From f21ff8e71367832069a254b7863f02b3eab5f27f Mon Sep 17 00:00:00 2001
From: Jan Lindemann <jan@janware.com>
Date: Tue, 26 May 2026 10:34:17 +0200
Subject: [PATCH] topdir.mk: Add dynamic file creation machinery

Add generic machinery to dynamically create files in $(TOPDIR). The
need arises because version controlled configuration files for
linters are going to be introduced.

For that, this commit introduces a variable $(TD_GENERATE_FILES),
which target all depends on, and which topdir.clean removes.

It defaults to another variable also introduced by this commit,
$(TD_COPY_FILES), which in turn defaults to $(TOPDIR)/conf/topdir.

This commit also adds support for JW_PKG_TOPDIR_COPY_PATH. It
supports a PATH-style syntax, which allows pointing to multiple
directories to be checked for source files. If they exist, they will
be appended to the files found in $(TOPDIR)/conf/topdir after
copying. Defining arbitray files to copy is not supported before
security implications during CI runs are better understood.

Having the copy prerequisites work comes at the cost of having to add
.SECONDEXPANSION. Since it's limited to the toplevel Makefile, I
suppose that's acceptable.

Signed-off-by: Jan Lindemann <jan@janware.com>
---
 conf/topdir/Makefile |  6 ++++++
 make/topdir.mk       | 28 ++++++++++++++++++++++++----
 2 files changed, 30 insertions(+), 4 deletions(-)
 create mode 100644 conf/topdir/Makefile

diff --git a/conf/topdir/Makefile b/conf/topdir/Makefile
new file mode 100644
index 00000000..7f6e10f5
--- /dev/null
+++ b/conf/topdir/Makefile
@@ -0,0 +1,6 @@
+TOPDIR = ../..
+
+CONFIG_SUBDIR = $(notdir $(shell pwd))
+
+include $(TOPDIR)/make/proj.mk
+include $(JWBDIR)/make/conf.mk
diff --git a/make/topdir.mk b/make/topdir.mk
index 9830022d..cde44114 100644
--- a/make/topdir.mk
+++ b/make/topdir.mk
@@ -1,3 +1,6 @@
+# Need second expansion for TD_COPY_XXX concatenation rule to work
+.SECONDEXPANSION:
+
 .PHONY: \
 	FORCE \
 	all \
@@ -107,10 +110,18 @@ STREAMLINE_PROJECT          ?= bash $(JWB_SCRIPT_DIR)/streamline-project.sh
 
 INSTALLED_TOPDIR_FILES       = $(addprefix $(INSTALL_DOCDIR)/, $(DOCS))
 
+TD_CONF_DIR                 ?= $(JW_PKG_CONF_BASE_DIR)/topdir
+TD_COPY_SRC                 ?= $(TD_CONF_DIR)
+TD_COPY_FILES               ?= $(filter-out Makefile,$(notdir $(wildcard $(TD_COPY_SRC)/*)))
+# -- Internal variables, define JW_PKG_TOPDIR_COPY_PATH if you want to
+#  add more files appended to the target files
+TD_COPY_SRC_PATH             = $(subst :,$(space),$(JW_PKG_TOPDIR_COPY_PATH))
+TD_GENERATE_FILES           += $(TD_COPY_FILES)
+
 all: config
 format:
-check-syntax:
-check-format:
+check-syntax: topdir
+check-format: topdir
 check: check-syntax check-format
 install: topdir.install
 clean: topdir.clean
@@ -129,10 +140,13 @@ local-%: FORCE
 unlocal:
 	$(RM) -f $(shell find . -name local.mk)
 
+topdir: $(TD_GENERATE_FILES)
+topdir.clean:
+	$(RM) -rf *.done $(TD_GENERATE_FILES)
+clean: topdir.clean
 topdir.distclean: topdir.clean
 	$(RM) -rf dist *.dist
-topdir.clean:
-	$(RM) -rf *.done
+distclean: topdir.distclean
 topdir.mrproper: topdir.distclean
 	find . -name '*.rep' | xargs -r $(RM) -f
 
@@ -282,3 +296,9 @@ recache-vars:
 
 canonicalize-remotes:
 	$(PYTHON) $(JWB_SCRIPT_DIR)/jw-pkg.py projects canonicalize-remotes
+
+Makefile: ;
+
+%: $(TD_COPY_SRC)/% $$(foreach path,$$(TD_COPY_SRC_PATH),$$(wildcard $$(addprefix $$(path)/,$$@))) $$(wildcard $$@.*)
+	cat $^ > $@.tmp
+	mv $@.tmp $@