Fixing rust map lowering interfaces by scoping each use.

crates/rust/src/bindgen.rs

@@ -775,12 +775,7 @@ impl Bindgen for FunctionBindgen<'_, '_> {
             } => {
                 let alloc = self.r#gen.path_to_std_alloc_module();
                 let rt = self.r#gen.r#gen.runtime_path().to_string();
-                self.r#gen.needs_wit_map = true;
-                self.r#gen.needs_runtime_module = true;
-                self.r#gen
-                    .r#gen
-                    .rt_module
-                    .insert(crate::RuntimeItem::WitMapTrait);
+                let wit_map = self.r#gen.r#gen.wit_map_path();
                 let body = self.blocks.pop().unwrap();
                 let tmp = self.tmp();
                 let map = format!("map{tmp}");
@@ -792,7 +787,9 @@ impl Bindgen for FunctionBindgen<'_, '_> {
                     "let {map} = {operand0};\n",
                     operand0 = operands[0]
                 ));
-                self.push_str(&format!("let {len} = {map}.wit_map_len();\n"));
+                self.push_str(&format!(
+                    "let {len} = {{ use {wit_map} as _; {map}.wit_map_len() }};\n"
+                ));
                 let entry = self.map_entry_layout(key, value);
                 self.push_str(&format!(
                     "let {layout} = {alloc}::Layout::from_size_align({len} * {}, {}).unwrap();\n",

crates/rust/src/interface.rs

@@ -27,7 +27,6 @@ pub struct InterfaceGenerator<'a> {
     pub return_pointer_area_size: ArchitectureSize,
     pub return_pointer_area_align: Alignment,
     pub(super) needs_runtime_module: bool,
-    pub(super) needs_wit_map: bool,
 }
 
 /// A description of the "mode" in which a type is printed.
@@ -449,12 +448,7 @@ macro_rules! {macro_name} {{
         if self.needs_runtime_module {
             let root = self.path_to_root();
             if !root.is_empty() {
-                let wit_map_use = if self.needs_wit_map {
-                    format!("use {root}_rt::WitMap;\n")
-                } else {
-                    String::new()
-                };
-                return format!("use {root}_rt;\n{wit_map_use}{src}");
+                return format!("use {root}_rt;\n{src}");
             }
         }
         src

crates/rust/src/lib.rs

@@ -116,7 +116,6 @@ enum RuntimeItem {
     AsF64,
     ResourceType,
     BoxType,
-    WitMapTrait,
 }
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
@@ -423,7 +422,6 @@ impl RustWasm {
             return_pointer_area_size: Default::default(),
             return_pointer_area_align: Default::default(),
             needs_runtime_module: false,
-            needs_wit_map: false,
         })
     }
 
@@ -755,11 +753,6 @@ pub fn run_ctors_once() {{
                 self.emit_runtime_as_trait("f64", &["f64"]);
             }
 
-            RuntimeItem::WitMapTrait => {
-                let rt = self.runtime_path().to_string();
-                uwriteln!(self.src, "pub use {rt}::WitMap;");
-            }
-
             RuntimeItem::ResourceType => {
                 self.src.push_str(
                     r#"

crates/test/src/d.rs

@@ -31,7 +31,12 @@ impl LanguageMethods for D {
         config: &crate::config::WitConfig,
         _args: &[String],
     ) -> bool {
-        config.async_ || config.error_context || name == "map.wit" || name == "issue1642.wit"
+        config.async_
+            || config.error_context
+            || name == "map.wit"
+            || name == "map-in-world.wit"
+            || name == "map-named-wit-map.wit"
+            || name == "issue1642.wit"
     }
 
     fn default_bindgen_args_for_codegen(&self) -> &[&str] {

tests/codegen/map-in-world.wit

@@ -0,0 +1,6 @@
+package foo:foo;
+
+world map-in-world {
+  import take-map: func(a: map<string, u32>);
+  export return-map: func() -> map<string, u32>;
+}

tests/codegen/map-named-wit-map.wit

@@ -0,0 +1,10 @@
+package foo:foo;
+
+interface wit-map {
+  type wit-map = map<string, u32>;
+  f: func(a: wit-map);
+}
+
+world map-named-wit-map {
+  import wit-map;
+}