From d63fc69b192a608f98c15d6014430f28138fd82e Mon Sep 17 00:00:00 2001
From: Gregory Heytings <gregory@heytings.org>
Date: Wed, 24 Nov 2021 07:58:11 +0100
Subject: [PATCH] Pass options from make to configure through a variable.

* GNUmakefile (configure): Use the variable.

* INSTALL.REPO: Document the variable (bug#51965).
---
 GNUmakefile  |  5 +++++
 INSTALL.REPO | 23 +++++++++++++++++++----
 Makefile.in  | 13 +++++++++++--
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/GNUmakefile b/GNUmakefile
index 5155487de28..76fd77ba1b0 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -104,8 +104,13 @@ configure:
 
 Makefile: configure
 	@echo >&2 'There seems to be no Makefile in this directory.'
+ifeq ($(configure),default)
 	@echo >&2 'Running ./configure ...'
 	./configure
+else
+	@echo >&2 'Running ./configure '$(configure)'...'
+	./configure $(configure)
+endif
 	@echo >&2 'Makefile built.'
 
 # 'make bootstrap' in a fresh checkout needn't run 'configure' twice.
diff --git a/INSTALL.REPO b/INSTALL.REPO
index da56d7611b2..182c2e95341 100644
--- a/INSTALL.REPO
+++ b/INSTALL.REPO
@@ -8,9 +8,15 @@ directory on your local machine:
 
 To build the repository code, simply run 'make' in the 'emacs'
 directory.  This should work if your files are freshly checked out
-from the repository, and if you have the proper tools installed.  If
-it doesn't work, or if you have special build requirements, the
-following information may be helpful.
+from the repository, and if you have the proper tools installed; the
+default configuration options will be used.  Other configuration
+options can be specified by setting a 'configure' variable, for
+example:
+
+  $ make configure="--prefix=/opt/emacs CFLAGS='-O0 -g3'"
+
+If the above doesn't work, or if you have special build requirements,
+the following information may be helpful.
 
 Building Emacs from the source-code repository requires some tools
 that are not needed when building from a release.  You will need:
@@ -58,7 +64,16 @@ To update loaddefs.el (and similar files), do:
 
 If either of the above partial procedures fails, try 'make bootstrap'.
 If CPU time is not an issue, 'make bootstrap' is a more thorough way
-to rebuild, avoiding spurious problems.
+to rebuild, avoiding spurious problems.  'make bootstrap' rebuilds
+Emacs with the same configuration options as the previous build; it
+can also be used to rebuild Emacs with other configuration options by
+setting a 'configure' variable, for example:
+
+  $ make bootstrap configure="CFLAGS='-O0 -g3'"
+
+To rebuild Emacs with the default configuration options, you can use:
+
+  $ make bootstrap configure=default
 
 Occasionally, there are changes that 'make bootstrap' won't be able to
 handle.  The most thorough cleaning can be achieved by 'git clean -fdx'
diff --git a/Makefile.in b/Makefile.in
index 3c092fa63df..4b40d8741d4 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -1145,14 +1145,23 @@ check-info: info
 
 .PHONY: bootstrap
 
-# Bootstrapping does the following:
+# Without a 'configure' variable, bootstrapping does the following:
 #  * Remove files to start from a bootstrap-clean slate.
 #  * Run autogen.sh.
 #  * Rebuild Makefile, to update the build procedure itself.
 #  * Do the actual build.
-bootstrap: bootstrap-clean
+# With a 'configure' variable, bootstrapping does the following:
+#  * Remove files to start from an extraclean slate.
+#  * Do the actual build, during which the 'configure' variable is
+#    used (see the Makefile goal in GNUmakefile).
+bootstrap:
+ifndef configure
+	$(MAKE) bootstrap-clean
 	cd $(srcdir) && ./autogen.sh autoconf
 	$(MAKE) MAKEFILE_NAME=force-Makefile force-Makefile
+else
+	$(MAKE) extraclean
+endif
 	$(MAKE) all
 
 .PHONY: ChangeLog change-history change-history-commit change-history-nocommit
-- 
2.39.2