build.rs (3117B)
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 5 use std::env; 6 use std::io::Write; 7 use std::path::Path; 8 use std::process::Command; 9 use std::str::{self, FromStr}; 10 11 fn main() { 12 println!("cargo:rustc-cfg=build_script_ran"); 13 let minor = match rustc_minor_version() { 14 Some(minor) => minor, 15 None => return, 16 }; 17 18 let target = env::var("TARGET").unwrap(); 19 20 if minor >= 34 { 21 println!("cargo:rustc-cfg=is_new_rustc"); 22 } else { 23 println!("cargo:rustc-cfg=is_old_rustc"); 24 } 25 26 if target.contains("android") { 27 println!("cargo:rustc-cfg=is_android"); 28 } 29 if target.contains("darwin") { 30 println!("cargo:rustc-cfg=is_mac"); 31 } 32 33 let feature_a_enabled = env::var_os("CARGO_FEATURE_MY_FEATURE_A").is_some(); 34 if feature_a_enabled { 35 println!("cargo:rustc-cfg=has_feature_a"); 36 } 37 let feature_b_enabled = env::var_os("CARGO_FEATURE_MY_FEATURE_B").is_some(); 38 if feature_b_enabled { 39 println!("cargo:rustc-cfg=has_feature_b"); 40 } 41 42 // Some tests as to whether we're properly emulating various cargo features. 43 let cargo_manifest_dir = &env::var_os("CARGO_MANIFEST_DIR").unwrap(); 44 let manifest_dir_path = Path::new(cargo_manifest_dir); 45 assert!( 46 !manifest_dir_path.is_absolute(), 47 "CARGO_MANIFEST_DIR={} should be relative path for build cache sharing.", 48 manifest_dir_path.display() 49 ); 50 assert!(manifest_dir_path.join("build.rs").exists()); 51 assert!(Path::new("build.rs").exists()); 52 assert!(Path::new(&env::var_os("OUT_DIR").unwrap()).exists()); 53 // Confirm the following env var is set, but do not attempt to validate content 54 // since the whole point is that it will differ on different platforms. 55 env::var_os("CARGO_CFG_TARGET_ARCH").unwrap(); 56 57 generate_some_code().unwrap(); 58 } 59 60 fn generate_some_code() -> std::io::Result<()> { 61 let output_dir = Path::new(&env::var_os("OUT_DIR").unwrap()).join("generated"); 62 let _ = std::fs::create_dir_all(&output_dir); 63 // Test that environment variables from .gn files are passed to build scripts 64 let preferred_number = env::var("ENV_VAR_FOR_BUILD_SCRIPT").unwrap(); 65 let mut file = std::fs::File::create(output_dir.join("generated.rs"))?; 66 write!(file, "fn run_some_generated_code() -> u32 {{ {} }}", preferred_number)?; 67 Ok(()) 68 } 69 70 fn rustc_minor_version() -> Option<u32> { 71 let rustc = match env::var_os("RUSTC") { 72 Some(rustc) => rustc, 73 None => return None, 74 }; 75 76 let output = match Command::new(rustc).arg("--version").output() { 77 Ok(output) => output, 78 Err(_) => return None, 79 }; 80 81 let version = match str::from_utf8(&output.stdout) { 82 Ok(version) => version, 83 Err(_) => return None, 84 }; 85 86 let mut pieces = version.split('.'); 87 if pieces.next() != Some("rustc 1") { 88 return None; 89 } 90 91 let next = match pieces.next() { 92 Some(next) => next, 93 None => return None, 94 }; 95 96 u32::from_str(next).ok() 97 }