| Issue |
131136
|
| Summary |
[C++][concepts] error implicit instantiation of undefined template reported from checking constraint satisfaction
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
thbwd
|
```
#include <string>
template <template <typename> class SB>
concept Trait = requires(SB<int> a) { a.holder0; };
template <typename T> void set_property(T);
template <template <typename> class SB, typename ST>
void set_property(SB<ST> *) requires Trait<SB>;
void initialize(std::string *name) { set_property(name); }
```
Produces the following output:
```
% /opt/homebrew/Cellar/llvm/19.1.7_1/bin/clang test.cpp -std=c++20
In file included from test.cpp:1:
/opt/homebrew/Cellar/llvm/19.1.7_1/bin/../include/c++/v1/string:820:42: error: implicit instantiation of undefined template 'std::char_traits<int>'
820 | static_assert(is_same<_CharT, typename traits_type::char_type>::value,
| ^
test.cpp:4:40: note: in instantiation of template class 'std::basic_string<int>' requested here
4 | concept Trait = requires(SB<int> a) { a.holder0; };
| ^
test.cpp:4:39: note: in instantiation of requirement here
4 | concept Trait = requires(SB<int> a) { a.holder0; };
| ^~~~~~~~~
test.cpp:4:17: note: while substituting template arguments into constraint _expression_ here
4 | concept Trait = requires(SB<int> a) { a.holder0; };
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
test.cpp:9:38: note: while checking the satisfaction of concept 'Trait<std::basic_string>' requested here
9 | void set_property(SB<ST> *) requires Trait<SB>;
| ^~~~~~~~~
test.cpp:9:38: note: while substituting template arguments into constraint _expression_ here
9 | void set_property(SB<ST> *) requires Trait<SB>;
| ^~~~~~~~~
test.cpp:11:38: note: while checking constraint satisfaction for template 'set_property<std::basic_string, char>' required here
11 | void initialize(std::string *name) { set_property(name); }
| ^~~~~~~~~~~~
test.cpp:11:38: note: in instantiation of function template specialization 'set_property<std::basic_string, char>' requested here
/opt/homebrew/Cellar/llvm/19.1.7_1/bin/../include/c++/v1/__fwd/string.h:23:29: note: template is declared here
23 | struct _LIBCPP_TEMPLATE_VIS char_traits;
| ^
1 error generated.
```
This compiles fine with 18.1.8.
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