Build .release_info files containing the version string

By adding build-dependencies to all *_parse_options files whenever the contents
of .release_info files differs from $(RELEASE_INFO), we ensure that binaries
print the correct version strings.

Author: tautschnig

.gitignore

@@ -28,6 +28,7 @@ Release/*
 *.obj
 *.a
 *.lib
+.release_info
 src/ansi-c/arm_builtin_headers.inc
 src/ansi-c/clang_builtin_headers.inc
 src/ansi-c/cprover_builtin_headers.inc

src/common

@@ -230,12 +230,28 @@ OBJ += $(patsubst %.cc, %$(OBJEXT), $(filter %.cc, $(SRC)))
 %.obj:%.c
 	$(CC) $(CP_CFLAGS) /nologo /c /EHsc $< /Fo$@
 
+# Use make >= 4.0's `file` function, if available - it should be faster than
+# `shell cat`
+ifeq ($(firstword $(subst ., , $(MAKE_VERSION))), 3)
+KNOWN_RELEASE_INFO = $(shell cat .release_info 2>/dev/null)
+else
+KNOWN_RELEASE_INFO = $(file < .release_info)
+endif
+ifneq ($(GIT_INFO), $(KNOWN_RELEASE_INFO))
+$(filter %_parse_options$(OBJEXT), $(OBJ)): .release_info
+
+.release_info:
+	echo $(GIT_INFO) > $@
+
+.PHONY: .release_info
+endif
+
 clean:
 	$(RM) $(patsubst %.cpp, %$(OBJEXT), $(filter %.cpp, $(SRC))) \
 		$(patsubst %.cpp, %$(DEPEXT), $(filter %.cpp, $(SRC))) \
 		$(patsubst %.cc, %$(OBJEXT), $(filter %.cc, $(SRC))) \
 		$(patsubst %.cc, %$(DEPEXT), $(filter %.cc, $(SRC))) \
-		$(CLEANFILES)
+		$(CLEANFILES) .release_info
 
 .PHONY: first_target clean all
 .PHONY: sources generated_files