Quuxplusone created this revision.
Quuxplusone added reviewers: ChuanqiXu, saar.raz, rsmith.
Quuxplusone added a project: clang.
Quuxplusone requested review of this revision.
Herald added a subscriber: cfe-commits.
PR52905 was originally papered over in a different way, but I believe this is
the actually proper fix, or at least closer to it. We need to detect
placeholder types as close to the front-end as possible, and cause them to fail
constraints, rather than letting them persist into later stages.
Fixes https://llvm.org/PR52905
Fixes https://llvm.org/PR52909
Fixes https://llvm.org/PR53075
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D118552
Files:
clang/lib/AST/ASTContext.cpp
clang/lib/Sema/SemaOverload.cpp
clang/lib/Sema/SemaTemplateInstantiate.cpp
clang/lib/Sema/TreeTransform.h
clang/test/SemaTemplate/constraints.cpp
clang/test/SemaTemplate/pr52909.cpp
Index: clang/test/SemaTemplate/pr52909.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaTemplate/pr52909.cpp
@@ -0,0 +1,71 @@
+// RUN: %clang_cc1 -std=c++20 -verify %s
+// RUN: %clang_cc1 -std=c++2b -verify %s
+
+namespace PR52905 {
+template <class> concept C = true;
+
+struct A {
+ int begin();
+ int begin() const;
+};
+
+template <class T>
+concept Beginable = requires (T t) {
+ { t.begin } -> C;
+ // expected-note@-1 {{because 't.begin' would be invalid: reference to non-static member function must be called}}
+};
+
+static_assert(Beginable<A>); // expected-error {{static_assert failed}}
+ // expected-note@-1 {{does not satisfy 'Beginable'}}
+} // namespace PR52905
+
+namespace PR52909a {
+
+template<class> constexpr bool B = true;
+template<class T> concept True = B<T>;
+
+template <class T>
+int foo(T t) requires requires { // expected-note {{candidate template ignored: constraints not satisfied}}
+ {t.begin} -> True; // expected-note {{because 't.begin' would be invalid: reference to non-static member function must be called}}
+}
+{}
+
+struct A { int begin(); };
+auto x = foo(A()); // expected-error {{no matching function for call to 'foo'}}
+
+} // namespace PR52909a
+
+namespace PR52909b {
+
+template<class> concept True = true;
+
+template<class T> concept C = requires {
+ { T::begin } -> True; // expected-note {{because 'T::begin' would be invalid: reference to overloaded function could not be resolved}}
+};
+
+struct A {
+ static void begin(int);
+ static void begin(double);
+};
+
+static_assert(C<A>); // expected-error {{static_assert failed}}
+ // expected-note@-1 {{because 'PR52909b::A' does not satisfy 'C'}}
+
+} // namespace PR52909b
+
+namespace PR53075 {
+template<class> concept True = true;
+
+template<class T> concept C = requires {
+ { &T::f } -> True; // expected-note {{because '&T::f' would be invalid: reference to overloaded function could not be resolved}}
+};
+
+struct S {
+ int *f();
+ int *f() const;
+};
+
+static_assert(C<S>); // expected-error {{static_assert failed}}
+ // expected-note@-1 {{because 'PR53075::S' does not satisfy 'C'}}
+
+} // namespace PR53075
Index: clang/test/SemaTemplate/constraints.cpp
===================================================================
--- clang/test/SemaTemplate/constraints.cpp
+++ clang/test/SemaTemplate/constraints.cpp
@@ -24,35 +24,3 @@
// FIXME: These diagnostics are excessive.
static_assert(test<false, char> == 1); // expected-note 2{{while}} expected-note 2{{during}}
}
-
-namespace PR52905 {
-// A mock for std::convertible_to. Not complete support.
-template <typename _From, typename _To>
-concept convertible_to = __is_convertible_to(_From, _To); // expected-note {{evaluated to false}}
-
-template <typename T>
-class A {
-public:
- using iterator = void **;
-
- iterator begin();
- const iterator begin() const;
-};
-
-template <class T>
-concept Beginable1 = requires(T t) {
- { t.begin }
- ->convertible_to<typename T::iterator>; // expected-note {{not satisfied}}
-};
-
-static_assert(Beginable1<A<int>>); // expected-error {{static_assert failed}}
- // expected-note@-1 {{does not satisfy 'Beginable1'}}
-
-template <class T>
-concept Beginable2 = requires(T t) {
- { t.begin() }
- ->convertible_to<typename T::iterator>;
-};
-
-static_assert(Beginable2<A<int>>);
-} // namespace PR52905
Index: clang/lib/Sema/TreeTransform.h
===================================================================
--- clang/lib/Sema/TreeTransform.h
+++ clang/lib/Sema/TreeTransform.h
@@ -12494,6 +12494,8 @@
TransExpr = Req->getExprSubstitutionDiagnostic();
else {
ExprResult TransExprRes = getDerived().TransformExpr(Req->getExpr());
+ if (TransExprRes.isUsable() && TransExprRes.get()->hasPlaceholderType())
+ TransExprRes = SemaRef.CheckPlaceholderExpr(TransExprRes.get());
if (TransExprRes.isInvalid())
return nullptr;
TransExpr = TransExprRes.get();
Index: clang/lib/Sema/SemaTemplateInstantiate.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1943,6 +1943,11 @@
if (ExprInst.isInvalid())
return nullptr;
ExprResult TransExprRes = TransformExpr(E);
+ if (TransExprRes.isUsable() && !Trap.hasErrorOccurred()) {
+ if (TransExprRes.get()->hasPlaceholderType()) {
+ TransExprRes = SemaRef.CheckPlaceholderExpr(TransExprRes.get());
+ }
+ }
if (TransExprRes.isInvalid() || Trap.hasErrorOccurred())
TransExpr = createSubstDiag(SemaRef, Info, [&](llvm::raw_ostream &OS) {
E->printPretty(OS, nullptr, SemaRef.getPrintingPolicy());
Index: clang/lib/Sema/SemaOverload.cpp
===================================================================
--- clang/lib/Sema/SemaOverload.cpp
+++ clang/lib/Sema/SemaOverload.cpp
@@ -14320,7 +14320,8 @@
FoundDecl = MemExpr->getFoundDecl();
Qualifier = MemExpr->getQualifier();
UnbridgedCasts.restore();
- } else if (auto *UnresExpr = dyn_cast<UnresolvedMemberExpr>(NakedMemExpr)) {
+ } else {
+ UnresolvedMemberExpr *UnresExpr = cast<UnresolvedMemberExpr>(NakedMemExpr);
Qualifier = UnresExpr->getQualifier();
QualType ObjectType = UnresExpr->getBaseType();
@@ -14433,9 +14434,7 @@
}
MemExpr = cast<MemberExpr>(MemExprE->IgnoreParens());
- } else
- // Unimaged NakedMemExpr type.
- return ExprError();
+ }
QualType ResultType = Method->getReturnType();
ExprValueKind VK = Expr::getValueKindForType(ResultType);
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -3370,8 +3370,9 @@
/// lvalue reference to the specified type.
QualType
ASTContext::getLValueReferenceType(QualType T, bool SpelledAsLValue) const {
- assert(getCanonicalType(T) != OverloadTy &&
- "Unresolved overloaded function type");
+ if (T->isPlaceholderType()) {
+ assert(T->isSpecificPlaceholderType(BuiltinType::UnknownAny) && "Unresolved placeholder type");
+ }
// Unique pointers, to guarantee there is only one pointer of a particular
// structure.
@@ -3409,6 +3410,10 @@
/// getRValueReferenceType - Return the uniqued reference to the type for an
/// rvalue reference to the specified type.
QualType ASTContext::getRValueReferenceType(QualType T) const {
+ if (T->isPlaceholderType()) {
+ assert(T->isSpecificPlaceholderType(BuiltinType::UnknownAny) && "Unresolved placeholder type");
+ }
+
// Unique pointers, to guarantee there is only one pointer of a particular
// structure.
llvm::FoldingSetNodeID ID;
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