From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Taylor Blau <me@ttaylorr.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
J Smith <dark.panda@gmail.com>, Jeff King <peff@peff.net>
Subject: Re: [PATCH 6/8] grep API: call grep_config() after grep_init()
Date: Tue, 09 Nov 2021 03:06:22 +0100 [thread overview]
Message-ID: <211109.86a6iedqpf.gmgdl@evledraar.gmail.com> (raw)
In-Reply-To: <YYmbTOR+uk7prM8A@nand.local>
On Mon, Nov 08 2021, Taylor Blau wrote:
> On Sat, Nov 06, 2021 at 10:10:52PM +0100, Ævar Arnfjörð Bjarmason wrote:
>> The grep_init() function used the odd pattern of initializing the
>> passed-in "struct grep_opt" with a statically defined "grep_defaults"
>> struct, which would be modified in-place when we invoked
>> grep_config().
>>
>> So we effectively (b) initialized config, (a) then defaults, (c)
>> followed by user options. Usually those are ordered as "a", "b" and
>> "c" instead.
>
> Do we risk changing any user-visible behavior here? Based on my reading
> of grep.c before and after this patch, I think the answer is "no", but I
> wasn't sure if you had done a similar analysis.
>
> In any case, I think the "bring your own structure" instead of getting
> one copied around is much easier to reason about. Even if we weren't
> accidentally stomping on ownership of the struct before, not having to
> reason about it is a nice benefit.
I don't think we're changing any behavior except the one noted in this
series.
We only set a few config variables, so I thought that was fairly easy to
trace...
> [...]
>> diff --git a/builtin/grep.c b/builtin/grep.c
>> index 960c7aac123..7f95f44e948 100644
>> --- a/builtin/grep.c
>> +++ b/builtin/grep.c
>> @@ -288,7 +288,7 @@ static int wait_all(void)
>> static int grep_cmd_config(const char *var, const char *value, void *cb)
>> {
>> int st = grep_config(var, value, cb);
>> - if (git_color_default_config(var, value, cb) < 0)
>> + if (git_color_default_config(var, value, NULL) < 0)
>
> This doesn't appear strictly related to the rest of your changes, but
> only serves to prevent the caller-provided data from being sent down to
> git_color_default_config().
>
> It didn't matter before because (a) the caller doesn't specify any data
> to begin with, and git_color_default_config() (or the functions that it
> calls) don't do anything with the extra pointer. Now cmd_grep() is going
> to start passing around a pointer to a struct grep_opt.
>
> But git_color_default_config() still doesn't do anything with the
> pointer it receives, and passing that pointer around is standard
> practice among config.c code. So I don't think that this hunk is
> strictly necessary, and it's somewhat different than the pattern
> established within config.c.
>
> I wouldn't be sad to see this hunk dropped (and in fact have a slight
> preference leaning this way), but I don't mind keeping it around,
> either.
Will either split it up or drop it.
> [...]
>> -/*
>> - * Initialize one instance of grep_opt and copy the
>> - * default values from the template we read the configuration
>> - * information in an earlier call to git_config(grep_config).
>> - */
>> void grep_init(struct grep_opt *opt, struct repository *repo)
>> {
>> - *opt = grep_defaults;
>> + struct grep_opt blank = GREP_OPT_INIT;
>> + memcpy(opt, &blank, sizeof(*opt));
>
> I'm nit-picking, but creating a throwaway struct for the convenience of
> using designated initialization (at the cost of having to memcpy an
> entire struct around) seems like overkill.
>
> Especially since we're just going to write into the other fields of the
> the target struct anyway, I'd probably rather have seen everything
> written out explicitly without the throwaway or memcpy.
It's a widely used pattern in the codebase at this point, see
5726a6b4012 (*.c *_init(): define in terms of corresponding *_INIT
macro, 2021-07-01) (mine, but I stole it from Jeff King).
As his linked-to compiler test shows the memcpy() is optimized away, so
modern compilers will treat these idioms the same way.
There was a suggestions somewhere that we should prorably move to that
"*<x> = <y>" or whatever it was briefer C99 (I think) syntax across the
board, it would be less verbose. But I haven't tested if it's as widely
supported, so I've just been sticking with that blank/memcpy() pattern
for "do init in terms of macro".
next prev parent reply other threads:[~2021-11-09 2:10 UTC|newest]
Thread overview: 151+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-06 21:10 [PATCH 0/8] grep: simplify & delete code by changing obscure cfg variable behavior Ævar Arnfjörð Bjarmason
2021-11-06 21:10 ` [PATCH 1/8] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2021-11-06 21:10 ` [PATCH 2/8] git.c & grep.c: assert that "prefix" is NULL or non-zero string Ævar Arnfjörð Bjarmason
2021-11-08 20:37 ` Taylor Blau
2021-11-06 21:10 ` [PATCH 3/8] grep: remove unused "prefix_length" member Ævar Arnfjörð Bjarmason
2021-11-08 20:42 ` Taylor Blau
2021-11-06 21:10 ` [PATCH 4/8] grep.c: move "prefix" out of "struct grep_opt" Ævar Arnfjörð Bjarmason
2021-11-08 20:56 ` Taylor Blau
2021-11-09 2:10 ` Ævar Arnfjörð Bjarmason
2021-11-10 0:18 ` Taylor Blau
2021-11-06 21:10 ` [PATCH 5/8] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2021-11-06 21:10 ` [PATCH 6/8] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2021-11-08 21:49 ` Taylor Blau
2021-11-09 2:06 ` Ævar Arnfjörð Bjarmason [this message]
2021-11-10 0:18 ` Taylor Blau
2021-11-06 21:10 ` [PATCH 7/8] grep: simplify config parsing, change grep.<rx config> interaction Ævar Arnfjörð Bjarmason
2021-11-08 23:04 ` Taylor Blau
2021-11-09 2:01 ` Ævar Arnfjörð Bjarmason
2021-11-10 0:16 ` Taylor Blau
2021-11-06 21:10 ` [PATCH 8/8] grep: make "extendedRegexp=true" the same as "patternType=extended" Ævar Arnfjörð Bjarmason
2021-11-10 1:43 ` [PATCH v2 0/8] grep: simplify & delete code by changing obscure cfg variable behavior Ævar Arnfjörð Bjarmason
2021-11-10 1:43 ` [PATCH v2 1/8] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2021-11-12 16:11 ` Junio C Hamano
2021-11-10 1:43 ` [PATCH v2 2/8] built-ins: trust the "prefix" from run_builtin() Ævar Arnfjörð Bjarmason
2021-11-12 16:38 ` Junio C Hamano
2021-11-10 1:43 ` [PATCH v2 3/8] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2021-11-12 17:09 ` Junio C Hamano
2021-11-10 1:43 ` [PATCH v2 4/8] grep docs: de-duplicate configuration sections Ævar Arnfjörð Bjarmason
2021-11-12 17:15 ` Junio C Hamano
2021-11-10 1:43 ` [PATCH v2 5/8] grep.c: don't pass along NULL callback value Ævar Arnfjörð Bjarmason
2021-11-12 17:18 ` Junio C Hamano
2021-11-10 1:43 ` [PATCH v2 6/8] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2021-11-12 17:32 ` Junio C Hamano
2021-11-10 1:43 ` [PATCH v2 7/8] grep: simplify config parsing, change grep.<rx config> interaction Ævar Arnfjörð Bjarmason
2021-11-12 19:19 ` Junio C Hamano
2021-11-13 9:55 ` Ævar Arnfjörð Bjarmason
2021-11-10 1:43 ` [PATCH v2 8/8] grep: make "extendedRegexp=true" the same as "patternType=extended" Ævar Arnfjörð Bjarmason
2021-11-12 19:32 ` Junio C Hamano
2021-11-10 2:23 ` [PATCH v2 0/8] grep: simplify & delete code by changing obscure cfg variable behavior Taylor Blau
2021-11-29 14:50 ` [PATCH v3 0/7] grep: simplify & delete "init" & "config" code Ævar Arnfjörð Bjarmason
2021-11-29 14:50 ` [PATCH v3 1/7] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2021-11-29 14:50 ` [PATCH v3 2/7] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2022-03-04 8:57 ` Tests in t4202 are aborted early, was: Re: [PATCH v3 2/7] log Fabian Stelzer
2022-03-04 10:05 ` [PATCH] log tests: fix "abort tests early" regression in ff37a60c369 Ævar Arnfjörð Bjarmason
2021-11-29 14:50 ` [PATCH v3 3/7] grep tests: add missing "grep.patternType" config test Ævar Arnfjörð Bjarmason
2021-11-29 21:52 ` Junio C Hamano
2021-12-03 0:48 ` Junio C Hamano
2021-11-29 14:50 ` [PATCH v3 4/7] built-ins: trust the "prefix" from run_builtin() Ævar Arnfjörð Bjarmason
2021-11-29 14:50 ` [PATCH v3 5/7] grep.c: don't pass along NULL callback value Ævar Arnfjörð Bjarmason
2021-11-29 14:50 ` [PATCH v3 6/7] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2021-11-29 14:50 ` [PATCH v3 7/7] grep: simplify config parsing and option parsing Ævar Arnfjörð Bjarmason
2021-11-29 21:06 ` [PATCH v3 0/7] grep: simplify & delete "init" & "config" code Junio C Hamano
2021-11-29 21:36 ` Junio C Hamano
2021-12-03 10:19 ` [PATCH v4 " Ævar Arnfjörð Bjarmason
2021-12-03 10:19 ` [PATCH v4 1/7] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2021-12-03 10:19 ` [PATCH v4 2/7] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2021-12-03 10:19 ` [PATCH v4 3/7] grep tests: add missing "grep.patternType" config test Ævar Arnfjörð Bjarmason
2021-12-03 10:19 ` [PATCH v4 4/7] built-ins: trust the "prefix" from run_builtin() Ævar Arnfjörð Bjarmason
2021-12-03 10:19 ` [PATCH v4 5/7] grep.c: don't pass along NULL callback value Ævar Arnfjörð Bjarmason
2021-12-03 10:19 ` [PATCH v4 6/7] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2021-12-03 10:19 ` [PATCH v4 7/7] grep: simplify config parsing and option parsing Ævar Arnfjörð Bjarmason
2021-12-22 2:58 ` [PATCH v5 0/7] grep: simplify & delete "init" & "config" code Ævar Arnfjörð Bjarmason
2021-12-22 2:58 ` [PATCH v5 1/7] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2021-12-22 2:58 ` [PATCH v5 2/7] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2021-12-22 2:58 ` [PATCH v5 3/7] grep tests: add missing "grep.patternType" config test Ævar Arnfjörð Bjarmason
2021-12-23 22:25 ` Junio C Hamano
2021-12-25 0:06 ` Re* " Junio C Hamano
2021-12-25 0:19 ` [RFC/PATCH] grep: allow scripts to ignore configured pattern type Junio C Hamano
2021-12-26 23:09 ` Ævar Arnfjörð Bjarmason
2021-12-25 1:04 ` Re* [PATCH v5 3/7] grep tests: add missing "grep.patternType" config test Junio C Hamano
2021-12-22 2:58 ` [PATCH v5 4/7] built-ins: trust the "prefix" from run_builtin() Ævar Arnfjörð Bjarmason
2021-12-22 2:58 ` [PATCH v5 5/7] grep.c: don't pass along NULL callback value Ævar Arnfjörð Bjarmason
2021-12-22 2:58 ` [PATCH v5 6/7] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2021-12-22 2:58 ` [PATCH v5 7/7] grep: simplify config parsing and option parsing Ævar Arnfjörð Bjarmason
2021-12-23 22:37 ` Junio C Hamano
2021-12-23 0:30 ` [PATCH v5 0/7] grep: simplify & delete "init" & "config" code Junio C Hamano
2021-12-26 22:37 ` [PATCH v6 " Ævar Arnfjörð Bjarmason
2021-12-26 22:37 ` [PATCH v6 1/7] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2021-12-26 22:37 ` [PATCH v6 2/7] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2021-12-26 22:37 ` [PATCH v6 3/7] grep tests: add missing "grep.patternType" config tests Ævar Arnfjörð Bjarmason
2021-12-26 22:37 ` [PATCH v6 4/7] built-ins: trust the "prefix" from run_builtin() Ævar Arnfjörð Bjarmason
2021-12-26 22:37 ` [PATCH v6 5/7] grep.c: don't pass along NULL callback value Ævar Arnfjörð Bjarmason
2021-12-26 22:37 ` [PATCH v6 6/7] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2021-12-26 22:37 ` [PATCH v6 7/7] grep: simplify config parsing and option parsing Ævar Arnfjörð Bjarmason
2021-12-27 6:06 ` Junio C Hamano
2021-12-27 18:51 ` Junio C Hamano
2021-12-28 1:07 ` [PATCH v7 00/10] grep: simplify & delete "init" & "config" code Ævar Arnfjörð Bjarmason
2021-12-28 1:07 ` [PATCH v7 01/10] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2021-12-28 1:07 ` [PATCH v7 02/10] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2021-12-28 1:07 ` [PATCH v7 03/10] grep tests: add missing "grep.patternType" config tests Ævar Arnfjörð Bjarmason
2021-12-28 1:07 ` [PATCH v7 04/10] built-ins: trust the "prefix" from run_builtin() Ævar Arnfjörð Bjarmason
2021-12-28 1:07 ` [PATCH v7 05/10] grep.c: don't pass along NULL callback value Ævar Arnfjörð Bjarmason
2021-12-28 1:07 ` [PATCH v7 06/10] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2021-12-28 1:07 ` [PATCH v7 07/10] grep.h: make "grep_opt.pattern_type_option" use its enum Ævar Arnfjörð Bjarmason
2021-12-28 1:07 ` [PATCH v7 08/10] grep.c: do "if (bool && memchr())" not "if (memchr() && bool)" Ævar Arnfjörð Bjarmason
2021-12-28 1:07 ` [PATCH v7 09/10] grep: simplify config parsing and option parsing Ævar Arnfjörð Bjarmason
2021-12-28 1:07 ` [PATCH v7 10/10] grep.[ch]: remove GREP_PATTERN_TYPE_UNSPECIFIED Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 00/10] grep: simplify & delete "init" & "config" code Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 01/10] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 02/10] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 03/10] grep tests: add missing "grep.patternType" config tests Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 04/10] built-ins: trust the "prefix" from run_builtin() Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 05/10] grep.c: don't pass along NULL callback value Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 06/10] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 07/10] grep.h: make "grep_opt.pattern_type_option" use its enum Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 08/10] grep.c: do "if (bool && memchr())" not "if (memchr() && bool)" Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 09/10] grep: simplify config parsing and option parsing Ævar Arnfjörð Bjarmason
2022-01-18 22:50 ` Junio C Hamano
2022-01-18 22:55 ` Junio C Hamano
2022-01-19 0:17 ` Ævar Arnfjörð Bjarmason
2022-01-19 1:09 ` Junio C Hamano
2022-01-19 1:15 ` Ævar Arnfjörð Bjarmason
2022-01-18 15:55 ` [PATCH v8 10/10] grep.[ch]: remove GREP_PATTERN_TYPE_UNSPECIFIED Ævar Arnfjörð Bjarmason
2022-01-27 11:56 ` [PATCH v9 0/9] grep: simplify & delete "init" & "config" code Ævar Arnfjörð Bjarmason
2022-01-27 11:56 ` [PATCH v9 1/9] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2022-01-27 11:56 ` [PATCH v9 2/9] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2022-01-27 11:56 ` [PATCH v9 3/9] grep tests: add missing "grep.patternType" config tests Ævar Arnfjörð Bjarmason
2022-01-27 11:56 ` [PATCH v9 4/9] built-ins: trust the "prefix" from run_builtin() Ævar Arnfjörð Bjarmason
2022-01-27 11:56 ` [PATCH v9 5/9] grep.c: don't pass along NULL callback value Ævar Arnfjörð Bjarmason
2022-01-27 11:56 ` [PATCH v9 6/9] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2022-01-27 11:56 ` [PATCH v9 7/9] grep.h: make "grep_opt.pattern_type_option" use its enum Ævar Arnfjörð Bjarmason
2022-01-27 11:56 ` [PATCH v9 8/9] grep.c: do "if (bool && memchr())" not "if (memchr() && bool)" Ævar Arnfjörð Bjarmason
2022-01-27 11:56 ` [PATCH v9 9/9] grep: simplify config parsing and option parsing Ævar Arnfjörð Bjarmason
2022-01-27 20:30 ` Junio C Hamano
2022-01-27 21:35 ` Junio C Hamano
2022-01-27 21:39 ` Junio C Hamano
2022-02-04 21:20 ` [PATCH v10 0/9] grep: simplify & delete "init" & "config" code Ævar Arnfjörð Bjarmason
2022-02-04 21:20 ` [PATCH v10 1/9] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2022-02-04 21:20 ` [PATCH v10 2/9] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2022-02-04 21:20 ` [PATCH v10 3/9] grep tests: add missing "grep.patternType" config tests Ævar Arnfjörð Bjarmason
2022-02-04 23:03 ` Junio C Hamano
2022-02-04 23:24 ` Junio C Hamano
2022-02-04 21:20 ` [PATCH v10 4/9] built-ins: trust the "prefix" from run_builtin() Ævar Arnfjörð Bjarmason
2022-02-04 21:20 ` [PATCH v10 5/9] grep.c: don't pass along NULL callback value Ævar Arnfjörð Bjarmason
2022-02-04 21:20 ` [PATCH v10 6/9] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2022-02-04 21:20 ` [PATCH v10 7/9] grep.h: make "grep_opt.pattern_type_option" use its enum Ævar Arnfjörð Bjarmason
2022-02-04 21:20 ` [PATCH v10 8/9] grep.c: do "if (bool && memchr())" not "if (memchr() && bool)" Ævar Arnfjörð Bjarmason
2022-02-04 21:20 ` [PATCH v10 9/9] grep: simplify config parsing and option parsing Ævar Arnfjörð Bjarmason
2022-02-04 23:41 ` Junio C Hamano
2022-02-16 0:00 ` [PATCH v11 00/10] grep: simplify & delete "init" & "config" code Ævar Arnfjörð Bjarmason
2022-02-16 0:00 ` [PATCH v11 01/10] grep.h: remove unused "regex_t regexp" from grep_opt Ævar Arnfjörð Bjarmason
2022-02-16 0:00 ` [PATCH v11 02/10] log tests: check if grep_config() is called by "log"-like cmds Ævar Arnfjörð Bjarmason
2022-02-16 0:00 ` [PATCH v11 03/10] grep tests: create a helper function for "BRE" or "ERE" Ævar Arnfjörð Bjarmason
2022-02-16 0:00 ` [PATCH v11 04/10] grep tests: add missing "grep.patternType" config tests Ævar Arnfjörð Bjarmason
2022-02-16 0:00 ` [PATCH v11 05/10] built-ins: trust the "prefix" from run_builtin() Ævar Arnfjörð Bjarmason
2022-02-16 0:00 ` [PATCH v11 06/10] grep.c: don't pass along NULL callback value Ævar Arnfjörð Bjarmason
2022-02-16 0:00 ` [PATCH v11 07/10] grep API: call grep_config() after grep_init() Ævar Arnfjörð Bjarmason
2022-02-16 0:00 ` [PATCH v11 08/10] grep.h: make "grep_opt.pattern_type_option" use its enum Ævar Arnfjörð Bjarmason
2022-02-16 0:00 ` [PATCH v11 09/10] grep.c: do "if (bool && memchr())" not "if (memchr() && bool)" Ævar Arnfjörð Bjarmason
2022-02-16 0:00 ` [PATCH v11 10/10] grep: simplify config parsing and option parsing Ævar Arnfjörð Bjarmason
2022-02-16 2:20 ` [PATCH v11 00/10] grep: simplify & delete "init" & "config" code Junio C Hamano
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