build/config/rust/BUILD.gn - fuchsia - Git at Google

 # Copyright 2021 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.

 #  ________  _________  ________  ________
 # |\   ____\|\___   ___\\   __  \|\   __  \
 # \ \  \___|\|___ \  \_\ \  \|\  \ \  \|\  \
 #  \ \_____  \   \ \  \ \ \  \\\  \ \   ____\
 #   \|____|\  \   \ \  \ \ \  \\\  \ \  \___|
 #     ____\_\  \   \ \__\ \ \_______\ \__\
 #    |\_________\   \|__|  \|_______|\|__|
 #    \|_________|
 #
 # Here to enable an unstable feature? All unstable features require special
 # approval because they create risk and may have stable alternatives that better
 # fit our needs. See the "Unstable features" section for more information.

 import("//build/images/filesystem_limits.gni")
 import("//build/rust/config.gni")
 import("//build/toolchain/rbe.gni")

 declare_args() {
   # Controls whether the rust compiler uses v0 symbol mangling scheme
   # (see https://github.com/rust-lang/rfcs/blob/HEAD/text/2603-rust-symbol-name-mangling-v0.md).
   # The v0 symbol mangling scheme requires upstream LLVM support when demangling,
   # so it is not on by default.
   # TODO(fxbug.dev/57302): Enable v0 mangling by default.
   rust_v0_symbol_mangling = false

   # Enable incremental rust compilation. Takes a path to the directory to use
   # as the cache.
   rust_incremental = ""
 }

 # Defines a Rust cfg flag with the value of the rust_panic build arg.
 # Useful for changing behavior of code based on panic behavior.
 config("panic_cfg") {
   rustflags = [ "--cfg=rust_panic=\"${rust_panic}\"" ]
 }

 # Turns on the rust compilation analysis generator. This will produce a
 # directory $OUT/save-analysis-temp, which will dump all the source analysis
 # that the compiler collected while analyzing the source.  This config is
 # included conditionally, see //build/config/BUILDCONFIG.gn for details.
 config("analysis") {
   rustflags = [ "-Zsave-analysis" ]
 }

 config("edition_2021") {
   rustflags = [ "--edition=2021" ]
 }

 config("edition_2018") {
   rustflags = [ "--edition=2018" ]
 }

 config("edition_2015") {
   rustflags = [ "--edition=2015" ]
 }

 config("no_features") {
   rustflags = [ "-Zallow-features=" ]
 }

 config("incremental") {
   if (rust_incremental != "") {
     rustflags = [ "-Cincremental=" + rust_incremental ]
   }
 }

 config("one_codegen_unit") {
   # Disable codegen parallelism.
   # Trades incremental rebuild speed for smaller code size.
   # See: fxbug.dev/74435, fxbug.dev/80514
   if (rust_incremental == "") {
     rustflags = [ "-Ccodegen-units=1" ]
   }
 }

 config("codegen_units_16") {
   # Enable default codegen parallelism (rustc default).
   # This will increase code size over `:one_codegen_unit` above.
   #
   # Used without any lto option, this will also enable thin-local lto.
   # https://doc.rust-lang.org/rustc/codegen-options/index.html#lto
   if (rust_incremental == "") {
     rustflags = [ "-Ccodegen-units=16" ]
   }
 }

 config("lto_disabled") {
   # Fully disable lto.
   #
   # This is the default when -Ccodegen_units=1 or when optimizations are off
   # (-Copt-level=0)
   rustflags = [ "-Clto=off" ]
 }

 config("lto_thin") {
   # Enable "thin" lto across all crates being linked
   rustflags = [ "-Clto=thin" ]
 }

 # Best practices for Rust binaries that go into size-constrained bootfs.
 config("bootfs") {
   # Optimize for size.
   # TODO(fxbug.dev/63313): use "z" when resolved.
   rustflags = [ "-Copt-level=s" ]

   if (is_debug &&  # Debug builds produce large Rust binaries
       max_fuchsia_zbi_size > 0) {  # So large they might not fit in the ZBI
     # Force ThinLTO to squeeze Rust binaries further.
     # See: fxbug.dev/80514
     # See: fxbug.dev/91325
     configs = [ "//build/config/lto:thinlto" ]
   }

   # Can't dynamically link libstd and libtest for ZBI binaries.
   # TODO(fxbug.dev/83081): reconsider this.
   rustflags += [ "-Cprefer-dynamic=no" ]
 }

 config("proc_macro_test") {
   rustflags = [
     "--extern",
     "proc_macro",
   ]
 }

 config("2018_idioms") {
   rustflags = [ "-Wrust-2018-idioms" ]
 }

 config("target") {
   rustflags = [
     "--target",
     rust_target,
     "--cap-lints=$rust_cap_lints",
   ]
 }

 config("panic_abort") {
   rustflags = [
     "-Cpanic=abort",
     "-Cforce-unwind-tables=yes",
     "-Zpanic_abort_tests",
   ]
 }

 config("v0_symbol_mangling") {
   if (rust_v0_symbol_mangling) {
     rustflags = [ "-Csymbol-mangling-version=v0" ]
   }
 }

 config("allow_unknown_lints") {
   rustflags = [ "-Aunknown-lints" ]
 }

 # TODO(fxbug.dev/67118) remove this allowance
 config("allow_redundant_semicolons") {
   rustflags = [ "-Aredundant-semicolons" ]
 }

 # TODO(fxbug.dev/69442) remove this allowance
 config("allow_legacy_derive_helpers") {
   rustflags = [ "-Alegacy-derive-helpers" ]
 }

 config("deny_unused_results") {
   rustflags = [ "-Dunused_results" ]
 }

 config("allow_unused_results") {
   rustflags = [ "-Aunused_results" ]

   # This visibility list allows for targets to opt out of allowing unused results.
   #
   # There is currently no platform mandate to adopt the unused_results lint and it's opt-in for
   # developers that want to use it. See https://fxbug.dev/73468 for more context.
   #
   # To adopt the lint, add the following to your rust target:
   #   configs -= ["//build/config/rust:allow_unused_results"]
   # The visibility list below can be used to enforce the list on certain areas of the tree while
   # we evaluate wider adoption.
   #
   # To update this list run:
   # $ scripts/gn/gen_visibility_globs.py \
   #    --all=//build/config/rust:deny_unused_results \
   #    --allow=//build/config/rust:allow_unused_results \
   #    --ignore-suffix=-rustc,_banjo_rust
   visibility = [
     "//build/*",
     "//examples/*",
     "//garnet/*",
     "//sdk/*",
     "//src/bringup/*",
     "//src/camera/*",
     "//src/cobalt/*",
     "//src/connectivity/bluetooth/lib/bt-a2dp:*",
     "//src/connectivity/location/*",
     "//src/connectivity/lowpan/*",
     "//src/connectivity/network/net-cli/ffx:*",
     "//src/connectivity/network/netstack:networking_metrics_rustlib",
     "//src/connectivity/network/testing/network-test-realm/ffx:*",
     "//src/connectivity/openthread/*",
     "//src/connectivity/overnet/*",
     "//src/connectivity/ppp/*",
     "//src/connectivity/telephony/*",
     "//src/connectivity/weave/*",
     "//src/connectivity/wlan/*",
     "//src/developer/*",
     "//src/devices/*",
     "//src/diagnostics/*",
     "//src/experiences/*",
     "//src/factory/*",
     "//src/fonts/*",
     "//src/graphics/*",
     "//src/hwinfo/*",
     "//src/identity/*",
     "//src/intl/*",
     "//src/lib/*",
     "//src/media/*",
     "//src/modular/*",
     "//src/power/*",
     "//src/proc/*",
     "//src/recovery/*",
     "//src/security/*",
     "//src/session/*",
     "//src/settings/*",
     "//src/storage/*",
     "//src/sys/*",
     "//src/testing/*",
     "//src/tests/*",
     "//src/ui/*",
     "//src/virtualization/*",
     "//src/zircon/*",
     "//third_party/*",
     "//tools/*",
     "//vendor/*",
     "//zircon/*",
   ]
 }

 config("coverage") {
   rustflags = [ "-Cinstrument-coverage" ]
 }

 # TODO(fxbug.dev/94355): Eliminate or identify all sources of output dir leaks.
 # This option makes it explicit that a particular build action is sensitive
 # to the output dir path, and informs remote execution to refrain from
 # normalizing the output dir, which improves caching.
 # As a goal, we should aim to minimize the need for this config.
 config("output_dir_sensitive") {
   if (rust_rbe_enable) {
     # --remote-flag=* is a pseudo flag that is intercepted by
     # build/rbe/rustc-remote-wrapper.sh and forwarded to rewrapper (reclient).
     rustflags = [ "--remote-flag=--canonicalize_working_dir=false" ]
   }
 }

 # Unstable features
 #
 # These configs enable unstable Rust features. Configs that enable unstable
 # features must go through an approval process before they may be added. See:
 # https://fuchsia.dev/fuchsia-src/development/languages/rust/unstable#the_process
 #
 # When adding a new config, make sure to add a TODO with a link to the tracking
 # issue.

 # TODO(fxbug.dev/98399)
 config("netstack3_only_specialization_feature") {
   rustflags = [
     "-Zallow-features=min_specialization,specialization",
     "-Aincomplete-features",
   ]
 }

 # TODO(fxbug.dev/94237)
 config("allow_simd") {
   rustflags = [ "-Zallow-features=stdsimd,aarch64_target_feature" ]
 }

 # TODO(fxbug.dev/103193)
 config("allow_non_exhaustive_omitted_patterns_lint") {
   rustflags = [ "-Zallow-features=non_exhaustive_omitted_patterns_lint" ]
   visibility =
       [ "//src/connectivity/network/netstack3/core/specialize-ip-macro:*" ]
 }
	# Copyright 2021 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.

	# ________ _________ ________ ________
	# \|\ ____\\|\___ ___\\ __ \\|\ __ \
	# \ \ \___\|\\|___ \ \_\ \ \\|\ \ \ \\|\ \
	# \ \_____ \ \ \ \ \ \ \\\ \ \ ____\
	# \\|____\|\ \ \ \ \ \ \ \\\ \ \ \___\|
	# ____\_\ \ \ \__\ \ \_______\ \__\
	# \|\_________\ \\|__\| \\|_______\|\\|__\|
	# \\|_________\|
	#
	# Here to enable an unstable feature? All unstable features require special
	# approval because they create risk and may have stable alternatives that better
	# fit our needs. See the "Unstable features" section for more information.

	import("//build/images/filesystem_limits.gni")
	import("//build/rust/config.gni")
	import("//build/toolchain/rbe.gni")

	declare_args() {
	# Controls whether the rust compiler uses v0 symbol mangling scheme
	# (see https://github.com/rust-lang/rfcs/blob/HEAD/text/2603-rust-symbol-name-mangling-v0.md).
	# The v0 symbol mangling scheme requires upstream LLVM support when demangling,
	# so it is not on by default.
	# TODO(fxbug.dev/57302): Enable v0 mangling by default.
	rust_v0_symbol_mangling = false

	# Enable incremental rust compilation. Takes a path to the directory to use
	# as the cache.
	rust_incremental = ""
	}

	# Defines a Rust cfg flag with the value of the rust_panic build arg.
	# Useful for changing behavior of code based on panic behavior.
	config("panic_cfg") {
	rustflags = [ "--cfg=rust_panic=\"${rust_panic}\"" ]
	}

	# Turns on the rust compilation analysis generator. This will produce a
	# directory $OUT/save-analysis-temp, which will dump all the source analysis
	# that the compiler collected while analyzing the source. This config is
	# included conditionally, see //build/config/BUILDCONFIG.gn for details.
	config("analysis") {
	rustflags = [ "-Zsave-analysis" ]
	}

	config("edition_2021") {
	rustflags = [ "--edition=2021" ]
	}

	config("edition_2018") {
	rustflags = [ "--edition=2018" ]
	}

	config("edition_2015") {
	rustflags = [ "--edition=2015" ]
	}

	config("no_features") {
	rustflags = [ "-Zallow-features=" ]
	}

	config("incremental") {
	if (rust_incremental != "") {
	rustflags = [ "-Cincremental=" + rust_incremental ]
	}
	}

	config("one_codegen_unit") {
	# Disable codegen parallelism.
	# Trades incremental rebuild speed for smaller code size.
	# See: fxbug.dev/74435, fxbug.dev/80514
	if (rust_incremental == "") {
	rustflags = [ "-Ccodegen-units=1" ]
	}
	}

	config("codegen_units_16") {
	# Enable default codegen parallelism (rustc default).
	# This will increase code size over `:one_codegen_unit` above.
	#
	# Used without any lto option, this will also enable thin-local lto.
	# https://doc.rust-lang.org/rustc/codegen-options/index.html#lto
	if (rust_incremental == "") {
	rustflags = [ "-Ccodegen-units=16" ]
	}
	}

	config("lto_disabled") {
	# Fully disable lto.
	#
	# This is the default when -Ccodegen_units=1 or when optimizations are off
	# (-Copt-level=0)
	rustflags = [ "-Clto=off" ]
	}

	config("lto_thin") {
	# Enable "thin" lto across all crates being linked
	rustflags = [ "-Clto=thin" ]
	}

	# Best practices for Rust binaries that go into size-constrained bootfs.
	config("bootfs") {
	# Optimize for size.
	# TODO(fxbug.dev/63313): use "z" when resolved.
	rustflags = [ "-Copt-level=s" ]

	if (is_debug && # Debug builds produce large Rust binaries
	max_fuchsia_zbi_size > 0) { # So large they might not fit in the ZBI
	# Force ThinLTO to squeeze Rust binaries further.
	# See: fxbug.dev/80514
	# See: fxbug.dev/91325
	configs = [ "//build/config/lto:thinlto" ]
	}

	# Can't dynamically link libstd and libtest for ZBI binaries.
	# TODO(fxbug.dev/83081): reconsider this.
	rustflags += [ "-Cprefer-dynamic=no" ]
	}

	config("proc_macro_test") {
	rustflags = [
	"--extern",
	"proc_macro",
	]
	}

	config("2018_idioms") {
	rustflags = [ "-Wrust-2018-idioms" ]
	}

	config("target") {
	rustflags = [
	"--target",
	rust_target,
	"--cap-lints=$rust_cap_lints",
	]
	}

	config("panic_abort") {
	rustflags = [
	"-Cpanic=abort",
	"-Cforce-unwind-tables=yes",
	"-Zpanic_abort_tests",
	]
	}

	config("v0_symbol_mangling") {
	if (rust_v0_symbol_mangling) {
	rustflags = [ "-Csymbol-mangling-version=v0" ]
	}
	}

	config("allow_unknown_lints") {
	rustflags = [ "-Aunknown-lints" ]
	}

	# TODO(fxbug.dev/67118) remove this allowance
	config("allow_redundant_semicolons") {
	rustflags = [ "-Aredundant-semicolons" ]
	}

	# TODO(fxbug.dev/69442) remove this allowance
	config("allow_legacy_derive_helpers") {
	rustflags = [ "-Alegacy-derive-helpers" ]
	}

	config("deny_unused_results") {
	rustflags = [ "-Dunused_results" ]
	}

	config("allow_unused_results") {
	rustflags = [ "-Aunused_results" ]

	# This visibility list allows for targets to opt out of allowing unused results.
	#
	# There is currently no platform mandate to adopt the unused_results lint and it's opt-in for
	# developers that want to use it. See https://fxbug.dev/73468 for more context.
	#
	# To adopt the lint, add the following to your rust target:
	# configs -= ["//build/config/rust:allow_unused_results"]
	# The visibility list below can be used to enforce the list on certain areas of the tree while
	# we evaluate wider adoption.
	#
	# To update this list run:
	# $ scripts/gn/gen_visibility_globs.py \
	# --all=//build/config/rust:deny_unused_results \
	# --allow=//build/config/rust:allow_unused_results \
	# --ignore-suffix=-rustc,_banjo_rust
	visibility = [
	"//build/*",
	"//examples/*",
	"//garnet/*",
	"//sdk/*",
	"//src/bringup/*",
	"//src/camera/*",
	"//src/cobalt/*",
	"//src/connectivity/bluetooth/lib/bt-a2dp:*",
	"//src/connectivity/location/*",
	"//src/connectivity/lowpan/*",
	"//src/connectivity/network/net-cli/ffx:*",
	"//src/connectivity/network/netstack:networking_metrics_rustlib",
	"//src/connectivity/network/testing/network-test-realm/ffx:*",
	"//src/connectivity/openthread/*",
	"//src/connectivity/overnet/*",
	"//src/connectivity/ppp/*",
	"//src/connectivity/telephony/*",
	"//src/connectivity/weave/*",
	"//src/connectivity/wlan/*",
	"//src/developer/*",
	"//src/devices/*",
	"//src/diagnostics/*",
	"//src/experiences/*",
	"//src/factory/*",
	"//src/fonts/*",
	"//src/graphics/*",
	"//src/hwinfo/*",
	"//src/identity/*",
	"//src/intl/*",
	"//src/lib/*",
	"//src/media/*",
	"//src/modular/*",
	"//src/power/*",
	"//src/proc/*",
	"//src/recovery/*",
	"//src/security/*",
	"//src/session/*",
	"//src/settings/*",
	"//src/storage/*",
	"//src/sys/*",
	"//src/testing/*",
	"//src/tests/*",
	"//src/ui/*",
	"//src/virtualization/*",
	"//src/zircon/*",
	"//third_party/*",
	"//tools/*",
	"//vendor/*",
	"//zircon/*",
	]
	}

	config("coverage") {
	rustflags = [ "-Cinstrument-coverage" ]
	}

	# TODO(fxbug.dev/94355): Eliminate or identify all sources of output dir leaks.
	# This option makes it explicit that a particular build action is sensitive
	# to the output dir path, and informs remote execution to refrain from
	# normalizing the output dir, which improves caching.
	# As a goal, we should aim to minimize the need for this config.
	config("output_dir_sensitive") {
	if (rust_rbe_enable) {
	# --remote-flag=* is a pseudo flag that is intercepted by
	# build/rbe/rustc-remote-wrapper.sh and forwarded to rewrapper (reclient).
	rustflags = [ "--remote-flag=--canonicalize_working_dir=false" ]
	}
	}

	# Unstable features
	#
	# These configs enable unstable Rust features. Configs that enable unstable
	# features must go through an approval process before they may be added. See:
	# https://fuchsia.dev/fuchsia-src/development/languages/rust/unstable#the_process
	#
	# When adding a new config, make sure to add a TODO with a link to the tracking
	# issue.

	# TODO(fxbug.dev/98399)
	config("netstack3_only_specialization_feature") {
	rustflags = [
	"-Zallow-features=min_specialization,specialization",
	"-Aincomplete-features",
	]
	}

	# TODO(fxbug.dev/94237)
	config("allow_simd") {
	rustflags = [ "-Zallow-features=stdsimd,aarch64_target_feature" ]
	}

	# TODO(fxbug.dev/103193)
	config("allow_non_exhaustive_omitted_patterns_lint") {
	rustflags = [ "-Zallow-features=non_exhaustive_omitted_patterns_lint" ]
	visibility =
	[ "//src/connectivity/network/netstack3/core/specialize-ip-macro:*" ]
	}