Fix msvc stdout not shown on error

src/lib.rs

@@ -1784,6 +1784,9 @@ impl Build {
         if cfg!(target_os = "macos") {
             self.fix_env_for_apple_os(&mut cmd)?;
         }
+        if msvc {
+            disable_localization(&mut cmd);
+        }
 
         Ok((cmd, name))
     }
@@ -4094,6 +4097,21 @@ fn check_disabled() -> Result<(), Error> {
     Ok(())
 }
 
+/// Copied from <https://github.com/rust-lang/rust/blob/5db81020006d2920fc9c62ffc0f4322f90bffa04/compiler/rustc_codegen_ssa/src/back/linker.rs#L27-L38>
+///
+/// Disables non-English messages from localized linkers.
+/// Such messages may cause issues with text encoding on Windows
+/// and prevent inspection of msvc output in case of errors, which we occasionally do.
+/// This should be acceptable because other messages from rustc are in English anyway,
+/// and may also be desirable to improve searchability of the linker diagnostics.
+fn disable_localization(cmd: &mut Command) {
+    // No harm in setting both env vars simultaneously.
+    // Unix-style linkers.
+    cmd.env("LC_ALL", "C");
+    // MSVC's `link.exe`.
+    cmd.env("VSLANG", "1033");
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;