On Friday, 19 November 2021 10:53:27 CET Matthias Kretz wrote: > > >> Ah, you're trying to omit defaulted parms from the <list>? I'm not > > >> sure > > >> that's necessary, leaving them out of the [with ...] list should be > > >> sufficient. > > > > > > I was thinking about all the std::allocator defaults in the standard > > > library. I don't want to see them. E.g. vector<int>::clear() on const > > > object: > > > > > > error: passing 'const std::vector<int>' as 'this' argument discards > > > qualifiers [...]/stl_vector.h:1498:7: note: in call to 'void > > > std::vector<_Tp, _Alloc>::clear() [with _Tp = int; _Alloc = > > > std::allocator<int>]' > > > > > > With my patch the last line becomes > > > [...]/stl_vector.h:1498:7: note: in call to 'void > > > std::vector<_Tp>::clear() [with _Tp = int]' > > > > > > > > > Another case I didn't consider before: > > > > > > template <class T, class U = int> struct A { > > > > > > [[deprecated]] void f(U); > > > > > > }; > > > > > > A<float> a; a.f(1); > > > > > > With my patch it prints 'void A<T>::f(U) [with T = float]', with your > > > suggestion 'void A<T, U>::f(U) [with T = float]'. Both are missing > > > important information in the substitution list, IMHO. Would 'void A<T, U > > > = int>::f(U) [with T = float]' be an improvement? Or should > > > find_typenames (in cp/error.c) find defaulted template parms and add > > > them > > > to its list? IIUC find_typenames would find all template parms and > > > couldn't know whether they're defaulted. > > > > That sounds good: omit defaulted parms only if they don't appear in the > > signature (other than as another default template argument). > > Let me check whether I have the right idea: > > I could extend find_typenames (which walks the complete) tree to look for > TEMPLATE_TYPE_PARM (and the 3 others I don't recall right now). But since > that walks the *complete* tree, it'll simply find all parms with no > indication whether they appear in the signature. Ideas: > > 1. Count occurrences: with 2 occurrences, one of them must be a use in the > signature. > > 2. Walk only over TYPE_ARG_TYPES (TREE_TYPE (DECL_TEMPLATE_RESULT (fn))) to > collect TEMPLATE_TYPE_PARMs.
I tried the latter: @@ -1641,8 +1652,11 @@ dump_substitution (cxx_pretty_printer *pp, && !(flags & TFF_NO_TEMPLATE_BINDINGS)) { vec<tree, va_gc> *typenames = t ? find_typenames (t) : NULL; - dump_template_bindings (pp, template_parms, template_args, typenames, - flags); + tree fn_arguments = TYPE_ARG_TYPES (TREE_TYPE (DECL_TEMPLATE_RESULT (t))); + tree used_template_parms = find_template_parameters (fn_arguments, + template_parms); + dump_template_bindings (pp, template_parms, template_args, + used_template_parms, typenames, flags); } } Now in dump_template_bindings it skips all defaulted template_parms that are not in used_template_parms. Makes this test pass: template <class T> struct id { using type = T; }; template <class T0, class T1 = int> struct A { template <class U0 = const T1&> [[deprecated]] static void f(typename id<U0>::type); }; int main() { A<int>::f(0); // { dg-warning "'static void A<T0>::f\\(typename id<U0>::type\\) .with U0 = const int&; T0 = int; typename id<U0>::type = const int&.'" } } -- ────────────────────────────────────────────────────────────────────────── Dr. Matthias Kretz https://mattkretz.github.io GSI Helmholtz Centre for Heavy Ion Research https://gsi.de stdₓ::simd ──────────────────────────────────────────────────────────────────────────