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* [gcc r13-5707] c++: equivalence of non-dependent calls [PR107461]
@ 2023-02-06 2:35 Patrick Palka
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From: Patrick Palka @ 2023-02-06 2:35 UTC (permalink / raw)
To: gcc-cvs
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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