# [BUG] "git diff --word-diff" gives a diff while they are only space changes 5 messages from 2026-05-06 to 2026-05-09. Participants: Vincent Lefevre, Johannes Sixt. Thread: https://gitlist.dev/t/65599 ## Vincent Lefevre, 2026-05-06 01:09 Subject: [BUG] "git diff --word-diff" gives a diff while they are only space changes Message-ID: <20260506010927.GE5260@qaa.vinc17.org> ``` Consider the following two 5-line files: file1: 1 2 3 2 4 file2: 1 2 3 2 4 On these files, "git diff --word-diff file1 file2" gives --- a/file1 +++ b/file2 @@ -1,5 +1,5 @@ 1 [-2-] [-3-] 2 {+3+} {+ 2+} 4 instead of --- a/file1 +++ b/file2 @@ -1,5 +1,5 @@ 1 2 3 2 4 (e.g. as output by GNU wdiff 1.2.2). Equivalently, the following command can be used under bash or zsh: git diff --word-diff <(printf "1\n2\n3\n 2\n4\n") \ <(printf "1\n 2\n 3\n 2\n 4\n") Tested with git 2.39.5 (Debian 12), 2.53.0 (Debian unstable) and 2.54.0 (Termux/Android). Issue initially found with git show --word-diff 1bf0b214deff2d0ccdcef3b2a4723369e014de3d and more precisely git show --word-diff 1bf0b214deff2d0ccdcef3b2a4723369e014de3d attach.c in the Mutt Git repository. -- Vincent Lefèvre - Web: 100% accessible validated (X)HTML - Blog: Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon) ``` ## Johannes Sixt, 2026-05-08 12:48 Subject: Re: [BUG] "git diff --word-diff" gives a diff while they are only space changes Message-ID: <7cedf86c-5db7-45ef-b8d4-034b792f0def@kdbg.org> In-Reply-To: <20260506010927.GE5260@qaa.vinc17.org> ``` Am 06.05.26 um 03:09 schrieb Vincent Lefevre: > Consider the following two 5-line files: > > file1: > > 1 > 2 > 3 > 2 > 4 > > file2: > > 1 > 2 > 3 > 2 > 4 > > On these files, "git diff --word-diff file1 file2" gives > > --- a/file1 > +++ b/file2 > @@ -1,5 +1,5 @@ > 1 > [-2-] > [-3-] > 2 > {+3+} > {+ 2+} > 4 > > instead of > > --- a/file1 > +++ b/file2 > @@ -1,5 +1,5 @@ > 1 > 2 > 3 > 2 > 4 > > (e.g. as output by GNU wdiff 1.2.2). This is expected behavior. git diff --word-diff is not agnostic to whitespace; if you drop --word-diff, you see the line-diff that the word-diff is based on. If you want whitespace-agnostic word-diff, you have to add -w. -- Hannes ``` ## Vincent Lefevre, 2026-05-08 21:39 Subject: Re: [BUG] "git diff --word-diff" gives a diff while they are only space changes Message-ID: <20260508213943.GP5260@qaa.vinc17.org> In-Reply-To: <7cedf86c-5db7-45ef-b8d4-034b792f0def@kdbg.org> ``` On 2026-05-08 14:48:01 +0200, Johannes Sixt wrote: > This is expected behavior. > > git diff --word-diff is not agnostic to whitespace; if you drop > --word-diff, you see the line-diff that the word-diff is based on. If > you want whitespace-agnostic word-diff, you have to add -w. This is not how it is documented. Even when using "git diff" without --word-diff, but with GNU wdiff instead, the output is fine: $ git diff file1 file2 | wdiff -d diff --git a/file1 b/file2 index da04344..0074613 100644 [--- a/file1-] {+++ b/file2+} @@ -1,5 +1,5 @@ 1 2 3 2 4 -- Vincent Lefèvre - Web: 100% accessible validated (X)HTML - Blog: Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon) ``` ## Johannes Sixt, 2026-05-09 06:16 Subject: Re: [BUG] "git diff --word-diff" gives a diff while they are only space changes Message-ID: In-Reply-To: <20260508213943.GP5260@qaa.vinc17.org> ``` Am 08.05.26 um 23:39 schrieb Vincent Lefevre: > On 2026-05-08 14:48:01 +0200, Johannes Sixt wrote: >> This is expected behavior. >> >> git diff --word-diff is not agnostic to whitespace; if you drop >> --word-diff, you see the line-diff that the word-diff is based on. If >> you want whitespace-agnostic word-diff, you have to add -w. > > This is not how it is documented. Even when using "git diff" without > --word-diff, but with GNU wdiff instead, the output is fine: > > $ git diff file1 file2 | wdiff -d > diff --git a/file1 b/file2 > index da04344..0074613 100644 > [--- a/file1-] > {+++ b/file2+} > @@ -1,5 +1,5 @@ > 1 > 2 > 3 > 2 > 4 It would have helped if you had pointed to, or cited, the documentation. I cannot find documentation from which I can derive that the above *must* be the correct output. In particular, I don't find any mention that --word-diff operates exactly like GNU wdiff. -- Hannes ``` ## Vincent Lefevre, 2026-05-09 15:55 Subject: Re: [BUG] "git diff --word-diff" gives a diff while they are only space changes Message-ID: <20260509155526.GQ5260@qaa.vinc17.org> In-Reply-To: ``` On 2026-05-09 08:16:48 +0200, Johannes Sixt wrote: > Am 08.05.26 um 23:39 schrieb Vincent Lefevre: > > On 2026-05-08 14:48:01 +0200, Johannes Sixt wrote: > >> This is expected behavior. > >> > >> git diff --word-diff is not agnostic to whitespace; if you drop > >> --word-diff, you see the line-diff that the word-diff is based on. If > >> you want whitespace-agnostic word-diff, you have to add -w. > > > > This is not how it is documented. Even when using "git diff" without > > --word-diff, but with GNU wdiff instead, the output is fine: > > > > $ git diff file1 file2 | wdiff -d > > diff --git a/file1 b/file2 > > index da04344..0074613 100644 > > [--- a/file1-] > > {+++ b/file2+} > > @@ -1,5 +1,5 @@ > > 1 > > 2 > > 3 > > 2 > > 4 > > It would have helped if you had pointed to, or cited, the documentation. > I cannot find documentation from which I can derive that the above > *must* be the correct output. In particular, I don't find any mention > that --word-diff operates exactly like GNU wdiff. For wdiff, it is just described as "display word differences between text files", and it does exactly that. For instance, if there are no differences in words, it shows no differences. For git with the --word-diff, there is actually no documentation, except the use of "changed words" and "word diff". No mention of line diff at all! So this is quite confusing. Note: This isn't even a line-based diff with highlighted word diff as done by some tools, such as Emacs diff-mode. -- Vincent Lefèvre - Web: 100% accessible validated (X)HTML - Blog: Work: CR INRIA - computer arithmetic / Pascaline project (LIP, ENS-Lyon) ```