https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126606
Bug ID: 126606
Summary: [16 Regression] gcc-17 fails to build qt-6.11.1:
qfutureinterface_p.h:150:25: error: call to
'QFutureInterfaceBasePrivate::RefCount::RefCount(int,
int)' uses the default argument for parameter 2, which
is not yet defined
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: slyfox at gcc dot gnu.org
Target Milestone: ---
Did not bisect yet. Saw the failure on r17-2878-g6bf6dad5347663 when building
qt-6.11.1 around
https://codebrowser.dev/qt6/qtbase/src/corelib/thread/qfutureinterface_p.h.html#QFutureInterfaceBasePrivate::refCount
as :
In file included from
/tmp/b/qtbase-everywhere-src-6.11.1/src/corelib/thread/qfutureinterface.cpp:7:
/tmp/b/qtbase-everywhere-src-6.11.1/src/corelib/thread/qfutureinterface_p.h:150:25:
error: call to 'QFutureInterfaceBasePrivate::RefCount::RefCount(int, int)' uses
the default argument for parameter 2, which is not yet defined
150 | RefCount refCount = 1;
| ^
pinskia suspects it's related to PR126481 and came up with the following
extracted case:
struct s1 {
struct s2
{
s2(int a = 0, int b = 1){}
};
s2 a = 1;
};
$ g++-16 -c a.cc
# works
$ gcc/xg++ -Bgcc -c a.cc
a.cc:6:10: error: call to ‘s1::s2::s2(int, int)’ uses the default argument for
parameter 2, which is not yet defined
6 | s2 a = 1;
| ^
$ gcc/xg++ -Bgcc -v
Reading specs from gcc/specs
COLLECT_GCC=gcc/xg++
COLLECT_LTO_WRAPPER=gcc/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /home/slyfox/dev/git/gcc/configure --disable-multilib
--disable-bootstrap --disable-lto --disable-libsanitizer
--enable-languages=c,c++ CFLAGS='-O1 -g0' CXXFLAGS='-O1 -g0' LDFLAGS='-O1 -g0'
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 17.0.0 20260802 (experimental) (GCC)
