EDG front end error on re-entrant evaluation of a consteval function used as constraint.

[zaides-blackduck]

Issue Summary

The code below compiles with GCC but fails with Clang.
Re-entrant evaluation of a copy-constructor with consteval caused an error.

Reproducing Source Code

`#include

struct Action
{
Action() = default;
template
Action(F f);
};

template
struct Matcher
{
Matcher() = default;
Matcher(T value);
};

using Elem = const Action&;
using Tup = std::tuple;
using MTup = Matcher<const Tup&>;

int main()
{
MTup src{};
MTup dst = src;
}`

Command-line Options

--g++ --gnu_version 150100 --c++23

Type of Issue

[Front End] This code SHOULD compile with these options.

Additional Details

This issue is reproducible on [https://godbolt.org/]

Errors:
"/cefs/38/383ad2f84cbd57a52fd68bbe_consolidated/compilers_c++_x86_gcc_16.1.0/include/c++/16.1.0/type_traits", line 1232: error: template constraint not satisfied
= __bool_constant<__is_constructible(_Tp, _Args...)>;
^
"/cefs/38/383ad2f84cbd57a52fd68bbe_consolidated/compilers_c++_x86_gcc_16.1.0/include/c++/16.1.0/tuple", line 981: note: substitution of arguments "<Matcher<const Tup &> &>" for requires-clause failed
&& (!__dangles<_UTypes...>())
^
"/cefs/38/383ad2f84cbd57a52fd68bbe_consolidated/compilers_c++_x86_gcc_16.1.0/include/c++/16.1.0/tuple", line 980: note: atomic constraint not constant
&& (__constructible<_UTypes...>())
^
"/cefs/38/383ad2f84cbd57a52fd68bbe_consolidated/compilers_c++_x86_gcc_16.1.0/include/c++/16.1.0/tuple", line 980: note: this call cannot be evaluated because the target function function "std::tuple<_Elements...>::__constructible<_UTypes...>() [with _Elements=, _UTypes=<Matcher<const Tup &> &>]" (declared at line 840 of "/cefs/38/383ad2f84cbd57a52fd68bbe_consolidated/compilers_c++_x86_gcc_16.1.0/include/c++/16.1.0/tuple") is not constexpr or not completely defined yet
&& (__constructible<_UTypes...>())
^
detected during:
instantiation of type "std::__is_constructible_impl<Elem, Matcher<const Tup &> &>" at line 1238
instantiation of class "std::is_constructible<_Tp, _Args...> [with _Tp=Elem, _Args=<Matcher<const Tup &> &>]" at line 207
instantiation of class "std::_and<_Bn...> [with _Bn=<std::is_constructible<Elem, Matcher<const Tup &> &>>]" at line 222
instantiation of "const bool std::__and_v [with _Bn=<std::is_constructible<Elem, Matcher<const Tup &> &>>]" at line 843 of "/cefs/38/383ad2f84cbd57a52fd68bbe_consolidated/compilers_c++_x86_gcc_16.1.0/include/c++/16.1.0/tuple"
instantiation of "bool std::tuple<_Elements...>::__constructible<_UTypes...>() [with _Elements=, _UTypes=<Matcher<const Tup &> &>]" at line 24 of ""

"", line 24: warning: variable "dst" was set but never used
MTup dst = src;
^

1 error detected in the compilation of "".
Compiler returned: 2

Reproducing (Standard) Configuration(s)

linux-gcc-release

Reproducing (Non-standard) Configuration

No response

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