gfortran compile error on debian-jessie-minimal

[mkoeppe]

This is with gcc version 4.9.2 (Debian 4.9.2-10+deb8u2).

​https://github.com/mkoeppe/sage/runs/430688708?check_suite_focus=true

2020-02-07T01:07:37.4585503Z In file included from ../../src/gcc/config/i386/i386.c:98:0:
2020-02-07T01:07:37.4586109Z ../../src/gcc/config/i386/x86-tune-costs.h:32:56: error: uninitialized const member 'stringop_algs::stringop_strategy::max'
2020-02-07T01:07:37.4586420Z    {rep_prefix_1_byte, {{-1, rep_prefix_1_byte, false}}}};
2020-02-07T01:07:37.4586500Z                                                         ^

This ticket fixes this by building gfortran using system g++ without passing the -std=gnu++11 flags.

9.1.beta5: ​https://github.com/mkoeppe/sage/runs/462462734

9.1.beta5 + this ticket: ​https://github.com/mkoeppe/sage/runs/463683795

[dimpase]

so, Sage's gfortran cannot be built with an ancient gcc. Nothing really new about it.

Perhaps the most meaningful fix would be to gfortran's spkg-configure to error out on not finding a system gfortran and finding an old gcc...

[mkoeppe]

On this system, the gcc package (including fortran) can be installed successfully, but not gfortran.

[dimpase]

if gcc is built then gfortran will be built with the new gcc.

apparently gfortran is more picky.

I really don't see a point of not having gfortran as a pre-req on Linux.

[mkoeppe]

What's happening here is that gfortran 9.2 cannot build without bootstrapping when the old g++ is invoked as g++ -std=gnu++11. This is apparently a build configuration untested by upstream. The ticket fixes it by avoiding the -std=gnu++11 flag (which is globally added to $CXX by build/pkgs/gcc/spkg-configure.m4 on old compilers).

The ticket is on top of #29052 (which needs review...)

Tests at ​https://github.com/mkoeppe/sage/actions/runs/44025504

---

New commits:

​5244060	Split out build/bin/sage-build-env-config from sage-env-config
​96b6c58	src/bin/sage: Add -buildsh
​3491a9d	build/make/deps, build/make.Makefile.in: Source build/bin/sage-build-env-config for building sagelib and for script packages
​11f6797	Document 'sage -buildsh' in the output of 'sage -advanced'
​ecb6a8b	src/doc/en/reference/repl/options.rst: Document sage --buildsh
​a0c3c59	Fix "--build-sh" -> "--buildsh" in a comment
​c1f0e62	Merge tag '9.1.beta4' into t/29052/create_build_bin_sage_build_env_and_call_it_from_build_make_deps__add_sage___buildsh
​0dc97db	Clean src/doc/en/installation/*.txt in bootstrap-clean, not misc-clean
​8bd4f53	Merge branch 't/29233/bootstrap____make_distclean_broken' into t/29052/create_build_bin_sage_build_env_and_call_it_from_build_make_deps__add_sage___buildsh
​833ab0e	Build gcc/gfortran without passing -std=gnu++11 to the system g++

[mkoeppe]

For the unrelated gfortran compile errors on *-i386-minimal that appear in ​https://github.com/mkoeppe/sage/runs/463683795, see #29241 (gfortran on 32bit: Configure for the same ABI as gcc).

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​2ab9b09	Move SAGE_PKG_CONFIG_PATH, SAGE_NAUTY_BINS_PREFIX back to src/bin/sage-env-config.in
​caeaaae	Merge branch 't/29052/create_build_bin_sage_build_env_and_call_it_from_build_make_deps__add_sage___buildsh' into t/29162/gfortran_compile_error_on_debian_jessie

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​1c36ede

Merge tag '9.1.beta6' into t/29162/gfortran_compile_error_on_debian_jessie

[mkoeppe]

Thank you.