Forward #pragma comment(lib/linker) through as flags metadata

Summary:
Most of this change is wiring the pragma all the way through from the
lexer, parser, and sema to codegen.  I considered adding a Decl AST node
for this, but it seemed too heavyweight.

Mach-O already uses a metadata flag called "Linker Options" to do this
kind of auto-linking.  This change follows that pattern.

LLVM knows how to forward the "Linker Options" metadata into the COFF
.drectve section where these flags belong.  ELF support is not
implemented, but possible.

This is related to auto-linking, which is http://llvm.org/PR13016.

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D723

llvm-svn: 181426

3 files changed, 21 insertions, 9 deletions

diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index 3d1249aa684..3c6f96ac2be 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -821,10 +821,16 @@ void PragmaCommentHandler::HandlePragma(Preprocessor &PP,
   }
 
   // Verify that this is one of the 5 whitelisted options.
-  // FIXME: warn that 'exestr' is deprecated.
-  const IdentifierInfo *II = Tok.getIdentifierInfo();
-  if (!II->isStr("compiler") && !II->isStr("exestr") && !II->isStr("lib") &&
-      !II->isStr("linker") && !II->isStr("user")) {
+  IdentifierInfo *II = Tok.getIdentifierInfo();
+  Sema::PragmaMSCommentKind Kind =
+    llvm::StringSwitch<Sema::PragmaMSCommentKind>(II->getName())
+    .Case("linker",   Sema::PCK_Linker)
+    .Case("lib",      Sema::PCK_Lib)
+    .Case("compiler", Sema::PCK_Compiler)
+    .Case("exestr",   Sema::PCK_ExeStr)
+    .Case("user",     Sema::PCK_User)
+    .Default(Sema::PCK_Unknown);
+  if (Kind == Sema::PCK_Unknown) {
     PP.Diag(Tok.getLocation(), diag::err_pragma_comment_unknown_kind);
     return;
   }
@@ -837,11 +843,12 @@ void PragmaCommentHandler::HandlePragma(Preprocessor &PP,
                                                  /*MacroExpansion=*/true))
     return;
 
+  // FIXME: warn that 'exestr' is deprecated.
   // FIXME: If the kind is "compiler" warn if the string is present (it is
   // ignored).
-  // FIXME: 'lib' requires a comment string.
-  // FIXME: 'linker' requires a comment string, and has a specific list of
-  // things that are allowable.
+  // The MSDN docs say that "lib" and "linker" require a string and have a short
+  // whitelist of linker options they support, but in practice MSVC doesn't
+  // issue a diagnostic.  Therefore neither does clang.
 
   if (Tok.isNot(tok::r_paren)) {
     PP.Diag(Tok.getLocation(), diag::err_pragma_comment_malformed);
@@ -857,4 +864,6 @@ void PragmaCommentHandler::HandlePragma(Preprocessor &PP,
   // If the pragma is lexically sound, notify any interested PPCallbacks.
   if (PP.getPPCallbacks())
     PP.getPPCallbacks()->PragmaComment(CommentLoc, II, ArgumentString);
+
+  Actions.ActOnPragmaMSComment(Kind, ArgumentString);
 }
diff --git a/clang/lib/Parse/ParsePragma.h b/clang/lib/Parse/ParsePragma.h
index d9560f3181d..3c6f3434ad0 100644
--- a/clang/lib/Parse/ParsePragma.h
+++ b/clang/lib/Parse/ParsePragma.h
@@ -116,9 +116,12 @@ public:
 /// PragmaCommentHandler - "\#pragma comment ...".
 class PragmaCommentHandler : public PragmaHandler {
 public:
-  PragmaCommentHandler() : PragmaHandler("comment") {}
+  PragmaCommentHandler(Sema &Actions)
+    : PragmaHandler("comment"), Actions(Actions) {}
   virtual void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
                             Token &FirstToken);
+private:
+  Sema &Actions;
 };
 
 }  // end namespace clang
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index 455139b881a..2117df45f3a 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -103,7 +103,7 @@ Parser::Parser(Preprocessor &pp, Sema &actions, bool skipFunctionBodies)
   PP.AddPragmaHandler(OpenMPHandler.get());
 
   if (getLangOpts().MicrosoftExt) {
-    MSCommentHandler.reset(new PragmaCommentHandler());
+    MSCommentHandler.reset(new PragmaCommentHandler(actions));
     PP.AddPragmaHandler(MSCommentHandler.get());
   }