Hi rsmith,
MSVC delays parsing of default arguments until instantiation. If the
default argument is never used, it is never parsed. We don't model
this.
Instead, if lookup of a type name fails in a template argument context,
we form a DependentNameType, which will be looked up at instantiation
time.
This fixes errors about 'CControlWinTraits' in atlwin.h.
http://reviews.llvm.org/D3995
Files:
include/clang/AST/Type.h
include/clang/Basic/DiagnosticSemaKinds.td
include/clang/Parse/Parser.h
include/clang/Sema/Sema.h
lib/AST/ASTContext.cpp
lib/Parse/ParseDecl.cpp
lib/Sema/SemaDecl.cpp
test/SemaTemplate/ms-delayed-default-template-args.cpp
Index: include/clang/AST/Type.h
===================================================================
--- include/clang/AST/Type.h
+++ include/clang/AST/Type.h
@@ -4075,11 +4075,8 @@
: TypeWithKeyword(Keyword, DependentName, CanonType, /*Dependent=*/true,
/*InstantiationDependent=*/true,
/*VariablyModified=*/false,
- NNS->containsUnexpandedParameterPack()),
- NNS(NNS), Name(Name) {
- assert(NNS->isDependent() &&
- "DependentNameType requires a dependent nested-name-specifier");
- }
+ NNS ? NNS->containsUnexpandedParameterPack() : false),
+ NNS(NNS), Name(Name) {}
friend class ASTContext; // ASTContext creates these
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -3195,6 +3195,9 @@
def ext_ms_deref_template_argument: ExtWarn<
"non-type template argument containing a dereference operation is a "
"Microsoft extension">, InGroup<Microsoft>;
+def ext_ms_delayed_template_argument: ExtWarn<
+ "using the undeclared type %0 as a default template argument is a "
+ "Microsoft extension">, InGroup<Microsoft>;
// C++ template specialization
def err_template_spec_unknown_kind : Error<
Index: include/clang/Parse/Parser.h
===================================================================
--- include/clang/Parse/Parser.h
+++ include/clang/Parse/Parser.h
@@ -1682,7 +1682,8 @@
DSC_type_specifier, // C++ type-specifier-seq or C specifier-qualifier-list
DSC_trailing, // C++11 trailing-type-specifier in a trailing return type
DSC_alias_declaration, // C++11 type-specifier-seq in an alias-declaration
- DSC_top_level // top-level/namespace declaration context
+ DSC_top_level, // top-level/namespace declaration context
+ DSC_template_type_arg // template type argument context
};
/// Is this a context in which we are parsing just a type-specifier (or
@@ -1694,6 +1695,7 @@
case DSC_top_level:
return false;
+ case DSC_template_type_arg:
case DSC_type_specifier:
case DSC_trailing:
case DSC_alias_declaration:
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -1418,6 +1418,13 @@
ParsedType &SuggestedType,
bool AllowClassTemplates = false);
+ /// \brief For compatibility with MSVC, we delay parsing of some default
+ /// template type arguments until instantiation time. Emits a warning and
+ /// returns a synthesized DependentNameType that isn't really dependent on any
+ /// other template arguments.
+ ParsedType ActOnDelayedDefaultTemplateArg(const IdentifierInfo &II,
+ SourceLocation NameLoc);
+
/// \brief Describes the result of the name lookup and resolution performed
/// by \c ClassifyName().
enum NameClassificationKind {
Index: lib/AST/ASTContext.cpp
===================================================================
--- lib/AST/ASTContext.cpp
+++ lib/AST/ASTContext.cpp
@@ -3318,8 +3318,6 @@
NestedNameSpecifier *NNS,
const IdentifierInfo *Name,
QualType Canon) const {
- assert(NNS->isDependent() && "nested-name-specifier must be dependent");
-
if (Canon.isNull()) {
NestedNameSpecifier *CanonNNS = getCanonicalNestedNameSpecifier(NNS);
ElaboratedTypeKeyword CanonKeyword = Keyword;
Index: lib/Parse/ParseDecl.cpp
===================================================================
--- lib/Parse/ParseDecl.cpp
+++ lib/Parse/ParseDecl.cpp
@@ -2227,6 +2227,8 @@
return DSC_class;
if (Context == Declarator::FileContext)
return DSC_top_level;
+ if (Context == Declarator::TemplateTypeArgContext)
+ return DSC_template_type_arg;
if (Context == Declarator::TrailingReturnContext)
return DSC_trailing;
if (Context == Declarator::AliasDeclContext ||
@@ -2753,6 +2755,17 @@
Actions.getTypeName(*Tok.getIdentifierInfo(),
Tok.getLocation(), getCurScope());
+ // MSVC: If we weren't able to parse a default template argument, and it's
+ // just a simple identifier, create a DependentNameType. This will allow us
+ // to defer the name lookup to template instantiation time, as long we forge a
+ // NestedNameSpecifier for the current context.
+ if (!TypeRep && getLangOpts().MSVCCompat &&
+ getCurScope()->isTemplateParamScope() &&
+ DSContext == DSC_template_type_arg) {
+ TypeRep = Actions.ActOnDelayedDefaultTemplateArg(
+ *Tok.getIdentifierInfo(), Tok.getLocation());
+ }
+
// If this is not a typedef name, don't parse it as part of the declspec,
// it must be an implicit int or an error.
if (!TypeRep) {
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -343,6 +343,49 @@
return ParsedType::make(T);
}
+// Builds a fake NNS for the given decl context.
+static NestedNameSpecifier *
+synthesizeCurrentNestedNameSpecifier(ASTContext &Context, DeclContext *DC,
+ NestedNameSpecifier *NNS = nullptr) {
+ if (!DC)
+ return NNS;
+ DC = DC->getPrimaryContext();
+ NestedNameSpecifier *SubNNS = synthesizeCurrentNestedNameSpecifier(
+ Context, DC->getLookupParent(), NNS);
+ NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC);
+ if (ND && !ND->isInline() && !ND->isAnonymousNamespace())
+ return NestedNameSpecifier::Create(Context, SubNNS, ND);
+ else if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(DC))
+ return NestedNameSpecifier::Create(Context, SubNNS, RD->isTemplateDecl(),
+ RD->getTypeForDecl());
+ return SubNNS;
+}
+
+ParsedType Sema::ActOnDelayedDefaultTemplateArg(const IdentifierInfo &II,
+ SourceLocation NameLoc) {
+ Diag(NameLoc, diag::ext_ms_delayed_template_argument) << &II;
+
+ // Build a fake NNS for the current decl context.
+ NestedNameSpecifier *NNS =
+ synthesizeCurrentNestedNameSpecifier(Context, CurContext);
+
+ // Build a QualType.
+ QualType T = Context.getDependentNameType(ETK_None, NNS, &II);
+
+ // Build type location information. We synthesized the qualifier, so we have
+ // to build a fake NestedNameSpecifierLoc.
+ NestedNameSpecifierLocBuilder NNSLocBuilder;
+ NNSLocBuilder.MakeTrivial(Context, NNS, SourceRange(NameLoc));
+ NestedNameSpecifierLoc QualifierLoc = NNSLocBuilder.getWithLocInContext(Context);
+
+ TypeLocBuilder Builder;
+ DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
+ DepTL.setNameLoc(NameLoc);
+ DepTL.setElaboratedKeywordLoc(SourceLocation());
+ DepTL.setQualifierLoc(QualifierLoc);
+ return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
+}
+
/// isTagName() - This method is called *for error recovery purposes only*
/// to determine if the specified name is a valid tag name ("struct foo"). If
/// so, this returns the TST for the tag corresponding to it (TST_enum,
Index: test/SemaTemplate/ms-delayed-default-template-args.cpp
===================================================================
--- /dev/null
+++ test/SemaTemplate/ms-delayed-default-template-args.cpp
@@ -0,0 +1,45 @@
+// RUN: %clang_cc1 -fms-compatibility -std=c++11 %s -verify
+
+// MSVC should compile this file without errors.
+
+namespace test_basic {
+template <typename T = Baz> // expected-warning {{using the undeclared type 'Baz' as a default template argument is a Microsoft extension}}
+struct Foo { T x; };
+typedef int Baz;
+template struct Foo<>;
+}
+
+namespace test_nested {
+namespace nested {
+template <typename T = Baz> // expected-warning {{using the undeclared type 'Baz' as a default template argument is a Microsoft extension}}
+struct Foo {
+ static_assert(sizeof(T) == 4, "should get int, not double");
+};
+typedef int Baz;
+}
+typedef double Baz;
+template struct nested::Foo<>;
+}
+
+#ifdef __clang__
+// These are negative test cases that MSVC doesn't compile either.
+
+namespace test_undeclared_nontype_parm_type {
+template <Qux N> // expected-error {{unknown type name 'Qux'}}
+struct Foo { int x[N]; };
+typedef int Qux;
+template struct Foo<4>;
+}
+
+namespace test_undeclared_nontype_parm_type_no_name {
+template <typename T, Asdf> // expected-error {{unknown type name 'Asdf'}}
+struct Foo { T x; };
+template struct Foo<int, 0>;
+}
+
+namespace test_undeclared_type_arg {
+template <typename T>
+struct Foo { T x; };
+template struct Foo<Yodel>; // expected-error {{use of undeclared identifier 'Yodel'}}
+}
+#endif
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