Bug 1565706 - Allow to run `mach build rust` without setting MOZ_RUST_TIER. r=froydnj

At the same time, make things a little more tangible in the tiers setup
in baseconfig.mk.

Differential Revision: https://phabricator.services.mozilla.com/D37942

--HG--
extra : moz-landing-system : lando

Makefile.in

@@ -51,7 +51,7 @@ ifndef TEST_MOZBUILD
 ifndef MOZ_PROFILE_USE
 # We need to explicitly put BUILD_BACKEND_FILES here otherwise the rule in
 # rules.mk doesn't run early enough.
-$(TIERS) binaries:: CLOBBER $(BUILD_BACKEND_FILES)
+$(RUNNABLE_TIERS) binaries:: CLOBBER $(BUILD_BACKEND_FILES)
 endif
 endif
 

config/baseconfig.mk

@@ -42,7 +42,30 @@ endif # WINNT
 ifndef INCLUDED_AUTOCONF_MK
 default::
 else
-TIERS := $(if $(MOZ_ARTIFACT_BUILDS),artifact )$(if $(MOZ_EME_WIN32_ARTIFACT),win32-artifact )$(if $(MOZ_ANDROID_FAT_AAR_ARCHITECTURES),android-fat-aar-artifact )pre-export export $(if $(COMPILE_ENVIRONMENT),$(if $(MOZ_RUST_TIER),rust )compile )misc libs tools$(if $(filter check recurse_check,$(MAKECMDGOALS)), check)
+# All possible tiers
+ALL_TIERS := artifact win32-artifact android-fat-aar-artifact pre-export export rust compile misc libs tools check
+
+# All tiers that may be used manually via `mach build $tier`
+RUNNABLE_TIERS := $(ALL_TIERS)
+ifndef MOZ_ARTIFACT_BUILDS
+RUNNABLE_TIERS := $(filter-out artifact,$(RUNNABLE_TIERS))
+endif
+ifndef MOZ_EME_WIN32_ARTIFACT
+RUNNABLE_TIERS := $(filter-out win32-artifact,$(RUNNABLE_TIERS))
+endif
+ifndef MOZ_ANDROID_FAT_AAR_ARCHITECTURES
+RUNNABLE_TIERS := $(filter-out android-fat-aar-artifact,$(RUNNABLE_TIERS))
+endif
+
+# All tiers that run automatically on `mach build`
+TIERS := $(filter-out check,$(RUNNABLE_TIERS))
+ifndef COMPILE_ENVIRONMENT
+TIERS := $(filter-out rust compile,$(TIERS))
+endif
+ifndef MOZ_RUST_TIER
+TIERS := $(filter-out rust,$(TIERS))
+endif
+
 endif
 
 # These defines are used to support the twin-topsrcdir model for comm-central.

config/recurse.mk

@@ -28,7 +28,7 @@ include root.mk
 
 # Main rules (export, compile, libs and tools) call recurse_* rules.
 # This wrapping is only really useful for build status.
-$(TIERS)::
+$(RUNNABLE_TIERS)::
 	$(if $(filter $@,$(MAKECMDGOALS)),$(call BUILDSTATUS,TIERS $@),)
 	$(call BUILDSTATUS,TIER_START $@)
 	+$(MAKE) recurse_$@
@@ -41,7 +41,7 @@ binaries::
 # Carefully avoid $(eval) type of rule generation, which makes pymake slower
 # than necessary.
 # Get current tier and corresponding subtiers from the data in root.mk.
-CURRENT_TIER := $(filter $(foreach tier,$(TIERS) $(non_default_tiers),recurse_$(tier) $(tier)-deps),$(MAKECMDGOALS))
+CURRENT_TIER := $(filter $(foreach tier,$(RUNNABLE_TIERS) $(non_default_tiers),recurse_$(tier) $(tier)-deps),$(MAKECMDGOALS))
 ifneq (,$(filter-out 0 1,$(words $(CURRENT_TIER))))
 $(error $(CURRENT_TIER) not supported on the same make command line)
 endif
@@ -129,7 +129,7 @@ else
 # Don't recurse if MAKELEVEL is NO_RECURSE_MAKELEVEL as defined above
 ifeq ($(NO_RECURSE_MAKELEVEL),$(MAKELEVEL))
 
-$(TIERS)::
+$(RUNNABLE_TIERS)::
 
 else
 #########################
@@ -144,7 +144,7 @@ $(1):: $$(SUBMAKEFILES)
 
 endef
 
-$(foreach subtier,$(filter-out compile,$(TIERS)),$(eval $(call CREATE_SUBTIER_TRAVERSAL_RULE,$(subtier))))
+$(foreach subtier,$(filter-out compile,$(RUNNABLE_TIERS)),$(eval $(call CREATE_SUBTIER_TRAVERSAL_RULE,$(subtier))))
 
 ifndef TOPLEVEL_BUILD
 ifdef COMPILE_ENVIRONMENT