https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93295
Steven Franzen <sfranzen85 at hotmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |sfranzen85 at hotmail dot com --- Comment #8 from Steven Franzen <sfranzen85 at hotmail dot com> --- Another example, with gcc trunk: https://godbolt.org/z/ovxr4a. --- template<typename T, bool B = false> struct Foo { Foo(T) {} }; template<typename T> Foo(T) -> Foo<T>; template<typename T> using Bar = Foo<T, true>; Bar b{0}; --- This error only seems to occur when using deduction guides that are different from the implicitly generated set, e.g. as in this case omitting a parameter.