wit-parser: inject package metadata when decoding component (#2443)

* fix: inject package metadata when decoding component

* test: component wit docs roundtrip

Author: rellfy

crates/wit-parser/src/decoding.rs

@@ -343,7 +343,10 @@ impl ComponentInfo {
             }
         }
 
-        let (resolve, _) = decoder.finish(package);
+        let (mut resolve, pkg) = decoder.finish(package);
+        if let Some(package_metadata) = &self.package_metadata {
+            package_metadata.inject(&mut resolve, pkg)?;
+        }
         Ok((resolve, world))
     }
 }

tests/cli/component-docs-roundtrip.wit

@@ -0,0 +1,17 @@
+// RUN: component wit % --wasm | component wit
+
+package foo:docs-test;
+
+/// The interface.
+interface my-interface {
+  /// The function.
+  my-func: func(
+    /// The function's argument.
+    my-arg: string,
+  ) -> string;
+}
+
+/// A world with documentation.
+world my-world {
+  export my-interface;
+}

tests/cli/component-docs-roundtrip.wit.stdout

@@ -0,0 +1,13 @@
+/// RUN: component wit % --wasm | component wit
+package foo:docs-test;
+
+/// The interface.
+interface my-interface {
+  /// The function.
+  my-func: func(my-arg: string) -> string;
+}
+
+/// A world with documentation.
+world my-world {
+  export my-interface;
+}