Re: [PATCH v2 5/5] travis-ci: build with the right compiler

> Our 'Makefile' hardcodes the compiler to build Git as 'CC = cc'.  This
> CC variable can be overridden from the command line, i.e. 'make
> CC=gcc-X.Y' will build with that particular GCC version, but not from
> the environment, i.e. 'CC=gcc-X.Y make' will still build with whatever
> 'cc' happens to be on the platform.
> 
> Our build jobs on Travis CI are badly affected by this.  In the build
> matrix we have dedicated build jobs to build Git with GCC and Clang
> both on Linux and macOS from the very beginning (522354d70f (Add
> Travis CI support, 2015-11-27)).  Alas, this never really worked as
> supposed to, because Travis CI specifies the compiler for those build
> jobs as 'export CC=gcc' and 'export CC=clang' (which works fine for
> projects built with './configure && make').  Consequently, our
> 'linux-clang' build job has always used GCC, because that's where 'cc'
> points at in Travis CI's Linux images, while the 'osx-gcc' build job
> has always used Clang.  Furthermore, 37fa4b3c78 (travis-ci: run gcc-8
> on linux-gcc jobs, 2018-05-19) added an 'export CC=gcc-8' in an
> attempt to build with a more modern compiler, but to no avail.
> 
> Set MAKEFLAGS with CC based on the $CC environment variable, so 'make'
> will run the "right" compiler.  The Xcode 10.1 macOS image on Travis
> CI already contains the gcc@8 package from Homebrew, but we have to
> 'brew link' it first to be able to use it.
> 
> So with this patch our build jobs will build Git with the following
> compiler versions:
> 
>   linux-clang: clang version 5.0.0 (tags/RELEASE_500/final)
>   linux-gcc:   gcc-8 (Ubuntu 8.1.0-5ubuntu1~14.04) 8.1.0
> 
>   osx-clang: Apple LLVM version 10.0.0 (clang-1000.11.45.5)
>   osx-gcc:   gcc-8 (Homebrew GCC 8.2.0) 8.2.0
> 
>   GETTEXT_POISON: gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4
> 
> Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>

> ---
>  ci/install-dependencies.sh |  5 +++++
>  ci/lib-travisci.sh         | 15 ++++++++++++---
>  2 files changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/ci/install-dependencies.sh b/ci/install-dependencies.sh
> index 06c3546e1e..dc719876bb 100755
> --- a/ci/install-dependencies.sh
> +++ b/ci/install-dependencies.sh
> @@ -40,6 +40,11 @@ osx-clang|osx-gcc)
>  	brew install git-lfs gettext
>  	brew link --force gettext
>  	brew install caskroom/cask/perforce
> +	case "$jobname" in
> +	osx-gcc)
> +		brew link gcc@8
> +		;;
> +	esac
>  	;;
>  StaticAnalysis)
>  	sudo apt-get -q update
> diff --git a/ci/lib-travisci.sh b/ci/lib-travisci.sh
> index 69dff4d1ec..a479613a57 100755
> --- a/ci/lib-travisci.sh
> +++ b/ci/lib-travisci.sh
> @@ -99,12 +99,14 @@ export DEFAULT_TEST_TARGET=prove
>  export GIT_PROVE_OPTS="--timer --jobs 3 --state=failed,slow,save"
>  export GIT_TEST_OPTS="--verbose-log -x --immediate"
>  export GIT_TEST_CLONE_2GB=YesPlease
> -if [ "$jobname" = linux-gcc ]; then
> -	export CC=gcc-8
> -fi
>  
>  case "$jobname" in
>  linux-clang|linux-gcc)
> +	if [ "$jobname" = linux-gcc ]
> +	then
> +		export CC=gcc-8
> +	fi
> +
>  	export GIT_TEST_HTTPD=YesPlease
>  
>  	# The Linux build installs the defined dependency versions below.
> @@ -118,6 +120,11 @@ linux-clang|linux-gcc)
>  	export PATH="$GIT_LFS_PATH:$P4_PATH:$PATH"
>  	;;
>  osx-clang|osx-gcc)
> +	if [ "$jobname" = osx-gcc ]
> +	then
> +		export CC=gcc-8
> +	fi
> +
>  	# t9810 occasionally fails on Travis CI OS X
>  	# t9816 occasionally fails with "TAP out of sequence errors" on
>  	# Travis CI OS X
> @@ -127,3 +134,5 @@ GIT_TEST_GETTEXT_POISON)
>  	export GIT_TEST_GETTEXT_POISON=YesPlease
>  	;;
>  esac
> +
> +export MAKEFLAGS="CC=${CC:-cc}"
> -- 
> 2.20.1.499.gf60de1223c
> 
>