1# Copyright 2023 The Pigweed Authors 2# 3# Licensed under the Apache License, Version 2.0 (the "License"); you may not 4# use this file except in compliance with the License. You may obtain a copy of 5# the License at 6# 7# https://www.apache.org/licenses/LICENSE-2.0 8# 9# Unless required by applicable law or agreed to in writing, software 10# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 11# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12# License for the specific language governing permissions and limitations under 13# the License. 14 15import("//build_overrides/pigweed.gni") 16 17import("$dir_pw_build/rust_library.gni") 18import("$dir_pw_toolchain/toolchain_args.gni") 19 20# Note: In general, prefer to import target_types.gni rather than this file. 21# 22# A wrapper for GN's built-in rust_proc_macro target, this template wraps a 23# configurable target type specified by the current toolchain to be used for all 24# pw_rust_proc_macro targets. 25# 26# Compiling procedural macros is... a bit awkward. 27# 28# Even though they're provided to crates that use them as if they were normal 29# external crates, they're actually '.so'/'.dylib's that are compiled for the 30# host machine and then linked into the compiler, so they and all their 31# dependencies should be built for the host target. 32# 33# For more information on the features provided by this template, see the full 34# docs at https://pigweed.dev/pw_build/?highlight=pw_rust_proc_macro. 35template("pw_rust_proc_macro") { 36 if (defined(pw_toolchain_SCOPE.rustc_macro_toolchain_name)) { 37 group(target_name) { 38 public_deps = 39 [ ":$target_name(${pw_toolchain_SCOPE.rustc_macro_toolchain_name})" ] 40 } 41 not_needed(invoker, "*") 42 } else if (defined(pw_toolchain_SCOPE.is_host_toolchain) && 43 pw_toolchain_SCOPE.is_host_toolchain) { 44 pw_rust_library(target_name) { 45 forward_variables_from(invoker, "*") 46 47 if (!defined(rustflags)) { 48 rustflags = [] 49 } 50 51 rustflags += [ 52 "--extern", 53 "proc_macro", 54 ] 55 underlying_target_type = "rust_proc_macro" 56 } 57 } else { 58 assert( 59 false, 60 "proc_macro target ${target_name}(${pw_toolchain_SCOPE.name}) is not " + 61 "a host target, please specify a host toolchain through " + 62 "`rustc_macro_toolchain_name` for it to be compiled.") 63 } 64} 65