gfortran breaks parallel build

[Volker Braun]

gfortran overwrites compiler parts non-atomically; This breaks parallel compilation:

[gfortran-7.2.0] /bin/sh ../../src/gcc/../mkinstalldirs /Users/buildslave-sage/slave/sage_git/build/local/libexec/gcc/x86_64-apple-darwin17.4.0/7.2.0/plugin
[gfortran-7.2.0] mkdir /Users/buildslave-sage/slave/sage_git/build/local/libexec/gcc/x86_64-apple-darwin17.4.0/7.2.0/plugin
[gfortran-7.2.0] /usr/bin/install -c gengtype /Users/buildslave-sage/slave/sage_git/build/local/libexec/gcc/x86_64-apple-darwin17.4.0/7.2.0/plugin/gengtype
[gfortran-7.2.0] for file in gnat1 brig1 cc1 cc1plus f951 go1  lto1 cc1obj cc1objplus; do \
[gfortran-7.2.0]          if [ -f $file ] ; then \
[gfortran-7.2.0]            rm -f /Users/buildslave-sage/slave/sage_git/build/local/libexec/gcc/x86_64-apple-darwin17.4.0/7.2.0/$file; \
[gfortran-7.2.0]            /usr/bin/install -c $file /Users/buildslave-sage/slave/sage_git/build/local/libexec/gcc/x86_64-apple-darwin17.4.0/7.2.0/$file; \
[gfortran-7.2.0]          else true; \
[gfortran-7.2.0]          fi; \
[gfortran-7.2.0]        done
[flint-2.5.2.p2] gcc: error trying to exec 'cc1': execvp: No such file or directory
[flint-2.5.2.p2] make[4]: *** [../build/fmpq_poly/test/t-scalar_mul_si] Error 1
[flint-2.5.2.p2] gcc -fno-common -ansi -pedantic -Wall -O2 -funroll-loops -g -mpopcnt  -I/Users/buildslave-sage/slave/sage_git/build/local/var/tmp/sage/build/flint-2.5.2.p2/src -I/Users/buildslave-sage/slave/sage_git/build/local/include -I/Users/buildslave-sage/slave/sage_git/build/local/include -I/Users/buildslave-sage/slave/sage_git/build/local/include test/t-scalar_mul_ui.c ../build/fmpq_poly/../../test_helpers.o -o ../build/fmpq_poly/test/t-scalar_mul_ui -L/Users/buildslave-sage/slave/sage_git/build/local/var/tmp/sage/build/flint-2.5.2.p2/src -L/Users/buildslave-sage/slave/sage_git/build/local/lib -L/Users/buildslave-sage/slave/sage_git/build/local/lib -L/Users/buildslave-sage/slave/sage_git/build/local/lib -lflint -lmpfr -lgmp -lm -lntl -lpthread  -MMD -MP -MF ../build/fmpq_poly/test/t-scalar_mul_ui.d -MT "../build/fmpq_poly/test/t-scalar_mul_ui" -MT "../build/fmpq_poly/test/t-scalar_mul_ui.d"

[Jeroen Demeyer]

Why is gfortran installing gcc in the first place?

[François Bissey]

Because you cannot build gfortran without a minimal gcc at this stage. There is a section at the end of spkg-install that renames it so it is not in the way. Patching to avoid install is hard.

[Jeroen Demeyer]

Replying to fbissey:

Because you cannot build gfortran without a minimal gcc at this stage.

Building, I understand. But installing?

[François Bissey]

Replying to jdemeyer:

Replying to fbissey:

Because you cannot build gfortran without a minimal gcc at this stage.

Building, I understand. But installing?

I know what you mean but as far as I know you cannot build it without it being an install target. If you know some more configure/install options feel free to enlighten me. Otherwise this is a perfect scenario for Erik's work on staging the install rather than installing directly on the system. You could fix something like that in the staging area before merging the install on the system.

[François Bissey]

There is a hack we could use, configure with one of --program-prefix or --program-suffix and then link the resulting gfortran binary to the expected name. Says we pass --program-prefix=sage and then we will have sage-gcc, sage-gfortran and so on installed. As the last step we create a link gfortran to sage-gfortran and since sage-{gcc,g++} is not an expected name for other configure scripts, we should be safe.

[Volker Braun]

Or maybe just not compile other stuff until gfortran is complete, like gcc

[Jeroen Demeyer]

Replying to fbissey:

Otherwise this is a perfect scenario for Erik's work on staging the install rather than installing directly on the system.

+1

[Jeroen Demeyer]

I'll try the staged install, just to see whether it might work.

[git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

​330e618	Introduce SAGE_DESTDIR_LOCAL variable
​04f992c	Don't install gcc as part of gfortran

[git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

​9d14972

Don't install gcc as part of gfortran

[François Bissey]

If the bits in sage-spkg do their jobs as expected then it looks good to me.