| Message ID | 20231212184037.3040106-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: unifying FUNCTION_DECLs [PR93740] | expand |
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, "");
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, "");