https://gcc.gnu.org/g:ba5a6787374dea3e90f09771134d16b9f6d2714e
commit r16-2519-gba5a6787374dea3e90f09771134d16b9f6d2714e
Author: Patrick Palka <ppa...@redhat.com>
Date: Fri Jul 25 10:55:35 2025 -0400
c++: more name lookup for non-dep rewritten cmp ops
As a follow-up to r16-2448-g7590c14b53a762, this patch attempts to teach
build_min_non_dep_op_overload how to rebuild all rewritten comparison
operators, not just != -> == ones, so that we don't incorrectly repeat
the unqualified name lookup at instantiation time.
Note that changes how we mangle such comparison ops, in a way that is
overall more consistent with how we've been mangling non-rewritten
operators, see PR c++/121239.
gcc/cp/ChangeLog:
* call.cc (build_new_op): If the selected candidate is
rewritten, communicate the LOOKUP_REWRITTEN/REVERSED flags to
the caller via the 'overload' out-parameter, and stop clearing
'*overload' in that case.
* tree.cc (build_min_non_dep_op_overload): Handle rebuilding all
C++20 rewritten comparison operator expressions.
gcc/testsuite/ChangeLog:
* g++.dg/lookup/operator-8.C: Remove XFAILs and properly
suppress all -Wunused-result warnings.
Reviewed-by: Jason Merrill <ja...@redhat.com>
Diff:
---
gcc/cp/call.cc | 16 +++---
gcc/cp/tree.cc | 85 +++++++++++++++++++++++++++-----
gcc/testsuite/g++.dg/lookup/operator-8.C | 16 +++---
3 files changed, 92 insertions(+), 25 deletions(-)
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index c76b15bcef6b..0f3143375261 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -7491,7 +7491,16 @@ build_new_op (const op_location_t &loc, enum tree_code
code, int flags,
else if (TREE_CODE (cand->fn) == FUNCTION_DECL)
{
if (overload)
- *overload = cand->fn;
+ {
+ if (cand->rewritten ())
+ /* build_min_non_dep_op_overload needs to know whether the
+ candidate is rewritten/reversed. */
+ *overload = build_tree_list (build_int_cst (integer_type_node,
+ cand->flags),
+ cand->fn);
+ else
+ *overload = cand->fn;
+ }
if (resolve_args (arglist, complain) == NULL)
result = error_mark_node;
@@ -7540,11 +7549,6 @@ build_new_op (const op_location_t &loc, enum tree_code
code, int flags,
/* If this was a C++20 rewritten comparison, adjust the result. */
if (cand->rewritten ())
{
- /* FIXME build_min_non_dep_op_overload can't handle rewrites. */
- if (code == NE_EXPR && !cand->reversed ())
- /* It can handle != rewritten to == though. */;
- else if (overload)
- *overload = NULL_TREE;
switch (code)
{
case EQ_EXPR:
diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc
index c260efb7f6ba..d56d73fe2179 100644
--- a/gcc/cp/tree.cc
+++ b/gcc/cp/tree.cc
@@ -3696,7 +3696,58 @@ build_min_non_dep_op_overload (enum tree_code op,
int nargs, expected_nargs;
tree fn, call, obj = NULL_TREE;
- bool negated = (TREE_CODE (non_dep) == TRUTH_NOT_EXPR);
+ releasing_vec args;
+ va_start (p, overload);
+
+ bool negated = false, rewritten = false, reversed = false;
+ if (cxx_dialect >= cxx20 && TREE_CODE (overload) == TREE_LIST)
+ {
+ /* Handle rebuilding a C++20 rewritten comparison operator expression,
+ e.g. !(x == y), y <=> x, (x <=> y) @ 0 etc, that resolved to a call
+ to a user-defined operator<=>/==. */
+ gcc_checking_assert (TREE_CODE_CLASS (op) == tcc_comparison
+ || op == SPACESHIP_EXPR);
+ int flags = TREE_INT_CST_LOW (TREE_PURPOSE (overload));
+ if (TREE_CODE (non_dep) == TRUTH_NOT_EXPR)
+ {
+ negated = true;
+ non_dep = TREE_OPERAND (non_dep, 0);
+ }
+ if (flags & LOOKUP_REWRITTEN)
+ rewritten = true;
+ if (flags & LOOKUP_REVERSED)
+ reversed = true;
+ if (rewritten
+ && DECL_OVERLOADED_OPERATOR_IS (TREE_VALUE (overload),
+ SPACESHIP_EXPR))
+ {
+ /* Handle (x <=> y) @ 0 and 0 @ (y <=> x) by recursing to first
+ rebuild the <=>. Note that both OVERLOAD and the provided
arguments
+ in this case already correspond to the selected operator<=>. */
+
+ tree spaceship_non_dep = CALL_EXPR_ARG (non_dep, reversed ? 1 : 0);
+ gcc_checking_assert (TREE_CODE (spaceship_non_dep) == CALL_EXPR);
+ tree spaceship_op0 = va_arg (p, tree);
+ tree spaceship_op1 = va_arg (p, tree);
+ if (reversed)
+ std::swap (spaceship_op0, spaceship_op1);
+
+ /* Push the correct arguments for the operator OP expression, and
+ set OVERLOAD appropriately. */
+ tree op0 = build_min_non_dep_op_overload (SPACESHIP_EXPR,
+ spaceship_non_dep,
+ TREE_VALUE (overload),
+ spaceship_op0,
+ spaceship_op1);
+ tree op1 = CALL_EXPR_ARG (non_dep, reversed ? 0 : 1);
+ gcc_checking_assert (integer_zerop (op1));
+ vec_safe_push (args, op0);
+ vec_safe_push (args, op1);
+ overload = CALL_EXPR_FN (non_dep);
+ }
+ else
+ overload = TREE_VALUE (overload);
+ }
non_dep = extract_call_expr (non_dep);
nargs = call_expr_nargs (non_dep);
@@ -3717,32 +3768,40 @@ build_min_non_dep_op_overload (enum tree_code op,
expected_nargs += 1;
gcc_assert (nargs == expected_nargs);
- releasing_vec args;
- va_start (p, overload);
-
if (!DECL_OBJECT_MEMBER_FUNCTION_P (overload))
{
fn = overload;
- if (op == ARRAY_REF)
- obj = va_arg (p, tree);
- for (int i = 0; i < nargs; i++)
+ if (vec_safe_length (args) != 0)
+ /* The correct arguments were already pushed above. */
+ gcc_checking_assert (rewritten);
+ else
{
- tree arg = va_arg (p, tree);
- vec_safe_push (args, arg);
+ if (op == ARRAY_REF)
+ obj = va_arg (p, tree);
+ for (int i = 0; i < nargs; i++)
+ {
+ tree arg = va_arg (p, tree);
+ vec_safe_push (args, arg);
+ }
}
+ if (reversed)
+ std::swap ((*args)[0], (*args)[1]);
}
else
{
+ gcc_checking_assert (vec_safe_length (args) == 0);
tree object = va_arg (p, tree);
- tree binfo = TYPE_BINFO (TREE_TYPE (object));
- tree method = build_baselink (binfo, binfo, overload, NULL_TREE);
- fn = build_min (COMPONENT_REF, TREE_TYPE (overload),
- object, method, NULL_TREE);
for (int i = 0; i < nargs; i++)
{
tree arg = va_arg (p, tree);
vec_safe_push (args, arg);
}
+ if (reversed)
+ std::swap (object, (*args)[0]);
+ tree binfo = TYPE_BINFO (TREE_TYPE (object));
+ tree method = build_baselink (binfo, binfo, overload, NULL_TREE);
+ fn = build_min (COMPONENT_REF, TREE_TYPE (overload),
+ object, method, NULL_TREE);
}
va_end (p);
diff --git a/gcc/testsuite/g++.dg/lookup/operator-8.C
b/gcc/testsuite/g++.dg/lookup/operator-8.C
index 7fe6a57061bd..32d432dd8432 100644
--- a/gcc/testsuite/g++.dg/lookup/operator-8.C
+++ b/gcc/testsuite/g++.dg/lookup/operator-8.C
@@ -16,12 +16,16 @@ struct A {
template<class T>
void f() {
A a;
- (void)(a != 0); // We only handle this simple case, after PR121179
- (void)(0 != a); // { dg-bogus "deleted" "" { xfail *-*-* } }
- (void)(a < 0, 0 < a); // { dg-bogus "deleted" "" { xfail *-*-* } }
- (void)(a <= 0, 0 <= a); // { dg-bogus "deleted" "" { xfail *-*-* } }
- (void)(a > 0, 0 > a); // { dg-bogus "deleted" "" { xfail *-*-* } }
- (void)(a >= 0, 0 >= a); // { dg-bogus "deleted" "" { xfail *-*-* } }
+ (void)(a != 0);
+ (void)(0 != a);
+ (void)(a < 0);
+ (void)(0 < a);
+ (void)(a <= 0);
+ (void)(0 <= a);
+ (void)(a > 0);
+ (void)(0 > a);
+ (void)(a >= 0);
+ (void)(0 >= a);
}
// These later-declared namespace-scope overloads shouldn't be considered
