Re: [PATCH] Makefile: dedup git-ls-files output to prevent duplicate targets

From: Junio C Hamano <gitster@pobox.com>
Date: May 26, 2022, 06:23 UTC
Message-ID: <xmqq5yls3j8i.fsf@gitster.g>
In-Reply-To: <CANYiYbEcNJ7+7XW-8-v+p8q=aiOP9RJYvST8ethVjxVdNugR5Q@mail.gmail.com>

Jiang Xin <worldhello.net@gmail.com> writes:

Show 21 quoted lines

>>         )
>> -FOUND_SOURCE_FILES := $(shell $(SOURCES_CMD))
>> +FOUND_SOURCE_FILES := $(sort $(shell $(SOURCES_CMD)))
>>
>>  FOUND_C_SOURCES = $(filter %.c,$(FOUND_SOURCE_FILES))
>>  FOUND_H_SOURCES = $(filter %.h,$(FOUND_SOURCE_FILES))
>>
>
> If I disabled the git-ls-files command like below,
>
>     @@ -846,7 +846,7 @@ generated-hdrs: $(GENERATED_H)
>...
> This is because the three generated header files (defined in
> $(GENERATED_H)) are also included in the result of "SOURCES_CMD". We
> can fix this by sorting LOCALIZED_C:
>
>     -LOCALIZED_C = $(FOUND_C_SOURCES) $(FOUND_H_SOURCES) $(SCALAR_SOURCES) \
>     -             $(GENERATED_H)
>     +LOCALIZED_C = $(sort $(FOUND_C_SOURCES) $(FOUND_H_SOURCES)
> $(SCALAR_SOURCES) \
>     +               $(GENERATED_H))

If you make FOUND_SOURCE_FILES unique upfront, the at least there wouldn't be any duplicates there. Do you mean that some of what is in FOUND_SOURCE_FILES appear in either SCALAR_SOURCES or GENERATED_H?

If not, I think deduplicating near the source of the issue, i.e.

  FOUND_SOURCE_FILES := $(sort $(shell $(SOURCES_CMD)))

may be sufficient. Deduplicating near the consumer, like LOCALIZED_C, may force us to dedup all the consumers of it (e.g. LOCALIZED_C is not the sole consumer of FOUND_C_SOURCES; you'd need to sort the input to COCCI_SOURCES, for example).

Thanks.