https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109183
--- Comment #11 from Allan W. Macdonald <allan.w.macdonald at gmail dot com> ---
The makefiles I've been maintaining contain a mechanism to make sure that any
change in a locally-included file will cause the c file that includes it to be
compiled again, like so:
### Extract of makefile:
%.d: %.c
gcc -MM -MD $<
-include $(OBJECTS:.o=.d)
###
So, if I understand this correctly (tell me if I'm wrong), preprocessing is
performed to generate the .d files before any file is compiled to an object in
this situation. These .d files are then included and turned into rules using a
substitution reference.
The 'a-' prefix breaks this mechanism.
The workaround I mentioned,
gcc -E -MMD $< > /dev/null
seems to achieve the same behaviour but there's probably a better way to do it.
