Add --line-length command line argument (#759)

src/cli.rs

@@ -87,6 +87,10 @@ pub struct Cli {
     /// The minimum Python version that should be supported.
     #[arg(long)]
     pub target_version: Option<PythonVersion>,
+    /// Set the line-length for length-associated checks and automatic
+    /// formatting.
+    #[arg(long)]
+    pub line_length: Option<usize>,
     /// Round-trip auto-formatting.
     // TODO(charlie): This should be a sub-command.
     #[arg(long, hide = true)]

src/main.rs

@@ -292,6 +292,9 @@ fn inner_main() -> Result<ExitCode> {
     if !cli.extend_ignore.is_empty() {
         configuration.extend_ignore = cli.extend_ignore;
     }
+    if let Some(line_length) = cli.line_length {
+        configuration.line_length = line_length;
+    }
     if let Some(target_version) = cli.target_version {
         configuration.target_version = target_version;
     }