Re: [GSoC PATCH v4 0/5] preserve promisor files content after repack

[Junio C Hamano <gitster@pobox.com>]

LorenzoPegorari <lorenzo.pegorari2002@gmail.com> writes:

> QUESTION:
> The "CodingGuidelines" explicitly state that:
>  "A C file must directly include the header files that declare the
>   functions and the types it uses, except for the functions and types
>   that are made available to it by including one of the header files
>   it must include by the previous rule"
> where "the previous rule" is (if I understand correctly), the one related
> to "<git-compat-util.h>". From what I understand then, I should have
> added an include for "strmap.h" (which is needed for `strset`), correct?
> And if I am correct, shouldn't "strbuf.h", "hash.h", "odb.h",
> "string-list.h" and "strvec.h" also be included?

If you are using any of the facilities declared in these header
files in your program, yes.

In practice many header files pull in other header files for
definitions they themselves use.  For example, <X.h> that defines
"struct X" may include <Y.h> for the definition of "struct Y" because
the former embeds an instance of the latter, instead of having a pointer
to an on-heap instance of the latter.

If you use both "struct X" and "struct Y", your program may compile
with only <X.h> included without <Y.h> included in such a case, but
the guideline suggests against doing so, because it should not be
relied on.  The implementation of "struct X" may change in the
future and stop depending on "struct Y", at which time <X.h> stops
including <Y.h> itself, and your program would start failing to
build, because you use "struct Y" but without including <Y.h>.

But in practice, use of strbuf is so widespread and the header is
included in some other headers that do not need to, so your build
may happen to work without including <strbuf.h>, for example.