On 12/12/23 13:40, Patrick Palka wrote:
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for trunk?
OK.
I considered removing the is_overloaded_fn test now as well, but it could in theory be hit (and not subsumed by the type_unknown_p test) for e.g. OVERLOAD of a single FUNCTION_DECL. I wonder if that's something we'd see here? If not, I can remove the test. It seems safe to remove as far as the testsuite is concerned.
Next stage 1, sure.
-- >8 -- unify currently always returns success when unifying two FUNCTION_DECLs (due to the is_overloaded_fn deferment within the default case), which means for the below testcase unify incorrectly matches &A::foo with &A::bar, which leads to deduction failure for the index_of calls due to a bogus base class ambiguity. This patch makes us instead handle unification of FUNCTION_DECL like other decls, i.e. according to their identity. PR c++/93740 gcc/cp/ChangeLog: * pt.cc (unify) <case FUNCTION_DECL>: Handle it like FIELD_DECL and TEMPLATE_DECL. gcc/testsuite/ChangeLog: * g++.dg/template/ptrmem34.C: New test. --- gcc/cp/pt.cc | 1 + gcc/testsuite/g++.dg/template/ptrmem34.C | 27 ++++++++++++++++++++++++ 2 files changed, 28 insertions(+) create mode 100644 gcc/testsuite/g++.dg/template/ptrmem34.C diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index c2ddbff405b..a8966e223f1 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -24967,6 +24967,7 @@ unify (tree tparms, tree targs, tree parm, tree arg, int strict, gcc_unreachable ();case FIELD_DECL:+ case FUNCTION_DECL: case TEMPLATE_DECL: /* Matched cases are handled by the ARG == PARM test above. */ return unify_template_argument_mismatch (explain_p, parm, arg); diff --git a/gcc/testsuite/g++.dg/template/ptrmem34.C b/gcc/testsuite/g++.dg/template/ptrmem34.C new file mode 100644 index 00000000000..c349ca55639 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/ptrmem34.C @@ -0,0 +1,27 @@ +// PR c++/93740 +// { dg-do compile { target c++11 } } + +struct A { + void foo(); + void bar(); +}; + +template <typename T, T val> +struct const_val{}; + +template <int N, typename T> +struct indexed_elem{}; + +using mem_fun_A_foo = const_val<decltype(&A::foo), &A::foo>; +using mem_fun_A_bar = const_val<decltype(&A::bar), &A::bar>; + +struct A_indexed_member_funcs + : indexed_elem<0, mem_fun_A_foo>, + indexed_elem<1, mem_fun_A_bar> +{}; + +template <typename T, int N> +constexpr int index_of(indexed_elem<N, T>) { return N; } + +static_assert(index_of<mem_fun_A_foo>(A_indexed_member_funcs{}) == 0, ""); +static_assert(index_of<mem_fun_A_bar>(A_indexed_member_funcs{}) == 1, "");
