Hi Ævar,

On Thu, 8 Sep 2022, Ævar Arnfjörð Bjarmason wrote:

> On Tue, Aug 23 2022, Johannes Schindelin via GitGitGadget wrote:
>
> > From: Johannes Schindelin <johannes.schindelin@gmx.de>
> >
> > In 7f5397a07c6c (cmake: support for testing git when building out of the
> > source tree, 2020-06-26), we implemented support for running Git's test
> > scripts even after building Git in a different directory than the source
> > directory.
> >
> > The way we did this was to edit the file `t/test-lib.sh` to override
> > `GIT_BUILD_DIR` to point somewhere else than the parent of the `t/`
> > directory.
> >
> > This is unideal because it always leaves a tracked file marked as
> > modified, and it is all too easy to commit that change by mistake.
> >
> > Let's change the strategy by teaching `t/test-lib.sh` to detect the
> > presence of a file called `GIT-BUILD-DIR` in the source directory. If it
> > exists, the contents are interpreted as the location to the _actual_
> > build directory. We then write this file as part of the CTest
> > definition.
> >
> > To support building Git via a regular `make` invocation after building
> > it using CMake, we ensure that the `GIT-BUILD-DIR` file is deleted (for
> > convenience, this is done as part of the Makefile rule that is already
> > run with every `make` invocation to ensure that `GIT-BUILD-OPTIONS` is
> > up to date).
> >
> > Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> > ---
> >  .gitignore                          |  1 +
> >  Makefile                            |  1 +
> >  contrib/buildsystems/CMakeLists.txt |  7 +------
> >  t/test-lib.sh                       | 11 ++++++++++-
> >  4 files changed, 13 insertions(+), 7 deletions(-)
> >
> > diff --git a/.gitignore b/.gitignore
> > index a4522157641..b72ddf09346 100644
> > --- a/.gitignore
> > +++ b/.gitignore
> > @@ -2,6 +2,7 @@
> >  /fuzz_corpora
> >  /fuzz-pack-headers
> >  /fuzz-pack-idx
> > +/GIT-BUILD-DIR
> >  /GIT-BUILD-OPTIONS
> >  /GIT-CFLAGS
> >  /GIT-LDFLAGS
> > diff --git a/Makefile b/Makefile
> > index 04d0fd1fe60..9347ed90da7 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -3028,6 +3028,7 @@ else
> >  	@echo RUNTIME_PREFIX=\'false\' >>$@+
> >  endif
> >  	@if cmp $@+ $@ >/dev/null 2>&1; then $(RM) $@+; else mv $@+ $@; fi
> > +	@if test -f GIT-BUILD-DIR; then rm GIT-BUILD-DIR; fi
> >
> >  ### Detect Python interpreter path changes
> >  ifndef NO_PYTHON
> > diff --git a/contrib/buildsystems/CMakeLists.txt b/contrib/buildsystems/CMakeLists.txt
> > index fe606c179f7..29d7e236ae1 100644
> > --- a/contrib/buildsystems/CMakeLists.txt
> > +++ b/contrib/buildsystems/CMakeLists.txt
> > @@ -1067,14 +1067,9 @@ endif()
> >  #Make the tests work when building out of the source tree
> >  get_filename_component(CACHE_PATH ${CMAKE_CURRENT_LIST_DIR}/../../CMakeCache.txt ABSOLUTE)
> >  if(NOT ${CMAKE_BINARY_DIR}/CMakeCache.txt STREQUAL ${CACHE_PATH})
> > -	file(RELATIVE_PATH BUILD_DIR_RELATIVE ${CMAKE_SOURCE_DIR} ${CMAKE_BINARY_DIR}/CMakeCache.txt)
> > -	string(REPLACE "/CMakeCache.txt" "" BUILD_DIR_RELATIVE ${BUILD_DIR_RELATIVE})
> >  	#Setting the build directory in test-lib.sh before running tests
> >  	file(WRITE ${CMAKE_BINARY_DIR}/CTestCustom.cmake
> > -		"file(STRINGS ${CMAKE_SOURCE_DIR}/t/test-lib.sh GIT_BUILD_DIR_REPL REGEX \"GIT_BUILD_DIR=(.*)\")\n"
> > -		"file(STRINGS ${CMAKE_SOURCE_DIR}/t/test-lib.sh content NEWLINE_CONSUME)\n"
> > -		"string(REPLACE \"\${GIT_BUILD_DIR_REPL}\" \"GIT_BUILD_DIR=\\\"$TEST_DIRECTORY/../${BUILD_DIR_RELATIVE}\\\"\" content \"\${content}\")\n"
> > -		"file(WRITE ${CMAKE_SOURCE_DIR}/t/test-lib.sh \${content})")
> > +		"file(WRITE ${CMAKE_SOURCE_DIR}/GIT-BUILD-DIR \"${CMAKE_BINARY_DIR}\")")
> >  	#misc copies
> >  	file(COPY ${CMAKE_SOURCE_DIR}/t/chainlint.sed DESTINATION ${CMAKE_BINARY_DIR}/t/)
> >  	file(COPY ${CMAKE_SOURCE_DIR}/po/is.po DESTINATION ${CMAKE_BINARY_DIR}/po/)
> > diff --git a/t/test-lib.sh b/t/test-lib.sh
> > index 55857af601b..4468ac51f25 100644
> > --- a/t/test-lib.sh
> > +++ b/t/test-lib.sh
> > @@ -42,7 +42,16 @@ then
> >  	TEST_OUTPUT_DIRECTORY=$TEST_DIRECTORY
> >  fi
> >  GIT_BUILD_DIR="${TEST_DIRECTORY%/t}"
> > -if test "$TEST_DIRECTORY" = "$GIT_BUILD_DIR"
> > +if test -f "$GIT_BUILD_DIR/GIT-BUILD-DIR"
> > +then
> > +	GIT_BUILD_DIR="$(cat "$GIT_BUILD_DIR/GIT-BUILD-DIR")" || exit 1
> > +	# On Windows, we must convert Windows paths lest they contain a colon
> > +	case "$(uname -s)" in
> > +	*MINGW*)
> > +		GIT_BUILD_DIR="$(cygpath -au "$GIT_BUILD_DIR")"
> > +		;;
> > +	esac
> > +elif test "$TEST_DIRECTORY" = "$GIT_BUILD_DIR"
> >  then
> >  	echo "PANIC: Running in a $TEST_DIRECTORY that doesn't end in '/t'?" >&2
> >  	exit 1
>
> As pointed out in the v1 this breaks the cmake<->make interaction in
> some scenarios, but from some brief testing there seemed to be an easy
> workaround which didn't suffer from that problem:
> https://lore.kernel.org/git/220811.86sfm3ov5z.gmgdl@evledraar.gmail.com/

I do not think that the CMake <-> make interaction will come up in any
other scenario than your and my tests in the context of this mailing list
thread.

Therefore, I am certain that we need not cater to that scenario at all.

Ciao,
Johannes