Drop dependency on m4

m4 was hugely popular in the past, because autotools, automake, flex, bison and
many other things used it. But nowadays it much less popular, and might not even
be installed in the buildroot. (m4 is small, so it doesn't make a big difference.)

(FWIW, Fedora dropped make from the buildroot now,
https://fedoraproject.org/wiki/Changes/Remove_make_from_BuildRoot. I think it's
reasonable to assume that m4 will be dropped at some point too.)

The main reason to drop m4 is that the syntax is not very nice, and we should
minimize the number of different syntaxes that we use. We still have two
(configure_file() with @FOO@ and jinja2 templates with {{foo}} and the
pythonesque conditional expressions), but at least we don't need m4 (with
m4_dnl and `quotes').

10 files changed, 2 insertions, 31 deletions

diff --git a/.mkosi/mkosi.arch b/.mkosi/mkosi.arch
index e0cd6f4834..9782a7d872 100644
--- a/.mkosi/mkosi.arch
+++ b/.mkosi/mkosi.arch
@@ -35,7 +35,6 @@ BuildPackages=
         libxkbcommon
         libxslt
         lz4
-        m4
         meson
         pam
         pkgconfig
diff --git a/.mkosi/mkosi.debian b/.mkosi/mkosi.debian
index cf3f3364b5..0d37937aea 100644
--- a/.mkosi/mkosi.debian
+++ b/.mkosi/mkosi.debian
@@ -46,7 +46,6 @@ BuildPackages=
         libtss2-dev
         libxkbcommon-dev
         libzstd-dev
-        m4
         meson
         pkg-config
         python3
diff --git a/.mkosi/mkosi.fedora b/.mkosi/mkosi.fedora
index efce52e1e8..540c85c026 100644
--- a/.mkosi/mkosi.fedora
+++ b/.mkosi/mkosi.fedora
@@ -45,7 +45,6 @@ BuildPackages=
         libzstd-devel
         lz4
         lz4-devel
-        m4
         meson
         ninja-build
         openssl-devel
diff --git a/.mkosi/mkosi.opensuse b/.mkosi/mkosi.opensuse
index 387f0af70c..bf05f8dd72 100644
--- a/.mkosi/mkosi.opensuse
+++ b/.mkosi/mkosi.opensuse
@@ -30,7 +30,6 @@ BuildPackages=
         libseccomp-devel
         libselinux-devel
         libxslt-tools
-        m4
         meson
         pam-devel
         pciutils-devel
diff --git a/.mkosi/mkosi.ubuntu b/.mkosi/mkosi.ubuntu
index 29df6ee238..32447c8b38 100644
--- a/.mkosi/mkosi.ubuntu
+++ b/.mkosi/mkosi.ubuntu
@@ -49,7 +49,6 @@ BuildPackages=
         libxkbcommon-dev
         libxtables-dev
         libzstd-dev
-        m4
         meson
         pkg-config
         python3
diff --git a/README b/README
index 88057d2d95..a2b19d656d 100644
--- a/README
+++ b/README
@@ -195,7 +195,7 @@ REQUIREMENTS:
         python >= 3.5
         meson >= 0.46 (>= 0.49 is required to build position-independent executables)
         ninja
-        gcc, awk, sed, grep, m4, and similar tools
+        gcc, awk, sed, grep, and similar tools
         clang >= 10.0, llvm >= 10.0 (optional, required to build BPF programs
                 from source code in C)
 
diff --git a/meson.build b/meson.build
index c98c4c1e7d..f43e9a775c 100644
--- a/meson.build
+++ b/meson.build
@@ -606,7 +606,6 @@ echo = find_program('echo')
 test = find_program('test')
 sed = find_program('sed')
 awk = find_program('awk')
-m4 = find_program('m4')
 stat = find_program('stat')
 ln = find_program('ln')
 git = find_program('git', required : false)
@@ -1650,7 +1649,6 @@ generate_gperfs = find_program('tools/generate-gperfs.py')
 make_autosuspend_rules_py = find_program('tools/make-autosuspend-rules.py')
 make_directive_index_py = find_program('tools/make-directive-index.py')
 make_man_index_py = find_program('tools/make-man-index.py')
-meson_apply_m4 = find_program('tools/meson-apply-m4.sh')
 meson_render_jinja2 = find_program('tools/meson-render-jinja2.py')
 update_dbus_docs_py = find_program('tools/update-dbus-docs.py')
 update_hwdb_sh = find_program('tools/update-hwdb.sh')
diff --git a/test/TEST-06-SELINUX/test.sh b/test/TEST-06-SELINUX/test.sh
index 978c930b71..421e1fe52d 100755
--- a/test/TEST-06-SELINUX/test.sh
+++ b/test/TEST-06-SELINUX/test.sh
@@ -48,7 +48,7 @@ test_append_files() {
         cp systemd_test.fc "$workspace/systemd-test-module"
         dracut_install -o sesearch
         dracut_install runcon
-        dracut_install checkmodule semodule semodule_package m4 make load_policy sefcontext_compile
+        dracut_install checkmodule semodule semodule_package make load_policy sefcontext_compile
         dracut_install -o /usr/libexec/selinux/hll/pp # Fedora/RHEL/...
         dracut_install -o /usr/lib/selinux/hll/pp     # Debian/Ubuntu/...
     )
diff --git a/test/mkosi.default.networkd-test b/test/mkosi.default.networkd-test
index e728e16aa5..fc9a5d3134 100644
--- a/test/mkosi.default.networkd-test
+++ b/test/mkosi.default.networkd-test
@@ -52,7 +52,6 @@ BuildPackages=
         libxslt
         lz4
         lz4-devel
-        m4
         meson
         ninja-build
         pam-devel
diff --git a/tools/meson-apply-m4.sh b/tools/meson-apply-m4.sh
deleted file mode 100755
index 6c5726a7d5..0000000000
--- a/tools/meson-apply-m4.sh
+++ /dev/null
@@ -1,21 +0,0 @@
-#!/usr/bin/env bash
-# SPDX-License-Identifier: LGPL-2.1-or-later
-set -eu
-
-CONFIG="${1:?Missing path to config.h}"
-TARGET="${2:?Missing target m4 file}"
-
-if [ ! -f "$CONFIG" ]; then
-    echo "$CONFIG not found."
-    exit 2
-fi
-
-if [ ! -f "$TARGET" ]; then
-    echo "$TARGET not found."
-    exit 3
-fi
-
-DEFINES=()
-mapfile -t DEFINES < <(awk '$1 == "#define" && $3 == "1" { printf "-D%s\n", $2 }' "$CONFIG")
-
-m4 -P "${DEFINES[@]}" "$TARGET"