fix: recognize script as module for Typescript type checking

Author: baseballyama

.changeset/purple-otters-hammer.md

@@ -0,0 +1,5 @@
+---
+"svelte-eslint-parser": patch
+---
+
+fix: recognize script as module for Typescript type checking

package.json

@@ -95,7 +95,6 @@
     "eslint-plugin-regexp": "^2.7.0",
     "eslint-plugin-svelte": "^2.46.1",
     "eslint-plugin-yml": "^1.15.0",
-    "estree-walker": "^3.0.3",
     "globals": "^15.12.0",
     "locate-character": "^3.0.0",
     "magic-string": "^0.30.14",

src/parser/typescript/analyze/index.ts

@@ -80,6 +80,12 @@ export function analyzeTypeScriptInSvelte(
 
   analyzeRenderScopes(code, ctx);
 
+  // When performing type checking on TypeScript code that is not a module, the error `Cannot redeclare block-scoped variable 'xxx'`. occurs. To fix this, add an `export`.
+  // see: https://github.com/sveltejs/svelte-eslint-parser/issues/557
+  if (!hasExportDeclaration(result.ast)) {
+    ctx.appendVirtualScript("export {};");
+  }
+
   ctx.appendOriginalToEnd();
 
   return ctx;
@@ -118,6 +124,18 @@ export function analyzeTypeScript(
   return ctx;
 }
 
+function hasExportDeclaration(ast: TSESParseForESLintResult["ast"]): boolean {
+  for (const node of ast.body) {
+    if (
+      node.type === "ExportNamedDeclaration" ||
+      node.type === "ExportDefaultDeclaration"
+    ) {
+      return true;
+    }
+  }
+  return false;
+}
+
 /**
  * Analyze the store reference names.
  * Insert type definitions code to provide correct type information for variables that begin with `$`.
@@ -380,7 +398,7 @@ function analyzeRuneVariables(
       // See https://github.com/sveltejs/svelte/blob/41b5cd6f5daae3970a9927e062f42b6b62440d16/packages/svelte/types/index.d.ts#L2615
       case "$props": {
         // Use type parameters to avoid `@typescript-eslint/no-unsafe-assignment` errors.
-        appendDeclareFunctionVirtualScripts(globalName, ["<T>(): T"]);
+        appendDeclareFunctionVirtualScripts(globalName, ["(): any"]);
         break;
       }
       // See https://github.com/sveltejs/svelte/blob/41b5cd6f5daae3970a9927e062f42b6b62440d16/packages/svelte/types/index.d.ts#L2626

tests/fixtures/parser/ast/svelte5/docs/runes/08-$props-ts-output.json

@@ -502,6 +502,27 @@
               "column": 57
             }
           }
+        },
+        {
+          "type": "ExportNamedDeclaration",
+          "declaration": null,
+          "exportKind": "value",
+          "source": null,
+          "specifiers": [],
+          "range": [
+            108,
+            108
+          ],
+          "loc": {
+            "start": {
+              "line": 5,
+              "column": 0
+            },
+            "end": {
+              "line": 5,
+              "column": 0
+            }
+          }
         }
       ],
       "endTag": {

tests/fixtures/parser/ast/svelte5/docs/runes/08-4-$bindable-ts-output.json

@@ -427,6 +427,27 @@
               "column": 75
             }
           }
+        },
+        {
+          "type": "ExportNamedDeclaration",
+          "declaration": null,
+          "exportKind": "value",
+          "source": null,
+          "specifiers": [],
+          "range": [
+            105,
+            105
+          ],
+          "loc": {
+            "start": {
+              "line": 4,
+              "column": 0
+            },
+            "end": {
+              "line": 4,
+              "column": 0
+            }
+          }
         }
       ],
       "endTag": {

tests/fixtures/parser/ast/svelte5/docs/runes/11-3-$inspect-ts-output.json

@@ -394,6 +394,27 @@
               "column": 38
             }
           }
+        },
+        {
+          "type": "ExportNamedDeclaration",
+          "declaration": null,
+          "exportKind": "value",
+          "source": null,
+          "specifiers": [],
+          "range": [
+            94,
+            94
+          ],
+          "loc": {
+            "start": {
+              "line": 6,
+              "column": 0
+            },
+            "end": {
+              "line": 6,
+              "column": 0
+            }
+          }
         }
       ],
       "endTag": {

tests/fixtures/parser/ast/svelte5/docs/snippets/10-typing-snippets-type-output.svelte

@@ -5,7 +5,7 @@
 		data: any[]; // data: any[]
 		children: Snippet; // Snippet: Snippet<Parameters>, children: Snippet<[]>
 		row: Snippet<[any]>; // Snippet: Snippet<Parameters>, row: Snippet<[any]>
-	} = $props(); // $props(): { data: any[]; children: Snippet<[]>; row: Snippet<[any]>; }
+	} = $props(); // $props(): any
 </script>
 
 <table>

tests/fixtures/parser/ast/svelte5/docs/snippets/11-typing-snippets-type-output.svelte

@@ -5,7 +5,7 @@
 		data: T[]; // T: unknown, data: unknown[]
 		children: Snippet; // Snippet: Snippet<Parameters>, children: Snippet<[]>
 		row: Snippet<[T]>; // Snippet: Snippet<Parameters>, T: unknown, row: Snippet<[unknown]>
-	} = $props(); // $props(): { data: unknown[]; children: Snippet<[]>; row: Snippet<[unknown]>; }
+	} = $props(); // $props(): any
 </script>
 
 <table>

tests/fixtures/parser/ast/svelte5/generics01-snippets-type-output.svelte

@@ -6,7 +6,7 @@
 		data: A[]; // A: unknown, data: unknown[]
 		children: Snippet; // Snippet: Snippet<Parameters>, children: Snippet<[]>
 		row: Snippet<[A]>; // Snippet: Snippet<Parameters>, A: unknown, row: Snippet<[unknown]>
-	} = $props(); // $props(): { data: unknown[]; children: Snippet<[]>; row: Snippet<[unknown]>; }
+	} = $props(); // $props(): any
 </script>
 
 <table>

tests/fixtures/parser/ast/svelte5/ts-$props01-type-output.svelte

@@ -5,7 +5,7 @@
     c: boolean; // c: boolean
     d: number; // d: number
   }
-  let { a, b, c, ...everythingElse }: MyProps = $props(); // a: number, a: number, b: string, b: string, c: boolean, c: boolean, everythingElse: { d: number; }, MyProps: MyProps, $props(): MyProps
+  let { a, b, c, ...everythingElse }: MyProps = $props(); // a: number, a: number, b: string, b: string, c: boolean, c: boolean, everythingElse: { d: number; }, MyProps: MyProps, $props(): any
 </script>
 
 {a} <!-- a: number -->