRIBUTE_USED void dump(SourceManager &SM) const;
+  void dump(llvm::raw_ostream &OS, SourceManager *SM) const;
 
   static bool classof(const Comment *) { return true; }
 
diff --git a/lib/AST/Comment.cpp b/lib/AST/Comment.cpp
index 1520d13..e215e63 100644
--- a/lib/AST/Comment.cpp
+++ b/lib/AST/Comment.cpp
@@ -9,6 +9,7 @@
 
 #include "clang/AST/Comment.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 
 namespace clang {
 namespace comments {
@@ -27,6 +28,19 @@
   llvm_unreachable("Unknown comment kind!");
 }
 
+void Comment::dump() const {
+  // It is important that Comment::dump() is defined in a different TU than
+  // Comment::dump(raw_ostream, SourceManager).  If both functions were defined
+  // in CommentDumper.cpp, that object file would be removed by linker because
+  // none of its functions are referenced by other object files, despite the
+  // LLVM_ATTRIBUTE_USED.
+  dump(llvm::errs(), NULL);
+}
+
+void Comment::dump(SourceManager &SM) const {
+  dump(llvm::errs(), &SM);
+}
+
 namespace {
 struct good {};
 struct bad {};
diff --git a/lib/AST/CommentDumper.cpp b/lib/AST/CommentDumper.cpp
index 7a075a6..5de5ef5 100644
--- a/lib/AST/CommentDumper.cpp
+++ b/lib/AST/CommentDumper.cpp
@@ -181,14 +181,8 @@
 
 } // unnamed namespace
 
-void Comment::dump() const {
-  CommentDumper D(llvm::errs(), NULL);
-  D.dumpSubtree(this);
-  llvm::errs() << '\n';
-}
-
-void Comment::dump(SourceManager &SM) const {
-  CommentDumper D(llvm::errs(), &SM);
+void Comment::dump(llvm::raw_ostream &OS, SourceManager *SM) const {
+  CommentDumper D(llvm::errs(), SM);
   D.dumpSubtree(this);
   llvm::errs() << '\n';
 }