Use <stdin> when emitting stdin as filename

src/config/file_lines.rs

@@ -60,7 +60,7 @@ impl fmt::Display for FileName {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             FileName::Real(p) => write!(f, "{}", p.display()),
-            FileName::Stdin => write!(f, "stdin"),
+            FileName::Stdin => write!(f, "<stdin>"),
         }
     }
 }

src/rustfmt/main.rs

@@ -708,7 +708,7 @@ mod test {
             .wait_with_output()
             .expect("Failed to wait on rustfmt child");
         assert!(!output.status.success());
-        assert_eq!(std::str::from_utf8(&output.stdout).unwrap(), "stdin\n");
+        assert_eq!(std::str::from_utf8(&output.stdout).unwrap(), "<stdin>\n");
     }
 
     #[cfg(nightly)]
@@ -818,7 +818,7 @@ fn foo() {
             assert!(output.stdout.is_empty());
             let exp_err = vec![
                 "\u{1b}[1;38;5;9merror\u{1b}[0m: \u{1b}[1minvalid attribute",
-                "\u{1b}[0m\n \u{1b}[1;38;5;12m-->\u{1b}[0m stdin:2\n",
+                "\u{1b}[0m\n \u{1b}[1;38;5;12m-->\u{1b}[0m <stdin>:2\n",
                 "\u{1b}[1;38;5;12m  |\u{1b}[0m\n",
                 "\u{1b}[1;38;5;12m2 |\u{1b}[0m         #![rustfmt::max_width(120)]\n",
                 "\u{1b}[1;38;5;12m  |\u{1b}[0m\n\n",

src/test/mod.rs

@@ -428,9 +428,9 @@ fn stdin_formatting_smoke_test() {
     .unwrap();
 
     #[cfg(not(windows))]
-    assert_eq!(buf, b"stdin:\n\nfn main() {}\n");
+    assert_eq!(buf, b"<stdin>:\n\nfn main() {}\n");
     #[cfg(windows)]
-    assert_eq!(buf, b"stdin:\n\nfn main() {}\r\n");
+    assert_eq!(buf, b"<stdin>:\n\nfn main() {}\r\n");
 }
 
 #[test]

tests/writemode/target/stdin.json

@@ -1 +1 @@
-[{"name":"stdin","mismatches":[{"original_begin_line":1,"original_end_line":6,"expected_begin_line":1,"expected_end_line":2,"original":"\nfn\n some( )\n{\n}\nfn main () {}\n","expected":"fn some() {}\nfn main() {}\n"}]}]
+[{"name":"<stdin>","mismatches":[{"original_begin_line":1,"original_end_line":6,"expected_begin_line":1,"expected_end_line":2,"original":"\nfn\n some( )\n{\n}\nfn main () {}\n","expected":"fn some() {}\nfn main() {}\n"}]}]

tests/writemode/target/stdin.xml

@@ -1,2 +1,2 @@
-<?xml version="1.0" encoding="utf-8"?>
-<checkstyle version="4.3"><file name="stdin"><error line="1" severity="warning" message="Should be `fn some() {}`" /><error line="2" severity="warning" message="Should be `fn main() {}`" /></file></checkstyle>
+<?xml version="1.0" encoding="utf-8"?>
+<checkstyle version="4.3"><file name="<stdin>"><error line="1" severity="warning" message="Should be `fn some() {}`" /><error line="2" severity="warning" message="Should be `fn main() {}`" /></file></checkstyle>