[clang] 02b6ed0 - [Clang] Added explanation why `is_constructible` evaluated to false. (#143309)
via cfe-commits
cfe-commits at lists.llvm.org
Fri Jun 13 00:53:18 PDT 2025
Author: Shamshura Egor
Date: 2025-06-13T09:53:15+02:00
New Revision: 02b6ed0bf139518c704a2996418e66f3a93260a1
URL: https://github.com/llvm/llvm-project/commit/02b6ed0bf139518c704a2996418e66f3a93260a1
DIFF: https://github.com/llvm/llvm-project/commit/02b6ed0bf139518c704a2996418e66f3a93260a1.diff
LOG: [Clang] Added explanation why `is_constructible` evaluated to false. (#143309)
Added explanation why a is constructible evaluated to false. Also fixed
problem with ```ExtractTypeTraitFromExpression```. In case
```std::is_xxx_v<>``` with variadic pack it tries to get template
argument, but fails in expression ```Arg.getAsType()``` due to
```Arg.getKind() == TemplateArgument::ArgKind::Pack```, but not
```TemplateArgument::ArgKind::Type```.
Added:
Modified:
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaTypeTraits.cpp
clang/test/CXX/drs/cwg18xx.cpp
clang/test/SemaCXX/overload-resolution-deferred-templates.cpp
clang/test/SemaCXX/type-traits-unsatisfied-diags-std.cpp
clang/test/SemaCXX/type-traits-unsatisfied-diags.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 0f77083dac9df..a2cf84d024193 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1767,7 +1767,8 @@ def note_unsatisfied_trait
: Note<"%0 is not %enum_select<TraitName>{"
"%TriviallyRelocatable{trivially relocatable}|"
"%Replaceable{replaceable}|"
- "%TriviallyCopyable{trivially copyable}"
+ "%TriviallyCopyable{trivially copyable}|"
+ "%Constructible{constructible with provided types}"
"}1">;
def note_unsatisfied_trait_reason
@@ -1797,7 +1798,10 @@ def note_unsatisfied_trait_reason
"%DeletedAssign{has a deleted %select{copy|move}1 "
"assignment operator}|"
"%UnionWithUserDeclaredSMF{is a union with a user-declared "
- "%sub{select_special_member_kind}1}"
+ "%sub{select_special_member_kind}1}|"
+ "%FunctionType{is a function type}|"
+ "%CVVoidType{is a cv void type}|"
+ "%IncompleteArrayType{is an incomplete array type}"
"}0">;
def warn_consteval_if_always_true : Warning<
diff --git a/clang/lib/Sema/SemaTypeTraits.cpp b/clang/lib/Sema/SemaTypeTraits.cpp
index 1738ab4466001..22c690bedc1ed 100644
--- a/clang/lib/Sema/SemaTypeTraits.cpp
+++ b/clang/lib/Sema/SemaTypeTraits.cpp
@@ -11,6 +11,7 @@
//===----------------------------------------------------------------------===//
#include "clang/AST/DeclCXX.h"
+#include "clang/AST/TemplateBase.h"
#include "clang/AST/Type.h"
#include "clang/Basic/DiagnosticParse.h"
#include "clang/Basic/DiagnosticSema.h"
@@ -1947,6 +1948,7 @@ static std::optional<TypeTrait> StdNameToTypeTrait(StringRef Name) {
TypeTrait::UTT_IsCppTriviallyRelocatable)
.Case("is_replaceable", TypeTrait::UTT_IsReplaceable)
.Case("is_trivially_copyable", TypeTrait::UTT_IsTriviallyCopyable)
+ .Case("is_constructible", TypeTrait::TT_IsConstructible)
.Default(std::nullopt);
}
@@ -1983,8 +1985,16 @@ static ExtractedTypeTraitInfo ExtractTypeTraitFromExpression(const Expr *E) {
Trait = StdNameToTypeTrait(Name);
if (!Trait)
return std::nullopt;
- for (const auto &Arg : VD->getTemplateArgs().asArray())
- Args.push_back(Arg.getAsType());
+ for (const auto &Arg : VD->getTemplateArgs().asArray()) {
+ if (Arg.getKind() == TemplateArgument::ArgKind::Pack) {
+ for (const auto &InnerArg : Arg.pack_elements())
+ Args.push_back(InnerArg.getAsType());
+ } else if (Arg.getKind() == TemplateArgument::ArgKind::Type) {
+ Args.push_back(Arg.getAsType());
+ } else {
+ llvm_unreachable("Unexpected kind");
+ }
+ }
return {{Trait.value(), std::move(Args)}};
}
@@ -2257,6 +2267,60 @@ static void DiagnoseNonTriviallyCopyableReason(Sema &SemaRef,
}
}
+static void DiagnoseNonConstructibleReason(
+ Sema &SemaRef, SourceLocation Loc,
+ const llvm::SmallVector<clang::QualType, 1> &Ts) {
+ if (Ts.empty()) {
+ return;
+ }
+
+ bool ContainsVoid = false;
+ for (const QualType &ArgTy : Ts) {
+ ContainsVoid |= ArgTy->isVoidType();
+ }
+
+ if (ContainsVoid)
+ SemaRef.Diag(Loc, diag::note_unsatisfied_trait_reason)
+ << diag::TraitNotSatisfiedReason::CVVoidType;
+
+ QualType T = Ts[0];
+ if (T->isFunctionType())
+ SemaRef.Diag(Loc, diag::note_unsatisfied_trait_reason)
+ << diag::TraitNotSatisfiedReason::FunctionType;
+
+ if (T->isIncompleteArrayType())
+ SemaRef.Diag(Loc, diag::note_unsatisfied_trait_reason)
+ << diag::TraitNotSatisfiedReason::IncompleteArrayType;
+
+ const CXXRecordDecl *D = T->getAsCXXRecordDecl();
+ if (!D || D->isInvalidDecl() || !D->hasDefinition())
+ return;
+
+ llvm::BumpPtrAllocator OpaqueExprAllocator;
+ SmallVector<Expr *, 2> ArgExprs;
+ ArgExprs.reserve(Ts.size() - 1);
+ for (unsigned I = 1, N = Ts.size(); I != N; ++I) {
+ QualType ArgTy = Ts[I];
+ if (ArgTy->isObjectType() || ArgTy->isFunctionType())
+ ArgTy = SemaRef.Context.getRValueReferenceType(ArgTy);
+ ArgExprs.push_back(
+ new (OpaqueExprAllocator.Allocate<OpaqueValueExpr>())
+ OpaqueValueExpr(Loc, ArgTy.getNonLValueExprType(SemaRef.Context),
+ Expr::getValueKindForType(ArgTy)));
+ }
+
+ EnterExpressionEvaluationContext Unevaluated(
+ SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
+ Sema::ContextRAII TUContext(SemaRef,
+ SemaRef.Context.getTranslationUnitDecl());
+ InitializedEntity To(InitializedEntity::InitializeTemporary(T));
+ InitializationKind InitKind(InitializationKind::CreateDirect(Loc, Loc, Loc));
+ InitializationSequence Init(SemaRef, To, InitKind, ArgExprs);
+
+ Init.Diagnose(SemaRef, To, InitKind, ArgExprs);
+ SemaRef.Diag(D->getLocation(), diag::note_defined_here) << D;
+}
+
static void DiagnoseNonTriviallyCopyableReason(Sema &SemaRef,
SourceLocation Loc, QualType T) {
SemaRef.Diag(Loc, diag::note_unsatisfied_trait)
@@ -2296,6 +2360,9 @@ void Sema::DiagnoseTypeTraitDetails(const Expr *E) {
case UTT_IsTriviallyCopyable:
DiagnoseNonTriviallyCopyableReason(*this, E->getBeginLoc(), Args[0]);
break;
+ case TT_IsConstructible:
+ DiagnoseNonConstructibleReason(*this, E->getBeginLoc(), Args);
+ break;
default:
break;
}
diff --git a/clang/test/CXX/drs/cwg18xx.cpp b/clang/test/CXX/drs/cwg18xx.cpp
index 5b4551ba0143b..9948075852135 100644
--- a/clang/test/CXX/drs/cwg18xx.cpp
+++ b/clang/test/CXX/drs/cwg18xx.cpp
@@ -564,11 +564,12 @@ struct A {
namespace ex2 {
#if __cplusplus >= 201103L
struct Bar {
- struct Baz {
+ struct Baz { // #cwg1890-Baz
int a = 0;
};
static_assert(__is_constructible(Baz), "");
// since-cxx11-error at -1 {{static assertion failed due to requirement '__is_constructible(cwg1890::ex2::Bar::Baz)'}}
+ // since-cxx11-note@#cwg1890-Baz {{'Baz' defined here}}
};
#endif
} // namespace ex2
diff --git a/clang/test/SemaCXX/overload-resolution-deferred-templates.cpp b/clang/test/SemaCXX/overload-resolution-deferred-templates.cpp
index 7cb71e075d50e..46c3670848529 100644
--- a/clang/test/SemaCXX/overload-resolution-deferred-templates.cpp
+++ b/clang/test/SemaCXX/overload-resolution-deferred-templates.cpp
@@ -80,21 +80,30 @@ struct ImplicitlyCopyable {
static_assert(__is_constructible(ImplicitlyCopyable, const ImplicitlyCopyable&));
-struct Movable {
+struct Movable { // #Movable
template <typename T>
requires __is_constructible(Movable, T) // #err-self-constraint-1
- explicit Movable(T op) noexcept; // #1
- Movable(Movable&&) noexcept = default; // #2
+ explicit Movable(T op) noexcept; // #Movable1
+ Movable(Movable&&) noexcept = default; // #Movable2
};
static_assert(__is_constructible(Movable, Movable&&));
static_assert(__is_constructible(Movable, const Movable&));
-// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(Movable, const Movable &)'}}
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(Movable, const Movable &)'}} \
+// expected-error at -1 {{call to implicitly-deleted copy constructor of 'Movable'}} \
+// expected-note@#Movable {{'Movable' defined here}} \
+// expected-note@#Movable {{candidate constructor (the implicit copy constructor) not viable: no known conversion from 'int' to 'const Movable' for 1st argument}} \
+// expected-note@#Movable2 {{copy constructor is implicitly deleted because 'Movable' has a user-declared move constructor}} \
+// expected-note@#Movable2 {{candidate constructor not viable: no known conversion from 'int' to 'Movable' for 1st argument}} \
+// expected-note@#Movable1 {{candidate template ignored: constraints not satisfied [with T = int]}}
+
static_assert(__is_constructible(Movable, int));
-// expected-error at -1{{static assertion failed due to requirement '__is_constructible(Movable, int)'}} \
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(Movable, int)'}} \
+// expected-error at -1 {{no matching constructor for initialization of 'Movable'}} \
// expected-note at -1 2{{}}
// expected-error@#err-self-constraint-1{{satisfaction of constraint '__is_constructible(Movable, T)' depends on itself}}
// expected-note@#err-self-constraint-1 4{{}}
+// expected-note@#Movable {{'Movable' defined here}}
template <typename T>
struct Members {
diff --git a/clang/test/SemaCXX/type-traits-unsatisfied-diags-std.cpp b/clang/test/SemaCXX/type-traits-unsatisfied-diags-std.cpp
index 329b611110c1d..a403a0450607a 100644
--- a/clang/test/SemaCXX/type-traits-unsatisfied-diags-std.cpp
+++ b/clang/test/SemaCXX/type-traits-unsatisfied-diags-std.cpp
@@ -20,6 +20,14 @@ struct is_trivially_copyable {
template <typename T>
constexpr bool is_trivially_copyable_v = __is_trivially_copyable(T);
+
+template <typename... Args>
+struct is_constructible {
+ static constexpr bool value = __is_constructible(Args...);
+};
+
+template <typename... Args>
+constexpr bool is_constructible_v = __is_constructible(Args...);
#endif
#ifdef STD2
@@ -44,6 +52,17 @@ using is_trivially_copyable = __details_is_trivially_copyable<T>;
template <typename T>
constexpr bool is_trivially_copyable_v = __is_trivially_copyable(T);
+
+template <typename... Args>
+struct __details_is_constructible{
+ static constexpr bool value = __is_constructible(Args...);
+};
+
+template <typename... Args>
+using is_constructible = __details_is_constructible<Args...>;
+
+template <typename... Args>
+constexpr bool is_constructible_v = __is_constructible(Args...);
#endif
@@ -73,6 +92,15 @@ using is_trivially_copyable = __details_is_trivially_copyable<T>;
template <typename T>
constexpr bool is_trivially_copyable_v = is_trivially_copyable<T>::value;
+
+template <typename... Args>
+struct __details_is_constructible : bool_constant<__is_constructible(Args...)> {};
+
+template <typename... Args>
+using is_constructible = __details_is_constructible<Args...>;
+
+template <typename... Args>
+constexpr bool is_constructible_v = is_constructible<Args...>::value;
#endif
}
@@ -100,6 +128,15 @@ static_assert(std::is_trivially_copyable_v<int&>);
// expected-note at -1 {{because it is a reference type}}
+static_assert(std::is_constructible<int, int>::value);
+
+static_assert(std::is_constructible<void>::value);
+// expected-error-re at -1 {{static assertion failed due to requirement 'std::{{.*}}is_constructible<void>::value'}} \
+// expected-note at -1 {{because it is a cv void type}}
+static_assert(std::is_constructible_v<void>);
+// expected-error at -1 {{static assertion failed due to requirement 'std::is_constructible_v<void>'}} \
+// expected-note at -1 {{because it is a cv void type}}
+
namespace test_namespace {
using namespace std;
static_assert(is_trivially_relocatable<int&>::value);
@@ -119,6 +156,13 @@ namespace test_namespace {
// expected-error at -1 {{static assertion failed due to requirement 'is_trivially_copyable_v<int &>'}} \
// expected-note at -1 {{'int &' is not trivially copyable}} \
// expected-note at -1 {{because it is a reference type}}
+
+ static_assert(is_constructible<void>::value);
+ // expected-error-re at -1 {{static assertion failed due to requirement '{{.*}}is_constructible<void>::value'}} \
+ // expected-note at -1 {{because it is a cv void type}}
+ static_assert(is_constructible_v<void>);
+ // expected-error at -1 {{static assertion failed due to requirement 'is_constructible_v<void>'}} \
+ // expected-note at -1 {{because it is a cv void type}}
}
@@ -139,6 +183,15 @@ concept C2 = std::is_trivially_copyable_v<T>; // #concept4
template <C2 T> void g2(); // #cand4
+template <typename... Args>
+requires std::is_constructible<Args...>::value void f3(); // #cand5
+
+template <typename... Args>
+concept C3 = std::is_constructible_v<Args...>; // #concept6
+
+template <C3 T> void g3(); // #cand6
+
+
void test() {
f<int&>();
// expected-error at -1 {{no matching function for call to 'f'}} \
@@ -169,6 +222,19 @@ void test() {
// expected-note@#concept4 {{because 'std::is_trivially_copyable_v<int &>' evaluated to false}} \
// expected-note@#concept4 {{'int &' is not trivially copyable}} \
// expected-note@#concept4 {{because it is a reference type}}
+
+ f3<void>();
+ // expected-error at -1 {{no matching function for call to 'f3'}} \
+ // expected-note@#cand5 {{candidate template ignored: constraints not satisfied [with Args = <void>]}} \
+ // expected-note-re@#cand5 {{because '{{.*}}is_constructible<void>::value' evaluated to false}} \
+ // expected-note@#cand5 {{because it is a cv void type}}
+
+ g3<void>();
+ // expected-error at -1 {{no matching function for call to 'g3'}} \
+ // expected-note@#cand6 {{candidate template ignored: constraints not satisfied [with T = void]}} \
+ // expected-note@#cand6 {{because 'void' does not satisfy 'C3'}} \
+ // expected-note@#concept6 {{because 'std::is_constructible_v<void>' evaluated to false}} \
+ // expected-note@#concept6 {{because it is a cv void type}}
}
}
diff --git a/clang/test/SemaCXX/type-traits-unsatisfied-diags.cpp b/clang/test/SemaCXX/type-traits-unsatisfied-diags.cpp
index a8c78f6304ca9..d0b3f294fbcab 100644
--- a/clang/test/SemaCXX/type-traits-unsatisfied-diags.cpp
+++ b/clang/test/SemaCXX/type-traits-unsatisfied-diags.cpp
@@ -488,3 +488,65 @@ static_assert(__is_trivially_copyable(S12));
// expected-note at -1 {{'S12' is not trivially copyable}} \
// expected-note@#tc-S12 {{'S12' defined here}}
}
+
+namespace constructible {
+
+struct S1 { // #c-S1
+ S1(int); // #cc-S1
+};
+static_assert(__is_constructible(S1, char*));
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(constructible::S1, char *)'}} \
+// expected-error at -1 {{no matching constructor for initialization of 'S1'}} \
+// expected-note@#c-S1 {{candidate constructor (the implicit copy constructor) not viable: no known conversion from 'char *' to 'const S1' for 1st argument}} \
+// expected-note@#c-S1 {{candidate constructor (the implicit move constructor) not viable: no known conversion from 'char *' to 'S1' for 1st argument}} \
+// expected-note@#cc-S1 {{candidate constructor not viable: no known conversion from 'char *' to 'int' for 1st argument; dereference the argument with *}} \
+// expected-note@#c-S1 {{'S1' defined here}}
+
+struct S2 { // #c-S2
+ S2(int, float, double); // #cc-S2
+};
+static_assert(__is_constructible(S2, float));
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(constructible::S2, float)'}} \
+// expected-note@#c-S2 {{candidate constructor (the implicit copy constructor) not viable: no known conversion from 'float' to 'const S2' for 1st argument}} \
+// expected-note@#c-S2 {{candidate constructor (the implicit move constructor) not viable: no known conversion from 'float' to 'S2' for 1st argument}} \
+// expected-error at -1 {{no matching constructor for initialization of 'S2'}} \
+// expected-note@#cc-S2 {{candidate constructor not viable: requires 3 arguments, but 1 was provided}} \
+// expected-note@#c-S2 {{'S2' defined here}}
+
+static_assert(__is_constructible(S2, float, void));
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(constructible::S2, float, void)'}} \
+// expected-note@#c-S2 {{candidate constructor (the implicit move constructor) not viable: requires 1 argument, but 2 were provided}} \
+// expected-note@#c-S2 {{candidate constructor (the implicit copy constructor) not viable: requires 1 argument, but 2 were provided}} \
+// expected-note at -1{{because it is a cv void type}} \
+// expected-error at -1 {{no matching constructor for initialization of 'S2'}} \
+// expected-note@#cc-S2 {{candidate constructor not viable: requires 3 arguments, but 2 were provided}} \
+// expected-note@#c-S2 {{'S2' defined here}}
+
+static_assert(__is_constructible(int[]));
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(int[])'}} \
+// expected-note at -1 {{because it is an incomplete array type}}
+
+static_assert(__is_constructible(void));
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(void)'}} \
+// expected-note at -1 {{because it is a cv void type}}
+
+static_assert(__is_constructible(void, void));
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(void, void)'}} \
+// expected-note at -1 {{because it is a cv void type}}
+
+static_assert(__is_constructible(const void));
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(const void)'}} \
+// expected-note at -1 {{because it is a cv void type}}
+
+static_assert(__is_constructible(volatile void));
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(volatile void)'}} \
+// expected-note at -1 {{because it is a cv void type}}
+
+static_assert(__is_constructible(int ()));
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(int ())'}} \
+// expected-note at -1 {{because it is a function type}}
+
+static_assert(__is_constructible(void (int, float)));
+// expected-error at -1 {{static assertion failed due to requirement '__is_constructible(void (int, float))'}} \
+// expected-note at -1 {{because it is a function type}}
+}
More information about the cfe-commits
mailing list