Date: Mon, 15 Aug 2022 22:23:06 +0100 From: Jessica Clarke <jrtc27@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: Dimitry Andric <dim@freebsd.org>, src-committers <src-committers@freebsd.org>, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 402dbdd98acc - main - Adjust function definition in arm's mv_common.c to avoid clang 15 warning Message-ID: <F33312A7-B4B3-4D1A-9FE6-7CEF4E0F4BD9@freebsd.org> In-Reply-To: <Yvq1lQqmq3Mwv9ZJ@kib.kiev.ua> References: <202208151849.27FInHmh027652@gitrepo.freebsd.org> <Yvq1lQqmq3Mwv9ZJ@kib.kiev.ua>
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=3DOn 15 Aug 2022, at 22:07, Konstantin Belousov <kostikbel@gmail.com> = wrote: >=20 > On Mon, Aug 15, 2022 at 06:49:17PM +0000, Dimitry Andric wrote: >> The branch main has been updated by dim: >>=20 >> URL: = https://cgit.FreeBSD.org/src/commit/?id=3D402dbdd98acc7fa94d1d4cd01903e987= d2409336 >>=20 >> commit 402dbdd98acc7fa94d1d4cd01903e987d2409336 >> Author: Dimitry Andric <dim@FreeBSD.org> >> AuthorDate: 2022-08-15 18:02:13 +0000 >> Commit: Dimitry Andric <dim@FreeBSD.org> >> CommitDate: 2022-08-15 18:48:33 +0000 >>=20 >> Adjust function definition in arm's mv_common.c to avoid clang 15 = warning >>=20 >> With clang 15, the following -Werror warning is produced: >>=20 >> sys/arm/mv/mv_common.c:414:20: error: a function declaration = without a prototype is deprecated in all versions of C = [-Werror,-Wstrict-prototypes] >> mv_check_soc_family() >> ^ >> void >>=20 >> This is because mv_check_soc_family() is declared with a (void) = argument >> list, but defined with an empty argument list. Make the definition = match >> the declaration. >>=20 >> MFC after: 3 days >> --- >> sys/arm/mv/mv_common.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >>=20 >> diff --git a/sys/arm/mv/mv_common.c b/sys/arm/mv/mv_common.c >> index 6e1d12f8c7a7..c2e25c686583 100644 >> --- a/sys/arm/mv/mv_common.c >> +++ b/sys/arm/mv/mv_common.c >> @@ -411,7 +411,7 @@ static int mv_win_cesa_attr_armadaxp(int eng_sel) >> } >>=20 >> enum soc_family >> -mv_check_soc_family() >> +mv_check_soc_family(void) >> { >> uint32_t dev, rev; >>=20 > I am actually curious about this and other commits. =46rom the = ISO/IEC 9899:2023 > draft N3047, 6.7.6.3 Function declarators, clause 13: >=20 > For a function declarator without a parameter type list: the effect > is as if it were declared with a parameter type list consisting of > the keyword void. A function declarator provides a prototype for the > function 177). >=20 > Then the note 177: > This implies that a function definition without a parameter list > provides a prototype, and that subsequent calls to that function in = the > same translation unit are constrained not to provide any argument to = the > function call. Thus a definition of a function without parameter list > and one that has such a list consisting of the keyword void are fully > equivalent. >=20 > And more, in the 6.9.1 Function definitions clause 13, there is an = example: > typedef int F(void); // type F is "function with no parameters > // returning int" > int g() { /* ... */ } // RIGHT: g has type compatible with F >=20 > So why does clang enforce the warning? I=E2=80=99m not sure why this is a warning; an empty parameter list in a function declaration that is part of a definition has always been the same as (void) (unless you have K&R-style arguments, which the compiler can also see). C99 6.11.6 Function declarators does however say: > 1 The use of function declarators with empty parentheses (not > prototype-format parameter type declarators) is an obsolescent = feature. So technically warning for pre-C23 is compliant with that, though a bit annoying in the definition case given the semantics have stayed the same and been un-deprecated. Regardless, it=E2=80=99s probably best = practice to be consistent and use (void) in the definitions so it matches any declarations rather than have this be a special case that can differ. Jess
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