https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111642
--- Comment #4 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
Looks like `-fchecking=1` and `-fno-checking` handle c++ a bit differently.
Two commands differing only in `-fno-checking`. One works, one does not:
```
$ /tmp/gb/./prev-gcc/xg++ -B/tmp/gb/./prev-gcc/
-B/usr/local/x86_64-pc-linux-gnu/bin/ -nostdinc++
-B/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/src/.libs
-B/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/libsupc++/.libs
-I/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/include/x86_64-pc-linux-gnu
-I/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/include
-I/home/slyfox/dev/git/gcc/libstdc++-v3/libsupc++
-L/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/src/.libs
-L/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/libsupc++/.libs -fno-PIE -c
-g -O2 -DIN_GCC -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W
-Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wmissing-format-attribute
-Wconditionally-supported -Woverloaded-virtual -pedantic -Wno-long-long
-Wno-variadic-macros -Wno-overlength-strings -Werror -fno-common
-DHAVE_CONFIG_H -fno-PIE -I. -I. -I/home/slyfox/dev/git/gcc/gcc
-I/home/slyfox/dev/git/gcc/gcc/. -I/home/slyfox/dev/git/gcc/gcc/../include
-I/home/slyfox/dev/git/gcc/gcc/../libcpp/include
-I/home/slyfox/dev/git/gcc/gcc/../libcody
-I/home/slyfox/dev/git/gcc/gcc/../libdecnumber
-I/home/slyfox/dev/git/gcc/gcc/../libdecnumber/bid -I../libdecnumber
-I/home/slyfox/dev/git/gcc/gcc/../libbacktrace -o rtl-tests.o -MT rtl-tests.o
-MMD -MP -MF ./.deps/rtl-tests.TPo /home/slyfox/dev/git/gcc/gcc/rtl-tests.cc
In file included from /home/slyfox/dev/git/gcc/gcc/coretypes.h:480,
from /home/slyfox/dev/git/gcc/gcc/rtl-tests.cc:22:
/home/slyfox/dev/git/gcc/gcc/poly-int.h: In instantiation of 'constexpr
poly_int<N, T>::poly_int(poly_int_full, const Cs& ...) [with Cs = {int, int};
unsigned int N = 1; C = long int]':
/home/slyfox/dev/git/gcc/gcc/poly-int.h:439:13: required from here
/home/slyfox/dev/git/gcc/gcc/rtl-tests.cc:249:25: in 'constexpr' expansion of
'poly_int<1, long int>(1, 1)'
/home/slyfox/dev/git/gcc/gcc/poly-int.h:453:5: error: too many initializers for
'long int [1]'
453 | : coeffs { (typename poly_coeff_traits<C>::
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
454 | template init_cast<Cs>::type (cs))... } {}
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# fails
```
```
$ /tmp/gb/./prev-gcc/xg++ -B/tmp/gb/./prev-gcc/
-B/usr/local/x86_64-pc-linux-gnu/bin/ -nostdinc++
-B/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/src/.libs
-B/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/libsupc++/.libs
-I/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/include/x86_64-pc-linux-gnu
-I/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/include
-I/home/slyfox/dev/git/gcc/libstdc++-v3/libsupc++
-L/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/src/.libs
-L/tmp/gb/prev-x86_64-pc-linux-gnu/libstdc++-v3/libsupc++/.libs -fno-PIE -c
-g -O2 -DIN_GCC -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W
-Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wmissing-format-attribute
-Wconditionally-supported -Woverloaded-virtual -pedantic -Wno-long-long
-Wno-variadic-macros -Wno-overlength-strings -Werror -fno-common
-DHAVE_CONFIG_H -fno-PIE -I. -I. -I/home/slyfox/dev/git/gcc/gcc
-I/home/slyfox/dev/git/gcc/gcc/. -I/home/slyfox/dev/git/gcc/gcc/../include
-I/home/slyfox/dev/git/gcc/gcc/../libcpp/include
-I/home/slyfox/dev/git/gcc/gcc/../libcody
-I/home/slyfox/dev/git/gcc/gcc/../libdecnumber
-I/home/slyfox/dev/git/gcc/gcc/../libdecnumber/bid -I../libdecnumber
-I/home/slyfox/dev/git/gcc/gcc/../libbacktrace -o rtl-tests.o -MT rtl-tests.o
-MMD -MP -MF ./.deps/rtl-tests.TPo /home/slyfox/dev/git/gcc/gcc/rtl-tests.cc
-fno-checking
# ok
```
