Noticed the warnings and -Werror build failures on today's gcc-master from r15-4297-gc38385ddbcce9f. Self-contained example extracted from fheroes2: // $ cat bug.cc struct Troops { virtual ~Troops(); }; struct Control { virtual int GetControl() const = 0; }; struct Army : Troops, Control { int GetControl() const override; }; $ g++ -c bug.cc -Woverloaded-virtual bug.cc:2:30: warning: 'virtual int Control::GetControl() const' was hidden [-Woverloaded-virtual=] 2 | struct Control { virtual int GetControl() const = 0; }; | ^~~~~~~~~~ bug.cc:3:37: note: by 'virtual int Army::GetControl() const' 3 | struct Army : Troops, Control { int GetControl() const override; }; | ^~~~~~~~~~ $ g++ -v Using built-in specs. COLLECT_GCC=/<<NIX>>/gcc-15.0.0/bin/g++ COLLECT_LTO_WRAPPER=/<<NIX>>/gcc-15.0.0/libexec/gcc/x86_64-unknown-linux-gnu/15.0.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../source/configure --prefix=/<<NIX>>/gcc-15.0.0 --with-gmp-include=/<<NIX>>/gmp-6.3.0-dev/include --with-gmp-lib=/<<NIX>>/gmp-6.3.0/lib --with-mpfr-include=/<<NIX>>/mpfr-4.2.1-dev/include --with-mpfr-lib=/<<NIX>>/mpfr-4.2.1/lib --with-mpc=/<<NIX>>/libmpc-1.3.1 --with-native-system-header-dir=/<<NIX>>/glibc-2.40-36-dev/include --with-build-sysroot=/ --with-gxx-include-dir=/<<NIX>>/gcc-15.0.0/include/c++/15.0.0/ --program-prefix= --enable-lto --disable-libstdcxx-pch --without-included-gettext --with-system-zlib --enable-checking=release --enable-static --enable-languages=c,c++ --disable-multilib --enable-plugin --disable-libcc1 --with-isl=/<<NIX>>/isl-0.20 --disable-bootstrap --build=x86_64-unknown-linux-gnu --host=x86_64-unknown-linux-gnu --target=x86_64-unknown-linux-gnu Thread model: posix Supported LTO compression algorithms: zlib gcc version 15.0.0 99999999 (experimental) (GCC)
most likely r15-4282-g60163c85730e6b7c56 this causes --languages=all bootstrap to fail when rust is included many many instances like: /src-local/gcc-master/gcc/rust/ast/rust-ast.h:161:26: error: ‘virtual Rust::AST::MacroMatch::MacroMatchType Rust::AST::MacroMatch::get_macro_match_type() const’ was hidden [-Werror=overloaded-virtual=] 161 | virtual MacroMatchType get_macro_match_type () const = 0;
Yeah, gcc bisect agrees: landed on r15-4282-g60163c85730e6b.
Sorry for the breakage. Triggering a rust build and will advise about next steps.
Submitted https://gcc.gnu.org/pipermail/gcc-patches/2024-October/665222.html to restore the rust front-end build.
*** Bug 117117 has been marked as a duplicate of this bug. ***
The patch I mentioned above did not pass regtest so I have reverted the offending commit for the moment; commit r15-4301-ga4eec6c712ec16 refers.
Resolving. Apologies for the fallout :-/
The master branch has been updated by Simon Martin <simartin@gcc.gnu.org>: https://gcc.gnu.org/g:d346af2af88caf1e21a5cc1f0afa33596198fb60 commit r15-7350-gd346af2af88caf1e21a5cc1f0afa33596198fb60 Author: Simon Martin <simon@nasilyan.com> Date: Tue Feb 4 10:58:17 2025 +0100 c++: Fix overeager Woverloaded-virtual with conversion operators [PR109918] 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 when iterating over ovl_range (fns), warn_hidden gets confused by the conversion operator marker, concludes that seen_non_override is true and therefore emits a warning for all conversion operators in A that do not convert to char, even if -Woverloaded-virtual is 1 (e.g. with -Wall, the case reported). A second set of problems is highlighted when -Woverloaded-virtual is 2. First, with the same test case, since base_fndecls contains all conversion operators in A (except the one to char, that's been removed when iterating over ovl_range (fns)), we emit a spurious warning for the conversion operator to int, even though it's unrelated. Second, in case there are several conversion operators with different cv-qualifiers to the same type in A, we rightfully emit a warning, however the note uses the location of the conversion operator marker instead of the right one; location_of should go over conv_op_marker. This patch fixes all these by explicitly keeping track of (1) base methods that are overriden, as well as (2) base methods that are hidden but not overriden (and by what), and warning about methods that are in (2) but not (1). It also ignores non virtual base methods, per "definition" of -Woverloaded-virtual. Co-authored-by: Jason Merrill <jason@redhat.com> PR c++/117114 PR c++/109918 gcc/cp/ChangeLog: * class.cc (warn_hidden): Keep track of overloaded and of hidden base methods. * error.cc (location_of): Skip over conv_op_marker. gcc/testsuite/ChangeLog: * g++.dg/warn/Woverloaded-virt1.C: Check that no warning is emitted for non virtual base methods. * g++.dg/warn/Woverloaded-virt10.C: New test. * g++.dg/warn/Woverloaded-virt11.C: New test. * g++.dg/warn/Woverloaded-virt12.C: New test. * g++.dg/warn/Woverloaded-virt13.C: New test. * g++.dg/warn/Woverloaded-virt5.C: New test. * g++.dg/warn/Woverloaded-virt6.C: New test. * g++.dg/warn/Woverloaded-virt7.C: New test. * g++.dg/warn/Woverloaded-virt8.C: New test. * g++.dg/warn/Woverloaded-virt9.C: New test.