On Mon, 2023-10-30 at 10:08 +0000, David Laight wrote:
From: David Woodhouse
Sent: 30 October 2023 09:46
On Sun, 2023-10-29 at 21:13 +0000, David Laight wrote:
From: David Woodhouse
Sent: 28 October 2023 20:35
Using -MD without -MP causes build failures when a header file is deleted or moved. With -MP, the compiler will emit phony targets for the header files it lists as dependencies, and the Makefiles won't refuse to attempt to rebuild a C unit which no longer includes the deleted header.
Won't a phony target stop a header being built if there is an actual rule to build it?
It probably would have taken you about the same time to find the answer for yourself, as it took to write that email. Why don't you try it?
I was sure that just adding
foo.h:
would generate a 'no rules to build' error. Maybe that was BSD make or SYS-V make.
But calling the 'phony' is probably wrong. PHONY has a very specific meaning to make - and these aren't PHONY.
I recommend filing a bug against the GCC documentation then.
https://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html#index-MP