topdir.mk: Add target gitignore

Add a target gitignore to topdir.mk, which blasts jw-pkg's default idea of
how .gitignore should look like into $(TOPDIR)/.gitignore. It's not a
prerequisite of any other target, because it's not meant to run
automatically. The idea is to keep some central maintenance of what should
be in there from jw-pkg's perspective, make it convenvient to update, but
leave the final decision to the commiter of any project using the
machinery.

Signed-off-by: Jan Lindemann <jan@janware.com>

conf/templates/gitignore

@@ -0,0 +1,55 @@
+{top}
+*.a
+*.dep.mk
+*.dist
+*.done
+*.jw-secret
+*.jw-secret-file
+*.ldscript
+*.o
+*.old
+*.orig
+*.out
+*.pc
+*.pyc
+*.rep
+*.secret
+*.so
+*.so.*
+*.swp
+*_generated_*
+*tmp*
+*~
+-test-out.txt
+.cache-project.mk
+.exrc
+.feedfs_history
+.gdb_history
+.jw-agit
+.mypy_cache
+.ruff_cache
+__init__.py
+__pycache__
+bin/*.bat
+bin/*.pl
+bin/*.pm
+bin/*.py
+bin/*.sh
+bin/*.tcl
+conftest.py
+core
+dist
+ld-*.conf
+local.conf
+local.mk
+local.mk
+local.yaml
+make/*.pc
+mkspec.sh
+pr-descr*.txt
+pre-local.mk
+pyproject.toml
+pyrightconfig.json
+!*.jw-tmpl
+!*.tmpl
+{end}

make/topdir.mk

@@ -99,6 +99,9 @@ JW_PKG_TMPL_SEARCH_PATH     ?= $(JW_PKG_CONF_BASE_DIR)/templates
 JW_PKG_TMPL_UPDATE          ?= $(PYTHON) $(JWB_SCRIPT_DIR)/jw-pkg.py -p $(PROJECTS_DIR) -t $(TOPDIR) --topdir-format unaltered \
 				projects create-file --format tmpl --search-path $(subst $(space),:,$(JW_PKG_TMPL_SEARCH_PATH)) --template-name
 
+GITIGNORE_PATTERNS_TOP      ?= $(PROJECT)
+GITIGNORE_PATTERNS_END      ?= $(addprefix !,$(shell git ls-files 2>/dev/null | grep "\(\b$(PROJECT)\b\|__init__.py\)" | xargs))
+
 all: topdir config
 test: all
 
@@ -311,3 +314,10 @@ Makefile: ;
 %: $(TD_COPY_SRC)/% $$(foreach path,$$(TD_COPY_SRC_PATH),$$(wildcard $$(addprefix $$(path)/,$$@))) $$(wildcard $$@.*)
 	cat $^ > $@.tmp
 	mv $@.tmp $@
+
+gitignore:
+	$(JW_PKG_TMPL_UPDATE) gitignore --field-keys top,end \
+		$(addprefix --field top=,$(GITIGNORE_PATTERNS_TOP)) \
+		$(addprefix --field end=,$(GITIGNORE_PATTERNS_END)) \
+		--field-separator='%n' $(PROJECT) | grep -v '^[[:space:]]*$$' > .gitignore.tmp
+	mv .gitignore.tmp .gitignore