fix: always set bindings/exports in Svelte 5 (#2423)

Those two methods are needed in Svelte 5, but we don't always set them. That was fine until TS 5.5, which infers generics slightly differently and turns `Exports` and `Bindings` to `never` if they don't show up in the input (before they were not)

Author: dummdidumm

packages/svelte2tsx/src/svelte2tsx/nodes/ExportedNames.ts

@@ -709,26 +709,33 @@ export class ExportedNames {
         const others = names.filter(([, { isLet }]) => !isLet);
         const needsAccessors = this.usesAccessors && names.length > 0 && !this.usesRunes(); // runes mode doesn't support accessors
 
-        if (this.isSvelte5Plus && (others.length > 0 || this.usesRunes() || needsAccessors)) {
+        if (this.isSvelte5Plus) {
             let str = '';
 
-            if (others.length > 0 || needsAccessors) {
-                if (this.isTsFile) {
-                    str +=
-                        ', exports: {} as any as { ' +
-                        this.createReturnElementsType(
-                            needsAccessors ? names : others,
-                            undefined,
-                            true
-                        ).join(',') +
-                        ' }';
+            if (others.length > 0 || this.usesRunes() || needsAccessors) {
+                if (others.length > 0 || needsAccessors) {
+                    if (this.isTsFile) {
+                        str +=
+                            ', exports: {} as any as { ' +
+                            this.createReturnElementsType(
+                                needsAccessors ? names : others,
+                                undefined,
+                                true
+                            ).join(',') +
+                            ' }';
+                    } else {
+                        str += `, exports: /** @type {{${this.createReturnElementsType(needsAccessors ? names : others, false, true)}}} */ ({})`;
+                    }
                 } else {
-                    str += `, exports: /** @type {{${this.createReturnElementsType(needsAccessors ? names : others, false, true)}}} */ ({})`;
+                    // Always add that, in TS5.5+ the type for Exports is infered to never when this is not present, which breaks types.
+                    // Don't cast to `Record<string, never>` because that will break the union type we use elsewhere
+                    str += ', exports: {}';
                 }
-            }
 
-            if (this.usesRunes()) {
                 str += `, bindings: ${this.createBindingsStr()}`;
+            } else {
+                // always add that, in TS5.5+ the type for Exports is infered to never when this is not present, which breaks types
+                str += `, exports: {}, bindings: ${this.createBindingsStr()}`;
             }
 
             return str;

packages/svelte2tsx/test/helpers.ts

@@ -330,7 +330,11 @@ export function test_samples(dir: string, transform: TransformSampleFn, js: 'js'
                         // retry with the last part (the returned default export) stripped because it's always differing between old and new,
                         // and if that fails then we're going to rethrow the original error
                         const expectedModified = expected.substring(0, expectDefaultExportPosition);
-                        const actualModified = actual.substring(0, actual.lastIndexOf('\nconst '));
+                        const actualModified = actual
+                            .substring(0, actual.lastIndexOf('\nconst '))
+                            // not added in Svelte 4
+                            .replace(', exports: {}', '')
+                            .replace(', bindings: ""', '');
                         try {
                             assert.strictEqual(
                                 actualModified,

packages/svelte2tsx/test/svelte2tsx/samples/accessors-config/expected-svelte5.ts

@@ -4,7 +4,7 @@
 	 let foo: number = undefined/*Ωignore_startΩ*/;foo = __sveltets_2_any(foo);/*Ωignore_endΩ*/;
 ;
 async () => {};
-return { props: {foo: foo}, exports: /** @type {{foo: number}} */ ({}), slots: {}, events: {} }}
+return { props: {foo: foo}, exports: /** @type {{foo: number}} */ ({}), bindings: "", slots: {}, events: {} }}
 const Input__SvelteComponent_ = __sveltets_2_isomorphic_component(__sveltets_2_partial(['foo'], __sveltets_2_with_any_event(render())));
 /*Ωignore_startΩ*/type Input__SvelteComponent_ = InstanceType<typeof Input__SvelteComponent_>;
 /*Ωignore_endΩ*/export default Input__SvelteComponent_;

packages/svelte2tsx/test/svelte2tsx/samples/component-slot-forward-with-props/expected-svelte5.ts

@@ -4,7 +4,7 @@
 async () => { { const $$_tneraP0C = __sveltets_2_ensureComponent(Parent); const $$_tneraP0 = new $$_tneraP0C({ target: __sveltets_2_any(), props: {      children:() => { return __sveltets_2_any(0); },"propA":true,propB,"propC":`val1`,"propD":`val2`,"propE":`a${a}b${b}`,}});{const {/*Ωignore_startΩ*/$$_$$/*Ωignore_endΩ*/,foo,} = $$_tneraP0.$$slot_def.default;$$_$$;
      { __sveltets_createSlot("default", { foo,});}
  }Parent}};
-return { props: /** @type {Record<string, never>} */ ({}), slots: {'default': {foo:__sveltets_2_instanceOf(Parent).$$slot_def['default'].foo}}, events: {} }}
+return { props: /** @type {Record<string, never>} */ ({}), exports: {}, bindings: "", slots: {'default': {foo:__sveltets_2_instanceOf(Parent).$$slot_def['default'].foo}}, events: {} }}
 const Input__SvelteComponent_ = __sveltets_2_isomorphic_component_slots(__sveltets_2_partial(__sveltets_2_with_any_event(render())));
 /*Ωignore_startΩ*/type Input__SvelteComponent_ = InstanceType<typeof Input__SvelteComponent_>;
 /*Ωignore_endΩ*/export default Input__SvelteComponent_;

packages/svelte2tsx/test/svelte2tsx/samples/component-slot-let-forward/expected-svelte5.ts

@@ -4,7 +4,7 @@
 async () => { { const $$_tnenopmoC0C = __sveltets_2_ensureComponent(Component); const $$_tnenopmoC0 = new $$_tnenopmoC0C({ target: __sveltets_2_any(), props: {     children:() => { return __sveltets_2_any(0); },}});{const {/*Ωignore_startΩ*/$$_$$/*Ωignore_endΩ*/,name:n,thing,whatever:{ bla },} = $$_tnenopmoC0.$$slot_def.default;$$_$$;
      { __sveltets_createSlot("default", {   n,thing,bla,});}
  }Component}};
-return { props: /** @type {Record<string, never>} */ ({}), slots: {'default': {n:__sveltets_2_instanceOf(Component).$$slot_def['default'].name, thing:__sveltets_2_instanceOf(Component).$$slot_def['default'].thing, bla:(({ bla }) => bla)(__sveltets_2_instanceOf(Component).$$slot_def['default'].whatever)}}, events: {} }}
+return { props: /** @type {Record<string, never>} */ ({}), exports: {}, bindings: "", slots: {'default': {n:__sveltets_2_instanceOf(Component).$$slot_def['default'].name, thing:__sveltets_2_instanceOf(Component).$$slot_def['default'].thing, bla:(({ bla }) => bla)(__sveltets_2_instanceOf(Component).$$slot_def['default'].whatever)}}, events: {} }}
 const Input__SvelteComponent_ = __sveltets_2_isomorphic_component_slots(__sveltets_2_partial(__sveltets_2_with_any_event(render())));
 /*Ωignore_startΩ*/type Input__SvelteComponent_ = InstanceType<typeof Input__SvelteComponent_>;
 /*Ωignore_endΩ*/export default Input__SvelteComponent_;

packages/svelte2tsx/test/svelte2tsx/samples/component-slot-nest-scope/expected-svelte5.ts

@@ -12,7 +12,7 @@ async () => {  for(let item of __sveltets_2_ensureArray(items)){
     d;
 }}
  { __sveltets_createSlot("third", {   d,c,}); }};
-return { props: /** @type {Record<string, never>} */ ({}), slots: {'default': {a:(({ a }) => a)(__sveltets_2_unwrapArr(__sveltets_2_unwrapArr(items)))}, 'second': {a:a}, 'third': {d:d, c:c}}, events: {} }}
+return { props: /** @type {Record<string, never>} */ ({}), exports: {}, bindings: "", slots: {'default': {a:(({ a }) => a)(__sveltets_2_unwrapArr(__sveltets_2_unwrapArr(items)))}, 'second': {a:a}, 'third': {d:d, c:c}}, events: {} }}
 const Input__SvelteComponent_ = __sveltets_2_isomorphic_component_slots(__sveltets_2_partial(__sveltets_2_with_any_event(render())));
 /*Ωignore_startΩ*/type Input__SvelteComponent_ = InstanceType<typeof Input__SvelteComponent_>;
 /*Ωignore_endΩ*/export default Input__SvelteComponent_;

packages/svelte2tsx/test/svelte2tsx/samples/component-slot-no-space/expected-svelte5.ts

@@ -8,7 +8,7 @@ function render() {
 async () => {
 
  { svelteHTML.createElement("div", {}); { const $$_tseT1C = __sveltets_2_ensureComponent(Test); const $$_tseT1 = new $$_tseT1C({ target: __sveltets_2_any(), props: { children:() => { return __sveltets_2_any(0); },}});{const {/*Ωignore_startΩ*/$$_$$/*Ωignore_endΩ*/,t,} = $$_tseT1.$$slot_def.default;$$_$$;  }Test} }};
-return { props: /** @type {Record<string, never>} */ ({}), slots: {}, events: {} }}
+return { props: /** @type {Record<string, never>} */ ({}), exports: {}, bindings: "", slots: {}, events: {} }}
 const Input__SvelteComponent_ = __sveltets_2_isomorphic_component(__sveltets_2_partial(__sveltets_2_with_any_event(render())));
 /*Ωignore_startΩ*/type Input__SvelteComponent_ = InstanceType<typeof Input__SvelteComponent_>;
 /*Ωignore_endΩ*/export default Input__SvelteComponent_;

packages/svelte2tsx/test/svelte2tsx/samples/component-with-documentation/expected-svelte5.ts

@@ -3,7 +3,7 @@
 async () => {
 
  { svelteHTML.createElement("main", {});     }};
-return { props: /** @type {Record<string, never>} */ ({}), slots: {}, events: {} }}
+return { props: /** @type {Record<string, never>} */ ({}), exports: {}, bindings: "", slots: {}, events: {} }}
 /** This component does nothing at all */
 const Input__SvelteComponent_ = __sveltets_2_isomorphic_component(__sveltets_2_partial(__sveltets_2_with_any_event(render())));
 /*Ωignore_startΩ*/type Input__SvelteComponent_ = InstanceType<typeof Input__SvelteComponent_>;

packages/svelte2tsx/test/svelte2tsx/samples/component-with-indented-multiline-documentation/expected-svelte5.ts

@@ -3,7 +3,7 @@
 async () => {
 
  { svelteHTML.createElement("main", {});     }};
-return { props: /** @type {Record<string, never>} */ ({}), slots: {}, events: {} }}
+return { props: /** @type {Record<string, never>} */ ({}), exports: {}, bindings: "", slots: {}, events: {} }}
 /**
  * This component has indented multiline documentation:
  *

packages/svelte2tsx/test/svelte2tsx/samples/component-with-multiline-documentation/expected-svelte5.ts

@@ -3,7 +3,7 @@
 async () => {
 
  { svelteHTML.createElement("main", {});     }};
-return { props: /** @type {Record<string, never>} */ ({}), slots: {}, events: {} }}
+return { props: /** @type {Record<string, never>} */ ({}), exports: {}, bindings: "", slots: {}, events: {} }}
 /**
  * This component has multiline documentation:
  *