Handle potentially throwing getters

Author: daxpedda

crates/cli-support/src/js/mod.rs

@@ -2578,6 +2578,38 @@ __wbg_set_wasm(wasm);"
         Ok(name)
     }
 
+    fn import_static(&mut self, import: &JsImport, optional: bool) -> Result<String, Error> {
+        let mut name = if let Some(name) = self.imported_names.get(&import.name) {
+            name.to_owned()
+        } else {
+            let JsImportName::Global { name } = &import.name else {
+                unreachable!("invalid static import")
+            };
+            let unique_name = self.generate_identifier(name);
+            if unique_name != *name {
+                bail!("cannot import `{}` from two locations", name);
+            }
+            unique_name
+        };
+
+        // After we've got an actual name handle field projections
+        if optional {
+            name = format!("typeof {name} === 'undefined' ? null: {name}");
+
+            for field in import.fields.iter() {
+                name.push_str("?.");
+                name.push_str(field);
+            }
+        } else {
+            for field in import.fields.iter() {
+                name.push('.');
+                name.push_str(field);
+            }
+        }
+
+        Ok(name)
+    }
+
     /// If a start function is present, it removes it from the `start` section
     /// of the Wasm module and then moves it to an exported function, named
     /// `__wbindgen_start`.
@@ -3269,24 +3301,7 @@ __wbg_set_wasm(wasm);"
                 assert!(kind == AdapterJsImportKind::Normal);
                 assert!(!variadic);
                 assert_eq!(args.len(), 0);
-                let js = self.import_name(js)?;
-
-                if *optional {
-                    writeln!(
-                        prelude,
-                        "\
-                        let result;
-                        try {{
-                            result = {js};
-                        }} catch (_) {{
-                            result = null;
-                        }}",
-                    )
-                    .unwrap();
-                    Ok("result".to_owned())
-                } else {
-                    Ok(js)
-                }
+                self.import_static(js, *optional)
             }
 
             AuxImport::String(string) => {

crates/cli/tests/reference/static.js

@@ -39,13 +39,7 @@ export function exported() {
 }
 
 export function __wbg_static_accessor_NAMESPACE_OPTIONAL_c9a4344c544120f4() {
-    let result;
-    try {
-        result = test.NAMESPACE_OPTIONAL;
-    } catch (_) {
-        result = null;
-    }
-    const ret = result;
+    const ret = typeof test === 'undefined' ? null: test?.NAMESPACE_OPTIONAL;
     return isLikeNone(ret) ? 0 : addToExternrefTable0(ret);
 };
 
@@ -55,13 +49,7 @@ export function __wbg_static_accessor_NAMESPACE_PLAIN_784c8d7f5bbac62a() {
 };
 
 export function __wbg_static_accessor_NESTED_NAMESPACE_OPTIONAL_a414abbeb018a35a() {
-    let result;
-    try {
-        result = test1.test2.NESTED_NAMESPACE_OPTIONAL;
-    } catch (_) {
-        result = null;
-    }
-    const ret = result;
+    const ret = typeof test1 === 'undefined' ? null: test1?.test2?.NESTED_NAMESPACE_OPTIONAL;
     return isLikeNone(ret) ? 0 : addToExternrefTable0(ret);
 };
 
@@ -71,13 +59,7 @@ export function __wbg_static_accessor_NESTED_NAMESPACE_PLAIN_1121b285cb8479df()
 };
 
 export function __wbg_static_accessor_OPTIONAL_ade71b6402851d0c() {
-    let result;
-    try {
-        result = OPTIONAL;
-    } catch (_) {
-        result = null;
-    }
-    const ret = result;
+    const ret = typeof OPTIONAL === 'undefined' ? null: OPTIONAL;
     return isLikeNone(ret) ? 0 : addToExternrefTable0(ret);
 };
 

guide/src/reference/static-js-objects.md

@@ -7,9 +7,8 @@ a named `static` in the `extern` block with an
 `JsThreadLocal` for these objects, which can be cloned into a `JsValue`.
 
 These values are cached in a thread-local and are meant to bind static values
-or objects only. Binding getters or expecting a new value or object when
-changed in JS is not supported. For these use
-[getters](attributes/on-js-imports/getter-and-setter.md).
+or objects only. For getters which can change their return value or throw see
+[how to import getters](attributes/on-js-imports/getter-and-setter.md).
 
 For example, given the following JavaScript: