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c++: over-eager friend matching [PR109649]

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A bug in the simplification I did around 91618; at this point X<int>::f has
DECL_IMPLICIT_INSTANTIATION set, but we've already identified what template
it corresponds to, so we don't want to call check_explicit_specialization.

To distinguish this case we need to look at DECL_TI_TEMPLATE.  grokfndecl
has for a long time set it to the OVERLOAD in this case, while the new cases
I added for 91618 were leaving DECL_TEMPLATE_INFO null; let's adjust them to
match.

	PR c++/91618
	PR c++/109649

gcc/cp/ChangeLog:

	* friend.cc (do_friend): Don't call check_explicit_specialization if
	DECL_TEMPLATE_INFO is already set.
	* decl2.cc (check_classfn): Set DECL_TEMPLATE_INFO.
	* name-lookup.cc (set_decl_namespace): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/template/friend77.C: New test.
This commit is contained in:
Jason Merrill 2023-05-03 13:32:55 -04:00
parent 3b7eecca20
commit 7ce078ceca
4 changed files with 23 additions and 1 deletions
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1
gcc/cp/decl2.cc
View file

@ -855,6 +855,7 @@ check_classfn (tree ctype, tree function, tree template_parms)
So tell check_explicit_specialization to look for a match. */
SET_DECL_IMPLICIT_INSTANTIATION (function);
DECL_TEMPLATE_INFO (function) = build_template_info (fns, NULL_TREE);
matched = function;
}

3
gcc/cp/friend.cc
View file

@ -661,7 +661,8 @@ do_friend (tree scope, tree declarator, tree decl,
if (decl == error_mark_node)
return error_mark_node;
if (!class_template_depth && DECL_IMPLICIT_INSTANTIATION (decl))
if (!class_template_depth && DECL_IMPLICIT_INSTANTIATION (decl)
&& TREE_CODE (DECL_TI_TEMPLATE (decl)) != TEMPLATE_DECL)
/* "[if no non-template match is found,] each remaining function template
is replaced with the specialization chosen by deduction from the
friend declaration or discarded if deduction fails."

1
gcc/cp/name-lookup.cc
View file

@ -5938,6 +5938,7 @@ set_decl_namespace (tree decl, tree scope, bool friendp)
So tell check_explicit_specialization to look for a match. */
SET_DECL_IMPLICIT_INSTANTIATION (decl);
DECL_TEMPLATE_INFO (decl) = build_template_info (old, NULL_TREE);
return;
}

19
gcc/testsuite/g++.dg/template/friend77.C Normal file
View file

@ -0,0 +1,19 @@
// PR c++/109649
template <typename>
class X
{
void f(){}
};
class Y
{
friend void X<int>::f(); // { dg-error "private" }
};
int main()
{
X<int> t;
t.f(); // { dg-error "private" }
Y b;
}