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From: Patrick Palka <ppalka@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-5707] c++: equivalence of non-dependent calls [PR107461] Date: Mon, 6 Feb 2023 02:35:48 +0000 (GMT) [thread overview] Message-ID: <20230206023548.2A5B33858D1E@sourceware.org> (raw) https://gcc.gnu.org/g:31924665c86d47af6b1f22a74f594f2e1dc0ed2d commit r13-5707-g31924665c86d47af6b1f22a74f594f2e1dc0ed2d Author: Patrick Palka <ppalka@redhat.com> Date: Sun Feb 5 21:35:33 2023 -0500 c++: equivalence of non-dependent calls [PR107461] After r13-5684-g59e0376f607805 the (pruned) callee of a non-dependent CALL_EXPR is a bare FUNCTION_DECL rather than ADDR_EXPR of FUNCTION_DECL. This innocent change revealed that cp_tree_equal doesn't first check dependence of a CALL_EXPR before treating a FUNCTION_DECL callee as a dependent name, which leads to us incorrectly accepting the first two testcases below and rejecting the third: * In the first testcase, cp_tree_equal incorrectly returns true for the two non-dependent CALL_EXPRs f(0) and f(0) (whose CALL_EXPR_FN are different FUNCTION_DECLs) which causes us to treat #2 as a redeclaration of #1. * Same issue in the second testcase, for f<int*>() and f<char>(). * In the third testcase, cp_tree_equal incorrectly returns true for f<int>() and f<void(*)(int)>() which causes us to conflate the two dependent specializations A<decltype(f<int>()(U()))> and A<decltype(f<void(*)(int)>()(U()))>. This patch fixes this by making called_fns_equal treat two callees as dependent names only if the overall CALL_EXPRs are dependent, via a new convenience function call_expr_dependent_name that is like dependent_name but also checks dependence of the overall CALL_EXPR. PR c++/107461 gcc/cp/ChangeLog: * cp-tree.h (call_expr_dependent_name): Declare. * pt.cc (iterative_hash_template_arg) <case CALL_EXPR>: Use call_expr_dependent_name instead of dependent_name. * tree.cc (call_expr_dependent_name): Define. (called_fns_equal): Adjust to take two CALL_EXPRs instead of CALL_EXPR_FNs thereof. Use call_expr_dependent_name instead of dependent_name. (cp_tree_equal) <case CALL_EXPR>: Adjust call to called_fns_equal. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/overload5.C: New test. * g++.dg/cpp0x/overload5a.C: New test. * g++.dg/cpp0x/overload6.C: New test. Diff: --- gcc/cp/cp-tree.h | 1 + gcc/cp/pt.cc | 2 +- gcc/cp/tree.cc | 24 +++++++++++++++++++----- gcc/testsuite/g++.dg/cpp0x/overload5.C | 12 ++++++++++++ gcc/testsuite/g++.dg/cpp0x/overload5a.C | 10 ++++++++++ gcc/testsuite/g++.dg/cpp0x/overload6.C | 16 ++++++++++++++++ 6 files changed, 59 insertions(+), 6 deletions(-) diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 31fd8af4f21..06bc64a6b8d 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -7902,6 +7902,7 @@ extern tree lookup_maybe_add (tree fns, tree lookup, extern int is_overloaded_fn (tree) ATTRIBUTE_PURE; extern bool really_overloaded_fn (tree) ATTRIBUTE_PURE; extern tree dependent_name (tree); +extern tree call_expr_dependent_name (tree); extern tree maybe_get_fns (tree) ATTRIBUTE_PURE; extern tree get_fns (tree) ATTRIBUTE_PURE; extern tree get_first_fn (tree) ATTRIBUTE_PURE; diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc index 51fc246ed71..e89dbf47097 100644 --- a/gcc/cp/pt.cc +++ b/gcc/cp/pt.cc @@ -1841,7 +1841,7 @@ iterative_hash_template_arg (tree arg, hashval_t val) case CALL_EXPR: { tree fn = CALL_EXPR_FN (arg); - if (tree name = dependent_name (fn)) + if (tree name = call_expr_dependent_name (arg)) { if (TREE_CODE (fn) == TEMPLATE_ID_EXPR) val = iterative_hash_template_arg (TREE_OPERAND (fn, 1), val); diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc index c1da868732b..cd0dd963532 100644 --- a/gcc/cp/tree.cc +++ b/gcc/cp/tree.cc @@ -2608,6 +2608,18 @@ dependent_name (tree x) return NULL_TREE; } +/* Like dependent_name, but instead takes a CALL_EXPR and also checks + its dependence. */ + +tree +call_expr_dependent_name (tree x) +{ + if (TREE_TYPE (x) != NULL_TREE) + /* X isn't dependent, so its callee isn't a dependent name. */ + return NULL_TREE; + return dependent_name (CALL_EXPR_FN (x)); +} + /* Returns true iff X is an expression for an overloaded function whose type cannot be known without performing overload resolution. */ @@ -3870,16 +3882,18 @@ decl_internal_context_p (const_tree decl) return !TREE_PUBLIC (decl); } -/* Subroutine of cp_tree_equal: t1 and t2 are the CALL_EXPR_FNs of two - CALL_EXPRS. Return whether they are equivalent. */ +/* Subroutine of cp_tree_equal: t1 and t2 are two CALL_EXPRs. + Return whether their CALL_EXPR_FNs are equivalent. */ static bool called_fns_equal (tree t1, tree t2) { /* Core 1321: dependent names are equivalent even if the overload sets are different. But do compare explicit template arguments. */ - tree name1 = dependent_name (t1); - tree name2 = dependent_name (t2); + tree name1 = call_expr_dependent_name (t1); + tree name2 = call_expr_dependent_name (t2); + t1 = CALL_EXPR_FN (t1); + t2 = CALL_EXPR_FN (t2); if (name1 || name2) { tree targs1 = NULL_TREE, targs2 = NULL_TREE; @@ -4037,7 +4051,7 @@ cp_tree_equal (tree t1, tree t2) if (KOENIG_LOOKUP_P (t1) != KOENIG_LOOKUP_P (t2)) return false; - if (!called_fns_equal (CALL_EXPR_FN (t1), CALL_EXPR_FN (t2))) + if (!called_fns_equal (t1, t2)) return false; call_expr_arg_iterator iter1, iter2; diff --git a/gcc/testsuite/g++.dg/cpp0x/overload5.C b/gcc/testsuite/g++.dg/cpp0x/overload5.C new file mode 100644 index 00000000000..e05b1594f51 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/overload5.C @@ -0,0 +1,12 @@ +// PR c++/107461 +// { dg-do compile { target c++11 } } + +int f(...); +template<class T> decltype(T() + f(0)) g(); // #1 + +char f(int); +template<class T> decltype(T() + f(0)) g(); // #2, distinct from #1 + +int main() { + g<int>(); // { dg-error "ambiguous" } +} diff --git a/gcc/testsuite/g++.dg/cpp0x/overload5a.C b/gcc/testsuite/g++.dg/cpp0x/overload5a.C new file mode 100644 index 00000000000..037114f199c --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/overload5a.C @@ -0,0 +1,10 @@ +// PR c++/107461 +// { dg-do compile { target c++11 } } + +template<class T> T f(); +template<class T> decltype(T() + f<int*>()) g(); // #1 +template<class T> decltype(T() + f<char>()) g(); // #2, distinct from #1 + +int main() { + g<int>(); // { dg-error "ambiguous" } +} diff --git a/gcc/testsuite/g++.dg/cpp0x/overload6.C b/gcc/testsuite/g++.dg/cpp0x/overload6.C new file mode 100644 index 00000000000..1fbee0501de --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/overload6.C @@ -0,0 +1,16 @@ +// PR c++/107461 +// { dg-do compile { target c++11 } } + +template<class T> T f(); + +template<class> struct A { }; + +template<class T> struct B { + template<class U, class = A<decltype(f<T>()(U()))>> + static void g(U); +}; + +int main() { + B<int> b; + B<void(*)(int)>::g(0); // { dg-bogus "no match" } +}
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