build: consolidate directory creation rules
This commit streamlines directory creation by introducing a single
pattern rule to automatically make directories for which there is a
dependency.
We currently use several macros to generate rules to create directories
upon dependence, which is a significant amount of code and a lot of
redundancy. The rule introduced by this change represents a catch-all:
any rule dependency on a path ending in a forward slash is automatically
created.
Now, rules can rely on an unordered dependency (`|`) on `$$(@D)/` which,
when secondary expansion is enabled, expands to the directory of the
target being built, e.g.:
build/main.o: main.c | $$(@D)/ # automatically creates `build/`
Change-Id: I7e554efa2ac850e779bb302fd9c7fbb239886c9f
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/make_helpers/build-rules.mk b/make_helpers/build-rules.mk
new file mode 100644
index 0000000..d325b3a
--- /dev/null
+++ b/make_helpers/build-rules.mk
@@ -0,0 +1,18 @@
+#
+# Copyright (c) 2024, Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+ifndef build-rules-mk
+ build-rules-mk := $(lastword $(MAKEFILE_LIST))
+
+ include $(dir $(build-rules-mk))common.mk
+ include $(dir $(build-rules-mk))utilities.mk
+
+ .SECONDEXPANSION:
+
+ %/:
+ $(s)echo ' MD '$(call escape-shell,$(abspath $@))
+ $(q)mkdir -p $(call escape-shell,$@)
+endif