commit message helpers (was Re: How can we decrease the cognitive overhead for contributors?)

[Giovanni Biscuolo]

Hello,

Andreas Enge <andreas@enge.fr> writes:

> Am Wed, Aug 30, 2023 at 02:22:01AM +0200 schrieb Danny Milosavljevic:
>> Writing the metadata into the commit messages is annoying. It totally should
>> be automated, especially since Scheme has pretty simple syntax (so it should
>> be easy to write such a thing/famous-last-words). It should just figure out
>> which procedures the changed lines were in, automatically.
>
> It does exist inside git itself for C code; "git diff" always shows

in the hunk header

> the function in which I make a change.

Does this mean that the function/procedure of the specific language - C
in this case - is/can be automatically provided in the generated draft
commit message by parsing the "git diff" output?

> I agree it should be easy to have the same support for scheme.

The documentation for this git feature is here:
«Defining a custom hunk-header»
https://git-scm.com/docs/gitattributes#_defining_a_custom_hunk_header

All is needed is to enable one of the built in patterns via
.gitattributes; in the Guix git root we defined this:

--8<---------------cut here---------------start------------->8---

*.scm       diff=scheme
*.scm.in    diff=scheme
*.texi      diff=texinfo

--8<---------------cut here---------------end--------------->8---

This means that when doing "git diff" in a Guix worktree we get
something like:

--8<---------------cut here---------------start------------->8---

[~/{git}/giovanni.biscuolo.net/guix/gnu/packages]
giovanni@roquette: git diff
diff --git a/gnu/packages/abiword.scm b/gnu/packages/abiword.scm
index 1635ed54fd..a9c937c39b 100644
--- a/gnu/packages/abiword.scm
+++ b/gnu/packages/abiword.scm
@@ -56,7 +56,7 @@ (define-public abiword
           (string-append "https://www.abisource.com/downloads/abiword/"; version
                          "/source/abiword-" version ".tar.gz"))
         (sha256
-         (base32 "1d1179pnslijpjhz1q155fsc828rrlqf7lsn2inqsl3hk5z28mqj"))
+         (base32 "BOGUS"))
         (patches
          (search-patches "abiword-explictly-cast-bools.patch"))))
 
@@ -67,7 +67,7 @@ (define-public abiword
           "--enable-clipart"     ;; TODO: The following plugins have unresolved
           "--enable-templates"   ;; dependencies: aiksaurus, grammar, wpg, gda,
           (string-append         ;; wordperfect, psion, mathview.
-            "--enable-plugins="
+            "--enable-plugins= FIXME"
               "applix " "babelfish " "bmp " "clarisworks " "collab " "command "
               "docbook " "eml " "epub " "freetranslation " "garble " "gdict "
               "gimp " "goffice " "google " "hancom " "hrtext " "iscii " "kword 
"

--8<---------------cut here---------------end--------------->8---

In the example above have two hunk headers:

1. @@ -56,7 +56,7 @@ (define-public abiword

2. @@ -67,7 +67,7 @@ (define-public abiword

each one showing the function I modified.

Furthermore, "git diff -W" (or --function-context) will show the whole
function in the hunk:

--8<---------------cut here---------------start------------->8---

[~/{git}/giovanni.biscuolo.net/guix/gnu/packages]
giovanni@roquette: git --no-pager diff -W
diff --git a/gnu/packages/abiword.scm b/gnu/packages/abiword.scm
index 1635ed54fd..a9c937c39b 100644
--- a/gnu/packages/abiword.scm
+++ b/gnu/packages/abiword.scm
@@ -48,89 +48,89 @@ (define-module (gnu packages abiword)
 (define-public abiword
   (package
     (name "abiword")
     (version "3.0.5")
     (source
       (origin
         (method url-fetch)
         (uri
           (string-append "https://www.abisource.com/downloads/abiword/"; version
                          "/source/abiword-" version ".tar.gz"))
         (sha256
-         (base32 "1d1179pnslijpjhz1q155fsc828rrlqf7lsn2inqsl3hk5z28mqj"))
+         (base32 "BOGUS"))
         (patches
          (search-patches "abiword-explictly-cast-bools.patch"))))
 
     (build-system glib-or-gtk-build-system)
     (arguments                   ;; NOTE: rsvg is disabled, since Abiword
       `(#:configure-flags        ;; supports it directly, and its BS is broken.
         (list                    ;; wmf was removed from Guix for security.
           "--enable-clipart"     ;; TODO: The following plugins have unresolved
           "--enable-templates"   ;; dependencies: aiksaurus, grammar, wpg, gda,
           (string-append         ;; wordperfect, psion, mathview.
-            "--enable-plugins="
+            "--enable-plugins= FIXME"
               "applix " "babelfish " "bmp " "clarisworks " "collab " "command "

[...]

     (license license:gpl2+)))

--8<---------------cut here---------------end--------------->8---

As you can see, here the hunk header is:

3. @@ -48,89 +48,89 @@ (define-module (gnu packages abiword)

showing the function in with "define-public abiword" is defined.

I don't know if this is/could be used to automatically set a more helpful
commit message draft, but this helps to "figure out which procedures the
changed lines were in, automatically."

WDYT?

Also, I can't find if there is some plan or feature request to add
tree-sitter support in the "git diff" parser, but that could be a great
improvement IMO, since it will allow git users to use all tree-sitter
available parsers and not just pattern matching to understand/show the
context in which the changes happened.

In this context, I found this two currently active project of
tree-sitter based diff tools:

1. Difftastic https://difftastic.wilfred.me.uk/

2. diffsitter https://github.com/afnanenayet/diffsitter

Both can be used as external "git difftool"s [1] [2]

None is currently packaged in Guix.


Happy hacking! Gio'


[1] https://difftastic.wilfred.me.uk/git.html#git-difftool

[2] https://github.com/afnanenayet/diffsitter#git-integration

-- 
Giovanni Biscuolo

Xelera IT Infrastructures

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