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# Copyright 2018 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import("//build/rust/rustc_artifact.gni")
import("//build/rust/rustc_test.gni")
import("//build/toolchain/restat.gni")
# Defines a Rust procedural macro
#
# Parameters
#
# output_name (optional)
# name (optional, deprecated)
# Name of the crate as defined in its manifest file. If not specified, it is
# assumed to be the same as the target name.
#
# version (optional)
# Semver version of the crate as seen on crates.io.
#
# edition
# Edition of the Rust language to be used. See
# https://doc.rust-lang.org/edition-guide/editions/index.html for more info on rust editions.
#
# configs (optional)
# A list of config labels applying to this target.
#
# enforce_source_listing (optional)
# When true, enforces that any source files used by the Rust compiler are
# listed in `sources`. Defaults to true.
#
# sources (optional)
# List of source files which this crate is allowed to compile. Only
# allowed when `enforce_source_listing = true`.
# The Rust compiler discovers source files by following `mod` declarations
# starting at the `source_root`. The discovered source files must match this
# list.
#
# inputs (optional)
# List of additional non-source files read by the compiler. These are typically
# configuration or test-data files included in the build with the `include_str!`
# macro. Only allowed when `enforce_source_listing = true`.
#
# deps (optional)
# List of rust_library GN targets on which this crate depends.
# Third party crates can be included through paths like
# "//third_party/rust_crates:<cratename>".
#
# test_deps (optional)
# List of rust_library GN targets on which this crate's tests depend.
#
# non_rust_deps (optional)
# List of non-rust_library GN targets on which this crate depends.
# Obsolete. Please use deps instead.
#
# data_deps (optional)
# List of GN targets that are only needed at runtime.
#
# with_unit_tests (optional)
# Builds unit tests associated with the library. This will create a
# `<name>_test` test file in the output directory. Equivalent to adding a
# `rustc_test` target with that name and the same source_root.
#
# source_root (optional)
# Location of the crate root (e.g. `src/main.rs` or `src/lib.rs`).
# This defaults to `./src/main.rs` for binaries and `./src/lib.rs` for libraries,
# and should only be changed when absolutely necessary
# (such as in the case of generated code).
#
# rustenv (optional)
# A list of environment variables that will be set when running the rust
# compiler. These can be accessed at compile time with
# [`std::env!`](https://doc.rust-lang.org/stable/std/macro.env.html)
#
# output_dir (optional)
# Directory that the resulting macro should be placed in.
# See: `gn help output_dir`
#
# disable_rbe (optional)
# Set to true to force this target to build locally, overriding the global
# `rust_rbe_enable`.
#
# disable_clippy (optional)
# Don't run clippy on this target.
#
# original_target_name (optional)
# The name of the target as it appears in the BUILD file. Enables tooling
# to find the template invocation in a BUILD file where this target was defined.
#
# Example of usage:
#
# rustc_macro("foo") {
# deps = [
# "//garnet/public/rust/bar",
# "//third_party/rust_crates:serde",
# "//third_party/rust_crates:slab",
# ]
# sources = [ "src/lib.rs" ]
# }
template("rustc_macro") {
# Compiling procedural macros is... a bit awkward.
#
# Even though they're provided to crates that use them as if they were normal
# external crates, they're actually '.so'/'.dylib's that are compiled for the host machine
# and then linked into the compiler, so they and all their dependencies should
# be built for the host target.
#
# Once this is done, the resulting artifacts are copied into the Fuchsia target
# directories to act as if they had been built for Fuchsia. In order to avoid
# conflicts, the outputs of the original (host) artifact are built with a
# `_proc_macro` suffix added onto the end, which is removed when they're copied
# into the final target directory.
forward_variables_from(invoker, [ "visibility" ])
proc_macro_target = "${target_name}_proc_macro"
if (defined(invoker.original_target_name)) {
_original_target_name = invoker.original_target_name
} else {
_original_target_name = target_name
}
not_needed([ "_original_target_name" ])
assert(!(defined(invoker.output_name) && defined(invoker.name)),
"Only one of output_name and name may be specified.")
# The 'is_host' var is true in situations that we don't want, such as
# sanitizers and cross-compiling for _other_ hosts.
#
# We only want this to be run in _this_ machine's host_toolchain, and then
# only in its base variant.
# This confirms that this is running on _this_ machine's host_toolchain.
in_host_compiler_toolchain = current_toolchain == host_toolchain
# This confirms that it's also running on the base variant of the host_toolchain.
in_host_base_variant =
in_host_compiler_toolchain && current_toolchain == toolchain_variant.base
# The actual host-target build of the proc macro crate.
if (in_host_base_variant) {
package_name = target_name
if (defined(invoker.output_name)) {
package_name = invoker.output_name
} else if (defined(invoker.name)) {
package_name = invoker.name
}
crate_name = string_replace(package_name, "-", "_")
if (!defined(invoker.source_root)) {
source_root = "src/lib.rs"
} else {
source_root = invoker.source_root
}
rustc_artifact(proc_macro_target) {
target_type = "rust_proc_macro"
configs = []
configs = invoker.configs
not_needed(invoker,
[
"version",
"non_rust_deps",
"force_opt",
])
crate_root = source_root
clippy_crate_type = "proc-macro"
pass_through = {
forward_variables_from(invoker,
[
"data_deps",
"output_dir",
])
output_name = crate_name
}
original_target_name = _original_target_name
forward_variables_from(invoker,
[
"disable_clippy",
"edition",
"enforce_source_listing",
"inputs",
"rustenv",
"sources",
"testonly",
])
deps = []
if (defined(invoker.deps)) {
deps += invoker.deps
}
# TODO(https://fxbug.dev/43781) remove "non_rust_deps"
if (defined(invoker.non_rust_deps)) {
deps += invoker.non_rust_deps
}
}
} else {
not_needed(invoker, "*")
}
# If "with_unit_tests" is set to true, generate an additional rust test
# target. Since the parent rule is used to compile macros, which only run on
# the host, only run the test code for the macros on the host.
# TODO(https://fxbug.dev/72931): accept a string.
if (defined(invoker.with_unit_tests) && invoker.with_unit_tests) {
if (in_host_compiler_toolchain) {
rustc_test("${target_name}_test") {
name = target_name
if (defined(invoker.name)) {
name = invoker.name + "_test"
}
original_target_name = _original_target_name
forward_variables_from(invoker, "*", [ "name" ])
configs += [ "//build/config/rust:proc_macro_test" ]
}
} else {
# For convenience, create a forwarding target that points to the on-host
# test target. This allows developers to list "${target_name}_test" in a
# test group instead of "${target_name}_test($host_toolchain)" to include
# the test target generated for this rule.
group("${target_name}_test") {
public_deps = [ ":${target_name}($host_toolchain)" ]
testonly = true
}
}
}
# proc_macros are loadable modules that are used by the rustc compiler itself,
# and as such, need to be compiled in the _base_ (non-sanitizer) variant of
# host toolchain.
#
# The following creates a set of dependencies through groups that
# link from the current toolchain to the base toolchain of the host_toolchain
# variant:
#
# target_name($current_toolchain) // omitted if already in host.
# |- target_name($host_toolchain)
# |- proc_macro_target($host_toolchain_base)
# If not in _this_ machine's host_toolchain, switch to it.
if (!in_host_compiler_toolchain) {
group(target_name) {
public_deps = [ ":${target_name}($host_toolchain)" ]
}
# the proc_macro_target isn't used.
not_needed([ "proc_macro_target" ])
} else {
# now in the proper host_toolchain, have the group depend on the base of the host
# toolchain's variant
group(target_name) {
public_deps = [ ":${proc_macro_target}(${toolchain_variant.base})" ]
}
}
}