return non-zero exit code if there were errors

[rust.git] / README.md

diff --git a/README.md b/README.md
index fbe605fb43073e19f50ce7ae27dbfefe4daed14a..b1bd8227b3d7a9c4512bd5bfc87982e28a7bf726 100644 (file)
--- a/README.md
+++ b/README.md
@@ -63,10 +63,18 @@ diff, replace, overwrite, display, coverage, and checkstyle.
 The write mode can be set by passing the `--write-mode` flag on
 the command line. For example `rustfmt --write-mode=display src/filename.rs`
 
-You can run `rustfmt --help` for more information.
-
 `cargo fmt` uses `--write-mode=replace` by default.
 
+If `rustfmt` successfully reformatted the code it will exit with `0` exit
+status. Exit status `1` signals some unexpected error, like an unknown option or
+a failure to read a file. Exit status `2` is returned if there are syntax errors
+in the input files. `rustfmt` can't format syntatically invalid code. Finally,
+exit status `3` is returned if there are some issues which can't be resolved
+automatically. For example, if you have a very long comment line `rustfmt`
+doesn't split it. Instead it prints a warning and exits with `3`.
+
+You can run `rustfmt --help` for more information.
+
 
 ## Running Rustfmt from your editor