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c++: P0848R3 and member function templates [PR95181]

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When comparing two special member function templates to see if one hides
the other (as per P0848R3), we need to check satisfaction which we can't
do on templates.  So this patch makes add_method skip the eligibility
test on member function templates and just lets them coexist.

gcc/cp/ChangeLog:

	PR c++/95181
	* class.c (add_method): Let special member function templates
	coexist if they are not equivalently constrained, or in a class
	template.

gcc/testsuite/ChangeLog:

	PR c++/95181
	* g++.dg/concepts/pr95181.C: New test.
	* g++.dg/concepts/pr95181-2.C: New test.

Co-authored-by: Jason Merrill <jason@redhat.com>
This commit is contained in:
Patrick Palka 2020-05-22 10:28:19 -04:00 • committed by Jason Merrill
parent 2fb595f834
commit c75ebe76ae
3 changed files with 28 additions and 4 deletions
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15
gcc/cp/class.c
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@ -1081,12 +1081,19 @@ add_method (tree type, tree method, bool via_using)
{
if (!equivalently_constrained (fn, method))
{
if (processing_template_decl)
/* We can't check satisfaction in dependent context, wait until
the class is instantiated. */
continue;
special_function_kind sfk = special_memfn_p (method);
if (sfk == sfk_none || DECL_INHERITED_CTOR (fn))
/* Non-special member functions coexist if they are not
equivalently constrained. A member function is not hidden
by an inherited constructor. */
if (sfk == sfk_none
|| DECL_INHERITED_CTOR (fn)
|| TREE_CODE (fn) == TEMPLATE_DECL)
/* Member function templates and non-special member functions
coexist if they are not equivalently constrained. A member
function is not hidden by an inherited constructor. */
continue;
/* P0848: For special member functions, deleted, unsatisfied, or

8
gcc/testsuite/g++.dg/concepts/pr95181-2.C Normal file
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@ -0,0 +1,8 @@
// { dg-do compile { target concepts } }
template<bool B> struct g {
g() requires B && false;
g() requires B;
};
g<true> b; // error

9
gcc/testsuite/g++.dg/concepts/pr95181.C Normal file
View file

@ -0,0 +1,9 @@
// PR c++/95181
// { dg-do compile { target concepts } }
template <typename> struct f {
template <typename T=int> f();
template <typename T=int> requires false f();
};
f<int> a;