Revert "[libc++][Clang] Added explanation why is_constructible evaluated to false. Updated the diagnostics checks in libc++ tests. (#144220)"

This reverts commit e476f96.

It has introduced a failure tracked by llvm/llvm-project#150601

One libcxx test fail if libcxx is build with no exceptions and no RTTI:
 - libcxx/utilities/expected/expected.expected/value.observers.verify.cpp

Author: vhscampos

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -1812,10 +1812,7 @@ 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}|"
-           "%FunctionType{is a function type}|"
-           "%CVVoidType{is a cv void type}|"
-           "%IncompleteArrayType{is an incomplete array type}"
+           "%sub{select_special_member_kind}1}"
            "}0">;
 
 def warn_consteval_if_always_true : Warning<

clang/lib/Sema/SemaTypeTraits.cpp

@@ -11,9 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/AST/DeclCXX.h"
-#include "clang/AST/TemplateBase.h"
 #include "clang/AST/Type.h"
-#include "clang/Basic/DiagnosticIDs.h"
 #include "clang/Basic/DiagnosticParse.h"
 #include "clang/Basic/DiagnosticSema.h"
 #include "clang/Basic/TypeTraits.h"
@@ -1965,7 +1963,6 @@ static std::optional<TypeTrait> StdNameToTypeTrait(StringRef Name) {
       .Case("is_assignable", TypeTrait::BTT_IsAssignable)
       .Case("is_empty", TypeTrait::UTT_IsEmpty)
       .Case("is_standard_layout", TypeTrait::UTT_IsStandardLayout)
-      .Case("is_constructible", TypeTrait::TT_IsConstructible)
       .Default(std::nullopt);
 }
 
@@ -2002,16 +1999,8 @@ static ExtractedTypeTraitInfo ExtractTypeTraitFromExpression(const Expr *E) {
     Trait = StdNameToTypeTrait(Name);
     if (!Trait)
       return std::nullopt;
-    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");
-      }
-    }
+    for (const auto &Arg : VD->getTemplateArgs().asArray())
+      Args.push_back(Arg.getAsType());
     return {{Trait.value(), std::move(Args)}};
   }
 
@@ -2284,60 +2273,6 @@ 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)
@@ -2624,9 +2559,6 @@ void Sema::DiagnoseTypeTraitDetails(const Expr *E) {
   case UTT_IsStandardLayout:
     DiagnoseNonStandardLayoutReason(*this, E->getBeginLoc(), Args[0]);
     break;
-  case TT_IsConstructible:
-    DiagnoseNonConstructibleReason(*this, E->getBeginLoc(), Args);
-    break;
   default:
     break;
   }

clang/test/CXX/drs/cwg18xx.cpp

@@ -564,12 +564,11 @@ struct A {
 namespace ex2 {
 #if __cplusplus >= 201103L
 struct Bar {
-  struct Baz { // #cwg1890-Baz
+  struct Baz {
     int a = 0;
   };
   static_assert(__is_constructible(Baz), "");
   // since-cxx11-error@-1 {{static assertion failed due to requirement '__is_constructible(cwg1890::ex2::Bar::Baz)'}}
-  // since-cxx11-note@#cwg1890-Baz {{'Baz' defined here}}
 };
 #endif
 } // namespace ex2

clang/test/SemaCXX/overload-resolution-deferred-templates.cpp

@@ -80,30 +80,21 @@ struct ImplicitlyCopyable {
 static_assert(__is_constructible(ImplicitlyCopyable, const ImplicitlyCopyable&));
 
 
-struct Movable { // #Movable
+struct Movable {
   template <typename T>
   requires __is_constructible(Movable, T) // #err-self-constraint-1
-  explicit Movable(T op) noexcept; // #Movable1
-  Movable(Movable&&) noexcept = default; // #Movable2
+  explicit Movable(T op) noexcept; // #1
+  Movable(Movable&&) noexcept = default; // #2
 };
 static_assert(__is_constructible(Movable, Movable&&));
 static_assert(__is_constructible(Movable, const Movable&));
-// expected-error@-1 {{static assertion failed due to requirement '__is_constructible(Movable, const Movable &)'}} \
-// expected-error@-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]}}
-
+// expected-error@-1 {{static assertion failed due to requirement '__is_constructible(Movable, const Movable &)'}}
 
 static_assert(__is_constructible(Movable, int));
-// expected-error@-1 {{static assertion failed due to requirement '__is_constructible(Movable, int)'}} \
-// expected-error@-1 {{no matching constructor for initialization of 'Movable'}} \
+// expected-error@-1{{static assertion failed due to requirement '__is_constructible(Movable, int)'}} \
 // expected-note@-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 {

clang/test/SemaCXX/type-traits-unsatisfied-diags-std.cpp

@@ -42,14 +42,6 @@ static constexpr bool value = __is_standard_layout(T);
 };
 template <typename T>
 constexpr bool is_standard_layout_v = __is_standard_layout(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
@@ -105,17 +97,6 @@ template <typename T>
 using is_standard_layout = __details_is_standard_layout<T>;
 template <typename T>
 constexpr bool is_standard_layout_v = __is_standard_layout(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
 
 
@@ -168,15 +149,6 @@ template <typename T>
 using is_standard_layout = __details_is_standard_layout<T>;
 template <typename T>
 constexpr bool is_standard_layout_v = is_standard_layout<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
 
 }
@@ -239,15 +211,6 @@ static_assert(std::is_assignable_v<int&, void>);
 // expected-error@-1 {{static assertion failed due to requirement 'std::is_assignable_v<int &, void>'}} \
 // expected-error@-1 {{assigning to 'int' from incompatible type 'void'}}
 
-static_assert(std::is_constructible<int, int>::value);
-
-static_assert(std::is_constructible<void>::value);
-// expected-error-re@-1 {{static assertion failed due to requirement 'std::{{.*}}is_constructible<void>::value'}} \
-// expected-note@-1 {{because it is a cv void type}}
-static_assert(std::is_constructible_v<void>);
-// expected-error@-1 {{static assertion failed due to requirement 'std::is_constructible_v<void>'}} \
-// expected-note@-1 {{because it is a cv void type}}
-
 namespace test_namespace {
     using namespace std;
     static_assert(is_trivially_relocatable<int&>::value);
@@ -293,13 +256,6 @@ namespace test_namespace {
     // expected-error@-1 {{static assertion failed due to requirement 'is_empty_v<int &>'}} \
     // expected-note@-1 {{'int &' is not empty}} \
     // expected-note@-1 {{because it is a reference type}}
-
-    static_assert(is_constructible<void>::value);
-    // expected-error-re@-1 {{static assertion failed due to requirement '{{.*}}is_constructible<void>::value'}} \
-    // expected-note@-1 {{because it is a cv void type}}
-    static_assert(is_constructible_v<void>);
-    // expected-error@-1 {{static assertion failed due to requirement 'is_constructible_v<void>'}} \
-    // expected-note@-1 {{because it is a cv void type}}
 }
 
 
@@ -328,15 +284,6 @@ concept C4 = std::is_assignable_v<T, U>; // #concept8
 
 template <C4<void> T> void g4();  // #cand8
 
-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@-1 {{no matching function for call to 'f'}} \
@@ -380,19 +327,6 @@ void test() {
     // expected-note@#cand8 {{because 'C4<int &, void>' evaluated to false}} \
     // expected-note@#concept8 {{because 'std::is_assignable_v<int &, void>' evaluated to false}} \
     // expected-error@#concept8 {{assigning to 'int' from incompatible type 'void'}}
-
-    f3<void>();
-    // expected-error@-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@-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}}
 }
 }
 

clang/test/SemaCXX/type-traits-unsatisfied-diags.cpp

@@ -489,68 +489,6 @@ static_assert(__is_trivially_copyable(S12));
 // 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@-1 {{static assertion failed due to requirement '__is_constructible(constructible::S1, char *)'}} \
-// expected-error@-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@-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@-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@-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@-1{{because it is a cv void type}} \
-// expected-error@-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@-1 {{static assertion failed due to requirement '__is_constructible(int[])'}} \
-// expected-note@-1 {{because it is an incomplete array type}}
-
-static_assert(__is_constructible(void));
-// expected-error@-1 {{static assertion failed due to requirement '__is_constructible(void)'}} \
-// expected-note@-1 {{because it is a cv void type}}
-
-static_assert(__is_constructible(void, void));
-// expected-error@-1 {{static assertion failed due to requirement '__is_constructible(void, void)'}} \
-// expected-note@-1 {{because it is a cv void type}}
-
-static_assert(__is_constructible(const void));
-// expected-error@-1 {{static assertion failed due to requirement '__is_constructible(const void)'}} \
-// expected-note@-1 {{because it is a cv void type}}
-
-static_assert(__is_constructible(volatile void));
-// expected-error@-1 {{static assertion failed due to requirement '__is_constructible(volatile void)'}} \
-// expected-note@-1 {{because it is a cv void type}}
-
-static_assert(__is_constructible(int ()));
-// expected-error@-1 {{static assertion failed due to requirement '__is_constructible(int ())'}} \
-// expected-note@-1 {{because it is a function type}}
-
-static_assert(__is_constructible(void (int, float)));
-// expected-error@-1 {{static assertion failed due to requirement '__is_constructible(void (int, float))'}} \
-// expected-note@-1 {{because it is a function type}}
-}
-
 namespace assignable {
 struct S1;
 static_assert(__is_assignable(S1&, const S1&));

libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp

@@ -55,7 +55,6 @@ void test() {
       // expected-error-re@*:* {{static assertion failed {{.*}}The result of f(value()) must be a specialization of std::expected}}
       // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
       // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
-      // expected-error@*:* 0-1{{excess elements in struct initializer}}
     }
 
     // !std::is_same_v<U:error_type, E>
@@ -75,7 +74,6 @@ void test() {
       // expected-error-re@*:* {{static assertion failed {{.*}}The result of f(value()) must be a specialization of std::expected}}
       // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
       // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
-      // expected-error@*:* 0-1{{excess elements in struct initializer}}
     }
 
     // !std::is_same_v<U:error_type, E>
@@ -96,7 +94,6 @@ void test() {
       // expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(value())) must be a specialization of std::expected}}
       // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
       // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
-      // expected-error@*:* 0-1{{excess elements in struct initializer}}
     }
 
     // !std::is_same_v<U:error_type, E>
@@ -116,7 +113,6 @@ void test() {
       // expected-error-re@*:* {{static assertion failed {{.*}}The result of f(std::move(value())) must be a specialization of std::expected}}
       // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
       // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
-      // expected-error@*:* 0-1{{excess elements in struct initializer}}
     }
 
     // !std::is_same_v<U:error_type, E>