Add a CLI flag to skip wit-component process (#40)

Can possibly be helpful when debugging various things.

Author: alexcrichton

src/lib.rs

@@ -280,6 +280,10 @@ struct ComponentLdArgs {
     /// only used when one or more `--component-type` options are specified.
     #[clap(long, value_parser = parse_encoding, default_value = "utf8")]
     string_encoding: StringEncoding,
+
+    /// Skip the `wit-component`-based process to generate a component.
+    #[clap(long)]
+    skip_wit_component: bool,
 }
 
 fn parse_adapter(s: &str) -> Result<(String, Vec<u8>)> {
@@ -525,7 +529,7 @@ impl App {
         // output directly at the desired output location. Otherwise output to a
         // temporary location for wit-component to read and then the real output
         // is created after wit-component runs.
-        if self.shared {
+        if self.skip_wit_component() {
             cmd.arg("-o").arg(self.component.output.as_ref().unwrap());
         } else {
             cmd.arg("-o").arg(lld_output.path());
@@ -541,9 +545,7 @@ impl App {
             bail!("failed to invoke LLD: {status}");
         }
 
-        // Skip componentization with `--shared` since that's creating a shared
-        // library that's not a component yet.
-        if self.shared {
+        if self.skip_wit_component() {
             return Ok(());
         }
 
@@ -640,6 +642,13 @@ impl App {
         Ok(())
     }
 
+    fn skip_wit_component(&self) -> bool {
+        self.component.skip_wit_component
+            // Skip componentization with `--shared` since that's creating a
+            // shared library that's not a component yet.
+            || self.shared
+    }
+
     fn lld(&self) -> Command {
         let mut lld = self.find_lld();
         lld.args(&self.lld_args);

tests/all.rs

@@ -50,6 +50,11 @@ fn assert_component(bytes: &[u8]) {
     wasmparser::Validator::new().validate_all(&bytes).unwrap();
 }
 
+fn assert_module(bytes: &[u8]) {
+    assert!(wasmparser::Parser::is_core_wasm(&bytes));
+    wasmparser::Validator::new().validate_all(&bytes).unwrap();
+}
+
 #[test]
 fn empty() {
     let output = compile(&["--crate-type", "cdylib"], "");
@@ -177,3 +182,15 @@ world root {
     );
     assert_component(&output);
 }
+
+#[test]
+fn skip_component() {
+    let output = compile(
+        &["-Clink-arg=--skip-wit-component"],
+        r#"
+fn main() {
+}
+        "#,
+    );
+    assert_module(&output);
+}