make: add targets to debug dependencies variables

Add a 'dependency-debug' and a 'DEPENDENCY_DEBUG=1' option for
'info-boards-supported' to save some variables used when resolving
dependencies.

Print some some 'sorted' variables to simplify comparing the actual value
when the parsing order changed.

This should help tracking changes introduced when refactoring the
dependency parsing.

Makefile.include

@@ -110,6 +110,9 @@ include $(RIOTMAKE)/info-nproc.inc.mk
 # List of boards variables
 include $(RIOTMAKE)/boards.inc.mk
 
+# Debug targets for build system migration
+include $(RIOTMAKE)/dependencies_debug.inc.mk
+
 GLOBAL_GOALS += buildtest buildtest-indocker info-boards-supported info-boards-features-missing info-buildsizes info-buildsizes-diff
 ifneq (, $(filter $(GLOBAL_GOALS), $(MAKECMDGOALS)))
   BOARD=none

makefiles/dependencies_debug.inc.mk

@@ -0,0 +1,55 @@
+# Debug targets to evaluate dependency migrations
+#
+# The goal is to get the value of variables used for dependency resolution
+# and the impact of refactoring
+
+# Files output can be generated through the normal resolution with executing
+# 'dependency-debug' for each board
+#
+#     BOARD=board_name make dependency-debug
+#
+# And the 'quick' version that is used by murdock with `info-boards-supported`.
+# This one currently uses only a subset of the files/values required for
+# dependency resolution.
+#
+#     DEPENDENCY_DEBUG=1 make info-boards-supported
+#
+#
+# To compare in an aggregated file, you can run in an application directory:
+#
+#    for board in $(make info-boards); do DEPENDENCY_DEBUG_OUTPUT_DIR=bin/info BOARD=${board} make dependency-debug; done; cat bin/info/* > bin/deps_info
+#    DEPENDENCY_DEBUG=1 DEPENDENCY_DEBUG_OUTPUT_DIR=bin/info-global make info-boards-supported; cat bin/info-global/* > bin/deps_info-boards-supported
+#    # And compare both files
+#    diff -u bin/deps_info bin/deps_info-boards-supported
+#
+# And when comparing two revisions, include the revision in the file names
+
+.PHONY: dependency-debug
+# Only generate the dependencies when the board is not disabled
+# This will allow comparing with the output of `info-boards-supported` more easily
+dependency-debug:
+ifneq (,$(filter-out $(BOARD_BLACKLIST),$(filter $(if $(BOARD_WHITELIST),$(BOARD_WHITELIST), %),$(BOARD))))
+	$(call file_save_dependencies_variables,dependencies_info)
+	@:
+else
+	@echo Skipping $(BOARD) is not whitelisted or blacklisted
+endif
+
+DEPENDENCY_DEBUG_OUTPUT_DIR ?= $(CURDIR)
+
+# Save variables that are used for parsing dependencies
+_DEPS_DEBUG_VARS += BOARD CPU CPU_MODEL CPU_FAM
+_DEPS_DEBUG_VARS += FEATURES_PROVIDED _FEATURES_PROVIDED_SORTED FEATURES_REQUIRED _FEATURES_REQUIRED_SORTED FEATURES_OPTIONAL FEATURES_USED FEATURES_MISSING FEATURES_CONFLICT FEATURES_CONFLICTING
+_DEPS_DEBUG_VARS += USEMODULE DEFAULT_MODULE DISABLE_MODULE
+DEPS_DEBUG_VARS ?= $(_DEPS_DEBUG_VARS)
+
+_FEATURES_PROVIDED_SORTED = $(sort $(FEATURES_PROVIDED))
+_FEATURES_REQUIRED_SORTED = $(sort $(FEATURES_REQUIRED))
+
+file_save_dependencies_variables = $(call file_save_variable,$(DEPENDENCY_DEBUG_OUTPUT_DIR)/$1_$(BOARD),$(DEPS_DEBUG_VARS))
+# Remove file before to be sure appending is started with an empty file
+file_save_variable = $(shell mkdir -p $(dir $1); rm -f $1)$(foreach v,$2,$(file >>$1,$(call _print_var,$v)))
+
+# Remove spaces in case of empty value
+# Remove spaces around value as it happens
+_print_var = $(strip $1 = $(strip $($1)))

makefiles/info-global.inc.mk

@@ -40,6 +40,10 @@ define board_missing_features
     BOARDS_FEATURES_MISSING += "$(1) $$(FEATURES_MISSING)"
     BOARDS_WITH_MISSING_FEATURES += $(1)
   endif
+
+  ifneq (,$$(DEPENDENCY_DEBUG))
+    $$(call file_save_dependencies_variables,dependencies_info-boards-supported)
+  endif
 endef
 
 BOARDS := $(filter $(if $(BOARD_WHITELIST), $(BOARD_WHITELIST), %), $(BOARDS))