https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103540
--- Comment #2 from Igel <ich.freak at gmx dot net> --- Ah thanks for copying the relevant code here. The error that you're referring to is: <source>: In instantiation of 'struct X<0>': <source>:5:14: required by substitution of 'template<class N> requires StrictNodeType<N> using Int = int [with N = X<0>]' <source>:15:27: required from here <source>:12:11: error: template constraint failure for 'template<class N> requires StrictNodeType<N> using Int = int' 12 | using something = Int<X>; | ^~~~~~~~~ <source>:12:11: note: constraints not satisfied I guess technically, you're right that it points to the correct spot and it is the programmers duty to translate this into "the concept StrictNodeType<X<0>> depends on itself because the type X<0>::something (also known as Int<X<0>>) declared in line 12 depends on the concept StrictNodeType<X<0>>". However, this information can be buried arbitrarily deep in the error messages. Consider, for example, the following adaptation: #include <type_traits> template<typename N> concept StrictNodeType = requires { typename N::something; }; template<StrictNodeType N> using Int = int; template<template<class> class P, class Q> using chooser = P<Q>; template<int> struct X { using something = chooser<Int, X>; }; using ThisBreaks = Int<X<0>>; The only hint towards the real problem (gcc cannot tell if X<0> has a type called 'something' or not) is now this: <source>:14:18: required from 'struct X<0>' I guess all I'm saying is that extracting the site of the problematic code is currently very hard for "depends on itself"-errors.