Support return type deduction for templates in -fdelayed-template-parsing (microsoft) mode

Please see http://llvm-reviews.chandlerc.com/D2053 for discussion and Richard's stamp.

llvm-svn: 193849

2 files changed, 26 insertions, 3 deletions

diff --git a/clang/lib/Parse/ParseCXXInlineMethods.cpp b/clang/lib/Parse/ParseCXXInlineMethods.cpp
index 863a09e89d3..0c8ace59e35 100644
--- a/clang/lib/Parse/ParseCXXInlineMethods.cpp
+++ b/clang/lib/Parse/ParseCXXInlineMethods.cpp
@@ -109,13 +109,15 @@ NamedDecl *Parser::ParseCXXInlineMethodDef(AccessSpecifier AS,
 
     return FnD;
   }
-
+  
   // In delayed template parsing mode, if we are within a class template
   // or if we are about to parse function member template then consume
   // the tokens and store them for parsing at the end of the translation unit.
   if (getLangOpts().DelayedTemplateParsing &&
       DefinitionKind == FDK_Definition &&
-      !D.getDeclSpec().isConstexprSpecified() &&
+      !D.getDeclSpec().isConstexprSpecified() && 
+      !(FnD && getFunctionDecl(FnD) && 
+          getFunctionDecl(FnD)->getResultType()->getContainedAutoType()) &&
       ((Actions.CurContext->isDependentContext() ||
         (TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
          TemplateInfo.Kind != ParsedTemplateInfo::ExplicitSpecialization)) &&
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index d95546af8ab..84aad4101fb 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -919,6 +919,26 @@ Parser::ParseDeclarationOrFunctionDefinition(ParsedAttributesWithRange &attrs,
   }
 }
 
+
+static inline bool isFunctionDeclaratorRequiringReturnTypeDeduction(
+    const Declarator &D) {
+  if (!D.isFunctionDeclarator() || !D.getDeclSpec().containsPlaceholderType()) 
+    return false;
+  for (unsigned I = 0, E = D.getNumTypeObjects(); I != E; ++I) {
+    unsigned chunkIndex = E - I - 1;
+    const DeclaratorChunk &DeclType = D.getTypeObject(chunkIndex);
+    if (DeclType.Kind == DeclaratorChunk::Function) {
+      const DeclaratorChunk::FunctionTypeInfo &FTI = DeclType.Fun;
+      if (!FTI.hasTrailingReturnType()) 
+        return true;
+      QualType TrailingRetType = FTI.getTrailingReturnType().get();
+      return TrailingRetType->getCanonicalTypeInternal()
+        ->getContainedAutoType();
+    }
+  } 
+  return false;
+}
+
 /// ParseFunctionDefinition - We parsed and verified that the specified
 /// Declarator is well formed.  If this is a K&R-style function, read the
 /// parameters declaration-list, then start the compound-statement.
@@ -992,7 +1012,8 @@ Decl *Parser::ParseFunctionDefinition(ParsingDeclarator &D,
   // tokens and store them for late parsing at the end of the translation unit.
   if (getLangOpts().DelayedTemplateParsing && Tok.isNot(tok::equal) &&
       TemplateInfo.Kind == ParsedTemplateInfo::Template &&
-      !D.getDeclSpec().isConstexprSpecified()) {
+      !D.getDeclSpec().isConstexprSpecified() && 
+      !isFunctionDeclaratorRequiringReturnTypeDeduction(D)) {
     MultiTemplateParamsArg TemplateParameterLists(*TemplateInfo.TemplateParams);
     
     ParseScope BodyScope(this, Scope::FnScope|Scope::DeclScope);