[nongnu] elpa/git-commit 2374c34ed4 2/3: make: Re-generate %.texi if HEAD changed since previous run

[ELPA Syncer]

branch: elpa/git-commit
commit 2374c34ed47d39ebfa4e2675cb2aa7eb995e47a9
Author: Jonas Bernoulli <jonas@bernoul.li>
Commit: Jonas Bernoulli <jonas@bernoul.li>

    make: Re-generate %.texi if HEAD changed since previous run
---
 .gitignore    | 1 +
 default.mk    | 1 +
 docs/Makefile | 6 +++++-
 3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/.gitignore b/.gitignore
index 453256ceb5..68802dd34d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,7 @@
 /docs/*.info
 /docs/*.pdf
 /docs/*.texi
+/docs/.revdesc
 /docs/dir
 /docs/stats/
 /lisp/*-autoloads.el
diff --git a/default.mk b/default.mk
index ec3e277532..22b0075b00 100644
--- a/default.mk
+++ b/default.mk
@@ -110,6 +110,7 @@ ELGS = magit-autoloads.el magit-version.el
 VERSION ?= $(shell \
   test -e $(TOP).git && \
   git describe --tags --abbrev=0 --always | cut -c2-)
+REVDESC := $(shell test -e $(TOP).git && git describe --tags)
 
 EMACS_VERSION = 26.1
 
diff --git a/docs/Makefile b/docs/Makefile
index 043c717d67..16fd1a58fa 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -24,7 +24,11 @@ redo-docs:
        @touch $(ORGPAGES)
        @make docs
 
-%.texi: %.org
+.revdesc: ;
+_    := $(shell test "$(REVDESC)" = "$$(cat .revdesc 2> /dev/null)" ||\
+        echo "$(REVDESC)" > .revdesc)
+
+%.texi: %.org .revdesc
        @printf "Generating $@\n"
        @$(EMACS) $(ORG_ARGS) $< $(ORG_EVAL)