Auto merge of #24469 - saschanaz:urp-default, r=Manishearth

Support USVString as default value of a union argument

<!-- Please describe your changes on the following line: -->

I don't expect this fixes any test though...

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #22543

<!-- Either: -->
- [x] There are tests for these changes

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

3 files changed, 10 insertions, 8 deletions

diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index c80e8a0697b..17ec39913d6 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -732,6 +732,10 @@ def getJSToNativeConversionInfo(type, descriptorProvider, failureCode=None,
                 default = "%s::Boolean(%s)" % (
                     union_native_type(type),
                     "true" if defaultValue.value else "false")
+            elif tag is IDLType.Tags.usvstring:
+                default = '%s::USVString(USVString("%s".to_owned()))' % (
+                    union_native_type(type),
+                    defaultValue.value)
             else:
                 raise("We don't currently support default values that aren't null, boolean or default dictionary")
         elif dictionaries:
diff --git a/components/script/dom/urlsearchparams.rs b/components/script/dom/urlsearchparams.rs
index 57c86898482..3664d30d1f7 100644
--- a/components/script/dom/urlsearchparams.rs
+++ b/components/script/dom/urlsearchparams.rs
@@ -47,12 +47,12 @@ impl URLSearchParams {
     // https://url.spec.whatwg.org/#dom-urlsearchparams-urlsearchparams
     pub fn Constructor(
         global: &GlobalScope,
-        init: Option<USVStringSequenceSequenceOrUSVStringUSVStringRecordOrUSVString>,
+        init: USVStringSequenceSequenceOrUSVStringUSVStringRecordOrUSVString,
     ) -> Fallible<DomRoot<URLSearchParams>> {
         // Step 1.
         let query = URLSearchParams::new(global, None);
         match init {
-            Some(USVStringSequenceSequenceOrUSVStringUSVStringRecordOrUSVString::USVStringSequenceSequence(init)) => {
+            USVStringSequenceSequenceOrUSVStringUSVStringRecordOrUSVString::USVStringSequenceSequence(init) => {
                 // Step 2.
 
                 // Step 2-1.
@@ -64,12 +64,12 @@ impl URLSearchParams {
                 *query.list.borrow_mut() =
                     init.iter().map(|pair| (pair[0].to_string(), pair[1].to_string())).collect::<Vec<_>>();
             },
-            Some(USVStringSequenceSequenceOrUSVStringUSVStringRecordOrUSVString::USVStringUSVStringRecord(init)) => {
+            USVStringSequenceSequenceOrUSVStringUSVStringRecordOrUSVString::USVStringUSVStringRecord(init) => {
                 // Step 3.
                 *query.list.borrow_mut() =
                     (*init).iter().map(|(name, value)| (name.to_string(), value.to_string())).collect::<Vec<_>>();
             },
-            Some(USVStringSequenceSequenceOrUSVStringUSVStringRecordOrUSVString::USVString(init)) => {
+            USVStringSequenceSequenceOrUSVStringUSVStringRecordOrUSVString::USVString(init) => {
                 // Step 4.
                 let init_bytes = match init.0.chars().next() {
                     Some(first_char) if first_char == '?' => {
@@ -82,8 +82,7 @@ impl URLSearchParams {
 
                 *query.list.borrow_mut() =
                     form_urlencoded::parse(init_bytes).into_owned().collect();
-            },
-            None => {},
+            }
         }
 
         // Step 5.
diff --git a/components/script/dom/webidls/URLSearchParams.webidl b/components/script/dom/webidls/URLSearchParams.webidl
index 70845900003..33ba9253624 100644
--- a/components/script/dom/webidls/URLSearchParams.webidl
+++ b/components/script/dom/webidls/URLSearchParams.webidl
@@ -8,8 +8,7 @@
 
 [Exposed=(Window,Worker)]
 interface URLSearchParams {
-  [Throws] constructor(
-  optional (sequence<sequence<USVString>> or record<USVString, USVString> or USVString) init);
+  [Throws] constructor(optional (sequence<sequence<USVString>> or record<USVString, USVString> or USVString) init = "");
   void append(USVString name, USVString value);
   void delete(USVString name);
   USVString? get(USVString name);