Delegate TARGET identification to target-triple crate

Cargo.toml

@@ -6,7 +6,7 @@ categories = ["development-tools::testing"]
 description = "Test harness for ui tests of compiler diagnostics"
 documentation = "https://docs.rs/trybuild"
 edition = "2021"
-exclude = ["screenshots/*"]
+exclude = ["build.rs", "screenshots/*"]
 keywords = ["macros", "testing", "dev-dependencies"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/dtolnay/trybuild"
@@ -24,6 +24,7 @@ glob = "0.3"
 serde = "1.0.194"
 serde_derive = "1.0.194"
 serde_json = "1.0.110"
+target-triple = "0.1"
 termcolor = "1.0.4"
 toml = "0.8"
 

build.rs

@@ -1,24 +1,6 @@
-use std::env;
-use std::fs;
-use std::io;
-use std::path::Path;
+fn main() {
+    // Warning: build.rs is not published to crates.io.
 
-fn main() -> io::Result<()> {
     println!("cargo:rerun-if-changed=src/tests");
-
     println!("cargo:rustc-check-cfg=cfg(trybuild_no_target)");
-    println!("cargo:rustc-check-cfg=cfg(host_os, values(\"windows\"))");
-
-    let out_dir = env::var_os("OUT_DIR").unwrap();
-    let target = env::var("TARGET").unwrap();
-    let path = Path::new(&out_dir).join("target");
-    let value = format!(r#""{}""#, target.escape_debug());
-    fs::write(path, value)?;
-
-    let host = env::var_os("HOST").unwrap();
-    if let Some("windows") = host.to_str().unwrap().split('-').nth(2) {
-        println!("cargo:rustc-cfg=host_os=\"windows\"");
-    }
-
-    Ok(())
 }

src/cargo.rs

@@ -183,12 +183,6 @@ fn features(project: &Project) -> Vec<String> {
 }
 
 fn target() -> Vec<&'static str> {
-    #[cfg(not(host_os = "windows"))]
-    const TARGET: &str = include!(concat!(env!("OUT_DIR"), "/target"));
-
-    #[cfg(host_os = "windows")]
-    const TARGET: &str = include!(concat!(env!("OUT_DIR"), "\\target"));
-
     // When --target flag is passed, cargo does not pass RUSTFLAGS to rustc when
     // building proc-macro and build script even if the host and target triples
     // are the same. Therefore, if we always pass --target to cargo, tools such
@@ -205,6 +199,6 @@ fn target() -> Vec<&'static str> {
     if cfg!(trybuild_no_target) {
         vec![]
     } else {
-        vec!["--target", TARGET]
+        vec!["--target", target_triple::TARGET]
     }
 }