clang 10.0 compiler error

[gabyx]

I get a compile error with clang 10.0:

meta/meta_fwd.hpp:286:20: error: expected concept name with optional arguments
[build]         { T{} } -> typename T::value_type;
[build]                    ^

Whats the fix?

[b1ackviking]

I am experiencing the same error on GCC 11 with -std=c++20.

[ericniebler]

Ah, should be something like { T{} } -> convertible_to<typename T::value_type>.

The concepts language feature changed between the Concepts TS and C++20.