From 58586721c79f77224b8571a5dba732620d5546ab Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Wed, 6 Apr 2022 23:46:53 -0400 Subject: [PATCH] c++: friend implicit template instantiation [PR91618] This rule that for a friend with a qualified name we try to find a matching template was already in C++98, but it seems we never implemented it, and nobody reported it until 2019. This patch sets DECL_IMPLICIT_INSTANTIATION to signal to check_explicit_specialization that we want to find a template, like grokfndecl already did for explicit template args. check_classfn also needs to call it, as check_classfn is called after the call to check_explicit_specialization in grokfndecl, whereas the call to set_decl_namespace comes sooner. This inconsistency is inelegant, but safer at this point in the release cycle; I'll unify them in stage 1. PR c++/91618 PR c++/96604 gcc/cp/ChangeLog: * name-lookup.cc (set_decl_namespace): Set DECL_IMPLICIT_INSTANTIATION if no non-template match. * pt.cc (check_explicit_specialization): Check it. * decl2.cc (check_classfn): Call it. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/friend7.C: Remove xfail. * g++.dg/template/friend72.C: New test. * g++.dg/template/friend72a.C: New test. * g++.dg/template/friend73.C: New test. --- gcc/cp/decl2.cc | 23 ++++++++++++++++++++++- gcc/cp/name-lookup.cc | 15 +++++++++++++++ gcc/cp/pt.cc | 4 +++- gcc/testsuite/g++.dg/cpp0x/friend7.C | 2 +- gcc/testsuite/g++.dg/template/friend72.C | 15 +++++++++++++++ gcc/testsuite/g++.dg/template/friend72a.C | 14 ++++++++++++++ gcc/testsuite/g++.dg/template/friend73.C | 5 +++++ 7 files changed, 75 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/g++.dg/template/friend72.C create mode 100644 gcc/testsuite/g++.dg/template/friend72a.C create mode 100644 gcc/testsuite/g++.dg/template/friend73.C diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc index dc2c924..c780702 100644 --- a/gcc/cp/decl2.cc +++ b/gcc/cp/decl2.cc @@ -734,11 +734,15 @@ check_classfn (tree ctype, tree function, tree template_parms) tree pushed_scope = push_scope (ctype); tree matched = NULL_TREE; tree fns = get_class_binding (ctype, DECL_NAME (function)); - + bool saw_template = false; + for (ovl_iterator iter (fns); !matched && iter; ++iter) { tree fndecl = *iter; + if (TREE_CODE (fndecl) == TEMPLATE_DECL) + saw_template = true; + /* A member template definition only matches a member template declaration. */ if (is_template != (TREE_CODE (fndecl) == TEMPLATE_DECL)) @@ -788,6 +792,23 @@ check_classfn (tree ctype, tree function, tree template_parms) matched = fndecl; } + if (!matched && !is_template && saw_template + && !processing_template_decl && DECL_UNIQUE_FRIEND_P (function)) + { + /* "[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." + + So ask check_explicit_specialization to find a matching template. */ + SET_DECL_IMPLICIT_INSTANTIATION (function); + tree spec = check_explicit_specialization (DECL_NAME (function), + function, /* tcount */0, + /* friend flag */4, + /* attrlist */NULL_TREE); + if (spec != error_mark_node) + matched = spec; + } + if (!matched) { if (!COMPLETE_TYPE_P (ctype)) diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc index b7fc278..118da09 100644 --- a/gcc/cp/name-lookup.cc +++ b/gcc/cp/name-lookup.cc @@ -5898,6 +5898,7 @@ set_decl_namespace (tree decl, tree scope, bool friendp) tree found = NULL_TREE; bool hidden_p = false; + bool saw_template = false; for (lkp_iterator iter (old); iter; ++iter) { @@ -5922,6 +5923,20 @@ set_decl_namespace (tree decl, tree scope, bool friendp) found = ofn; hidden_p = iter.hidden_p (); } + else if (TREE_CODE (decl) == FUNCTION_DECL + && TREE_CODE (ofn) == TEMPLATE_DECL) + saw_template = true; + } + + if (!found && friendp && saw_template) + { + /* "[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." + + So tell check_explicit_specialization to look for a match. */ + SET_DECL_IMPLICIT_INSTANTIATION (decl); + return; } if (found) diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 63794a4..7851956 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -2863,7 +2863,9 @@ check_explicit_specialization (tree declarator, specialization = 1; SET_DECL_TEMPLATE_SPECIALIZATION (decl); } - else if (TREE_CODE (declarator) == TEMPLATE_ID_EXPR) + else if (TREE_CODE (declarator) == TEMPLATE_ID_EXPR + || (DECL_LANG_SPECIFIC (decl) + && DECL_IMPLICIT_INSTANTIATION (decl))) { if (is_friend) /* This could be something like: diff --git a/gcc/testsuite/g++.dg/cpp0x/friend7.C b/gcc/testsuite/g++.dg/cpp0x/friend7.C index e1d5f44..4d0961c 100644 --- a/gcc/testsuite/g++.dg/cpp0x/friend7.C +++ b/gcc/testsuite/g++.dg/cpp0x/friend7.C @@ -21,7 +21,7 @@ struct S { friend class __attribute__((deprecated)) N3; [[deprecated]] friend void foo<>(int, int); // { dg-warning "attribute ignored" } [[deprecated]] friend void ::foo(int, int); // { dg-warning "attribute ignored" } - // { dg-bogus "should have" "PR100339" { xfail *-*-* } .-1 } + // { dg-bogus "should have" "PR100339" } }; template diff --git a/gcc/testsuite/g++.dg/template/friend72.C b/gcc/testsuite/g++.dg/template/friend72.C new file mode 100644 index 0000000..b499909 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/friend72.C @@ -0,0 +1,15 @@ +// PR c++/91618 +// { dg-do link } + +template int f(T t) +{ return t.i; } + +class A { + friend int ::f(A); + int i; +}; + +int main() +{ + f(A()); // link error, trying to call non-template function +} diff --git a/gcc/testsuite/g++.dg/template/friend72a.C b/gcc/testsuite/g++.dg/template/friend72a.C new file mode 100644 index 0000000..ef6834a --- /dev/null +++ b/gcc/testsuite/g++.dg/template/friend72a.C @@ -0,0 +1,14 @@ +// PR c++/91618 + +template int f(T t, int) +{ return t.i; } + +class A { + friend int ::f(A); // { dg-error "" } + int i; +}; + +int main() +{ + f(A()); // { dg-error "no match" } +} diff --git a/gcc/testsuite/g++.dg/template/friend73.C b/gcc/testsuite/g++.dg/template/friend73.C new file mode 100644 index 0000000..d009ec7 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/friend73.C @@ -0,0 +1,5 @@ +// PR c++/96604 + +struct A { template operator T(); }; +struct X {}; +struct B { friend A::operator X(); }; -- 2.7.4