feat: support specifying tsconfig for emitDts (#2454)

part of #2355

Author: quentinderoubaix

packages/svelte2tsx/index.d.ts

@@ -108,6 +108,10 @@ export interface EmitDtsConfig {
      * set to `src/lib` by default.
      */
     libRoot?: string;
+    /**
+     * Name of your tsconfig file, if it's not the standard `tsconfig.json` or `jsconfig.json` 
+     */
+    tsconfig?: string;
 }
 
 // to make typo fix non-breaking, continue to export the old name but mark it as deprecated

packages/svelte2tsx/src/emitDts.ts

@@ -6,6 +6,7 @@ export interface EmitDtsConfig {
     declarationDir: string;
     svelteShimsPath: string;
     libRoot?: string;
+    tsconfig?: string;
 }
 
 export async function emitDts(config: EmitDtsConfig) {
@@ -47,7 +48,7 @@ function loadTsconfig(config: EmitDtsConfig, svelteMap: SvelteMap) {
     const libRoot = config.libRoot || process.cwd();
 
     const jsconfigFile = ts.findConfigFile(libRoot, ts.sys.fileExists, 'jsconfig.json');
-    let tsconfigFile = ts.findConfigFile(libRoot, ts.sys.fileExists);
+    let tsconfigFile = ts.findConfigFile(libRoot, ts.sys.fileExists, config.tsconfig);
 
     if (!tsconfigFile && !jsconfigFile) {
         throw new Error('Failed to locate tsconfig or jsconfig');

packages/svelte2tsx/test/emitDts/samples/typescript-custom-tsconfig/config.json

@@ -0,0 +1,3 @@
+{
+    "tsconfig": "tsconfig.build.json"
+}

packages/svelte2tsx/test/emitDts/samples/typescript-custom-tsconfig/expected/runes.svelte.d.ts

@@ -0,0 +1,2 @@
+/** Calculate how much someone earns in a week */
+export declare function weeklySalary(dayRate: number): number;

packages/svelte2tsx/test/emitDts/samples/typescript-custom-tsconfig/src/runes.svelte.ts

@@ -0,0 +1,10 @@
+/**
+ * Days available in a week
+ * @internal
+ */
+export const daysInAWeek = 7;
+ 
+/** Calculate how much someone earns in a week */
+export function weeklySalary(dayRate: number) {
+  return daysInAWeek * dayRate;
+}

packages/svelte2tsx/test/emitDts/samples/typescript-custom-tsconfig/tsconfig.build.json

@@ -0,0 +1,6 @@
+{
+	"extends": "./tsconfig.json",
+	"compilerOptions": {
+		"stripInternal": true
+	}
+}

packages/svelte2tsx/test/emitDts/samples/typescript-custom-tsconfig/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"]
+}