Bug 1859851 - Share the rule that avoids invoking cargo between the two places that use the trick. r=firefox-build-system-reviewers,ahochheiden

There are subtle differences in the two implementations that actually
make the variant for RUST_PROGRAMS not work currently:
- there is a %.h leftover from bug 1855623
- there is a missing $(basename) when trying to find the .d file,
  preventing it from being found.

With a common rule, we avoid such subtle differences, and that also
allows to further implement fixes without missing one of the cases.

This will also allow to add the same trick to other rules, which should
already have it.

Differential Revision: https://phabricator.services.mozilla.com/D191378

config/makefiles/rust.mk

@@ -432,6 +432,27 @@ $(1):
 
 endef
 
+# make_cargo_rule(target, real-target [, extra-deps])
+# Generates a rule suitable to rebuild $(target) only if its dependencies are
+# obsolete.
+# It relies on the fact that upon build, cargo generates a dependency file named
+# `$(target).d'. Unfortunately the lhs of the rule has an absolute path,
+# so we extract it under the name $(target)_deps below.
+#
+# If the dependencies are empty, the file was not created so we force a rebuild.
+# Otherwise we add it to the dependency list.
+#
+# The actual rule is a bit tricky. The `+' prefix allow for recursive parallel
+# make, and it's skipped (`:') if we already triggered a rebuild as part of the
+# dependency chain.
+define make_cargo_rule
+$(1)_deps := $$(wordlist 2, 10000000, $$(if $$(wildcard $(basename $(1)).d),$$(shell cat $(basename $(1)).d)))
+$(1): $(CARGO_FILE) $(3) $$(if $$($(1)_deps),$$($(1)_deps),$(2))
+	$$(if $$($(1)_deps),+$(MAKE) $(2),:)
+
+$$(foreach dep, $$(call normalize_sep,$$($(1)_deps)),$$(eval $$(call make_default_rule,$$(dep))))
+endef
+
 ifdef RUST_LIBRARY_FILE
 
 rust_features_flag := --features '$(if $(RUST_LIBRARY_FEATURES),$(RUST_LIBRARY_FEATURES) )mozilla-central-workspace-hack'
@@ -453,11 +474,6 @@ force-cargo-library-build:
 	$(call BUILDSTATUS,START_Rust $(notdir $(RUST_LIBRARY_FILE)))
 	$(call CARGO_BUILD) --lib $(cargo_target_flag) $(rust_features_flag) -- $(cargo_rustc_flags)
 	$(call BUILDSTATUS,END_Rust $(notdir $(RUST_LIBRARY_FILE)))
-
-RUST_LIBRARY_DEP_FILE := $(basename $(RUST_LIBRARY_FILE)).d
-RUST_LIBRARY_DEPS := $(wordlist 2, 10000000, $(if $(wildcard $(RUST_LIBRARY_DEP_FILE)),$(shell cat $(RUST_LIBRARY_DEP_FILE))))
-$(RUST_LIBRARY_FILE): $(CARGO_FILE) $(if $(RUST_LIBRARY_DEPS),$(RUST_LIBRARY_DEPS), force-cargo-library-build)
-	$(if $(RUST_LIBRARY_DEPS),+$(MAKE) force-cargo-library-build,:)
 # When we are building in --enable-release mode; we add an additional check to confirm
 # that we are not importing any networking-related functions in rust code. This reduces
 # the chance of proxy bypasses originating from rust code.
@@ -468,15 +484,14 @@ ifeq ($(OS_ARCH), Linux)
 ifeq (,$(rustflags_sancov)$(MOZ_ASAN)$(MOZ_TSAN)$(MOZ_UBSAN))
 ifndef MOZ_LTO_RUST_CROSS
 ifneq (,$(filter -Clto,$(cargo_rustc_flags)))
-	$(call py_action,check_binary $(@F),--networking $@)
+	$(call py_action,check_binary $(@F),--networking $(RUST_LIBRARY_FILE))
 endif
 endif
 endif
 endif
 endif
 
-$(foreach dep, $(call normalize_sep,$(RUST_LIBRARY_DEPS)),$(eval $(call make_default_rule,$(dep))))
-
+$(eval $(call make_cargo_rule,$(RUST_LIBRARY_FILE),force-cargo-library-build))
 
 SUGGEST_INSTALL_ON_FAILURE = (ret=$$?; if [ $$ret = 101 ]; then echo If $1 is not installed, install it using: cargo install $1; fi; exit $$ret)
 
@@ -543,28 +558,7 @@ force-cargo-program-build: $(call resfile,module)
 	$(call CARGO_BUILD) $(addprefix --bin ,$(RUST_CARGO_PROGRAMS)) $(cargo_target_flag) $(program_features_flag) -- $(addprefix -C link-arg=$(CURDIR)/,$(call resfile,module)) $(CARGO_RUSTCFLAGS)
 	$(call BUILDSTATUS,END_Rust $(RUST_CARGO_PROGRAMS))
 
-# RUST_PROGRAM_DEPENDENCIES(RUST_PROGRAM)
-# Generates a rule suitable to rebuild RUST_PROGRAM only if its dependencies are
-# obsolete.
-# It relies on the fact that upon build, cargo generates a dependency file named
-# `$(RUST_PROGRAM).d'. Unfortunately the lhs of the rule has an absolute path,
-# so we extract it under the name $(RUST_PROGRAM)_deps below.
-#
-# If the dependencies are empty, the file was not created so we force a rebuild.
-# Otherwise we add it to the dependency list.
-#
-# The actual rule is a bit tricky. The `+' prefix allow for recursive parallel
-# make, and it's skipped (`:') if we already triggered a rebuild as part of the
-# dependency chain.
-#
-define RUST_PROGRAM_DEPENDENCIES
-$(1)_deps := $(wordlist 2, 10000000, $(if $(wildcard $(1).d),$(shell cat $(1).d)))
-$(1): $(CARGO_FILE) $(call resfile,module) $$(if $$($(1)_deps),$$($(1)_deps),force-cargo-program-build)
-	$$(if $$($(1)_deps),+$(MAKE) force-cargo-program-build,:)
-$$(foreach dep,$$(call normalize_sep, %.h,$$($(1)_deps)),$$(eval $$(call make_default_rule,$$(dep))))
-endef
-
-$(foreach RUST_PROGRAM,$(RUST_PROGRAMS), $(eval $(call RUST_PROGRAM_DEPENDENCIES,$(RUST_PROGRAM))))
+$(foreach RUST_PROGRAM,$(RUST_PROGRAMS), $(eval $(call make_cargo_rule,$(RUST_PROGRAM),force-cargo-program-build,$(call resfile,module))))
 
 ifndef CARGO_NO_AUTO_ARG
 force-cargo-program-%: