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Also they don't add an empty rule for the source file (like they can do for headers), so if you rename from e.g. foo.c to foo.cpp, which still produces a foo.o,
by glandium 5y ago
Also they don't add an empty rule for the source file (like they can do for headers), so if you rename from e.g. foo.c to foo.cpp, which still produces a foo.o, your incremental build fails because the dep file still has the dep on foo.c which doesn't exist anymore.
- brandmeyer 5y agoThe original sin here is generating the dependencies from the source files in the same step that was used to generate the object files. The only way to ensure that Make observes structural changes in the dependency DAG is if the graph is rebuilt.
- glandium 5y agoGood old "make depend". If only it didn't add a significant overhead...
- brandmeyer 5y agoYou can get make to only re-generate its rules incrementally based on what was changed. https://www.gnu.org/software/make/manual/html_node/Remaking-Makefiles.html#Remaking-Makefiles https://www.gnu.org/software/make/manual/html_node/Remaking-...
- sigjuice 5y agoLooks like gcc does not plan to do this https://gcc.gnu.org/bugzilla/show_bug.cgi?id=28810 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=28810