Add -fdelayed-template-parsing option. Using this option all templated function definitions are parsed at the end of the translation unit only if it is required by an actual instantiation. As such all the symbols of the TU are available during name lookup.

Using this flag is necessary for compatibility with Microsoft template code.
This also provides some parsing speed improvement.

llvm-svn: 130022

1 files changed, 47 insertions, 0 deletions

diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index 492b8f53097..6522306dce2 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "RAIIObjectsForParser.h"
 #include "ParsePragma.h"
+#include "clang/AST/DeclTemplate.h"
 using namespace clang;
 
 Parser::Parser(Preprocessor &pp, Sema &actions)
@@ -362,6 +363,11 @@ Parser::~Parser() {
   for (unsigned i = 0, e = NumCachedScopes; i != e; ++i)
     delete ScopeCache[i];
 
+  // Free LateParsedTemplatedFunction nodes.
+  for (LateParsedTemplateMapT::iterator it = LateParsedTemplateMap.begin();
+      it != LateParsedTemplateMap.end(); ++it)
+    delete it->second;
+
   // Remove the pragma handlers we installed.
   PP.RemovePragmaHandler(AlignHandler.get());
   AlignHandler.reset();
@@ -438,6 +444,10 @@ bool Parser::ParseTopLevelDecl(DeclGroupPtrTy &Result) {
 
   Result = DeclGroupPtrTy();
   if (Tok.is(tok::eof)) {
+    // Late template parsing can begin.
+    if (getLang().DelayedTemplateParsing)
+      Actions.SetLateTemplateParser(LateTemplateParserCallback, this);
+
     Actions.ActOnEndOfTranslationUnit();
     return true;
   }
@@ -786,6 +796,43 @@ Decl *Parser::ParseFunctionDefinition(ParsingDeclarator &D,
       return 0;
   }
 
+  // In delayed template parsing mode, for function template we consume the
+  // tokens and store them for late parsing at the end of the translation unit.
+  if (getLang().DelayedTemplateParsing &&
+      TemplateInfo.Kind == ParsedTemplateInfo::Template) {
+    MultiTemplateParamsArg TemplateParameterLists(Actions,
+                                         TemplateInfo.TemplateParams->data(),
+                                         TemplateInfo.TemplateParams->size());
+    
+    ParseScope BodyScope(this, Scope::FnScope|Scope::DeclScope);
+    Scope *ParentScope = getCurScope()->getParent();
+
+    Decl *DP = Actions.HandleDeclarator(ParentScope, D,
+                                move(TemplateParameterLists),
+                                /*IsFunctionDefinition=*/true);
+    D.complete(DP);
+    D.getMutableDeclSpec().abort();
+
+    if (DP) {
+      LateParsedTemplatedFunction *LPT = new LateParsedTemplatedFunction(this, DP);
+
+      FunctionDecl *FnD = 0;
+      if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(DP))
+        FnD = FunTmpl->getTemplatedDecl();
+      else
+        FnD = cast<FunctionDecl>(DP);
+
+      LateParsedTemplateMap[FnD] = LPT;
+      Actions.MarkAsLateParsedTemplate(FnD);
+      LexTemplateFunctionForLateParsing(LPT->Toks);
+    } else {
+      CachedTokens Toks;
+      LexTemplateFunctionForLateParsing(Toks);
+    }
+    return DP;
+  }
+
+
   // Enter a scope for the function body.
   ParseScope BodyScope(this, Scope::FnScope|Scope::DeclScope);