cmake: avoid editing t/test-lib.sh

In 7f5397a (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 <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: dscho

.gitignore

@@ -1,4 +1,5 @@
 /fuzz_corpora
+/GIT-BUILD-DIR
 /GIT-BUILD-OPTIONS
 /GIT-CFLAGS
 /GIT-LDFLAGS

Makefile

@@ -3041,6 +3041,7 @@ 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

contrib/buildsystems/CMakeLists.txt

@@ -1074,14 +1074,9 @@ 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.pl DESTINATION ${CMAKE_BINARY_DIR}/t/)
 	file(COPY ${CMAKE_SOURCE_DIR}/po/is.po DESTINATION ${CMAKE_BINARY_DIR}/po/)

t/test-lib.sh

@@ -47,6 +47,16 @@ then
 	echo "PANIC: Running in a $TEST_DIRECTORY that doesn't end in '/t'?" >&2
 	exit 1
 fi
+if test -f "$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
+fi
 
 # Prepend a string to a VAR using an arbitrary ":" delimiter, not
 # adding the delimiter if VAR or VALUE is empty. I.e. a generalized: