Support -Zfmt-debug=none

dtolnay · dtolnay · commit 052138c8c8c6 · 2025-05-22T09:04:03.000-07:00
diff --git a/build/build.rs b/build/build.rs
@@ -9,6 +9,7 @@ mod rustc;
 
 use std::env;
 use std::ffi::OsString;
+use std::fmt::{self, Debug, Display};
 use std::fs;
 use std::iter;
 use std::path::Path;
@@ -91,7 +92,7 @@ fn main() {
         println!("cargo:rustc-check-cfg=cfg(host_os, values(\"windows\"))");
     }
 
-    let version = format!("{:#?}\n", version);
+    let version = format!("{:#}\n", Render(&version));
     let out_dir = env::var_os("OUT_DIR").expect("OUT_DIR not set");
     let out_file = Path::new(&out_dir).join("version.expr");
     fs::write(out_file, version).expect("failed to write version.expr");
@@ -101,3 +102,13 @@ fn main() {
         println!("cargo:rustc-cfg=host_os=\"windows\"");
     }
 }
+
+// Shim Version's {:?} format into a {} format, because {:?} is unusable in
+// format strings when building with `-Zfmt-debug=none`.
+struct Render<'a>(&'a rustc::Version);
+
+impl<'a> Display for Render<'a> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(self.0, formatter)
+    }
+}
