Building with GCC 11 fails

[awvwgk]

GCC 11 is now available and we already have packages for Ubuntu 21.04 and homebrew, would be nice if we could start testing this here as well. Since our Linux runner is using Ubuntu 20.04 it might be a bit more involved to install GCC 11 there.

[jvdp1]

AFAIK Ubuntu 21.04 is not available among the supported Github runners.

Here and here are some discussions on GCC 11 on Ubuntu 20.04

[awvwgk]

We are triggering an ICE with GCC 11 in stdlib_optval:

cd /home/runner/work/stdlib/stdlib/build/src/tests/optval && /usr/bin/gfortran-11  -I/home/runner/work/stdlib/stdlib/build/src/mod_files  -O3 -DNDEBUG -O3   -fimplicit-none -ffree-line-length-132 -Wall -Wextra -Wimplicit-procedure -Wconversion-extra -pedantic-errors -std=f2018 -Wno-error=pedantic -c /home/runner/work/stdlib/stdlib/src/tests/optval/test_optval.f90 -o CMakeFiles/test_optval.dir/test_optval.f90.o
f951: internal compiler error: Segmentation fault
0xd40aeb internal_error(char const*, ...)
	???:0
0x15913ef gfc_resolve_code(gfc_code*, gfc_namespace*)
	???:0
0x1572ad1 gfc_parse_file()
	???:0
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <file:///usr/share/doc/gcc-11/README.Bugs> for instructions.

[LKedward]

I opened a possible fix in awvwgk#80. Works locally, but not tested in Github actions CI yet.

[awvwgk]

This seems to do the trick, thanks.

For information, current git~master builds unmodified with GCC-11-x86-64 on Windows 10 x64, using make -f Makefile.manual FYPPFLAGS=-DMAXRANK=4 clean test.

[awvwgk]

The manual makefile does not set the -pedantic-errors option which is triggering the ICE in the CMake based build.

[awvwgk]

Maybe worth reporting on https://gcc.gnu.org/bugzilla/, stdlib_optval.fypp should be self-contained enough for a good minimal reproducer. I might be able to upgrade my toolchains to GCC11 by the end of this month and create a report, until then please feel free to go ahead, report this issue and post the ticket here if you have already a GCC11 version around.