From 37caa3d71fd8bb4d0d9204e4a2f5cac234fa25fd Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Mon, 29 Apr 2024 15:30:39 -0400
Subject: build: Replace `make config` with a `./configure` script

This lets us do more traditional out-of-tree builds like

    $ ../path/to/bfs/configure
    $ make

The .mk files are moved from ./config to ./build, mostly so that
./configure will auto-complete easily.
---
 build/config.mk | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 build/config.mk

(limited to 'build/config.mk')

diff --git a/build/config.mk b/build/config.mk
new file mode 100644
index 0000000..153838d
--- /dev/null
+++ b/build/config.mk
@@ -0,0 +1,62 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Makefile that implements `./configure`
+
+include build/prelude.mk
+include build/exports.mk
+
+# All configuration steps
+config: gen/config.mk gen/config.h
+.PHONY: config
+
+# Makefile fragments generated by `./configure`
+MKS := \
+    gen/vars.mk \
+    gen/flags.mk \
+    gen/deps.mk \
+    gen/pkgs.mk
+
+# The main configuration file, which includes the others
+gen/config.mk: ${MKS}
+	${MSG} "[ GEN] $@"
+	@printf '# %s\n' "$@" >$@
+	@printf 'include %s\n' ${.ALLSRC} >>$@
+	${VCAT} gen/config.mk
+.PHONY: gen/config.mk
+
+# Saves the configurable variables
+gen/vars.mk::
+	@${MKDIR} ${@D}
+	${MSG} "[ GEN] $@"
+	@printf '# %s\n' "$@" >$@
+	@printf 'PREFIX := %s\n' "$$XPREFIX" >>$@
+	@printf 'MANDIR := %s\n' "$$XMANDIR" >>$@
+	@printf 'OS := %s\n' "$${OS:-$$(uname)}" >>$@
+	@printf 'CC := %s\n' "$$XCC" >>$@
+	@printf 'INSTALL := %s\n' "$$XINSTALL" >>$@
+	@printf 'MKDIR := %s\n' "$$XMKDIR" >>$@
+	@printf 'PKG_CONFIG := %s\n' "$$XPKG_CONFIG" >>$@
+	@printf 'RM := %s\n' "$$XRM" >>$@
+	${VCAT} $@
+
+# Sets the build flags.  This depends on vars.mk and uses a recursive make so
+# that the default flags can depend on variables like ${OS}.
+gen/flags.mk: gen/vars.mk
+	@+${MAKE} -sf build/flags.mk $@
+.PHONY: gen/flags.mk
+
+# Check for dependency generation support
+gen/deps.mk: gen/flags.mk
+	@+${MAKE} -sf build/deps.mk $@
+.PHONY: gen/deps.mk
+
+# Auto-detect dependencies and their build flags
+gen/pkgs.mk: gen/flags.mk
+	@+${MAKE} -sf build/pkgs.mk $@
+.PHONY: gen/pkgs.mk
+
+# Compile-time feature detection
+gen/config.h: gen/config.mk
+	@+${MAKE} -sf build/header.mk $@
+.PHONY: gen/config.h
-- 
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