fix: deduplicate exports (#2083)

#2072

Author: dummdidumm

packages/svelte2tsx/src/svelte2tsx/addComponentExport.ts

@@ -121,11 +121,25 @@ function addSimpleComponentExport({
 
     let statement: string;
     if (mode === 'dts' && isTsFile) {
+        const addTypeExport = (type: string) => {
+            const exportName = className + type;
+
+            if (!str.original.includes(exportName)) {
+                return `export type ${exportName} = typeof __propDef.${type.toLowerCase()};\n`;
+            }
+
+            let replacement = exportName + '_';
+            while (str.original.includes(replacement)) {
+                replacement += '_';
+            }
+            return `type ${replacement} = typeof __propDef.${type.toLowerCase()};\nexport { ${replacement} as ${exportName} };\n`;
+        };
+
         statement =
             `\nconst __propDef = ${propDef};\n` +
-            `export type ${className}Props = typeof __propDef.props;\n` +
-            `export type ${className}Events = typeof __propDef.events;\n` +
-            `export type ${className}Slots = typeof __propDef.slots;\n` +
+            addTypeExport('Props') +
+            addTypeExport('Events') +
+            addTypeExport('Slots') +
             `\n${doc}export default class${
                 className ? ` ${className}` : ''
             } extends SvelteComponentTyped<${className}Props, ${className}Events, ${className}Slots> {` +

packages/svelte2tsx/test/emitDts/samples/typescript-deduplicate/expected/Test.svelte.d.ts

@@ -0,0 +1,22 @@
+import { SvelteComponentTyped } from "svelte";
+import { type TestProps } from './foo';
+declare const __propDef: {
+    props: {
+        p: TestProps;
+        x?: {
+            x: {
+                b: string;
+            };
+        };
+    };
+    events: {
+        [evt: string]: CustomEvent<any>;
+    };
+    slots: {};
+};
+type TestProps_ = typeof __propDef.props;
+export { TestProps_ as TestProps };
+export type TestEvents = typeof __propDef.events;
+export type TestSlots = typeof __propDef.slots;
+export default class Test extends SvelteComponentTyped<TestProps, TestEvents, TestSlots> {
+}

packages/svelte2tsx/test/emitDts/samples/typescript-deduplicate/expected/foo.d.ts

@@ -0,0 +1,10 @@
+export type TestProps = {
+    a: true;
+};
+type EventProps = {
+    b: string;
+};
+export declare function eventProps(): {
+    x: EventProps;
+};
+export {};

packages/svelte2tsx/test/emitDts/samples/typescript-deduplicate/src/Test.svelte

@@ -0,0 +1,9 @@
+<script lang="ts">
+    import { eventProps, type TestProps } from './foo';
+
+    export let p: TestProps;
+    export let x = eventProps();
+</script>
+
+{p}
+{x}

packages/svelte2tsx/test/emitDts/samples/typescript-deduplicate/src/foo.ts

@@ -0,0 +1,7 @@
+export type TestProps = { a: true };
+
+type EventProps = { b: string };
+
+export function eventProps(): { x: EventProps } {
+    return { x: { b: 'b' } };
+}

packages/svelte2tsx/test/emitDts/samples/typescript-deduplicate/tsconfig.json

@@ -0,0 +1,14 @@
+{
+    "compilerOptions": {
+        "moduleResolution": "node",
+        "module": "es2020",
+        "lib": ["es2020", "DOM"],
+        "target": "es2019",
+        "isolatedModules": true,
+        "resolveJsonModule": true,
+        "esModuleInterop": true,
+        "allowJs": true,
+        "checkJs": true
+    },
+    "include": ["./src/**/*.d.ts", "./src/**/*.js", "./src/**/*.ts", "./src/**/*.svelte"]
+}