Merge pull request #293 from SimonSapin/arg-file

Pass lib.exe arguments though a file when the arg list is too long.

Author: alexcrichton

src/lib.rs

@@ -1331,12 +1331,46 @@ impl Build {
                     )
                 }
             };
+
             let mut out = OsString::from("/OUT:");
             out.push(dst);
-            run(
-                cmd.arg(out).arg("/nologo").args(&objects).args(&self.objects),
-                "lib.exe",
-            )?;
+            cmd.arg(out).arg("/nologo");
+
+            // Similar to https://github.com/rust-lang/rust/pull/47507
+            // and https://github.com/rust-lang/rust/pull/48548
+            let estimated_command_line_len =
+                objects.iter().chain(&self.objects).map(|a| a.as_os_str().len()).sum::<usize>();
+            if estimated_command_line_len > 1024 * 6 {
+                let mut args = String::from("\u{FEFF}");  // BOM
+                for arg in objects.iter().chain(&self.objects) {
+                    args.push('"');
+                    for c in arg.to_str().unwrap().chars() {
+                        if c == '"' {
+                            args.push('\\')
+                        }
+                        args.push(c)
+                    }
+                    args.push('"');
+                    args.push('\n');
+                }
+
+                let mut utf16le = Vec::new();
+                for code_unit in args.encode_utf16() {
+                    utf16le.push(code_unit as u8);
+                    utf16le.push((code_unit >> 8) as u8);
+                }
+
+                let mut args_file = OsString::from(dst);
+                args_file.push(".args");
+                fs::File::create(&args_file).unwrap().write_all(&utf16le).unwrap();
+
+                let mut args_file_arg = OsString::from("@");
+                args_file_arg.push(args_file);
+                cmd.arg(args_file_arg);
+            } else {
+                cmd.args(&objects).args(&self.objects);
+            }
+            run(&mut cmd, "lib.exe")?;
 
             // The Rust compiler will look for libfoo.a and foo.lib, but the
             // MSVC linker will also be passed foo.lib, so be sure that both