(fix) no diagnostics for coffeescript (#780)

Author: dummdidumm

packages/language-server/src/lib/documents/Document.ts

@@ -62,6 +62,19 @@ export class Document extends WritableDocument {
         return this.url;
     }
 
+    /**
+     * Returns the language associated to either script or style.
+     * Returns an empty string if there's nothing set.
+     */
+    getLanguageAttribute(tag: 'script' | 'style'): string {
+        const attrs =
+            (tag === 'style'
+                ? this.styleInfo?.attributes
+                : this.scriptInfo?.attributes || this.moduleScriptInfo?.attributes) || {};
+        const lang = attrs.lang || attrs.type || '';
+        return lang.replace(/^text\//, '');
+    }
+
     private addDefaultLanguage(
         tagInfo: TagInformation | null,
         tag: 'style' | 'script'

packages/language-server/src/plugins/typescript/features/DiagnosticsProvider.ts

@@ -11,6 +11,11 @@ export class DiagnosticsProviderImpl implements DiagnosticsProvider {
 
     async getDiagnostics(document: Document): Promise<Diagnostic[]> {
         const { lang, tsDoc } = this.getLSAndTSDoc(document);
+
+        if (['coffee', 'coffeescript'].includes(document.getLanguageAttribute('script'))) {
+            return [];
+        }
+
         const isTypescript = tsDoc.scriptKind === ts.ScriptKind.TSX;
 
         // Document preprocessing failed, show parser error instead

packages/language-server/test/plugins/typescript/features/DiagnosticsProvider.test.ts

@@ -258,4 +258,11 @@ describe('DiagnosticsProvider', () => {
             }
         ]);
     });
+
+    it('ignores coffeescript', async () => {
+        const { plugin, document } = setup('diagnostics-coffeescript.svelte');
+        const diagnostics = await plugin.getDiagnostics(document);
+
+        assert.deepStrictEqual(diagnostics, []);
+    });
 });

packages/language-server/test/plugins/typescript/testfiles/diagnostics-coffeescript.svelte

@@ -0,0 +1,30 @@
+<script lang="coffee">
+# Assignment:
+number   = 42
+opposite = true
+
+# Conditions:
+number = -42 if opposite
+
+# Functions:
+square = (x) -> x * x
+
+# Arrays:
+list = [1, 2, 3, 4, 5]
+
+# Objects:
+math =
+  root:   Math.sqrt
+  square: square
+  cube:   (x) -> x * square x
+
+# Splats:
+race = (winner, runners...) ->
+  print winner, runners
+
+# Existence:
+alert "I knew it!" if elvis?
+
+# Array comprehensions:
+cubes = (math.cube num for num in list)
+</script>