如果未设置diff.tool，则Git(2.22.0)difftool不再通过git diff

TLDR;新的错误消息"This message is displayed because 'diff.tool' is not configured."可能是实际的错误修复，而不是是新的错误.

TLDR; The new error message "This message is displayed because 'diff.tool' is not configured." might be an actual bug fix, and not a new error.

我只是尝试过......没有收到任何错误消息(当使用不带参数时).

I just tried and... didn't get any error message (when used without parameters).

vonc@vonvb:~/git/cplgit/linux$ ./set_git 2.22.0
git set to v2.22.0
vonc@vonvb:~/git/cplgit/linux$ git version
git version 2.22.0

vonc@vonvb:~/git/cplgit/linux$ git config -l|grep -i tool

vonc@vonvb:~/git/cplgit/linux$ git difftool

此外，此错误消息已在 commit 5338a6a，2013年1月，Git v1中引入. 8.2-rc0 .
我确实提到了 commit 05fb872 from Git 2.22 ，它使用的是${GIT_MERGETOOL_GUI}.
该环境变量未在我的计算机上设置，并且没有收到任何错误消息.
检查您自己的git config和环境变量.

Plus, this error message has been introduced in commit 5338a6a, Jan. 2013, Git v1.8.2-rc0.
I did mentioned commit 05fb872 from Git 2.22, which uses ${GIT_MERGETOOL_GUI}.
That environment variable is not set on my machine, and I don't get any error message.
Check your own git config and environment variables.

我确实在Git 2.22中看到以下错误消息:

I do see the error message in Git 2.22 with:

vonc@vonvb:~/gits/src/git$ git difftool --no-index color.c color.h

This message is displayed because 'diff.tool' is not configured.
See 'git difftool --tool-help' or 'git help config' for more details.
'git difftool' will now attempt to use one of the following tools:
meld opendiff kdiff3 tkdiff xxdiff kompare gvimdiff diffuse diffmerge ecmerge p4merge araxis bc codecompare smerge emerge vimdiff

Viewing (1/1): 'color.c'
Launch 'bc' [Y/n]? 
The diff tool bc is not available as 'bcompare'
fatal: external diff died, stopping at color.c

在Git 2.21.0中，它默认为常规的git diff:

With Git 2.21.0, it does default to a regular git diff:

vonc@vonvb:~/git/cplgit/linux$ ./set_git 2.21.0
git set to v2.21.0
vonc@vonvb:~/git/cplgit/linux$ git version
git version 2.21.0
vonc@vonvb:~/git/cplgit/linux$ cdgg
vonc@vonvb:~/gits/src/git$ git difftool --no-index color.c color.h
diff --git a/color.c b/color.h
index ebb222ec33..98894d6a17 100644

从 OP Git邮件列表线程:

刘登顿 原始的提交287ab28 (2019年2月16日)通过 Junio C Hamano-gitster-在

Denton Liu pinpoints the original commit 287ab28 (16 Feb 2019) by Jeff King (peff).
^{(Merged by Junio C Hamano -- gitster -- in commit 12e5bdd, 07 Mar 2019)}

diff:针对--no-index情况重用差异设置

当"--no-index"有效(或由参数隐含)时，git-diff 提早跳转到特殊的代码路径来执行该差异.
这意味着我们会错过某些设置，例如默认情况下启用--ext-diff和--textconv.

diff: reuse diff setup for --no-index case

When "--no-index" is in effect (or implied by the arguments), git-diff jumps early to a special code path to perform that diff.
This means we miss out on some settings like enabling --ext-diff and --textconv by default.

杰夫·金答复:>

我不太了解git-difftool的工作原理，但是看起来像 设置GIT_EXTERNAL_DIFF=git-difftool--helper.

I don't know much about how git-difftool works, but it looks like it sets GIT_EXTERNAL_DIFF=git-difftool--helper.

在 287ab28bfa 之前，我们不会考虑任何外部差异 运行git-diff时的命令.但是之后，我们照做.

Prior to 287ab28bfa, we would not have respected any external diff command when running git-diff. But after it, we do.

如果用户未提供--no-index，则全部 我猜difftool的意思是:它运行帮助程序并说嘿， 您尚未配置".

In the case that the user has not provided --no-index, then this all works as I guess difftool is meant to: it runs the helper and says "hey, you have not configured this".

似乎上述命令在 287ab28bfa 之前的行为是 不是故意的.
它会运行git-diff，希望它触发辅助程序，但是它从没有执行(而是执行了普通的no-index diff).

It seems like the behavior of the above command prior to 287ab28bfa was not intentional.
It would run git-diff, expecting it to trigger the helper, but it never did (and instead just did a normal no-index diff).

因此，看来新行为实际上是正确的选择，因为它使--no-index案件与常规案件保持一致?
我不清楚您为什么不在这里运行"difftool" 配置，您只需要直接的diff输出.

So it seems like the new behavior is actually the right thing, as it makes the --no-index case consistent with the regular one?
I'm not at all clear why you would run "difftool" here if you it is not configured and you just want the straight diff output.