[Buildroot] [PATCH v9 4/8] rust: new package

Thu Dec 28 21:08:53 UTC 2017

Hello,

On Thu, 28 Dec 2017 16:51:42 +0100, Eric Le Bihan wrote:
> This new package provides rustc, the compiler for the Rust programming
> language, built from source.
> 
> Currently, only the host variant is built.
> 
> The Rust compiler uses LLVM as its backend: a copy of LLVM source code
> is provided and CMake is used to build it. It is possible to use a
> pre-built external copy. When LLVM/clang will be available in Buildroot,
> it would be possible to benefit from this feature and thus decrease
> build time.
> 
> LLVM is configured to generate code for x86, ARM, PowerPC and MIPS
> architectures.
> 
> The Rust compiler uses Cargo as its build system and is written in Rust.
> Therefore this package depends on cargo-bin and rust-bin.
> 
> The internal build process is as follows:
> 
>  1. rustc-stage0, provided by rust-bin, is used to build rustc-stage1.
>  2. rust-stage1 builds the final Rust compiler (rust-stage2)
>     and the standard library for the host architecture.

You're sometimes using rustc-stageX, sometimes just rust-stageX. Is
this intentional ?

> diff --git a/package/rust/rust.mk b/package/rust/rust.mk
> new file mode 100644
> index 0000000000..8dbec99bc5
> --- /dev/null
> +++ b/package/rust/rust.mk
> @@ -0,0 +1,82 @@
> +################################################################################
> +#
> +# rust
> +#
> +################################################################################
> +
> +RUST_VERSION = 1.22.1
> +RUST_SOURCE = rustc-$(RUST_VERSION)-src.tar.xz
> +RUST_SITE = https://static.rust-lang.org/dist
> +RUST_LICENSE = Apache-2.0 or MIT
> +RUST_LICENSE_FILES = LICENSE-APACHE LICENSE-MIT
> +
> +HOST_RUST_PROVIDES = host-rustc
> +
> +HOST_RUST_DEPENDENCIES = \
> +	toolchain \

It is somewhat unusual to have a host package depend on the target
toolchain. I'm not sure we have any other host package in the tree
doing this. I do understand why you're doing this, I'm just a little
bit concerned that this special situation may be forgotten in the
future. But there isn't much other solution, so it's probably good as
it is.

> +	host-rust-bin \
> +	host-cargo-bin \
> +	host-python \

So you absolutely need python2 ? The build system is not python3
compliant ?

> +	host-cmake

Could you use $(BR2_CMAKE_HOST_DEPENDENCY) instead ? This way, it would
only build host-cmake if CMake is not already present on the system.
This would save a bit of build time.

> +ifeq ($(BR2_PACKAGE_JEMALLOC),y)
> +HOST_RUST_DEPENDENCIES += jemalloc
> +HOST_RUST_JEMALLOC_ENABLED = true
> +HOST_RUST_JEMALLOC_CONF = 'jemalloc = "$(STAGING_DIR)/usr/lib/libjemalloc_pic.a"'
> +else
> +HOST_RUST_JEMALLOC_ENABLED = false
> +endif
> +
> +HOST_RUST_VERBOSITY = $(if $(VERBOSE),2,0)
> +
> +# Some vendored crates contain Cargo.toml.orig files. The associated

vendored -> vendor ?

> +# .cargo-checksum.json file will contain a checksum for Cargo.toml.orig but
> +# support/scripts/apply-patches.sh will delete them. This will cause the build
> +# to fail, as Cargo will not be able to find the file and verify the checksum.
> +# So, remove all Cargo.toml.orig entries from the affected .cargo-checksum.json
> +# files
> +define HOST_RUST_EXCLUDE_ORIG_FILES
> +	for file in $$(find $(@D) -name '*.orig'); do \
> +		crate=$$(dirname $${file}); \
> +		fn=$${crate}/.cargo-checksum.json; \
> +		sed -i -e 's/"Cargo.toml.orig":"[a-z0-9]\+",//g' $${fn}; \
> +	done
> +endef
> +
> +HOST_RUST_POST_EXTRACT_HOOKS += HOST_RUST_EXCLUDE_ORIG_FILES
> +
> +define HOST_RUST_CONFIGURE_CMDS
> +	( \
> +		echo '[build]'; \
> +		echo 'target = ["$(RUST_TARGET_NAME)"]'; \
> +		echo 'cargo = "$(HOST_CARGO_BIN_DIR)/cargo/bin/cargo"'; \
> +		echo 'rustc = "$(HOST_RUST_BIN_DIR)/rustc/bin/rustc"'; \
> +		echo 'python = "$(HOST_DIR)/bin/python2"'; \
> +		echo 'submodules = false'; \
> +		echo 'vendor = true'; \
> +		echo 'compiler-docs = false'; \
> +		echo 'docs = false'; \
> +		echo 'verbose = $(HOST_RUST_VERBOSITY)'; \
> +		echo '[install]'; \
> +		echo 'prefix = "$(HOST_DIR)"'; \
> +		echo '[rust]'; \
> +		echo 'use-jemalloc = $(HOST_RUST_JEMALLOC_ENABLED)'; \
> +		echo '[target.$(RUST_TARGET_NAME)]'; \
> +		echo 'cc = "$(TARGET_CROSS)gcc"'; \
> +		echo $(HOST_RUST_JEMALLOC_CONF); \
> +	) > $(@D)/config.toml
> +endef
> +
> +define HOST_RUST_BUILD_CMDS
> +	(cd $(@D); $(HOST_MAKE_ENV) $(HOST_DIR)/bin/python2 x.py \
> +		build $(HOST_RUST_BUILD_OPTS))
> +endef
> +
> +define HOST_RUST_INSTALL_CMDS
> +	(cd $(@D); $(HOST_MAKE_ENV) $(HOST_DIR)/bin/python2 x.py \
> +		dist $(HOST_RUST_BUILD_OPTS))
> +	(cd $(@D); $(HOST_MAKE_ENV) $(HOST_DIR)/bin/python2 x.py \
> +		install $(HOST_RUST_BUILD_OPTS))
> +endef
> +
> +$(eval $(host-generic-package))
> diff --git a/package/rustc/Config.in.host b/package/rustc/Config.in.host
> index e42187d477..3a03140bcd 100644
> --- a/package/rustc/Config.in.host
> +++ b/package/rustc/Config.in.host
> @@ -26,6 +26,21 @@ choice
>  	help
>  	  Select a Rust compiler
>  
> +config BR2_PACKAGE_HOST_RUST
> +	bool "host rust"
> +	depends on BR2_HOST_GCC_AT_LEAST_4_7 # required by LLVM
> +	# triggers ICE on trunc_int_for_mode, at explow.c:56
> +	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_5 || !BR2_aarch64
> +	select BR2_PACKAGE_HAS_HOST_RUSTC
> +	help
> +	  This package will build the compiler for the host as well as
> +	  two flavors of the standard library: one for the host, another
> +	  for the target. Both are installed in the host directory.
> +
> +comment "host-rust needs a toolchain w/ gcc >= 5"
> +	depends on BR2_aarch64
> +	depends on !BR2_TOOLCHAIN_GCC_AT_LEAST_5

What about the gcc 4.7 dependency? It would also need a comment.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com