pkg-meson: new infrastructure

Add a new infrastructure to ease the development of packages that use Meson as
their build system.

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>
[Thomas:
 - move global variables definition outside of the inner-meson-package
   macro
 - for consistency, remove double quote around value passed to meson
   in the host configure step.
 - minor formatting fixes.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

DEVELOPERS

@@ -578,6 +578,7 @@ F:	package/hicolor-icon-theme/
 F:	package/jemalloc/
 F:	package/meson/
 F:	package/ninja/
+F:	package/pkg-meson.mk
 F:	package/rust-bin/
 F:	package/rust/
 F:	package/s6/

package/Makefile.in

@@ -447,3 +447,4 @@ include package/pkg-rebar.mk
 include package/pkg-kernel-module.mk
 include package/pkg-waf.mk
 include package/pkg-golang.mk
+include package/pkg-meson.mk

package/pkg-meson.mk

@@ -0,0 +1,160 @@
+################################################################################
+# Meson package infrastructure
+#
+# This file implements an infrastructure that eases development of
+# package .mk files for Meson packages. It should be used for all
+# packages that use Meson as their build system.
+#
+# See the Buildroot documentation for details on the usage of this
+# infrastructure
+#
+# In terms of implementation, this Meson infrastructure requires
+# the .mk file to only specify metadata information about the
+# package: name, version, download URL, etc.
+#
+# We still allow the package .mk file to override what the different
+# steps are doing, if needed. For example, if <PKG>_BUILD_CMDS is
+# already defined, it is used as the list of commands to perform to
+# build the package, instead of the default Meson behaviour. The
+# package can also define some post operation hooks.
+#
+################################################################################
+
+#
+# Pass PYTHONNOUSERSITE environment variable when invoking Meson or Ninja, so
+# $(HOST_DIR)/bin/python3 will not look for Meson modules in
+# $HOME/.local/lib/python3.x/site-packages
+#
+MESON		= PYTHONNOUSERSITE=y $(HOST_DIR)/bin/meson
+NINJA		= PYTHONNOUSERSITE=y $(HOST_DIR)/bin/ninja
+NINJA_OPTS	= $(if $(VERBOSE),-v) -j$(PARALLEL_JOBS)
+
+################################################################################
+# inner-meson-package -- defines how the configuration, compilation and
+# installation of a Meson package should be done, implements a few hooks to
+# tune the build process and calls the generic package infrastructure to
+# generate the necessary make targets
+#
+#  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)
+################################################################################
+
+define inner-meson-package
+
+$(2)_CONF_ENV		?=
+$(2)_CONF_OPTS		?=
+$(2)_NINJA_ENV		?=
+$(2)_SRCDIR		= $$($(2)_DIR)/$$($(2)_SUBDIR)
+
+#
+# Configure step. Only define it if not already defined by the package
+# .mk file. And take care of the differences between host and target
+# packages.
+#
+ifndef $(2)_CONFIGURE_CMDS
+ifeq ($(4),target)
+
+# Configure package for target
+#
+#
+define $(2)_CONFIGURE_CMDS
+	rm -rf $$($$(PKG)_SRCDIR)/build
+	mkdir -p $$($$(PKG)_SRCDIR)/build
+	PATH=$$(BR_PATH) $$($$(PKG)_CONF_ENV) $$(MESON) \
+		--prefix=/usr \
+		--libdir=lib \
+		--default-library=$(if $(BR2_STATIC_LIBS),static,shared) \
+		--buildtype=$(if $(BR2_ENABLE_DEBUG),debug,release) \
+		--cross-file=$(HOST_DIR)/etc/meson/cross-compilation.conf \
+		$$($$(PKG)_CONF_OPTS) \
+		$$($$(PKG)_SRCDIR) $$($$(PKG)_SRCDIR)/build
+endef
+else
+
+# Configure package for host
+define $(2)_CONFIGURE_CMDS
+	rm -rf $$($$(PKG)_SRCDIR)/build
+	mkdir -p $$($$(PKG)_SRCDIR)/build
+	$$(HOST_CONFIGURE_OPTS) \
+	$$($$(PKG)_CONF_ENV) $$(MESON) \
+		--prefix=$$(HOST_DIR) \
+		--libdir=lib \
+		--sysconfdir=$$(HOST_DIR)/etc \
+		--localstatedir=$$(HOST_DIR)/var \
+		--default-library=shared \
+		--buildtype=release \
+		$$($$(PKG)_CONF_OPTS) \
+		$$($$(PKG)_SRCDIR) $$($$(PKG)_SRCDIR)/build
+endef
+endif
+endif
+
+$(2)_DEPENDENCIES += host-meson
+
+#
+# Build step. Only define it if not already defined by the package .mk
+# file.
+#
+ifndef $(2)_BUILD_CMDS
+ifeq ($(4),target)
+define $(2)_BUILD_CMDS
+	$$(TARGET_MAKE_ENV) $$($$(PKG)_NINJA_ENV) \
+		$$(NINJA) $$(NINJA_OPTS) -C $$($$(PKG)_SRCDIR)/build
+endef
+else
+define $(2)_BUILD_CMDS
+	$$(HOST_MAKE_ENV) $$($$(PKG)_NINJA_ENV) \
+		$$(NINJA) $$(NINJA_OPTS) -C $$($$(PKG)_SRCDIR)/build
+endef
+endif
+endif
+
+#
+# Host installation step. Only define it if not already defined by the
+# package .mk file.
+#
+ifndef $(2)_INSTALL_CMDS
+define $(2)_INSTALL_CMDS
+	$$(HOST_MAKE_ENV) $$($$(PKG)_NINJA_ENV) \
+		$$(NINJA) $$(NINJA_OPTS) -C $$($$(PKG)_SRCDIR)/build install
+endef
+endif
+
+#
+# Staging installation step. Only define it if not already defined by
+# the package .mk file.
+#
+ifndef $(2)_INSTALL_STAGING_CMDS
+define $(2)_INSTALL_STAGING_CMDS
+	$$(TARGET_MAKE_ENV) $$($$(PKG)_NINJA_ENV) DESTDIR=$$(STAGING_DIR) \
+		$$(NINJA) $$(NINJA_OPTS) -C $$($$(PKG)_SRCDIR)/build install
+endef
+endif
+
+#
+# Target installation step. Only define it if not already defined by
+# the package .mk file.
+#
+ifndef $(2)_INSTALL_TARGET_CMDS
+define $(2)_INSTALL_TARGET_CMDS
+	$$(TARGET_MAKE_ENV) $$($$(PKG)_NINJA_ENV) DESTDIR=$$(TARGET_DIR) \
+		$$(NINJA) $$(NINJA_OPTS) -C $$($$(PKG)_SRCDIR)/build install
+endef
+endif
+
+# Call the generic package infrastructure to generate the necessary
+# make targets
+$(call inner-generic-package,$(1),$(2),$(3),$(4))
+
+endef
+
+################################################################################
+# meson-package -- the target generator macro for Meson packages
+################################################################################
+
+meson-package = $(call inner-meson-package,$(pkgname),$(call UPPERCASE,$(pkgname)),$(call UPPERCASE,$(pkgname)),target)
+host-meson-package = $(call inner-meson-package,host-$(pkgname),$(call UPPERCASE,host-$(pkgname)),$(call UPPERCASE,$(pkgname)),host)