Support decltype in member initializers.

This is the last piece of N3031 (decltype in weird places) - supporting
the use of decltype in a class ctor's member-initializer-list to
specify the base classes to initialize.

Reviewed by Richard Smith.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@148789 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Sema/Sema.h

@@ -3507,6 +3507,7 @@ public:
                                     CXXScopeSpec &SS,
                                     IdentifierInfo *MemberOrBase,
                                     ParsedType TemplateTypeTy,
+                                    const DeclSpec &DS,
                                     SourceLocation IdLoc,
                                     SourceLocation LParenLoc,
                                     Expr **Args, unsigned NumArgs,
@@ -3518,6 +3519,7 @@ public:
                                     CXXScopeSpec &SS,
                                     IdentifierInfo *MemberOrBase,
                                     ParsedType TemplateTypeTy,
+                                    const DeclSpec &DS,
                                     SourceLocation IdLoc,
                                     Expr *InitList,
                                     SourceLocation EllipsisLoc);
@@ -3527,6 +3529,7 @@ public:
                                     CXXScopeSpec &SS,
                                     IdentifierInfo *MemberOrBase,
                                     ParsedType TemplateTypeTy,
+                                    const DeclSpec &DS,
                                     SourceLocation IdLoc,
                                     const MultiInitializer &Init,
                                     SourceLocation EllipsisLoc);

lib/Parse/ParseDeclCXX.cpp

@@ -2414,15 +2414,28 @@ Parser::MemInitResult Parser::ParseMemInitializer(Decl *ConstructorDecl) {
       TemplateTypeTy = getTypeAnnotation(Tok);
     }
   }
-  if (!TemplateTypeTy && Tok.isNot(tok::identifier)) {
+  // Uses of decltype will already have been converted to annot_decltype by
+  // ParseOptionalCXXScopeSpecifier at this point.
+  if (!TemplateTypeTy && Tok.isNot(tok::identifier)
+      && Tok.isNot(tok::annot_decltype)) {
     Diag(Tok, diag::err_expected_member_or_base_name);
     return true;
   }
 
-  // Get the identifier. This may be a member name or a class name,
-  // but we'll let the semantic analysis determine which it is.
-  IdentifierInfo *II = Tok.is(tok::identifier) ? Tok.getIdentifierInfo() : 0;
-  SourceLocation IdLoc = ConsumeToken();
+  IdentifierInfo *II = 0;
+  DeclSpec DS(AttrFactory);
+  SourceLocation IdLoc = Tok.getLocation();
+  if (Tok.is(tok::annot_decltype)) {
+    // Get the decltype expression, if there is one.
+    ParseDecltypeSpecifier(DS);
+  } else {
+    if (Tok.is(tok::identifier))
+      // Get the identifier. This may be a member name or a class name,
+      // but we'll let the semantic analysis determine which it is.
+      II = Tok.getIdentifierInfo();
+    ConsumeToken();
+  }
+
 
   // Parse the '('.
   if (getLang().CPlusPlus0x && Tok.is(tok::l_brace)) {
@@ -2437,8 +2450,8 @@ Parser::MemInitResult Parser::ParseMemInitializer(Decl *ConstructorDecl) {
       EllipsisLoc = ConsumeToken();
 
     return Actions.ActOnMemInitializer(ConstructorDecl, getCurScope(), SS, II,
-                                       TemplateTypeTy, IdLoc, InitList.take(),
-                                       EllipsisLoc);
+                                       TemplateTypeTy, DS, IdLoc, 
+                                       InitList.take(), EllipsisLoc);
   } else if(Tok.is(tok::l_paren)) {
     BalancedDelimiterTracker T(*this, tok::l_paren);
     T.consumeOpen();
@@ -2458,7 +2471,7 @@ Parser::MemInitResult Parser::ParseMemInitializer(Decl *ConstructorDecl) {
       EllipsisLoc = ConsumeToken();
 
     return Actions.ActOnMemInitializer(ConstructorDecl, getCurScope(), SS, II,
-                                       TemplateTypeTy, IdLoc,
+                                       TemplateTypeTy, DS, IdLoc,
                                        T.getOpenLocation(), ArgExprs.take(),
                                        ArgExprs.size(), T.getCloseLocation(),
                                        EllipsisLoc);

lib/Sema/SemaDeclCXX.cpp

@@ -1722,11 +1722,13 @@ Sema::ActOnMemInitializer(Decl *ConstructorD,
                           CXXScopeSpec &SS,
                           IdentifierInfo *MemberOrBase,
                           ParsedType TemplateTypeTy,
+                          const DeclSpec &DS,
                           SourceLocation IdLoc,
                           Expr *InitList,
                           SourceLocation EllipsisLoc) {
   return BuildMemInitializer(ConstructorD, S, SS, MemberOrBase, TemplateTypeTy,
-                             IdLoc, MultiInitializer(InitList), EllipsisLoc);
+                             DS, IdLoc, MultiInitializer(InitList), 
+                             EllipsisLoc);
 }
 
 /// \brief Handle a C++ member initializer using parentheses syntax.
@@ -1736,14 +1738,15 @@ Sema::ActOnMemInitializer(Decl *ConstructorD,
                           CXXScopeSpec &SS,
                           IdentifierInfo *MemberOrBase,
                           ParsedType TemplateTypeTy,
+                          const DeclSpec &DS,
                           SourceLocation IdLoc,
                           SourceLocation LParenLoc,
                           Expr **Args, unsigned NumArgs,
                           SourceLocation RParenLoc,
                           SourceLocation EllipsisLoc) {
   return BuildMemInitializer(ConstructorD, S, SS, MemberOrBase, TemplateTypeTy,
-                             IdLoc, MultiInitializer(LParenLoc, Args, NumArgs,
-                                                     RParenLoc),
+                             DS, IdLoc, MultiInitializer(LParenLoc, Args, 
+                                                         NumArgs, RParenLoc),
                              EllipsisLoc);
 }
 
@@ -1779,6 +1782,7 @@ Sema::BuildMemInitializer(Decl *ConstructorD,
                           CXXScopeSpec &SS,
                           IdentifierInfo *MemberOrBase,
                           ParsedType TemplateTypeTy,
+                          const DeclSpec &DS,
                           SourceLocation IdLoc,
                           const MultiInitializer &Args,
                           SourceLocation EllipsisLoc) {
@@ -1831,6 +1835,8 @@ Sema::BuildMemInitializer(Decl *ConstructorD,
 
   if (TemplateTypeTy) {
     BaseType = GetTypeFromParser(TemplateTypeTy, &TInfo);
+  } else if (DS.getTypeSpecType() == TST_decltype) {
+    BaseType = BuildDecltypeType(DS.getRepAsExpr(), DS.getTypeSpecTypeLoc());
   } else {
     LookupResult R(*this, MemberOrBase, IdLoc, LookupOrdinaryName);
     LookupParsedName(R, S, &SS);

test/SemaCXX/class-base-member-init.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -std=c++11 -verify %s
 
 class S {
 public:
@@ -74,3 +74,19 @@ namespace test4 {
     A(long _) : a(0), d(0) {} // expected-error {{initializing multiple members of union}} expected-note {{previous initialization is here}}
   };
 }
+
+namespace test5 {
+  struct Base {
+    Base(int);
+  };
+  struct A : Base {
+    A() : decltype(Base(1))(3) {
+    }
+    A(int) : Base(3), // expected-note {{previous initialization is here}}
+             decltype(Base(1))(2), // expected-error {{multiple initializations given for base 'decltype(test5::Base(1))' (aka 'test5::Base')}}
+             decltype(int())() { // expected-error {{constructor initializer 'decltype(int())' (aka 'int') does not name a class}}
+    }
+    A(float) : decltype(A())(3) {
+    }
+  };
+}