Implement C++ DR 106 and C++ DR 540, both of which deal with
reference-collapsing.
Implement diagnostic for formation of a reference to cv void.
Drop cv-qualifiers added to a reference type when the reference type
comes from a typedef.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@58612 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 93f182c..85c57f5 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -232,6 +232,17 @@
Result.getAsString(), DS.getSourceRange());
}
+ // C++ [dcl.ref]p1:
+ // Cv-qualified references are ill-formed except when the
+ // cv-qualifiers are introduced through the use of a typedef
+ // (7.1.3) or of a template type argument (14.3), in which
+ // case the cv-qualifiers are ignored.
+ if (DS.getTypeSpecType() == DeclSpec::TST_typedef &&
+ TypeQuals && Result->isReferenceType()) {
+ TypeQuals &= ~QualType::Const;
+ TypeQuals &= ~QualType::Volatile;
+ }
+
Result = Result.getQualifiedType(TypeQuals);
}
return Result;
@@ -283,13 +294,33 @@
// Apply the pointer typequals to the pointer object.
T = Context.getPointerType(T).getQualifiedType(DeclType.Ptr.TypeQuals);
break;
- case DeclaratorChunk::Reference:
- if (const ReferenceType *RT = T->getAsReferenceType()) {
- // C++ 8.3.2p4: There shall be no references to references.
- Diag(DeclType.Loc, diag::err_illegal_decl_reference_to_reference,
- D.getIdentifier() ? D.getIdentifier()->getName() : "type name");
+ case DeclaratorChunk::Reference: {
+ // Whether we should suppress the creation of the reference.
+ bool SuppressReference = false;
+ if (T->isReferenceType()) {
+ // C++ [dcl.ref]p4: There shall be no references to references.
+ //
+ // According to C++ DR 106, references to references are only
+ // diagnosed when they are written directly (e.g., "int & &"),
+ // but not when they happen via a typedef:
+ //
+ // typedef int& intref;
+ // typedef intref& intref2;
+ //
+ // Parser::ParserDeclaratorInternal diagnoses the case where
+ // references are written directly; here, we handle the
+ // collapsing of references-to-references as described in C++
+ // DR 106 and amended by C++ DR 540.
+ SuppressReference = true;
+ }
+
+ // C++ [dcl.ref]p1:
+ // A declarator that specifies the type “reference to cv void”
+ // is ill-formed.
+ if (T->isVoidType()) {
+ Diag(DeclType.Loc, diag::err_reference_to_void);
D.setInvalidType(true);
- T = RT->getPointeeType();
+ T = Context.IntTy;
}
// Enforce C99 6.7.3p2: "Types other than pointer types derived from
@@ -302,12 +333,14 @@
DeclType.Ref.HasRestrict = false;
}
- T = Context.getReferenceType(T);
+ if (!SuppressReference)
+ T = Context.getReferenceType(T);
// Handle restrict on references.
if (DeclType.Ref.HasRestrict)
T.addRestrict();
break;
+ }
case DeclaratorChunk::Array: {
DeclaratorChunk::ArrayTypeInfo &ATI = DeclType.Arr;
Expr *ArraySize = static_cast<Expr*>(ATI.NumElts);