[clang++-19][regression] "error: type constraint differs in template redeclaration" #110231
Labels
clang:frontend
Language frontend issues, e.g. anything involving "Sema"
concepts
C++20 concepts
needs-reduction
Large reproducer that should be reduced into a simpler form
regression:19
Regression in 19 release
Comments
github-actions
bot
added
the
clang
|
A repro can be found here: https://godbolt.org/z/6brEd3de6. It also fails on "clang (trunk)," but it works fine on the other compilers mentioned. |
EugeneZelenko
added
clang:frontend
|
@llvm/issue-subscribers-clang-frontend Author: Mateusz Pusz (mpusz)
I get the following error while compiling on clang-19:
Here are the offending declarations:
The same code works fine on clang-17, clang-18, gcc-13, and gcc-14. |
zyn0217
added
concepts
|
I came to open an issue exactly about this with llvm-19.1.0 via homebrew on Apple M1 Pro CPU. |
|
Looks like this started in clang-19: https://godbolt.org/z/oxPf3oWjM I would like a reduction to understand what is going on better though. |
|
Confirmed on 19 and trunk. Note several declarations between struct array {
int __elems_[4] = {1, 2, 3, 4};
};
template < typename, template < typename > typename >
int is_specialization_of;
template < typename, template < auto... > typename >
constexpr bool is_specialization_of_v = 0;
template < auto... Params, template < auto... > typename Type >
constexpr bool is_specialization_of_v< Type< Params... >, Type > = 1;
constexpr auto get_first_of(int n) {
auto g = [&]{};
int __elems_[4] = {1, 2, 3, 4};
int* first = __elems_;
for (;;++first)
if (n % (*first))
return *first;
return 0;
}
consteval int find_first_factor(int n) {
constexpr auto basis = array{};
auto k = get_first_of(n);
return k;
}
template < typename T >
concept PowerVBase = true;
template < PowerVBase auto, int >
struct power_v {
static constexpr auto base = 0;
};
template < typename T >
concept MagnitudeSpec = is_specialization_of_v< T, power_v >;
template < MagnitudeSpec auto... >
struct magnitude;
template < typename T >
concept Magnitude = is_specialization_of_v< T, magnitude >;
template < auto V >
consteval auto power_v_or_T() {
return power_v< V, 0 >{};
}
template < typename >
struct magnitude_base {};
template < MagnitudeSpec auto... Ms >
struct magnitude : magnitude_base< magnitude< Ms... > > {
template < Magnitude M >
friend consteval auto operator*(magnitude m1, M) {
return m1;
}
friend auto operator/(magnitude, auto r) {
return pow(r);
}
friend auto pow(magnitude) {
return magnitude< power_v_or_T< Ms >()... >{};
}
};
template < int N >
struct prime_factorization {
static constexpr int first_base = find_first_factor(N);
static constexpr int remainder = N / first_base;
static constexpr auto value = magnitude< power_v_or_T< first_base >() >{} * prime_factorization< remainder >::value;
};
template <>
struct prime_factorization< 0 > {
static magnitude<> value;
};
template < int N >
auto prime_factorization_v = prime_factorization< N >::value;
template < auto, auto >
concept NestedQuantityKindSpecOf = true;
template < typename T, auto >
concept QuantitySpecOf = NestedQuantityKindSpecOf< 0, T{} >;
template < Magnitude auto >
struct scaled_unit {};
template < typename T >
concept Reference = true;
template < typename T, auto >
concept PointOriginFor = true;
struct unit_interface {};
template < typename M >
consteval auto operator*(M, unit_interface) -> scaled_unit< M{} > {
return scaled_unit< M{} >{};
}
template < auto >
struct named_unit;
template < auto U >
requires(true)
struct named_unit< U > {};
template < Reference auto R, PointOriginFor< R > auto >
struct quantity_point;
auto mag_ratio = prime_factorization_v< 0 > / prime_factorization_v< 1000 >;
template class named_unit< mag_ratio * unit_interface{} >;
template < Reference auto R, PointOriginFor< R > auto >
struct quantity_point;Clang 20 output: |
|
CC @mizvekov because I saw several TTPs are at play (where the situation could be horrible) |
hubert-reinterpretcast
changed the title
|
Somewhat surprisingly, when I locally ran Clang 19.1 binary that CE uses against the reduction, I got a crash: |
|
When I feed a local debug build of trunk with the reduction, I consistently get the following diagnostics: |
|
On godbolt using It |
I guess it runs out of stack like it did for me several comments above |
|
Bisected to #92425 |
Also see bc62fb9 which introduced CC @zygoloid who implemented that patch |
mizvekov
added a commit
that referenced
this issue
Oct 3, 2024
…ck argument This fixes a regression introduced in #96023, reported in #110231 (comment)
That's a separate regression introduced by a recent commit, should be fixed by #110963 |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
I get the following error while compiling on clang-19:
Here are the offending declarations:
The same code works fine on clang-17, clang-18, gcc-13, and gcc-14.
The text was updated successfully, but these errors were encountered: