1# Copyright 2021 The Chromium Authors 2# Use of this source code is governed by a BSD-style license that can be 3# found in the LICENSE file. 4 5import("//build/rust/rust_executable.gni") 6import("//build/rust/rust_macro.gni") 7import("//build/rust/rust_static_library.gni") 8 9# This template allows for building Cargo crates within gn. 10# 11# It is intended for use with pre-existing (third party) code and 12# is none too efficient. (It will stall the build pipeline whilst 13# it runs build scripts to work out what flags are needed). First 14# party code should directly use first-class gn targets, such as 15# //build/rust/rust_static_library.gni or similar. 16# 17# Because it's intended for third-party code, it automatically 18# defaults to //build/config/compiler:no_chromium_code which 19# suppresses some warnings. If you *do* use this for first party 20# code, you should remove that config and add the equivalent 21# //build/config/compiler:chromium_code config. 22# 23# Arguments: 24# sources 25# crate_root 26# deps 27# aliased_deps 28# features 29# build_native_rust_unit_tests 30# edition 31# crate_name 32# All just as in rust_static_library.gni 33# library_configs/executable_configs 34# All just as in rust_target.gni 35# 36# epoch (optional) 37# The major version of the library, which is used to differentiate between 38# multiple versions of the same library name. This includes all leading 0s 39# and the first non-zero value in the crate's version. This should be left 40# as the default, which is "0", for first-party code unless there are 41# multiple versions of a crate present. For third-party code, the version 42# epoch (matching the directory it is found in) should be specified. 43# 44# Examples: 45# 1.0.2 => epoch = "1" 46# 4.2.0 => epoch = "4" 47# 0.2.7 => epoch = "0.2" 48# 0.0.3 => epoch = "0.0.3" 49# 50# dev_deps 51# Same meaning as test_deps in rust_static_library.gni, but called 52# dev_deps to match Cargo.toml better. 53# 54# build_root (optional) 55# Filename of build.rs build script. 56# 57# build_deps (optional) 58# Build script dependencies 59# 60# build_sources (optional) 61# List of sources for build script. Must be specified if 62# build_root is specified. 63# 64# build_script_outputs (optional) 65# List of .rs files generated by the build script, if any. 66# Fine to leave undefined even if you have a build script. 67# This doesn't directly correspond to any Cargo variable, 68# but unfortunately is necessary for gn to build its dependency 69# trees automatically. 70# Many build scripts just output --cfg directives, in which case 71# no source code is generated and this can remain empty. 72# 73# build_script_inputs (optional) 74# If the build script reads any files generated by build_deps, 75# as opposed to merely linking against them, add a list of such 76# files here. Again, this doesn't correspond to a Cargo variable 77# but is necessary for gn. 78# 79# native_libs (optional) 80# Paths to library files that need to be in the linking search path when 81# depending on the crate's library, as it links against them via #[link] 82# directives. 83# 84# crate_type "bin", "proc-macro" or "rlib" (optional) 85# Whether to build an executable. The default is "rlib". 86# At present others are not supported. 87# 88# cargo_pkg_authors 89# cargo_pkg_version 90# cargo_pkg_name 91# cargo_pkg_description 92# Strings as found within 'version' and similar fields within Cargo.toml. 93# Converted to environment variables passed to rustc, in case the crate 94# uses clap `crate_version!` or `crate_authors!` macros (fairly common in 95# command line tool help) 96 97template("cargo_crate") { 98 _orig_target_name = target_name 99 100 _crate_name = _orig_target_name 101 if (defined(invoker.crate_name)) { 102 _crate_name = invoker.crate_name 103 } 104 105 # Construct metadata from the crate epoch or an explicitly provided metadata 106 # field. 107 _rustc_metadata = "" 108 if (defined(invoker.rustc_metadata)) { 109 _rustc_metadata = invoker.rustc_metadata 110 } else if (defined(invoker.epoch)) { 111 _rustc_metadata = "${_crate_name}-${invoker.epoch}" 112 } 113 114 # Executables need to have unique names. Work out a prefix. 115 if (defined(invoker.build_root)) { 116 _epochlabel = "vunknown" 117 if (defined(invoker.epoch)) { 118 _tempepoch = string_replace(invoker.epoch, ".", "_") 119 _epochlabel = "v${_tempepoch}" 120 } 121 122 # This name includes the target name to ensure it's unique for each possible 123 # build target in the same BUILD.gn file. 124 _build_script_name = 125 "${_crate_name}_${target_name}_${_epochlabel}_build_script" 126 127 # Where the OUT_DIR will point when running the build script exe, and 128 # compiling the crate library/binaries. This directory must include the 129 # target name to avoid collisions between multiple GN targets that exist 130 # in the same BUILD.gn. 131 _build_script_env_out_dir = "$target_gen_dir/$target_name" 132 } 133 134 _rustenv = [] 135 if (defined(invoker.rustenv)) { 136 _rustenv = invoker.rustenv 137 } 138 if (defined(invoker.cargo_pkg_authors)) { 139 _rustenv += [ "CARGO_PKG_AUTHORS=${invoker.cargo_pkg_authors}" ] 140 } 141 if (defined(invoker.cargo_pkg_version)) { 142 _rustenv += [ "CARGO_PKG_VERSION=${invoker.cargo_pkg_version}" ] 143 } 144 if (defined(invoker.cargo_pkg_name)) { 145 _rustenv += [ "CARGO_PKG_NAME=${invoker.cargo_pkg_name}" ] 146 } 147 if (defined(invoker.cargo_pkg_description)) { 148 _rustenv += [ "CARGO_PKG_DESCRIPTION=${invoker.cargo_pkg_description}" ] 149 } 150 151 # Try to determine the CARGO_MANIFEST_DIR, preferring the directory 152 # with build.rs and otherwise assuming that the target contains a 153 # `crate/` subdirectory. 154 if (defined(invoker.build_root)) { 155 manifest_dir = "." 156 } else { 157 build_gn_dir = get_label_info(target_name, "dir") 158 manifest_dir = rebase_path(build_gn_dir + "/crate", root_build_dir) 159 } 160 _rustenv += [ "CARGO_MANIFEST_DIR=${manifest_dir}" ] 161 162 # cargo_crate() should set library_configs, executable_configs, 163 # proc_macro_configs. Not configs. 164 assert(!defined(invoker.configs)) 165 166 # Work out what we're building. 167 _crate_type = "rlib" 168 if (defined(invoker.crate_type)) { 169 _crate_type = invoker.crate_type 170 } 171 if (_crate_type == "cdylib") { 172 # Crates are rarely cdylibs. The example encountered so far aims 173 # to expose a C API to other code. In a Chromium context, we don't 174 # want to build that as a dylib for a couple of reasons: 175 # * rust_shared_library does not work on Mac. rustc does not know 176 # how to export the __llvm_profile_raw_version symbol. 177 # * even if it did work, this might require us to distribute extra 178 # binaries (.so/.dylib etc.) 179 # For the only case we've had so far, it makes more sense to build 180 # the code as a static library which we can then link into downstream 181 # binaries. 182 _crate_type = "rlib" 183 } 184 if (_crate_type == "bin") { 185 _target_type = "rust_executable" 186 assert(!defined(invoker.epoch)) 187 if (defined(invoker.executable_configs)) { 188 _configs = invoker.executable_configs 189 } 190 } else if (_crate_type == "proc-macro") { 191 _target_type = "rust_macro" 192 if (defined(invoker.proc_macro_configs)) { 193 _configs = invoker.proc_macro_configs 194 } 195 } else { 196 assert(_crate_type == "rlib") 197 _target_type = "rust_static_library" 198 if (defined(invoker.library_configs)) { 199 _configs = invoker.library_configs 200 } 201 } 202 203 if (defined(invoker.output_name)) { 204 _output_name = invoker.output_name 205 } else if (_crate_type != "bin") { 206 # Note that file names of libraries must start with the crate name in 207 # order for the compiler to find transitive dependencies in the 208 # directory search paths (since they are not all explicitly specified). 209 # 210 # For bin targets, we expect the target name to be unique, and the name 211 # of the exe should not add magic stuff to it. And bin crates can not be 212 # transitive dependencies. 213 _output_name = "${_crate_name}_${_orig_target_name}" 214 } 215 216 _testonly = false 217 if (defined(invoker.testonly)) { 218 _testonly = invoker.testonly 219 } 220 221 if (defined(invoker.native_libs)) { 222 _native_libs_action = "copy_${target_name}_native_libs" 223 _native_libs_config = "config_${target_name}_native_libs" 224 _native_libs_dir = 225 "${root_out_dir}/rustlib/${_crate_name}_${target_name}_${_epochlabel}" 226 227 copy(_native_libs_action) { 228 testonly = _testonly 229 visibility = [ ":$target_name" ] 230 sources = invoker.native_libs 231 outputs = [ "${_native_libs_dir}/{{source_file_part}}" ] 232 } 233 config(_native_libs_config) { 234 lib_dirs = [ "${_native_libs_dir}" ] 235 } 236 } 237 238 # The main target, either a Rust source set or an executable. 239 target(_target_type, target_name) { 240 forward_variables_from(invoker, 241 "*", 242 TESTONLY_AND_VISIBILITY + [ 243 "build_root", 244 "build_deps", 245 "build_sources", 246 "build_script_inputs", 247 "build_script_outputs", 248 "epoch", 249 "unit_test_target", 250 "configs", 251 "executable_configs", 252 "library_configs", 253 "proc_macro_configs", 254 "rustenv", 255 "dev_deps", 256 "native_libs_dir", 257 ]) 258 259 testonly = _testonly 260 if (defined(invoker.visibility)) { 261 visibility = invoker.visibility 262 } 263 if (defined(crate_type) && crate_type == "cdylib") { 264 # See comments above about cdylib. 265 crate_type = "rlib" 266 } 267 crate_name = _crate_name 268 269 if (defined(_output_name)) { 270 output_name = _output_name 271 } 272 273 # Don't import the `chromium` crate into third-party code. 274 no_chromium_prelude = true 275 276 rustc_metadata = _rustc_metadata 277 278 # TODO(crbug.com/40259764): don't default to true. This requires changes to 279 # third_party.toml and gnrt when generating third-party build targets. 280 allow_unsafe = true 281 282 configs = [] 283 if (defined(_configs)) { 284 configs += _configs 285 } 286 287 if (_crate_type == "rlib") { 288 # Forward configs for unit tests. 289 if (defined(invoker.executable_configs)) { 290 executable_configs = invoker.executable_configs 291 } 292 } 293 294 if (!defined(rustflags)) { 295 rustflags = [] 296 } 297 rustenv = _rustenv 298 299 if (!defined(build_native_rust_unit_tests)) { 300 build_native_rust_unit_tests = _crate_type != "proc-macro" 301 } 302 if (build_native_rust_unit_tests) { 303 # Unit tests in a proc-macro crate type don't make sense, you can't 304 # compile executables against the `proc_macro` crate. 305 assert(_crate_type != "proc-macro") 306 } 307 308 # The unit tests for each target, if generated, should be unique as well. 309 # a) It needs to be unique even if multiple build targets have the same 310 # `crate_name`, but different target names. 311 # b) It needs to be unique even if multiple build targets have the same 312 # `crate_name` and target name, but different epochs. 313 _unit_test_unique_target_name = "" 314 if (_crate_name != _orig_target_name) { 315 _unit_test_unique_target_name = "${_orig_target_name}_" 316 } 317 _unit_test_unique_epoch = "" 318 if (defined(invoker.epoch)) { 319 _epoch_str = string_replace(invoker.epoch, ".", "_") 320 _unit_test_unique_epoch = "v${_epoch_str}_" 321 } 322 if (defined(output_dir) && output_dir != "") { 323 unit_test_output_dir = output_dir 324 } 325 unit_test_target = "${_unit_test_unique_target_name}${_crate_name}_${_unit_test_unique_epoch}unittests" 326 327 if ((!defined(output_dir) || output_dir == "") && _crate_type == "rlib") { 328 # Cargo crate rlibs can be compiled differently for tests, and must not 329 # collide with the production outputs. This does *not* override the 330 # unit_test_output_dir, which is set above, as that target is not an rlib. 331 output_dir = "$target_out_dir/$_orig_target_name" 332 } 333 334 if (defined(invoker.dev_deps)) { 335 test_deps = invoker.dev_deps 336 } 337 338 if (defined(invoker.build_root)) { 339 # Uh-oh, we have a build script 340 if (!defined(deps)) { 341 deps = [] 342 } 343 if (!defined(sources)) { 344 sources = [] 345 } 346 if (!defined(inputs)) { 347 inputs = [] 348 } 349 350 # This... is a bit weird. We generate a file called cargo_flags.rs which 351 # does not actually contain Rust code, but instead some flags to add 352 # to the rustc command line. We need it to end in a .rs extension so that 353 # we can include it in the 'sources' line and thus have dependency 354 # calculation done correctly. data_deps won't work because targets don't 355 # require them to be present until runtime. 356 flags_file = "$_build_script_env_out_dir/cargo_flags.rs" 357 rustflags += [ "@" + rebase_path(flags_file, root_build_dir) ] 358 sources += [ flags_file ] 359 if (defined(invoker.build_script_outputs)) { 360 # Build scripts may output arbitrary files. They are usually included in 361 # the main Rust target using include! or include_str! and therefore the 362 # filename may be .rs or may be arbitrary. We want to educate ninja 363 # about the dependency either way. 364 foreach(extra_source, 365 filter_include(invoker.build_script_outputs, [ "*.rs" ])) { 366 sources += [ "$_build_script_env_out_dir/$extra_source" ] 367 } 368 foreach(extra_source, 369 filter_exclude(invoker.build_script_outputs, [ "*.rs" ])) { 370 inputs += [ "$_build_script_env_out_dir/$extra_source" ] 371 } 372 } 373 deps += [ ":${_build_script_name}_output" ] 374 if (defined(_native_libs_action)) { 375 deps += [ ":${_native_libs_action}" ] 376 configs += [ ":${_native_libs_config}" ] 377 } 378 } 379 } 380 381 if (defined(invoker.build_root)) { 382 # Extra targets required to make build script work 383 action("${_build_script_name}_output") { 384 script = rebase_path("//build/rust/run_build_script.py") 385 build_script_target = ":${_build_script_name}($rust_macro_toolchain)" 386 deps = [ build_script_target ] 387 testonly = _testonly 388 if (defined(invoker.visibility)) { 389 visibility = invoker.visibility 390 } 391 392 # The build script may be built with a different toolchain when 393 # cross-compiling (the host toolchain) so we must find the path relative 394 # to that. 395 _build_script_root_out_dir = 396 get_label_info(build_script_target, "root_out_dir") 397 _build_script_exe = "$_build_script_root_out_dir/$_build_script_name" 398 399 # The executable is always built with the `rust_macro_toolchain` which 400 # targets the `host_os`. The rule here is on the `target_toolchain` which 401 # can be different (e.g. compiling on Linux, targeting Windows). 402 if (host_os == "win") { 403 _build_script_exe = "${_build_script_exe}.exe" 404 } 405 406 _flags_file = "$_build_script_env_out_dir/cargo_flags.rs" 407 408 inputs = [ _build_script_exe ] 409 outputs = [ _flags_file ] 410 args = [ 411 "--build-script", 412 rebase_path(_build_script_exe, root_build_dir), 413 "--output", 414 rebase_path(_flags_file, root_build_dir), 415 "--rust-prefix", 416 rebase_path("${rust_sysroot}/bin", root_build_dir), 417 "--out-dir", 418 rebase_path(_build_script_env_out_dir, root_build_dir), 419 "--src-dir", 420 rebase_path(get_path_info(invoker.build_root, "dir"), root_build_dir), 421 ] 422 if (defined(rust_abi_target) && rust_abi_target != "") { 423 args += [ 424 "--target", 425 rust_abi_target, 426 ] 427 } 428 if (defined(invoker.features)) { 429 args += [ "--features" ] 430 args += invoker.features 431 } 432 if (defined(invoker.build_script_outputs)) { 433 args += [ "--generated-files" ] 434 args += invoker.build_script_outputs 435 foreach(generated_file, invoker.build_script_outputs) { 436 outputs += [ "$_build_script_env_out_dir/$generated_file" ] 437 } 438 } 439 if (_rustenv != []) { 440 args += [ "--env" ] 441 args += _rustenv 442 } 443 if (defined(invoker.build_script_inputs)) { 444 inputs += invoker.build_script_inputs 445 } 446 } 447 448 if (toolchain_for_rust_host_build_tools) { 449 # The build script is only available to be built on the host, and we use 450 # the rust_macro_toolchain for it to unblock building them while the 451 # Chromium stdlib is still being compiled. 452 rust_executable(_build_script_name) { 453 crate_name = _build_script_name 454 sources = invoker.build_sources 455 crate_root = invoker.build_root 456 testonly = _testonly 457 if (defined(invoker.visibility)) { 458 visibility = invoker.visibility 459 } 460 if (defined(invoker.build_deps)) { 461 deps = invoker.build_deps 462 } 463 if (defined(invoker.build_script_inputs)) { 464 inputs = invoker.build_script_inputs 465 } 466 467 # Don't import the `chromium` crate into third-party code. 468 no_chromium_prelude = true 469 470 # The ${_build_script_name}_output target looks for the exe in this 471 # location. Due to how the Windows component build works, this has to 472 # be $root_out_dir for all EXEs. In component build, C++ links to the 473 # CRT as a DLL, and if Rust does not match, we can't link mixed target 474 # Rust EXE/DLLs, as the headers in C++ said something different than 475 # what Rust links. Since the CRT DLL is placed in the $root_out_dir, 476 # an EXE can find it if it's also placed in that dir. 477 output_dir = root_out_dir 478 rustenv = _rustenv 479 forward_variables_from(invoker, 480 [ 481 "features", 482 "edition", 483 "rustflags", 484 ]) 485 configs -= [ 486 "//build/config/compiler:chromium_code", 487 488 # Avoid generating profiling data for build scripts. 489 # 490 # TODO(crbug.com/40261306): determine for sure whether to remove this 491 # config. I'm not sure of the overlap between PGO instrumentation and 492 # code coverage instrumentation, but we definitely don't want build 493 # script coverage for PGO, while we might for test coverage metrics. 494 # 495 # If we do include build script output in test metrics, it could be 496 # misleading: exercising some code from a build script doesn't give us 497 # the same signal as an actual test. 498 "//build/config/coverage:default_coverage", 499 ] 500 configs += [ "//build/config/compiler:no_chromium_code" ] 501 } 502 } else { 503 not_needed(invoker, 504 [ 505 "build_sources", 506 "build_deps", 507 "build_root", 508 "build_script_inputs", 509 "build_script_outputs", 510 ]) 511 } 512 } else { 513 not_needed([ 514 "_name_specific_output_dir", 515 "_orig_target_name", 516 ]) 517 } 518} 519 520set_defaults("cargo_crate") { 521 library_configs = default_compiler_configs 522 executable_configs = default_executable_configs 523 proc_macro_configs = default_rust_proc_macro_configs 524} 525