On 8/23/24 12:44 PM, Simon Martin wrote:
We currently emit an incorrect -Woverloaded-virtual warning upon the following
test case
=== cut here ===
struct A {
virtual operator int() { return 42; }
virtual operator char() = 0;
};
struct B : public A {
operator char() { return 'A'; }
};
=== cut here ===
The problem is that warn_hidden relies on get_basefndecls to find the methods
in A possibly hidden B's operator char(), and gets both the conversion operator
to int and to char. It eventually wrongly concludes that the conversion to int
is hidden.
This patch fixes this by filtering out conversion operators to different types
from the list returned by get_basefndecls.
Hmm, same_signature_p already tries to handle comparing conversion
operators, why isn't that working?
Successfully tested on x86_64-pc-linux-gnu.
PR c++/109918
gcc/cp/ChangeLog:
* class.cc (warn_hidden): Filter out conversion operators to different
types.
gcc/testsuite/ChangeLog:
* g++.dg/warn/Woverloaded-virt5.C: New test.
---
gcc/cp/class.cc | 33 ++++++++++++-------
gcc/testsuite/g++.dg/warn/Woverloaded-virt5.C | 12 +++++++
2 files changed, 34 insertions(+), 11 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/warn/Woverloaded-virt5.C
diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc
index fb6c3370950..a8178a31fe8 100644
--- a/gcc/cp/class.cc
+++ b/gcc/cp/class.cc
@@ -3267,18 +3267,29 @@ warn_hidden (tree t)
if (TREE_CODE (fndecl) == FUNCTION_DECL
&& DECL_VINDEX (fndecl))
{
- /* If the method from the base class has the same
- signature as the method from the derived class, it
- has been overridden. Note that we can't move on
- after finding one match: fndecl might override
- multiple base fns. */
for (size_t k = 0; k < base_fndecls.length (); k++)
- if (base_fndecls[k]
- && same_signature_p (fndecl, base_fndecls[k]))
- {
- base_fndecls[k] = NULL_TREE;
- any_override = true;
- }
+ {
+ if (!base_fndecls[k])
+ continue;
+ /* If FNS is a conversion operator, base_fndecls contains
+ all conversion operators from base classes; we need to
+ remove those converting to a different type. */
+ if (IDENTIFIER_CONV_OP_P (name)
+ && !same_type_p (DECL_CONV_FN_TYPE (fndecl),
+ DECL_CONV_FN_TYPE (base_fndecls[k])))
+ {
+ base_fndecls[k] = NULL_TREE;
+ }
+ /* If the method from the base class has the same signature
+ as the method from the derived class, it has been
+ overriden. Note that we can't move on after finding
+ one match: fndecl might override multiple base fns. */
+ else if (same_signature_p (fndecl, base_fndecls[k]))
+ {
+ base_fndecls[k] = NULL_TREE;
+ any_override = true;
+ }
+ }
}
if (!any_override)
seen_non_override = true;
diff --git a/gcc/testsuite/g++.dg/warn/Woverloaded-virt5.C
b/gcc/testsuite/g++.dg/warn/Woverloaded-virt5.C
new file mode 100644
index 00000000000..ea26569e565
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Woverloaded-virt5.C
@@ -0,0 +1,12 @@
+// PR c++/109918
+// { dg-do compile }
+// { dg-additional-options -Woverloaded-virtual }
+
+struct A {
+ virtual operator int() { return 42; }
+ virtual operator char() = 0;
+};
+
+struct B : public A {
+ operator char() { return 'A'; }
+};
