Builtins (__add_lvalue_reference/__add_rvalue_reference/etc.) return incorrect types for CV/ref-qualified function types

[Michael137]

Issue Summary

Given following code:

template<class, class>
constexpr bool is_same_v = false;
template<class T>
constexpr bool is_same_v<T, T> = true;

template <class T> struct add_lvalue_reference { using type = __add_lvalue_reference(T); };
template <class T> struct add_rvalue_reference { using type = __add_rvalue_reference(T); };
template <class T> struct add_pointer          { using type = __add_pointer(T); };
template <class T> struct decay                { using type = __decay(T); };

using WithCVQual = void() const;
using WithRefQual = void() const;

static_assert(is_same_v<WithCVQual, typename add_lvalue_reference<WithCVQual>::type>);
static_assert(is_same_v<WithCVQual, typename add_rvalue_reference<WithCVQual>::type>);
static_assert(is_same_v<WithCVQual, typename add_pointer<WithCVQual>::type>);
static_assert(is_same_v<WithCVQual, typename decay<WithCVQual>::type>);

static_assert(is_same_v<WithRefQual, typename add_lvalue_reference<WithRefQual>::type>);
static_assert(is_same_v<WithRefQual, typename add_rvalue_reference<WithRefQual>::type>);
static_assert(is_same_v<WithRefQual, typename add_pointer<WithRefQual>::type>);
static_assert(is_same_v<WithRefQual, typename decay<WithRefQual>::type>);

int main() {}

The static_asserts fail with stock EDG (checked 6.8 and 6.9) but pass with clang/gcc: https://godbolt.org/z/b44zKeosb

For reference: https://cplusplus.github.io/LWG/issue2101
patch.txt

Attached an LLM-generated patch and EDG config.

edg_config.txt
patch.txt

Reproducing Source Code

template<class, class>
constexpr bool is_same_v = false;
template
constexpr bool is_same_v<T, T> = true;

template struct add_lvalue_reference { using type = __add_lvalue_reference(T); };
template struct add_rvalue_reference { using type = __add_rvalue_reference(T); };
template struct add_pointer          { using type = __add_pointer(T); };
template struct decay                { using type = __decay(T); };

using WithCVQual = void() const;
using WithRefQual = void() const;

static_assert(is_same_v<WithCVQual, typename add_lvalue_reference::type>);
static_assert(is_same_v<WithCVQual, typename add_rvalue_reference::type>);
static_assert(is_same_v<WithCVQual, typename add_pointer::type>);
static_assert(is_same_v<WithCVQual, typename decay::type>);

static_assert(is_same_v<WithRefQual, typename add_lvalue_reference::type>);
static_assert(is_same_v<WithRefQual, typename add_rvalue_reference::type>);
static_assert(is_same_v<WithRefQual, typename add_pointer::type>);
static_assert(is_same_v<WithRefQual, typename decay::type>);

int main() {}

Command-line Options

edgcpfe --c++17

Type of Issue

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

Additional Details

Compiles with GCC 15 and Clang 16

Reproducing (Standard) Configuration(s)

linux-clang-release, linux-gcc-release

Reproducing (Non-standard) Configuration

No response

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• The reproducing source code that I have provided does not depend on headers that I have not included with my submission.
• I have reduced the reproducing source code to the best of my ability.
• I have selected at least one standard configuration or uploaded a non-standard configuration dump.
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[daveedvdv-nvidia]

The proposed patch looks good, programmatically. I'd add some comments.