https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96169
Bug ID: 96169
Summary: Don't provide internal lambda names in diagnostics?
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: barry.revzin at gmail dot com
Target Milestone: ---
Consider the erroneous program:
#include <concepts>
#include <string>
template <std::regular_invocable<int> F>
void call_with_ints(F);
void foo() {
call_with_ints([](std::string const& s){
return s.size();
});
}
This (correctly) doesn't compile, but the tail end of the diagnostic we get is:
In file included from <source>:1:
/opt/compiler-explorer/gcc-10.1.0/include/c++/10.1.0/concepts: In instantiation
of 'void call_with_ints(F) [with F = foo()::<lambda(const string&)>]':
<source>:10:6: required from here
/opt/compiler-explorer/gcc-10.1.0/include/c++/10.1.0/concepts:338:13:
required for the satisfaction of 'invocable<_Fn, _Args ...>' [with _Fn =
foo::._anon_92; _Args = {int}]
/opt/compiler-explorer/gcc-10.1.0/include/c++/10.1.0/concepts:342:13:
required for the satisfaction of 'regular_invocable<F, int>' [with F =
foo::._anon_92]
/opt/compiler-explorer/gcc-10.1.0/include/c++/10.1.0/concepts:338:25: note: the
expression 'is_invocable_v<_Fn, _Args ...> [with _Fn = foo::._anon_92; _Args =
{int}]' evaluated to 'false'
338 | concept invocable = is_invocable_v<_Fn, _Args...>;
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Compiler returned: 1
The lambda is initially introduced as "foo()::<lambda(const string&)>" but then
throughout the rest of the error is presented as "foo::._anon_92". The former
is a useful descriptor, especially in this specific example where the argument
the lambda takes is critical in understanding the error. The latter is not
useful - it doesn't really tell me anything.
Could we use the former name in diagnostics, instead of the latter?
