Re: [PATCH] meson: regenerate config-list.h when Documentation changes

["D. Ben Knoble" <ben.knoble+github@gmail.com>]

Hi Patrick,

> On Sat, Feb 07, 2026 at 04:59:17PM -0500, D. Ben Knoble wrote:
> > The Meson-based build doesn't know when to rebuild config-list.h, so the
> > header is sometimes stale.
> >
> > For example, an old build directory might have config-list.h from before
> > 4173df5187 (submodule: introduce extensions.submodulePathConfig,
> > 2026-01-12), which added submodule.<name>.gitdir to the list. Without
> > it, t9902-completion.sh fails. Regenerating the config-list.h artifact
> > from sources fixes the artifact and the test.
> >
> > Teach the meson build to depend on the Documentation files that
> > generate-configlist.sh reads by having it use the output of
> > generate-configlist-deps.sh as a list of dependency files, since Meson
> > does not have (or want) builtin support for globbing like Make.
> >
> > Signed-off-by: D. Ben Knoble <ben.knoble+github@gmail.com>
> > ---
> >
> > Notes (benknoble/commits):
> >     I considered having generate-configlist.sh write its own dependency
> >     list, which Meson also supports… idk though. Input welcome :)
>
> I think that would actually be the better approach, also because the
> list of files with `run_command()` would only be computed at setup time.

Oh, interesting. I didn't consider that, but it seems that adding a new file
doesn't cause the dependency list to get updated in my version. Good catch

> I guess it could look something like the below patch -- please feel free
> to reuse it at will.
>
> Thanks!
>
> Patrick

[snip patch]

I've applied this locally as so (tinkering since I saw the same symptoms below
with your version):

---- 8< ----
diff --git c/generate-configlist.sh w/generate-configlist.sh
index 75c39ade20..2c93ffc58a 100755
--- c/generate-configlist.sh
+++ w/generate-configlist.sh
@@ -2,10 +2,11 @@
 
 SOURCE_DIR="$1"
 OUTPUT="$2"
+DEPFILE="$3"
 
 if test -z "$SOURCE_DIR" || ! test -d "$SOURCE_DIR" || test -z "$OUTPUT"
 then
-	echo >&2 "USAGE: $0 <SOURCE_DIR> <OUTPUT>"
+	echo >&2 "USAGE: $0 <SOURCE_DIR> <OUTPUT> [<DEPFILE>]"
 	exit 1
 fi
 
@@ -36,3 +37,9 @@ print_config_list () {
 	echo
 	print_config_list
 } >"$OUTPUT"
+
+if test -n "$DEPFILE"
+then
+	printf "$OUTPUT: %s\n" "$SOURCE_DIR"/Documentation/*config.adoc \
+	    "$SOURCE_DIR"/Documentation/config/*.adoc >"$DEPFILE"
+fi
diff --git c/meson.build w/meson.build
index 3a1d12caa4..fb5d7367f5 100644
--- c/meson.build
+++ w/meson.build
@@ -720,11 +720,13 @@ endif
 
 builtin_sources += custom_target(
   output: 'config-list.h',
+  depfile: 'config-list.h.d',
   command: [
     shell,
-    meson.current_source_dir() + '/generate-configlist.sh',
+    meson.current_source_dir() / 'generate-configlist.sh',
     meson.current_source_dir(),
     '@OUTPUT@',
+    '@DEPFILE@',
   ],
   env: script_environment,
 )
---- 8< ----

Only, things are behaving oddly. For example:

    λ meson setup build2
    λ ninja -C build2

works fine, but

    λ ls -l build2/config*
    -rw-r--r-- 1 benknoble benknoble 17169  9 févr. 16:39 build2/config-list.h

I don't see the dependency file. Further, re-building seems to get stuck (I get
similar symptoms if I add or remove a relevant config.adoc file, but let's keep
it simple for now):

    λ ninja -C build2
    ninja: Entering directory `build2'
    [1/28] Generating GIT-VERSION-FILE with a custom command (wrapped by meson to set env)

Of course, if I invoke the command myself, I can fix the build:

    λ grep generate-config build2/build.ninja
     COMMAND = /usr/bin/sh /home/benknoble/code/git/generate-configlist.sh /home/benknoble/code/git config-list.h config-list.h.d
    λ (cd build2 && ../generate-configlist.sh .. config-list.h config-list.h.d)
    λ ninja -C build2
    ninja: Entering directory `build2'
    [7/7] Linking target git-upload-pack

but I certainly wouldn't have expected to have to do that!

Interestingly, after the "setup" step, build2/meson-info/intro-targets.json has
this block

  {
    "name": "config-list.h",
    "id": "config-list.h@cus",
    "type": "custom",
    "defined_in": "/home/benknoble/code/git/meson.build",
    "filename": [
      "/home/benknoble/code/git/build2/config-list.h"
    ],
    "build_by_default": false,
    "target_sources": [
      {
        "language": "unknown",
        "compiler": [
          "/usr/bin/sh",
          "/home/benknoble/code/git/generate-configlist.sh",
          "/home/benknoble/code/git",
          "@OUTPUT@",
          "@DEPFILE@"
        ],
        "parameters": [],
        "sources": [],
        "generated_sources": []
      }
    ],
    "extra_files": [],
    "subproject": null,
    "dependencies": [],
    "depends": [],
    "installed": false
  },

which doesn't mention the .d file anywhere. The _only_ reference to it is
build2/build.ninja. This doesn't change (nor are there more references to the
generate-config script) that I can find inside build2/ after any of these steps,
which is odd.

I can't think of any good next debugging steps, so I'm open to ideas on this
oddity.