Subject: Re: [PATCH v6] build: regenerate config-list.h when Documentation changes

From: Patrick Steinhardt <[email-masked]>
Date: Tue, 24 Feb 2026 10:58:06 +0100

On Mon, Feb 23, 2026 at 04:41:48PM -0500, Ben Knoble wrote:
> > Le 23 févr. 2026 à 01:55, SZEDER Gábor <[email-masked]> a écrit :
> > On Sat, Feb 21, 2026 at 09:07:17AM -0500, D. Ben Knoble wrote:
> >> diff --git a/Makefile b/Makefile
> >> index 7f37ad8f58..6f926ffb1f 100644
> >> --- a/Makefile
> >> +++ b/Makefile
> >> @@ -2688,9 +2688,10 @@ $(BUILT_INS): git$X
> >>    cp $< $@
> >> 
> >> config-list.h: generate-configlist.sh
> >> +    @mkdir -p .depend
> >> +    $(QUIET_GEN)$(SHELL_PATH) ./generate-configlist.sh . $@ .depend/config-list.h.d
> >> 
> >> -config-list.h: Documentation/*config.adoc Documentation/config/*.adoc
> >> -    $(QUIET_GEN)$(SHELL_PATH) ./generate-configlist.sh . $@
> >> +-include .depend/config-list.h.d
> > 
> > This breaks the build when something disappears from
> > Documentation/config/:
> > 
> >  $ git checkout origin/seen
> >  HEAD is now at 57edfa3ce8 Merge branch 'ty/setup-error-tightening' into seen
> >  $ ls -l Documentation/config/hook.adoc
> >  -rw-rw-r-- 1 szeder szeder 3828 Feb 23 07:50 Documentation/config/hook.adoc
> >  $ git grep hook.adoc
> >  Documentation/git-hook.adoc:include::config/hook.adoc[]
> >  Documentation/howto/meson.build:  'rebuild-from-update-hook.adoc',
> >  Documentation/meson.build:  'git-hook.adoc' : 1,
> >  $ make V=1 config-list.h
> >  /bin/sh ./generate-configlist.sh . config-list.h .depend/config-list.h.d
> >  $ git checkout 0aabf70f60
> >  Previous HEAD position was 57edfa3ce8 Merge branch 'ty/setup-error-tightening' into seen
> >  HEAD is now at 0aabf70f60 build: regenerate config-list.h when Documentation changes
> >  $ ls -l Documentation/config/hook.adoc
> >  ls: cannot access 'Documentation/config/hook.adoc': No such file or directory
> >  $ git grep hook.adoc
> >  Documentation/howto/meson.build:  'rebuild-from-update-hook.adoc',
> >  Documentation/meson.build:  'git-hook.adoc' : 1,
> >  $ make V=1 config-list.h
> >  GIT_VERSION=2.53.0.119.g0aabf70f60
> >  make: *** No rule to make target 'Documentation/config/hook.adoc', needed by 'config-list.h'.  Stop.
> >  $ grep hook.adoc .depend/config-list.h.d
> >  config-list.h: ./Documentation/config/hook.adoc
> 
> Indeed. This might arise while bisecting, which was my original
> motivation. Thoughts on a path forward? At least this issue (to me) is
> clearer than a spurious test failure :)

For Meson this case works alright. So maybe we just drop the changes to
the Makefile and call it a day?

An alternative would be to have the following patch on top:

diff --git a/generate-configlist.sh b/generate-configlist.sh
index 39ac8845ab..e28054f9e0 100755
--- a/generate-configlist.sh
+++ b/generate-configlist.sh
@@ -41,7 +41,12 @@ EOF
 if test -n "$DEPFILE"
 then
 	QUOTED_OUTPUT="$(printf '%s\n' "$OUTPUT" | sed 's,[&/\],\\&,g')"
-	printf '%s\n' "$SOURCE_DIR"/Documentation/*config.adoc \
-		"$SOURCE_DIR"/Documentation/config/*.adoc |
-		sed -e 's/[# ]/\\&/g' -e "s/^/$QUOTED_OUTPUT: /" >"$DEPFILE"
+	{
+		printf '%s\n' "$SOURCE_DIR"/Documentation/*config.adoc \
+			"$SOURCE_DIR"/Documentation/config/*.adoc |
+			sed -e 's/[# ]/\\&/g' -e "s/^/$QUOTED_OUTPUT: /"
+		printf '%s:\n' "$SOURCE_DIR"/Documentation/*config.adoc \
+			"$SOURCE_DIR"/Documentation/config/*.adoc |
+			sed -e 's/[# ]/\\&/g'
+	} >"$DEPFILE"
 fi

What it does is to also create an empty target for all of the
dependencies. Which is in fact what GCC/Clang also do when you pass -MP:

    $ cat main.c
    #include "foo.h"
    int main()
    {
        puts("foobar");
        return 0;
    }

    $ clang -MMD -MP main.c
    $ cat main.d
    main.o: main.c foo.h
    foo.h:

Patrick