Makefile: add a prerequisite to the coverage-report target

Directly invoking make coverage-report as a target results in an error because
its prerequisites are missing,

This patch adds the compile-test prerequisite, which is run only once each time
the compile-report target is invoked. In practice, the developer may decide to
review the coverage-report results without necessarily rerunning for this
coverage-test, if it has already been run.

Signed-off-by: Elia Pinto <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Makefile

@@ -3398,6 +3398,7 @@ coverage-clean-results:
 	$(RM) coverage-untested-functions
 	$(RM) -r cover_db/
 	$(RM) -r cover_db_html/
+	$(RM) coverage-test.made
 
 coverage-clean: coverage-clean-results
 	$(RM) $(addsuffix *.gcno,$(object_dirs))
@@ -3412,13 +3413,17 @@ coverage-compile:
 coverage-test: coverage-clean-results coverage-compile
 	$(MAKE) CFLAGS="$(COVERAGE_CFLAGS)" LDFLAGS="$(COVERAGE_LDFLAGS)" \
 		DEFAULT_TEST_TARGET=test -j1 test
+	touch coverage-test.made
+
+coverage-test.made:
+	$(MAKE) coverage-test
 
 coverage-prove: coverage-clean-results coverage-compile
 	$(MAKE) CFLAGS="$(COVERAGE_CFLAGS)" LDFLAGS="$(COVERAGE_LDFLAGS)" \
 		DEFAULT_TEST_TARGET=prove GIT_PROVE_OPTS="$(GIT_PROVE_OPTS) -j1" \
 		-j1 test
 
-coverage-report:
+coverage-report: coverage-test.made
 	$(QUIET_GCOV)for dir in $(object_dirs); do \
 		$(GCOV) $(GCOVFLAGS) --object-directory=$$dir $$dir*.c || exit; \
 	done