From: Junio C Hamano <gitster@pobox.com>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: Johannes Sixt <j6t@kdbg.org>,
Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>,
git@vger.kernel.org, Denton Liu <liu.denton@gmail.com>
Subject: Re: [PATCH v2 02/13] msvc: avoid using minus operator on unsigned types
Date: Sun, 06 Oct 2019 09:02:43 +0900 [thread overview]
Message-ID: <xmqqr23q68rg.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <nycvar.QRO.7.76.6.1910042319190.46@tvgsbejvaqbjf.bet> (Johannes Schindelin's message of "Fri, 4 Oct 2019 23:24:26 +0200 (CEST)")
Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
>> IMHO, if you don't accompany insert_pos_as_negative_offset() with a
>> corresponding extract_pos_and_found_condition() and use it everywhere,
>> it is more obfuscating than necessary.
>
> I do disagree here. No overflow checking needs to be performed for `-1 -
> <int-value>`. And that's what the opposite of this function really boils
> down to.
I do not think j6t is referring to the over/underflow issues at all.
The suggestion is that, because insert-pos-as-negative-offset
abstracts away (in addition to the overflow checks) the fact that
"does not exist but here is the location it would be inserted" is
encoded in a certain way (i.e. not just the array index negated, but
also is offset by -1, because we wouldn't be able to say "at the
very beginning at index 0" without the -1 offset), the side that
consumes the encoded "pos" (i.e. "we got a negative, so we know the
element does not exist, and the index into the array we would insert
a new element is computed this way") should be abstracted away, as
it must know that the extra negative offset used when encoding is
"-1".
I think that is a reasonable thing to consider; it is not necessary
for correctness, but contributes to the conceptual clarity (iow, it
can be left as a separate clean-up step done after the series is
done).
next prev parent reply other threads:[~2019-10-06 0:02 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 8:30 [PATCH 00/13] ci: include a Visual Studio build & test in our Azure Pipeline Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 01/13] push: do not pretend to return `int` from `die_push_simple()` Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 02/13] msvc: avoid using minus operator on unsigned types Johannes Schindelin via GitGitGadget
2019-09-26 17:20 ` Denton Liu
2019-09-26 21:01 ` Johannes Schindelin
2019-09-26 23:57 ` Denton Liu
2019-09-30 9:50 ` Johannes Schindelin
2019-09-26 8:30 ` [PATCH 03/13] winansi: use FLEX_ARRAY to avoid compiler warning Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 04/13] compat/win32/path-utils.h: add #include guards Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 05/13] msvc: ignore some libraries when linking Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 06/13] msvc: handle DEVELOPER=1 Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 07/13] msvc: work around a bug in GetEnvironmentVariable() Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 08/13] vcxproj: only copy `git-remote-http.exe` once it was built Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 09/13] vcxproj: include more generated files Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 10/13] test-tool run-command: learn to run (parts of) the testsuite Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 11/13] tests: let --immediate and --write-junit-xml play well together Johannes Schindelin via GitGitGadget
2019-09-28 22:22 ` Junio C Hamano
2019-09-30 9:52 ` Johannes Schindelin
2019-09-26 8:30 ` [PATCH 12/13] ci: really use shallow clones on Azure Pipelines Johannes Schindelin via GitGitGadget
2019-09-26 8:30 ` [PATCH 13/13] ci: also build and test with MS Visual Studio " Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 00/13] ci: include a Visual Studio build & test in our Azure Pipeline Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 01/13] push: do not pretend to return `int` from `die_push_simple()` Johannes Schindelin via GitGitGadget
2019-10-03 22:37 ` Junio C Hamano
2019-10-04 9:36 ` Johannes Schindelin
2019-09-30 9:55 ` [PATCH v2 02/13] msvc: avoid using minus operator on unsigned types Johannes Schindelin via GitGitGadget
2019-10-03 22:44 ` Junio C Hamano
2019-10-04 9:55 ` Johannes Schindelin
2019-10-04 17:09 ` Johannes Sixt
2019-10-04 21:24 ` Johannes Schindelin
2019-10-06 0:02 ` Junio C Hamano [this message]
2019-10-06 10:53 ` Johannes Sixt
2019-10-08 12:04 ` Johannes Schindelin
2019-10-08 21:13 ` Johannes Sixt
2019-09-30 9:55 ` [PATCH v2 03/13] winansi: use FLEX_ARRAY to avoid compiler warning Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 05/13] msvc: ignore some libraries when linking Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 04/13] compat/win32/path-utils.h: add #include guards Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 06/13] msvc: handle DEVELOPER=1 Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 07/13] msvc: work around a bug in GetEnvironmentVariable() Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 08/13] vcxproj: only copy `git-remote-http.exe` once it was built Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 09/13] vcxproj: include more generated files Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 10/13] test-tool run-command: learn to run (parts of) the testsuite Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 11/13] tests: let --immediate and --write-junit-xml play well together Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 12/13] ci: really use shallow clones on Azure Pipelines Johannes Schindelin via GitGitGadget
2019-09-30 9:55 ` [PATCH v2 13/13] ci: also build and test with MS Visual Studio " Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 00/13] ci: include a Visual Studio build & test in our Azure Pipeline Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 01/13] push: do not pretend to return `int` from `die_push_simple()` Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 02/13] msvc: avoid using minus operator on unsigned types Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 03/13] winansi: use FLEX_ARRAY to avoid compiler warning Johannes Schindelin via GitGitGadget
2019-10-07 19:16 ` Alban Gruin
2019-10-04 15:09 ` [PATCH v3 04/13] compat/win32/path-utils.h: add #include guards Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 05/13] msvc: ignore some libraries when linking Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 07/13] msvc: work around a bug in GetEnvironmentVariable() Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 06/13] msvc: handle DEVELOPER=1 Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 08/13] vcxproj: only copy `git-remote-http.exe` once it was built Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 09/13] vcxproj: include more generated files Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 10/13] test-tool run-command: learn to run (parts of) the testsuite Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 11/13] tests: let --immediate and --write-junit-xml play well together Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 12/13] ci: really use shallow clones on Azure Pipelines Johannes Schindelin via GitGitGadget
2019-10-04 15:09 ` [PATCH v3 13/13] ci: also build and test with MS Visual Studio " Johannes Schindelin via GitGitGadget
2019-10-06 0:19 ` [PATCH v3 00/13] ci: include a Visual Studio build & test in our Azure Pipeline Junio C Hamano
2019-10-06 10:45 ` Johannes Schindelin
2019-10-06 20:38 ` Johannes Schindelin
2019-10-07 1:14 ` Junio C Hamano
2019-10-07 21:51 ` Johannes Schindelin
2019-10-08 2:19 ` Junio C Hamano
2019-10-08 12:46 ` Johannes Schindelin
2019-10-09 13:57 ` Philip Oakley
2019-10-10 9:03 ` Johannes Schindelin
2019-10-10 10:12 ` Philip Oakley
2019-10-07 0:59 ` Junio C Hamano
2019-10-07 16:08 ` Thomas Gummerer
2019-10-11 22:06 ` Johannes Schindelin
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