kumquat-buildroot/package/pkg-virtual.mk
Peter Korsgaard 32d2de2a6f pkg-virtual.mk: explicitly set <pkg>_VERSION / _SOURCE for robustness
Recently a build failure was reported which was traced back to to the fact
that the user had a TOOLCHAIN_VERSION environment variable set which leads
to a strange looking error message:

toolchain/toolchain/toolchain.mk:40: *** TOOLCHAIN_SITE cannot be empty when
TOOLCHAIN_SOURCE is not.  Stop.

Environment variables automatically gets converted to make variables by GNU
make - E.G. from the manual
(https://www.gnu.org/software/make/manual/html_node/Environment.html):

Variables in make can come from the environment in which make is run.  Every
environment variable that make sees when it starts up is transformed into a
make variable with the same name and value

So we end up in make with TOOLCHAIN_VERSION set to the value of the
environment variable.  As virtual packages do not have a version, there is
no explicit TOOLCHAIN_VERSION = ..  line in toolchain.mk overriding this
value, and the logic in package/pkg-generic.mk sets a default value for
TOOLCHAIN_SOURCE when TOOLCHAIN_VERSION is set, and finally errors out as
TOOLCHAIN_SITE isn't set.

As a workaround, explicitly set <pkg>_VERSION and <pkg>_SOURCE to the empty
string in the virtual package infrastructure.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
2018-03-14 08:39:12 +01:00

78 lines
3.0 KiB
Makefile

################################################################################
# Virtual package infrastructure
#
# This file implements an infrastructure that eases development of
# package .mk files for virtual packages. It should be used for all
# virtual packages.
#
# See the Buildroot documentation for details on the usage of this
# infrastructure
#
# In terms of implementation, this virtual infrastructure requires
# the .mk file to only call the 'virtual-package' macro.
#
################################################################################
################################################################################
# inner-virtual-package -- defines the dependency rules of the virtual
# package against its provider.
#
# argument 1 is the lowercase package name
# argument 2 is the uppercase package name, including a HOST_ prefix
# for host packages
# argument 3 is the uppercase package name, without the HOST_ prefix
# for host packages
# argument 4 is the type (target or host)
################################################################################
# Note: putting this comment here rather than in the define block, otherwise
# make would try to expand the $(error ...) in the comment, which is not
# really what we want.
# We need to use second-expansion for the $(error ...) call, below,
# so it is not evaluated now, but as part of the generated make code.
define inner-virtual-package
# Ensure the virtual package has an implementation defined.
ifeq ($$(BR2_PACKAGE_HAS_$(2)),y)
ifeq ($$(call qstrip,$$(BR2_PACKAGE_PROVIDES_$(2))),)
$$(error No implementation selected for virtual package $(1). Configuration error)
endif
endif
# explicitly set these so we do not get confused by environment
# variables with the same names.
$(2)_VERSION =
$(2)_SOURCE =
$(2)_IS_VIRTUAL = YES
# Add dependency against the provider
# For a host package, there is no corresponding BR2_PACKAGE_PROVIDES_HOST_FOO,
# so we need to compute it from the target variant.
ifeq ($(4),target)
$(2)_DEPENDENCIES += $$(call qstrip,$$(BR2_PACKAGE_PROVIDES_$(2)))
else
ifeq ($$(call qstrip,$$(BR2_PACKAGE_PROVIDES_$(2))),)
# Inherit from target package BR2_PACKAGE_PROVIDES_FOO
$(2)_DEPENDENCIES += host-$$(call qstrip,$$(BR2_PACKAGE_PROVIDES_$(3)))
else
# BR2_PACKAGE_PROVIDES_HOST_<pkg> is explicitly defined
$(2)_DEPENDENCIES += $$(call qstrip,$$(BR2_PACKAGE_PROVIDES_$(2)))
endif
endif
# Call the generic package infrastructure to generate the necessary
# make targets
$(call inner-generic-package,$(1),$(2),$(3),$(4))
endef
################################################################################
# virtual-package -- the target generator macro for virtual packages
################################################################################
virtual-package = $(call inner-virtual-package,$(pkgname),$(call UPPERCASE,$(pkgname)),$(call UPPERCASE,$(pkgname)),target)
host-virtual-package = $(call inner-virtual-package,host-$(pkgname),$(call UPPERCASE,host-$(pkgname)),$(call UPPERCASE,$(pkgname)),host)