Rewatch: add support for "rescript -w" for compatibility (#7649)

* Add support for "rescript -w" for compatibility

* CHANGELOG

Author: cknitt

CHANGELOG.md

@@ -25,6 +25,7 @@
 - Clean up `config.ml`. https://github.com/rescript-lang/rescript/pull/7636
 - Rewatch: simplify getting bsc path. https://github.com/rescript-lang/rescript/pull/7634
 - Rewatch: only get `"type": "dev"` source files for local packages. https://github.com/rescript-lang/rescript/pull/7646
+- Rewatch: add support for `rescript -w` for compatibility. https://github.com/rescript-lang/rescript/pull/7649
 
 #### :rocket: New Feature
 

rewatch/src/cli.rs

@@ -107,6 +107,10 @@ pub struct BuildArgs {
 
     #[command(flatten)]
     pub snapshot_output: SnapshotOutputArg,
+
+    /// Watch mode (deprecated, use `rescript watch` instead)
+    #[arg(short, default_value_t = false, num_args = 0..=1)]
+    pub watch: bool,
 }
 
 #[derive(Args, Clone, Debug)]
@@ -130,6 +134,19 @@ pub struct WatchArgs {
     pub snapshot_output: SnapshotOutputArg,
 }
 
+impl From<BuildArgs> for WatchArgs {
+    fn from(build_args: BuildArgs) -> Self {
+        Self {
+            folder: build_args.folder,
+            filter: build_args.filter,
+            after_build: build_args.after_build,
+            create_sourcedirs: build_args.create_sourcedirs,
+            dev: build_args.dev,
+            snapshot_output: build_args.snapshot_output,
+        }
+    }
+}
+
 #[derive(Subcommand, Clone, Debug)]
 pub enum Command {
     /// Build the project

rewatch/src/main.rs

@@ -17,13 +17,20 @@ fn main() -> Result<()> {
         .target(env_logger::fmt::Target::Stdout)
         .init();
 
-    let command = args.command.unwrap_or(cli::Command::Build(args.build_args));
+    let mut command = args.command.unwrap_or(cli::Command::Build(args.build_args));
+
+    if let cli::Command::Build(build_args) = &command {
+        if build_args.watch {
+            log::warn!("`rescript build -w` is deprecated. Please use `rescript watch` instead.");
+            command = cli::Command::Watch(build_args.clone().into());
+        }
+    }
 
     // The 'normal run' mode will show the 'pretty' formatted progress. But if we turn off the log
     // level, we should never show that.
     let show_progress = log_level_filter == LevelFilter::Info;
 
-    match command.clone() {
+    match command {
         cli::Command::CompilerArgs { path, dev } => {
             println!("{}", build::get_compiler_args(Path::new(&path), *dev)?);
             std::process::exit(0);