mk/main.mk - third_party/rust - Git at Google

 # Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
 # file at the top-level directory of this distribution and at
 # http://rust-lang.org/COPYRIGHT.
 #
 # Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 # http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 # <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 # option. This file may not be copied, modified, or distributed
 # except according to those terms.

 ######################################################################
 # Version numbers and strings
 ######################################################################

 # The version number
 CFG_RELEASE_NUM=1.2.0

 # An optional number to put after the label, e.g. '.2' -> '-beta.2'
 # NB Make sure it starts with a dot to conform to semver pre-release
 # versions (section 9)
 CFG_PRERELEASE_VERSION=.6

 # Append a version-dependent hash to each library, so we can install different
 # versions in the same place
 CFG_FILENAME_EXTRA=$(shell printf '%s' $(CFG_RELEASE) | $(CFG_HASH_COMMAND))

 ifeq ($(CFG_RELEASE_CHANNEL),stable)
 # This is the normal semver version string, e.g. "0.12.0", "0.12.0-nightly"
 CFG_RELEASE=$(CFG_RELEASE_NUM)
 # This is the string used in dist artifact file names, e.g. "0.12.0", "nightly"
 CFG_PACKAGE_VERS=$(CFG_RELEASE_NUM)
 CFG_DISABLE_UNSTABLE_FEATURES=1
 endif
 ifeq ($(CFG_RELEASE_CHANNEL),beta)
 CFG_RELEASE=$(CFG_RELEASE_NUM)-beta$(CFG_PRERELEASE_VERSION)
 # When building beta distributables just reuse the same "beta" name
 # so when we upload we'll always override the previous beta. This
 # doesn't actually impact the version reported by rustc - it's just
 # for file naming.
 CFG_PACKAGE_VERS=beta
 CFG_DISABLE_UNSTABLE_FEATURES=1
 endif
 ifeq ($(CFG_RELEASE_CHANNEL),nightly)
 CFG_RELEASE=$(CFG_RELEASE_NUM)-nightly
 # When building nightly distributables just reuse the same "nightly" name
 # so when we upload we'll always override the previous nighly. This
 # doesn't actually impact the version reported by rustc - it's just
 # for file naming.
 CFG_PACKAGE_VERS=nightly
 endif
 ifeq ($(CFG_RELEASE_CHANNEL),dev)
 CFG_RELEASE=$(CFG_RELEASE_NUM)-dev
 CFG_PACKAGE_VERS=$(CFG_RELEASE_NUM)-dev
 endif

 # The name of the package to use for creating tarballs, installers etc.
 CFG_PACKAGE_NAME=rustc-$(CFG_PACKAGE_VERS)

 # The version string plus commit information - this is what rustc reports
 CFG_VERSION = $(CFG_RELEASE)
 CFG_GIT_DIR := $(CFG_SRC_DIR).git
 # since $(CFG_GIT) may contain spaces (especially on Windows),
 # we need to escape them. (" " to r"\ ")
 # Note that $(subst ...) ignores space after `subst`,
 # so we use a hack: define $(SPACE) which contains space character.
 SPACE :=
 SPACE +=
 ifneq ($(CFG_GIT),)
 ifneq ($(wildcard $(subst $(SPACE),\$(SPACE),$(CFG_GIT_DIR))),)
     CFG_VER_DATE = $(shell git --git-dir='$(CFG_GIT_DIR)' log -1 --date=short --pretty=format:'%cd')
     CFG_VER_HASH = $(shell git --git-dir='$(CFG_GIT_DIR)' rev-parse HEAD)
     CFG_SHORT_VER_HASH = $(shell git --git-dir='$(CFG_GIT_DIR)' rev-parse --short=9 HEAD)
     CFG_VERSION += ($(CFG_SHORT_VER_HASH) $(CFG_VER_DATE))
 endif
 endif

 # Windows exe's need numeric versions - don't use anything but
 # numbers and dots here
 CFG_VERSION_WIN = $(CFG_RELEASE_NUM)

 CFG_INFO := $(info cfg: version $(CFG_VERSION))

 ######################################################################
 # More configuration
 ######################################################################

 MKFILE_DEPS := config.stamp $(call rwildcard,$(CFG_SRC_DIR)mk/,*)
 MKFILES_FOR_TARBALL:=$(MKFILE_DEPS)
 ifneq ($(NO_MKFILE_DEPS),)
 MKFILE_DEPS :=
 endif
 NON_BUILD_HOST = $(filter-out $(CFG_BUILD),$(CFG_HOST))
 NON_BUILD_TARGET = $(filter-out $(CFG_BUILD),$(CFG_TARGET))

 ifneq ($(MAKE_RESTARTS),)
 CFG_INFO := $(info cfg: make restarts: $(MAKE_RESTARTS))
 endif

 CFG_INFO := $(info cfg: build triple $(CFG_BUILD))
 CFG_INFO := $(info cfg: host triples $(CFG_HOST))
 CFG_INFO := $(info cfg: target triples $(CFG_TARGET))

 ifneq ($(wildcard $(NON_BUILD_HOST)),)
 CFG_INFO := $(info cfg: non-build host triples $(NON_BUILD_HOST))
 endif
 ifneq ($(wildcard $(NON_BUILD_TARGET)),)
 CFG_INFO := $(info cfg: non-build target triples $(NON_BUILD_TARGET))
 endif

 CFG_RUSTC_FLAGS := $(RUSTFLAGS)
 CFG_GCCISH_CFLAGS :=
 CFG_GCCISH_LINK_FLAGS :=

 # Turn off broken quarantine (see jemalloc/jemalloc#161)
 CFG_JEMALLOC_FLAGS := --disable-fill

 ifdef CFG_DISABLE_OPTIMIZE
   $(info cfg: disabling rustc optimization (CFG_DISABLE_OPTIMIZE))
   CFG_RUSTC_FLAGS +=
   CFG_JEMALLOC_FLAGS += --enable-debug
 else
   # The rtopt cfg turns off runtime sanity checks
   CFG_RUSTC_FLAGS += -O --cfg rtopt
 endif

 CFG_JEMALLOC_FLAGS += $(JEMALLOC_FLAGS)

 ifdef CFG_ENABLE_DEBUG_ASSERTIONS
   $(info cfg: enabling debug assertions (CFG_ENABLE_DEBUG_ASSERTIONS))
   CFG_RUSTC_FLAGS += -C debug-assertions=on
 endif

 ifdef CFG_ENABLE_DEBUGINFO
   $(info cfg: enabling debuginfo (CFG_ENABLE_DEBUGINFO))
   CFG_RUSTC_FLAGS += -g
 endif

 ifdef SAVE_TEMPS
   CFG_RUSTC_FLAGS += --save-temps
 endif
 ifdef ASM_COMMENTS
   CFG_RUSTC_FLAGS += -Z asm-comments
 endif
 ifdef TIME_PASSES
   CFG_RUSTC_FLAGS += -Z time-passes
 endif
 ifdef TIME_LLVM_PASSES
   CFG_RUSTC_FLAGS += -Z time-llvm-passes
 endif
 ifdef TRACE
   CFG_RUSTC_FLAGS += -Z trace
 endif
 ifdef CFG_ENABLE_RPATH
 CFG_RUSTC_FLAGS += -C rpath
 endif

 # The executables crated during this compilation process have no need to include
 # static copies of libstd and libextra. We also generate dynamic versions of all
 # libraries, so in the interest of space, prefer dynamic linking throughout the
 # compilation process.
 #
 # Note though that these flags are omitted for the *bins* in stage2+. This means
 # that the snapshot will be generated with a statically linked rustc so we only
 # have to worry about the distribution of one file (with its native dynamic
 # dependencies)
 RUSTFLAGS_STAGE0 += -C prefer-dynamic
 RUSTFLAGS_STAGE1 += -C prefer-dynamic
 RUST_LIB_FLAGS_ST2 += -C prefer-dynamic
 RUST_LIB_FLAGS_ST3 += -C prefer-dynamic

 # Landing pads require a lot of codegen. We can get through bootstrapping faster
 # by not emitting them.
 RUSTFLAGS_STAGE0 += -Z no-landing-pads

 # platform-specific auto-configuration
 include $(CFG_SRC_DIR)mk/platform.mk

 # Run the stage1/2 compilers under valgrind
 ifdef VALGRIND_COMPILE
   CFG_VALGRIND_COMPILE :=$(CFG_VALGRIND)
 else
   CFG_VALGRIND_COMPILE :=
 endif


 ifndef CFG_DISABLE_VALGRIND_RPASS
   $(info cfg: enabling valgrind run-pass tests (CFG_ENABLE_VALGRIND_RPASS))
   $(info cfg: valgrind-rpass command set to $(CFG_VALGRIND))
   CFG_VALGRIND_RPASS :=$(CFG_VALGRIND)
 else
   $(info cfg: disabling valgrind run-pass tests)
   CFG_VALGRIND_RPASS :=
 endif


 ifdef CFG_ENABLE_VALGRIND
   $(info cfg: enabling valgrind (CFG_ENABLE_VALGRIND))
 else
   CFG_VALGRIND :=
 endif

 ######################################################################
 # Target-and-rule "utility variables"
 ######################################################################

 define DEF_FOR_TARGET
 X_$(1) := $(CFG_EXE_SUFFIX_$(1))
 ifndef CFG_LLVM_TARGET_$(1)
 CFG_LLVM_TARGET_$(1) := $(1)
 endif
 endef
 $(foreach target,$(CFG_TARGET), \
   $(eval $(call DEF_FOR_TARGET,$(target))))

 # "Source" files we generate in builddir along the way.
 GENERATED :=

 # Delete the built-in rules.
 .SUFFIXES:
 %:: %,v
 %:: RCS/%,v
 %:: RCS/%
 %:: s.%
 %:: SCCS/s.%


 ######################################################################
 # Cleaning out old crates
 ######################################################################

 # $(1) is the path for directory to match against
 # $(2) is the glob to use in the match
 #
 # Note that a common bug is to accidentally construct the glob denoted
 # by $(2) with a space character prefix, which invalidates the
 # construction $(1)$(2).
 define CHECK_FOR_OLD_GLOB_MATCHES
   $(Q)MATCHES="$(wildcard $(1))"; if [ -n "$$MATCHES" ] ; then echo "warning: there are previous" \'$(notdir $(2))\' "libraries:" $$MATCHES; fi
 endef

 # Same interface as above, but deletes rather than just listing the files.
 ifdef VERBOSE
 define REMOVE_ALL_OLD_GLOB_MATCHES
   $(Q)MATCHES="$(wildcard $(1))"; if [ -n "$$MATCHES" ] ; then echo "warning: removing previous" \'$(notdir $(1))\' "libraries:" $$MATCHES; rm $$MATCHES ; fi
 endef
 else
 define REMOVE_ALL_OLD_GLOB_MATCHES
   $(Q)MATCHES="$(wildcard $(1))"; if [ -n "$$MATCHES" ] ; then rm $$MATCHES ; fi
 endef
 endif

 # We use a different strategy for LIST_ALL_OLD_GLOB_MATCHES_EXCEPT
 # than in the macros above because it needs the result of running the
 # `ls` command after other rules in the command list have run; the
 # macro-expander for $(wildcard ...) would deliver its results too
 # soon. (This is in contrast to the macros above, which are meant to
 # be run at the outset of a command list in a rule.)
 ifdef VERBOSE
 define LIST_ALL_OLD_GLOB_MATCHES
   @echo "info: now are following matches for" '$(notdir $(1))' "libraries:"
   @( ls $(1) 2>/dev/null || true )
 endef
 else
 define LIST_ALL_OLD_GLOB_MATCHES
 endef
 endif

 ######################################################################
 # LLVM macros
 ######################################################################

 # FIXME: x86-ism
 LLVM_COMPONENTS=x86 arm aarch64 mips powerpc ipo bitreader bitwriter linker asmparser mcjit \
                 interpreter instrumentation

 # Only build these LLVM tools
 LLVM_TOOLS=bugpoint llc llvm-ar llvm-as llvm-dis llvm-mc opt llvm-extract

 define DEF_LLVM_VARS
 # The configure script defines these variables with the target triples
 # separated by Z. This defines new ones with the expected format.
 ifeq ($$(CFG_LLVM_ROOT),)
 CFG_LLVM_BUILD_DIR_$(1):=$$(CFG_LLVM_BUILD_DIR_$(subst -,_,$(1)))
 CFG_LLVM_INST_DIR_$(1):=$$(CFG_LLVM_INST_DIR_$(subst -,_,$(1)))
 else
 CFG_LLVM_INST_DIR_$(1):=$$(CFG_LLVM_ROOT)
 endif

 # Any rules that depend on LLVM should depend on LLVM_CONFIG
 LLVM_CONFIG_$(1):=$$(CFG_LLVM_INST_DIR_$(1))/bin/llvm-config$$(X_$(1))
 LLVM_MC_$(1):=$$(CFG_LLVM_INST_DIR_$(1))/bin/llvm-mc$$(X_$(1))
 LLVM_AR_$(1):=$$(CFG_LLVM_INST_DIR_$(1))/bin/llvm-ar$$(X_$(1))
 LLVM_VERSION_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --version)
 LLVM_BINDIR_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --bindir)
 LLVM_INCDIR_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --includedir)
 LLVM_LIBDIR_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --libdir)
 LLVM_LIBDIR_RUSTFLAGS_$(1)=-L "$$(LLVM_LIBDIR_$(1))"
 LLVM_LIBS_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --libs $$(LLVM_COMPONENTS))
 LLVM_LDFLAGS_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --ldflags)
 ifeq ($$(findstring freebsd,$(1)),freebsd)
 # On FreeBSD, it may search wrong headers (that are for pre-installed LLVM),
 # so we replace -I with -iquote to ensure that it searches bundled LLVM first.
 LLVM_CXXFLAGS_$(1)=$$(subst -I, -iquote , $$(shell "$$(LLVM_CONFIG_$(1))" --cxxflags))
 else
 LLVM_CXXFLAGS_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --cxxflags)
 endif
 LLVM_HOST_TRIPLE_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --host-target)

 LLVM_AS_$(1)=$$(CFG_LLVM_INST_DIR_$(1))/bin/llvm-as$$(X_$(1))
 LLC_$(1)=$$(CFG_LLVM_INST_DIR_$(1))/bin/llc$$(X_$(1))

 endef

 $(foreach host,$(CFG_HOST), \
  $(eval $(call DEF_LLVM_VARS,$(host))))

 ######################################################################
 # Exports for sub-utilities
 ######################################################################

 # Note that any variable that re-configure should pick up needs to be
 # exported

 export CFG_SRC_DIR
 export CFG_SRC_DIR_RELATIVE
 export CFG_BUILD_DIR
 ifdef CFG_VER_DATE
 export CFG_VER_DATE
 endif
 ifdef CFG_VER_HASH
 export CFG_VER_HASH
 endif
 export CFG_VERSION
 export CFG_VERSION_WIN
 export CFG_RELEASE
 export CFG_PACKAGE_NAME
 export CFG_BUILD
 export CFG_RELEASE_CHANNEL
 export CFG_LLVM_ROOT
 export CFG_PREFIX
 export CFG_LIBDIR
 export CFG_LIBDIR_RELATIVE
 export CFG_DISABLE_INJECT_STD_VERSION
 ifdef CFG_DISABLE_UNSTABLE_FEATURES
 CFG_INFO := $(info cfg: disabling unstable features (CFG_DISABLE_UNSTABLE_FEATURES))
 # Turn on feature-staging
 export CFG_DISABLE_UNSTABLE_FEATURES
 # Subvert unstable feature lints to do the self-build
 export RUSTC_BOOTSTRAP_KEY:=$(CFG_BOOTSTRAP_KEY)
 endif
 export CFG_BOOTSTRAP_KEY

 ######################################################################
 # Per-stage targets and runner
 ######################################################################

 # Valid setting-strings are 'all', 'none', 'gdb', 'lldb'
 # This 'function' will determine which debugger scripts to copy based on a
 # target triple. See debuggers.mk for more information.
 TRIPLE_TO_DEBUGGER_SCRIPT_SETTING=\
  $(if $(findstring windows,$(1)),none,$(if $(findstring darwin,$(1)),lldb,gdb))

 STAGES = 0 1 2 3

 define SREQ
 # $(1) is the stage number
 # $(2) is the target triple
 # $(3) is the host triple

 # Destinations of artifacts for the host compiler
 HROOT$(1)_H_$(3) = $(3)/stage$(1)
 HBIN$(1)_H_$(3) = $$(HROOT$(1)_H_$(3))/bin
 ifeq ($$(CFG_WINDOWSY_$(3)),1)
 HLIB$(1)_H_$(3) = $$(HROOT$(1)_H_$(3))/$$(CFG_LIBDIR_RELATIVE)
 else
 ifeq ($(1),0)
 HLIB$(1)_H_$(3) = $$(HROOT$(1)_H_$(3))/lib
 else
 HLIB$(1)_H_$(3) = $$(HROOT$(1)_H_$(3))/$$(CFG_LIBDIR_RELATIVE)
 endif
 endif

 # Destinations of artifacts for target architectures
 TROOT$(1)_T_$(2)_H_$(3) = $$(HLIB$(1)_H_$(3))/rustlib/$(2)
 TBIN$(1)_T_$(2)_H_$(3) = $$(TROOT$(1)_T_$(2)_H_$(3))/bin
 TLIB$(1)_T_$(2)_H_$(3) = $$(TROOT$(1)_T_$(2)_H_$(3))/lib

 # Preqrequisites for using the stageN compiler
 ifeq ($(1),0)
 HSREQ$(1)_H_$(3) = $$(HBIN$(1)_H_$(3))/rustc$$(X_$(3))
 else
 HSREQ$(1)_H_$(3) = \
 	$$(HBIN$(1)_H_$(3))/rustc$$(X_$(3)) \
 	$$(MKFILE_DEPS) \
 	tmp/install-debugger-scripts$(1)_H_$(3)-$$(call TRIPLE_TO_DEBUGGER_SCRIPT_SETTING,$(3)).done
 endif

 # Prerequisites for using the stageN compiler to build target artifacts
 TSREQ$(1)_T_$(2)_H_$(3) = \
 	$$(HSREQ$(1)_H_$(3)) \
 	$$(foreach obj,$$(INSTALLED_OBJECTS_$(2)),\
 		$$(TLIB$(1)_T_$(2)_H_$(3))/$$(obj))

 # Prerequisites for a working stageN compiler and libraries, for a specific
 # target
 SREQ$(1)_T_$(2)_H_$(3) = \
 	$$(TSREQ$(1)_T_$(2)_H_$(3)) \
 	$$(foreach dep,$$(TARGET_CRATES), \
 	    $$(TLIB$(1)_T_$(2)_H_$(3))/stamp.$$(dep)) \
 	tmp/install-debugger-scripts$(1)_T_$(2)_H_$(3)-$$(call TRIPLE_TO_DEBUGGER_SCRIPT_SETTING,$(2)).done

 # Prerequisites for a working stageN compiler and complete set of target
 # libraries
 CSREQ$(1)_T_$(2)_H_$(3) = \
 	$$(TSREQ$(1)_T_$(2)_H_$(3)) \
 	$$(HBIN$(1)_H_$(3))/rustdoc$$(X_$(3)) \
 	$$(foreach dep,$$(CRATES),$$(TLIB$(1)_T_$(2)_H_$(3))/stamp.$$(dep))

 ifeq ($(1),0)
 # Don't run the stage0 compiler under valgrind - that ship has sailed
 CFG_VALGRIND_COMPILE$(1) =
 else
 CFG_VALGRIND_COMPILE$(1) = $$(CFG_VALGRIND_COMPILE)
 endif

 # Add RUSTFLAGS_STAGEN values to the build command
 EXTRAFLAGS_STAGE$(1) = $$(RUSTFLAGS_STAGE$(1))

 CFGFLAG$(1)_T_$(2)_H_$(3) = stage$(1)

 endef

 # Same macro/variables as above, but defined in a separate loop so it can use
 # all the variables above for all archs. The RPATH_VAR setup sometimes needs to
 # reach across triples to get things in order.
 #
 # Defines (with the standard $(1)_T_$(2)_H_$(3) suffix):
 # * `LD_LIBRARY_PATH_ENV_NAME`: the name for the key to use in the OS
 #   environment to access or extend the lookup path for dynamic
 #   libraries.  Note on Windows, that key is `$PATH`, and thus not
 #   only conflates programs with dynamic libraries, but also often
 #   contains spaces which confuse make.
 # * `LD_LIBRARY_PATH_ENV_HOSTDIR`: the entry to add to lookup path for the host
 # * `LD_LIBRARY_PATH_ENV_TARGETDIR`: the entry to add to lookup path for target
 #
 # Below that, HOST_RPATH_VAR and TARGET_RPATH_VAR are defined in terms of the
 # above settings.
 #
 define SREQ_CMDS

 ifeq ($$(OSTYPE_$(3)),apple-darwin)
   LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3) := DYLD_LIBRARY_PATH
 else
 ifeq ($$(CFG_WINDOWSY_$(3)),1)
   LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3) := PATH
 else
   LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3) := LD_LIBRARY_PATH
 endif
 endif

 LD_LIBRARY_PATH_ENV_HOSTDIR$(1)_T_$(2)_H_$(3) := \
     $$(CURDIR)/$$(HLIB$(1)_H_$(3))
 LD_LIBRARY_PATH_ENV_TARGETDIR$(1)_T_$(2)_H_$(3) := \
     $$(CURDIR)/$$(TLIB1_T_$(2)_H_$(CFG_BUILD))

 HOST_RPATH_VAR$(1)_T_$(2)_H_$(3) := \
   $$(LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3))=$$(LD_LIBRARY_PATH_ENV_HOSTDIR$(1)_T_$(2)_H_$(3)):$$$$$$(LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3))
 TARGET_RPATH_VAR$(1)_T_$(2)_H_$(3) := \
   $$(LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3))=$$(LD_LIBRARY_PATH_ENV_TARGETDIR$(1)_T_$(2)_H_$(3)):$$$$$$(LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3))

 RPATH_VAR$(1)_T_$(2)_H_$(3) := $$(HOST_RPATH_VAR$(1)_T_$(2)_H_$(3))

 # Pass --cfg stage0 only for the build->host part of stage0;
 # if you're building a cross config, the host->* parts are
 # effectively stage1, since it uses the just-built stage0.
 #
 # This logic is similar to how the LD_LIBRARY_PATH variable must
 # change be slightly different when doing cross compilations.
 # The build doesn't copy over all target libraries into
 # a new directory, so we need to point the library path at
 # the build directory where all the target libraries came
 # from (the stage0 build host). Otherwise the relative rpaths
 # inside of the rustc binary won't get resolved correctly.
 ifeq ($(1),0)
 ifneq ($(strip $(CFG_BUILD)),$(strip $(3)))
 CFGFLAG$(1)_T_$(2)_H_$(3) = stage1

 RPATH_VAR$(1)_T_$(2)_H_$(3) := $$(TARGET_RPATH_VAR$(1)_T_$(2)_H_$(3))
 endif
 endif

 STAGE$(1)_T_$(2)_H_$(3) := \
 	$$(Q)$$(RPATH_VAR$(1)_T_$(2)_H_$(3)) \
 		$$(call CFG_RUN_TARG_$(3),$(1), \
 		$$(CFG_VALGRIND_COMPILE$(1)) \
 		$$(HBIN$(1)_H_$(3))/rustc$$(X_$(3)) \
 		--cfg $$(CFGFLAG$(1)_T_$(2)_H_$(3)) \
 		$$(CFG_RUSTC_FLAGS) $$(EXTRAFLAGS_STAGE$(1)) --target=$(2)) \
                 $$(RUSTC_FLAGS_$(2))

 PERF_STAGE$(1)_T_$(2)_H_$(3) := \
 	$$(Q)$$(call CFG_RUN_TARG_$(3),$(1), \
 		$$(CFG_PERF_TOOL) \
 		$$(HBIN$(1)_H_$(3))/rustc$$(X_$(3)) \
 		--cfg $$(CFGFLAG$(1)_T_$(2)_H_$(3)) \
 		$$(CFG_RUSTC_FLAGS) $$(EXTRAFLAGS_STAGE$(1)) --target=$(2)) \
                 $$(RUSTC_FLAGS_$(2))

 endef

 $(foreach build,$(CFG_HOST), \
  $(eval $(foreach target,$(CFG_TARGET), \
   $(eval $(foreach stage,$(STAGES), \
    $(eval $(call SREQ,$(stage),$(target),$(build))))))))

 $(foreach build,$(CFG_HOST), \
  $(eval $(foreach target,$(CFG_TARGET), \
   $(eval $(foreach stage,$(STAGES), \
    $(eval $(call SREQ_CMDS,$(stage),$(target),$(build))))))))

 ######################################################################
 # rustc-H-targets
 #
 # Builds a functional Rustc for the given host.
 ######################################################################

 define DEF_RUSTC_STAGE_TARGET
 # $(1) == architecture
 # $(2) == stage

 rustc-stage$(2)-H-$(1): \
 	$$(foreach target,$$(CFG_TARGET),$$(SREQ$(2)_T_$$(target)_H_$(1)))

 endef

 $(foreach host,$(CFG_HOST), \
  $(eval $(foreach stage,1 2 3, \
   $(eval $(call DEF_RUSTC_STAGE_TARGET,$(host),$(stage))))))

 rustc-stage1: rustc-stage1-H-$(CFG_BUILD)
 rustc-stage2: rustc-stage2-H-$(CFG_BUILD)
 rustc-stage3: rustc-stage3-H-$(CFG_BUILD)

 define DEF_RUSTC_TARGET
 # $(1) == architecture

 rustc-H-$(1): rustc-stage2-H-$(1)
 endef

 $(foreach host,$(CFG_TARGET), \
  $(eval $(call DEF_RUSTC_TARGET,$(host))))

 rustc-stage1: rustc-stage1-H-$(CFG_BUILD)
 rustc-stage2: rustc-stage2-H-$(CFG_BUILD)
 rustc-stage3: rustc-stage3-H-$(CFG_BUILD)
 rustc: rustc-H-$(CFG_BUILD)

 rustc-H-all: $(foreach host,$(CFG_HOST),rustc-H-$(host))

 ######################################################################
 # Entrypoint rule
 ######################################################################

 .DEFAULT_GOAL := all

 define ALL_TARGET_N
 ifneq ($$(findstring $(1),$$(CFG_HOST)),)
 # This is a host
 all-target-$(1)-host-$(2): $$(CSREQ2_T_$(1)_H_$(2))
 else
 # This is a target only
 all-target-$(1)-host-$(2): $$(SREQ2_T_$(1)_H_$(2))
 endif
 endef

 $(foreach target,$(CFG_TARGET), \
  $(foreach host,$(CFG_HOST), \
  $(eval $(call ALL_TARGET_N,$(target),$(host)))))

 ALL_TARGET_RULES = $(foreach target,$(CFG_TARGET), \
 	$(foreach host,$(CFG_HOST), \
  all-target-$(target)-host-$(host)))

 all: $(ALL_TARGET_RULES) $(GENERATED) docs

 ######################################################################
 # Build system documentation
 ######################################################################

 # $(1) is the name of the doc <section> in Makefile.in
 # pick everything between tags | remove first line | remove last line
 # | remove extra (?) line | strip leading `#` from lines
 SHOW_DOCS = $(Q)awk '/<$(1)>/,/<\/$(1)>/' $(S)/Makefile.in | sed '1d' | sed '$$d' | sed 's/^\# \?//'

 help:
 	$(call SHOW_DOCS,help)

 tips:
 	$(call SHOW_DOCS,tips)

 nitty-gritty:
 	$(call SHOW_DOCS,nitty-gritty)
	# Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
	# file at the top-level directory of this distribution and at
	# http://rust-lang.org/COPYRIGHT.
	#
	# Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	# http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	# <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	# option. This file may not be copied, modified, or distributed
	# except according to those terms.

	######################################################################
	# Version numbers and strings
	######################################################################

	# The version number
	CFG_RELEASE_NUM=1.2.0

	# An optional number to put after the label, e.g. '.2' -> '-beta.2'
	# NB Make sure it starts with a dot to conform to semver pre-release
	# versions (section 9)
	CFG_PRERELEASE_VERSION=.6

	# Append a version-dependent hash to each library, so we can install different
	# versions in the same place
	CFG_FILENAME_EXTRA=$(shell printf '%s' $(CFG_RELEASE) \| $(CFG_HASH_COMMAND))

	ifeq ($(CFG_RELEASE_CHANNEL),stable)
	# This is the normal semver version string, e.g. "0.12.0", "0.12.0-nightly"
	CFG_RELEASE=$(CFG_RELEASE_NUM)
	# This is the string used in dist artifact file names, e.g. "0.12.0", "nightly"
	CFG_PACKAGE_VERS=$(CFG_RELEASE_NUM)
	CFG_DISABLE_UNSTABLE_FEATURES=1
	endif
	ifeq ($(CFG_RELEASE_CHANNEL),beta)
	CFG_RELEASE=$(CFG_RELEASE_NUM)-beta$(CFG_PRERELEASE_VERSION)
	# When building beta distributables just reuse the same "beta" name
	# so when we upload we'll always override the previous beta. This
	# doesn't actually impact the version reported by rustc - it's just
	# for file naming.
	CFG_PACKAGE_VERS=beta
	CFG_DISABLE_UNSTABLE_FEATURES=1
	endif
	ifeq ($(CFG_RELEASE_CHANNEL),nightly)
	CFG_RELEASE=$(CFG_RELEASE_NUM)-nightly
	# When building nightly distributables just reuse the same "nightly" name
	# so when we upload we'll always override the previous nighly. This
	# doesn't actually impact the version reported by rustc - it's just
	# for file naming.
	CFG_PACKAGE_VERS=nightly
	endif
	ifeq ($(CFG_RELEASE_CHANNEL),dev)
	CFG_RELEASE=$(CFG_RELEASE_NUM)-dev
	CFG_PACKAGE_VERS=$(CFG_RELEASE_NUM)-dev
	endif

	# The name of the package to use for creating tarballs, installers etc.
	CFG_PACKAGE_NAME=rustc-$(CFG_PACKAGE_VERS)

	# The version string plus commit information - this is what rustc reports
	CFG_VERSION = $(CFG_RELEASE)
	CFG_GIT_DIR := $(CFG_SRC_DIR).git
	# since $(CFG_GIT) may contain spaces (especially on Windows),
	# we need to escape them. (" " to r"\ ")
	# Note that $(subst ...) ignores space after `subst`,
	# so we use a hack: define $(SPACE) which contains space character.
	SPACE :=
	SPACE +=
	ifneq ($(CFG_GIT),)
	ifneq ($(wildcard $(subst $(SPACE),\$(SPACE),$(CFG_GIT_DIR))),)
	CFG_VER_DATE = $(shell git --git-dir='$(CFG_GIT_DIR)' log -1 --date=short --pretty=format:'%cd')
	CFG_VER_HASH = $(shell git --git-dir='$(CFG_GIT_DIR)' rev-parse HEAD)
	CFG_SHORT_VER_HASH = $(shell git --git-dir='$(CFG_GIT_DIR)' rev-parse --short=9 HEAD)
	CFG_VERSION += ($(CFG_SHORT_VER_HASH) $(CFG_VER_DATE))
	endif
	endif

	# Windows exe's need numeric versions - don't use anything but
	# numbers and dots here
	CFG_VERSION_WIN = $(CFG_RELEASE_NUM)

	CFG_INFO := $(info cfg: version $(CFG_VERSION))

	######################################################################
	# More configuration
	######################################################################

	MKFILE_DEPS := config.stamp $(call rwildcard,$(CFG_SRC_DIR)mk/,*)
	MKFILES_FOR_TARBALL:=$(MKFILE_DEPS)
	ifneq ($(NO_MKFILE_DEPS),)
	MKFILE_DEPS :=
	endif
	NON_BUILD_HOST = $(filter-out $(CFG_BUILD),$(CFG_HOST))
	NON_BUILD_TARGET = $(filter-out $(CFG_BUILD),$(CFG_TARGET))

	ifneq ($(MAKE_RESTARTS),)
	CFG_INFO := $(info cfg: make restarts: $(MAKE_RESTARTS))
	endif

	CFG_INFO := $(info cfg: build triple $(CFG_BUILD))
	CFG_INFO := $(info cfg: host triples $(CFG_HOST))
	CFG_INFO := $(info cfg: target triples $(CFG_TARGET))

	ifneq ($(wildcard $(NON_BUILD_HOST)),)
	CFG_INFO := $(info cfg: non-build host triples $(NON_BUILD_HOST))
	endif
	ifneq ($(wildcard $(NON_BUILD_TARGET)),)
	CFG_INFO := $(info cfg: non-build target triples $(NON_BUILD_TARGET))
	endif

	CFG_RUSTC_FLAGS := $(RUSTFLAGS)
	CFG_GCCISH_CFLAGS :=
	CFG_GCCISH_LINK_FLAGS :=

	# Turn off broken quarantine (see jemalloc/jemalloc#161)
	CFG_JEMALLOC_FLAGS := --disable-fill

	ifdef CFG_DISABLE_OPTIMIZE
	$(info cfg: disabling rustc optimization (CFG_DISABLE_OPTIMIZE))
	CFG_RUSTC_FLAGS +=
	CFG_JEMALLOC_FLAGS += --enable-debug
	else
	# The rtopt cfg turns off runtime sanity checks
	CFG_RUSTC_FLAGS += -O --cfg rtopt
	endif

	CFG_JEMALLOC_FLAGS += $(JEMALLOC_FLAGS)

	ifdef CFG_ENABLE_DEBUG_ASSERTIONS
	$(info cfg: enabling debug assertions (CFG_ENABLE_DEBUG_ASSERTIONS))
	CFG_RUSTC_FLAGS += -C debug-assertions=on
	endif

	ifdef CFG_ENABLE_DEBUGINFO
	$(info cfg: enabling debuginfo (CFG_ENABLE_DEBUGINFO))
	CFG_RUSTC_FLAGS += -g
	endif

	ifdef SAVE_TEMPS
	CFG_RUSTC_FLAGS += --save-temps
	endif
	ifdef ASM_COMMENTS
	CFG_RUSTC_FLAGS += -Z asm-comments
	endif
	ifdef TIME_PASSES
	CFG_RUSTC_FLAGS += -Z time-passes
	endif
	ifdef TIME_LLVM_PASSES
	CFG_RUSTC_FLAGS += -Z time-llvm-passes
	endif
	ifdef TRACE
	CFG_RUSTC_FLAGS += -Z trace
	endif
	ifdef CFG_ENABLE_RPATH
	CFG_RUSTC_FLAGS += -C rpath
	endif

	# The executables crated during this compilation process have no need to include
	# static copies of libstd and libextra. We also generate dynamic versions of all
	# libraries, so in the interest of space, prefer dynamic linking throughout the
	# compilation process.
	#
	# Note though that these flags are omitted for the bins in stage2+. This means
	# that the snapshot will be generated with a statically linked rustc so we only
	# have to worry about the distribution of one file (with its native dynamic
	# dependencies)
	RUSTFLAGS_STAGE0 += -C prefer-dynamic
	RUSTFLAGS_STAGE1 += -C prefer-dynamic
	RUST_LIB_FLAGS_ST2 += -C prefer-dynamic
	RUST_LIB_FLAGS_ST3 += -C prefer-dynamic

	# Landing pads require a lot of codegen. We can get through bootstrapping faster
	# by not emitting them.
	RUSTFLAGS_STAGE0 += -Z no-landing-pads

	# platform-specific auto-configuration
	include $(CFG_SRC_DIR)mk/platform.mk

	# Run the stage1/2 compilers under valgrind
	ifdef VALGRIND_COMPILE
	CFG_VALGRIND_COMPILE :=$(CFG_VALGRIND)
	else
	CFG_VALGRIND_COMPILE :=
	endif


	ifndef CFG_DISABLE_VALGRIND_RPASS
	$(info cfg: enabling valgrind run-pass tests (CFG_ENABLE_VALGRIND_RPASS))
	$(info cfg: valgrind-rpass command set to $(CFG_VALGRIND))
	CFG_VALGRIND_RPASS :=$(CFG_VALGRIND)
	else
	$(info cfg: disabling valgrind run-pass tests)
	CFG_VALGRIND_RPASS :=
	endif


	ifdef CFG_ENABLE_VALGRIND
	$(info cfg: enabling valgrind (CFG_ENABLE_VALGRIND))
	else
	CFG_VALGRIND :=
	endif

	######################################################################
	# Target-and-rule "utility variables"
	######################################################################

	define DEF_FOR_TARGET
	X_$(1) := $(CFG_EXE_SUFFIX_$(1))
	ifndef CFG_LLVM_TARGET_$(1)
	CFG_LLVM_TARGET_$(1) := $(1)
	endif
	endef
	$(foreach target,$(CFG_TARGET), \
	$(eval $(call DEF_FOR_TARGET,$(target))))

	# "Source" files we generate in builddir along the way.
	GENERATED :=

	# Delete the built-in rules.
	.SUFFIXES:
	%:: %,v
	%:: RCS/%,v
	%:: RCS/%
	%:: s.%
	%:: SCCS/s.%


	######################################################################
	# Cleaning out old crates
	######################################################################

	# $(1) is the path for directory to match against
	# $(2) is the glob to use in the match
	#
	# Note that a common bug is to accidentally construct the glob denoted
	# by $(2) with a space character prefix, which invalidates the
	# construction $(1)$(2).
	define CHECK_FOR_OLD_GLOB_MATCHES
	$(Q)MATCHES="$(wildcard $(1))"; if [ -n "$$MATCHES" ] ; then echo "warning: there are previous" \'$(notdir $(2))\' "libraries:" $$MATCHES; fi
	endef

	# Same interface as above, but deletes rather than just listing the files.
	ifdef VERBOSE
	define REMOVE_ALL_OLD_GLOB_MATCHES
	$(Q)MATCHES="$(wildcard $(1))"; if [ -n "$$MATCHES" ] ; then echo "warning: removing previous" \'$(notdir $(1))\' "libraries:" $$MATCHES; rm $$MATCHES ; fi
	endef
	else
	define REMOVE_ALL_OLD_GLOB_MATCHES
	$(Q)MATCHES="$(wildcard $(1))"; if [ -n "$$MATCHES" ] ; then rm $$MATCHES ; fi
	endef
	endif

	# We use a different strategy for LIST_ALL_OLD_GLOB_MATCHES_EXCEPT
	# than in the macros above because it needs the result of running the
	# `ls` command after other rules in the command list have run; the
	# macro-expander for $(wildcard ...) would deliver its results too
	# soon. (This is in contrast to the macros above, which are meant to
	# be run at the outset of a command list in a rule.)
	ifdef VERBOSE
	define LIST_ALL_OLD_GLOB_MATCHES
	@echo "info: now are following matches for" '$(notdir $(1))' "libraries:"
	@( ls $(1) 2>/dev/null \|\| true )
	endef
	else
	define LIST_ALL_OLD_GLOB_MATCHES
	endef
	endif

	######################################################################
	# LLVM macros
	######################################################################

	# FIXME: x86-ism
	LLVM_COMPONENTS=x86 arm aarch64 mips powerpc ipo bitreader bitwriter linker asmparser mcjit \
	interpreter instrumentation

	# Only build these LLVM tools
	LLVM_TOOLS=bugpoint llc llvm-ar llvm-as llvm-dis llvm-mc opt llvm-extract

	define DEF_LLVM_VARS
	# The configure script defines these variables with the target triples
	# separated by Z. This defines new ones with the expected format.
	ifeq ($$(CFG_LLVM_ROOT),)
	CFG_LLVM_BUILD_DIR_$(1):=$$(CFG_LLVM_BUILD_DIR_$(subst -,_,$(1)))
	CFG_LLVM_INST_DIR_$(1):=$$(CFG_LLVM_INST_DIR_$(subst -,_,$(1)))
	else
	CFG_LLVM_INST_DIR_$(1):=$$(CFG_LLVM_ROOT)
	endif

	# Any rules that depend on LLVM should depend on LLVM_CONFIG
	LLVM_CONFIG_$(1):=$$(CFG_LLVM_INST_DIR_$(1))/bin/llvm-config$$(X_$(1))
	LLVM_MC_$(1):=$$(CFG_LLVM_INST_DIR_$(1))/bin/llvm-mc$$(X_$(1))
	LLVM_AR_$(1):=$$(CFG_LLVM_INST_DIR_$(1))/bin/llvm-ar$$(X_$(1))
	LLVM_VERSION_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --version)
	LLVM_BINDIR_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --bindir)
	LLVM_INCDIR_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --includedir)
	LLVM_LIBDIR_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --libdir)
	LLVM_LIBDIR_RUSTFLAGS_$(1)=-L "$$(LLVM_LIBDIR_$(1))"
	LLVM_LIBS_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --libs $$(LLVM_COMPONENTS))
	LLVM_LDFLAGS_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --ldflags)
	ifeq ($$(findstring freebsd,$(1)),freebsd)
	# On FreeBSD, it may search wrong headers (that are for pre-installed LLVM),
	# so we replace -I with -iquote to ensure that it searches bundled LLVM first.
	LLVM_CXXFLAGS_$(1)=$$(subst -I, -iquote , $$(shell "$$(LLVM_CONFIG_$(1))" --cxxflags))
	else
	LLVM_CXXFLAGS_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --cxxflags)
	endif
	LLVM_HOST_TRIPLE_$(1)=$$(shell "$$(LLVM_CONFIG_$(1))" --host-target)

	LLVM_AS_$(1)=$$(CFG_LLVM_INST_DIR_$(1))/bin/llvm-as$$(X_$(1))
	LLC_$(1)=$$(CFG_LLVM_INST_DIR_$(1))/bin/llc$$(X_$(1))

	endef

	$(foreach host,$(CFG_HOST), \
	$(eval $(call DEF_LLVM_VARS,$(host))))

	######################################################################
	# Exports for sub-utilities
	######################################################################

	# Note that any variable that re-configure should pick up needs to be
	# exported

	export CFG_SRC_DIR
	export CFG_SRC_DIR_RELATIVE
	export CFG_BUILD_DIR
	ifdef CFG_VER_DATE
	export CFG_VER_DATE
	endif
	ifdef CFG_VER_HASH
	export CFG_VER_HASH
	endif
	export CFG_VERSION
	export CFG_VERSION_WIN
	export CFG_RELEASE
	export CFG_PACKAGE_NAME
	export CFG_BUILD
	export CFG_RELEASE_CHANNEL
	export CFG_LLVM_ROOT
	export CFG_PREFIX
	export CFG_LIBDIR
	export CFG_LIBDIR_RELATIVE
	export CFG_DISABLE_INJECT_STD_VERSION
	ifdef CFG_DISABLE_UNSTABLE_FEATURES
	CFG_INFO := $(info cfg: disabling unstable features (CFG_DISABLE_UNSTABLE_FEATURES))
	# Turn on feature-staging
	export CFG_DISABLE_UNSTABLE_FEATURES
	# Subvert unstable feature lints to do the self-build
	export RUSTC_BOOTSTRAP_KEY:=$(CFG_BOOTSTRAP_KEY)
	endif
	export CFG_BOOTSTRAP_KEY

	######################################################################
	# Per-stage targets and runner
	######################################################################

	# Valid setting-strings are 'all', 'none', 'gdb', 'lldb'
	# This 'function' will determine which debugger scripts to copy based on a
	# target triple. See debuggers.mk for more information.
	TRIPLE_TO_DEBUGGER_SCRIPT_SETTING=\
	$(if $(findstring windows,$(1)),none,$(if $(findstring darwin,$(1)),lldb,gdb))

	STAGES = 0 1 2 3

	define SREQ
	# $(1) is the stage number
	# $(2) is the target triple
	# $(3) is the host triple

	# Destinations of artifacts for the host compiler
	HROOT$(1)_H_$(3) = $(3)/stage$(1)
	HBIN$(1)_H_$(3) = $$(HROOT$(1)_H_$(3))/bin
	ifeq ($$(CFG_WINDOWSY_$(3)),1)
	HLIB$(1)_H_$(3) = $$(HROOT$(1)_H_$(3))/$$(CFG_LIBDIR_RELATIVE)
	else
	ifeq ($(1),0)
	HLIB$(1)_H_$(3) = $$(HROOT$(1)_H_$(3))/lib
	else
	HLIB$(1)_H_$(3) = $$(HROOT$(1)_H_$(3))/$$(CFG_LIBDIR_RELATIVE)
	endif
	endif

	# Destinations of artifacts for target architectures
	TROOT$(1)_T_$(2)_H_$(3) = $$(HLIB$(1)_H_$(3))/rustlib/$(2)
	TBIN$(1)_T_$(2)_H_$(3) = $$(TROOT$(1)_T_$(2)_H_$(3))/bin
	TLIB$(1)_T_$(2)_H_$(3) = $$(TROOT$(1)_T_$(2)_H_$(3))/lib

	# Preqrequisites for using the stageN compiler
	ifeq ($(1),0)
	HSREQ$(1)_H_$(3) = $$(HBIN$(1)_H_$(3))/rustc$$(X_$(3))
	else
	HSREQ$(1)_H_$(3) = \
	$$(HBIN$(1)_H_$(3))/rustc$$(X_$(3)) \
	$$(MKFILE_DEPS) \
	tmp/install-debugger-scripts$(1)_H_$(3)-$$(call TRIPLE_TO_DEBUGGER_SCRIPT_SETTING,$(3)).done
	endif

	# Prerequisites for using the stageN compiler to build target artifacts
	TSREQ$(1)_T_$(2)_H_$(3) = \
	$$(HSREQ$(1)_H_$(3)) \
	$$(foreach obj,$$(INSTALLED_OBJECTS_$(2)),\
	$$(TLIB$(1)_T_$(2)_H_$(3))/$$(obj))

	# Prerequisites for a working stageN compiler and libraries, for a specific
	# target
	SREQ$(1)_T_$(2)_H_$(3) = \
	$$(TSREQ$(1)_T_$(2)_H_$(3)) \
	$$(foreach dep,$$(TARGET_CRATES), \
	$$(TLIB$(1)_T_$(2)_H_$(3))/stamp.$$(dep)) \
	tmp/install-debugger-scripts$(1)_T_$(2)_H_$(3)-$$(call TRIPLE_TO_DEBUGGER_SCRIPT_SETTING,$(2)).done

	# Prerequisites for a working stageN compiler and complete set of target
	# libraries
	CSREQ$(1)_T_$(2)_H_$(3) = \
	$$(TSREQ$(1)_T_$(2)_H_$(3)) \
	$$(HBIN$(1)_H_$(3))/rustdoc$$(X_$(3)) \
	$$(foreach dep,$$(CRATES),$$(TLIB$(1)_T_$(2)_H_$(3))/stamp.$$(dep))

	ifeq ($(1),0)
	# Don't run the stage0 compiler under valgrind - that ship has sailed
	CFG_VALGRIND_COMPILE$(1) =
	else
	CFG_VALGRIND_COMPILE$(1) = $$(CFG_VALGRIND_COMPILE)
	endif

	# Add RUSTFLAGS_STAGEN values to the build command
	EXTRAFLAGS_STAGE$(1) = $$(RUSTFLAGS_STAGE$(1))

	CFGFLAG$(1)_T_$(2)_H_$(3) = stage$(1)

	endef

	# Same macro/variables as above, but defined in a separate loop so it can use
	# all the variables above for all archs. The RPATH_VAR setup sometimes needs to
	# reach across triples to get things in order.
	#
	# Defines (with the standard $(1)_T_$(2)_H_$(3) suffix):
	# * `LD_LIBRARY_PATH_ENV_NAME`: the name for the key to use in the OS
	# environment to access or extend the lookup path for dynamic
	# libraries. Note on Windows, that key is `$PATH`, and thus not
	# only conflates programs with dynamic libraries, but also often
	# contains spaces which confuse make.
	# * `LD_LIBRARY_PATH_ENV_HOSTDIR`: the entry to add to lookup path for the host
	# * `LD_LIBRARY_PATH_ENV_TARGETDIR`: the entry to add to lookup path for target
	#
	# Below that, HOST_RPATH_VAR and TARGET_RPATH_VAR are defined in terms of the
	# above settings.
	#
	define SREQ_CMDS

	ifeq ($$(OSTYPE_$(3)),apple-darwin)
	LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3) := DYLD_LIBRARY_PATH
	else
	ifeq ($$(CFG_WINDOWSY_$(3)),1)
	LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3) := PATH
	else
	LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3) := LD_LIBRARY_PATH
	endif
	endif

	LD_LIBRARY_PATH_ENV_HOSTDIR$(1)_T_$(2)_H_$(3) := \
	$$(CURDIR)/$$(HLIB$(1)_H_$(3))
	LD_LIBRARY_PATH_ENV_TARGETDIR$(1)_T_$(2)_H_$(3) := \
	$$(CURDIR)/$$(TLIB1_T_$(2)_H_$(CFG_BUILD))

	HOST_RPATH_VAR$(1)_T_$(2)_H_$(3) := \
	$$(LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3))=$$(LD_LIBRARY_PATH_ENV_HOSTDIR$(1)_T_$(2)_H_$(3)):$$$$$$(LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3))
	TARGET_RPATH_VAR$(1)_T_$(2)_H_$(3) := \
	$$(LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3))=$$(LD_LIBRARY_PATH_ENV_TARGETDIR$(1)_T_$(2)_H_$(3)):$$$$$$(LD_LIBRARY_PATH_ENV_NAME$(1)_T_$(2)_H_$(3))

	RPATH_VAR$(1)_T_$(2)_H_$(3) := $$(HOST_RPATH_VAR$(1)_T_$(2)_H_$(3))

	# Pass --cfg stage0 only for the build->host part of stage0;
	# if you're building a cross config, the host->* parts are
	# effectively stage1, since it uses the just-built stage0.
	#
	# This logic is similar to how the LD_LIBRARY_PATH variable must
	# change be slightly different when doing cross compilations.
	# The build doesn't copy over all target libraries into
	# a new directory, so we need to point the library path at
	# the build directory where all the target libraries came
	# from (the stage0 build host). Otherwise the relative rpaths
	# inside of the rustc binary won't get resolved correctly.
	ifeq ($(1),0)
	ifneq ($(strip $(CFG_BUILD)),$(strip $(3)))
	CFGFLAG$(1)_T_$(2)_H_$(3) = stage1

	RPATH_VAR$(1)_T_$(2)_H_$(3) := $$(TARGET_RPATH_VAR$(1)_T_$(2)_H_$(3))
	endif
	endif

	STAGE$(1)_T_$(2)_H_$(3) := \
	$$(Q)$$(RPATH_VAR$(1)_T_$(2)_H_$(3)) \
	$$(call CFG_RUN_TARG_$(3),$(1), \
	$$(CFG_VALGRIND_COMPILE$(1)) \
	$$(HBIN$(1)_H_$(3))/rustc$$(X_$(3)) \
	--cfg $$(CFGFLAG$(1)_T_$(2)_H_$(3)) \
	$$(CFG_RUSTC_FLAGS) $$(EXTRAFLAGS_STAGE$(1)) --target=$(2)) \
	$$(RUSTC_FLAGS_$(2))

	PERF_STAGE$(1)_T_$(2)_H_$(3) := \
	$$(Q)$$(call CFG_RUN_TARG_$(3),$(1), \
	$$(CFG_PERF_TOOL) \
	$$(HBIN$(1)_H_$(3))/rustc$$(X_$(3)) \
	--cfg $$(CFGFLAG$(1)_T_$(2)_H_$(3)) \
	$$(CFG_RUSTC_FLAGS) $$(EXTRAFLAGS_STAGE$(1)) --target=$(2)) \
	$$(RUSTC_FLAGS_$(2))

	endef

	$(foreach build,$(CFG_HOST), \
	$(eval $(foreach target,$(CFG_TARGET), \
	$(eval $(foreach stage,$(STAGES), \
	$(eval $(call SREQ,$(stage),$(target),$(build))))))))

	$(foreach build,$(CFG_HOST), \
	$(eval $(foreach target,$(CFG_TARGET), \
	$(eval $(foreach stage,$(STAGES), \
	$(eval $(call SREQ_CMDS,$(stage),$(target),$(build))))))))

	######################################################################
	# rustc-H-targets
	#
	# Builds a functional Rustc for the given host.
	######################################################################

	define DEF_RUSTC_STAGE_TARGET
	# $(1) == architecture
	# $(2) == stage

	rustc-stage$(2)-H-$(1): \
	$$(foreach target,$$(CFG_TARGET),$$(SREQ$(2)_T_$$(target)_H_$(1)))

	endef

	$(foreach host,$(CFG_HOST), \
	$(eval $(foreach stage,1 2 3, \
	$(eval $(call DEF_RUSTC_STAGE_TARGET,$(host),$(stage))))))

	rustc-stage1: rustc-stage1-H-$(CFG_BUILD)
	rustc-stage2: rustc-stage2-H-$(CFG_BUILD)
	rustc-stage3: rustc-stage3-H-$(CFG_BUILD)

	define DEF_RUSTC_TARGET
	# $(1) == architecture

	rustc-H-$(1): rustc-stage2-H-$(1)
	endef

	$(foreach host,$(CFG_TARGET), \
	$(eval $(call DEF_RUSTC_TARGET,$(host))))

	rustc-stage1: rustc-stage1-H-$(CFG_BUILD)
	rustc-stage2: rustc-stage2-H-$(CFG_BUILD)
	rustc-stage3: rustc-stage3-H-$(CFG_BUILD)
	rustc: rustc-H-$(CFG_BUILD)

	rustc-H-all: $(foreach host,$(CFG_HOST),rustc-H-$(host))

	######################################################################
	# Entrypoint rule
	######################################################################

	.DEFAULT_GOAL := all

	define ALL_TARGET_N
	ifneq ($$(findstring $(1),$$(CFG_HOST)),)
	# This is a host
	all-target-$(1)-host-$(2): $$(CSREQ2_T_$(1)_H_$(2))
	else
	# This is a target only
	all-target-$(1)-host-$(2): $$(SREQ2_T_$(1)_H_$(2))
	endif
	endef

	$(foreach target,$(CFG_TARGET), \
	$(foreach host,$(CFG_HOST), \
	$(eval $(call ALL_TARGET_N,$(target),$(host)))))

	ALL_TARGET_RULES = $(foreach target,$(CFG_TARGET), \
	$(foreach host,$(CFG_HOST), \
	all-target-$(target)-host-$(host)))

	all: $(ALL_TARGET_RULES) $(GENERATED) docs

	######################################################################
	# Build system documentation
	######################################################################

	# $(1) is the name of the doc <section> in Makefile.in
	# pick everything between tags \| remove first line \| remove last line
	# \| remove extra (?) line \| strip leading `#` from lines
	SHOW_DOCS = $(Q)awk '/<$(1)>/,/<\/$(1)>/' $(S)/Makefile.in \| sed '1d' \| sed '$$d' \| sed 's/^\# \?//'

	help:
	$(call SHOW_DOCS,help)

	tips:
	$(call SHOW_DOCS,tips)

	nitty-gritty:
	$(call SHOW_DOCS,nitty-gritty)