Warn and quick-fix inline comments in .editorconfig

src/EditorConfigDiagnosticsProvider.ts

@@ -0,0 +1,90 @@
+import {
+	Diagnostic,
+	DiagnosticCollection,
+	DiagnosticSeverity,
+	Disposable,
+	languages,
+	Range,
+	TextDocument,
+	workspace,
+} from 'vscode'
+
+/**
+ * Matches an inline comment: any line that contains non-whitespace content
+ * followed by required whitespace and then an unquoted `#` or `;`.
+ * Lines where `#` or `;` is the first non-whitespace character are proper
+ * standalone comments and are excluded before this regex is applied.
+ */
+const INLINE_COMMENT_RE = /\S.*[ \t]+([#;].*)$/
+
+export default class EditorConfigDiagnosticsProvider {
+	private collection: DiagnosticCollection
+	private disposable: Disposable
+
+	public constructor() {
+		this.collection = languages.createDiagnosticCollection('editorconfig')
+
+		const subscriptions: Disposable[] = []
+
+		// Analyze documents that are already open when the extension activates
+		for (const doc of workspace.textDocuments) {
+			this.analyze(doc)
+		}
+
+		subscriptions.push(
+			workspace.onDidOpenTextDocument(doc => this.analyze(doc)),
+		)
+		subscriptions.push(
+			workspace.onDidChangeTextDocument(e => this.analyze(e.document)),
+		)
+		subscriptions.push(
+			workspace.onDidCloseTextDocument(doc =>
+				this.collection.delete(doc.uri),
+			),
+		)
+
+		this.disposable = Disposable.from(...subscriptions)
+	}
+
+	private analyze(doc: TextDocument) {
+		if (doc.languageId !== 'editorconfig') {
+			return
+		}
+
+		const diagnostics: Diagnostic[] = []
+
+		for (let i = 0; i < doc.lineCount; i++) {
+			const { text } = doc.lineAt(i)
+
+			// Skip blank lines and proper standalone comment lines
+			const trimmed = text.trimStart()
+			if (
+				trimmed.length === 0 ||
+				trimmed.startsWith('#') ||
+				trimmed.startsWith(';')
+			) {
+				continue
+			}
+
+			const match = INLINE_COMMENT_RE.exec(text)
+			if (match) {
+				const commentStart = text.length - match[1].length
+				const range = new Range(i, commentStart, i, text.length)
+				diagnostics.push(
+					new Diagnostic(
+						range,
+						'Inline comments are not supported in EditorConfig. Move this comment to its own line.',
+						DiagnosticSeverity.Warning,
+					),
+				)
+			}
+		}
+
+		this.collection.set(doc.uri, diagnostics)
+	}
+
+	public dispose() {
+		this.collection.dispose()
+		this.disposable.dispose()
+	}
+}

src/editorConfigMain.ts

@@ -9,12 +9,14 @@ import {
 import { generateEditorConfig } from './commands/generateEditorConfig'
 import DocumentWatcher from './DocumentWatcher'
 import EditorConfigCompletionProvider from './EditorConfigCompletionProvider'
+import EditorConfigDiagnosticsProvider from './EditorConfigDiagnosticsProvider'
 
 /**
  * Main entry
  */
 export function activate(ctx: ExtensionContext) {
 	ctx.subscriptions.push(new DocumentWatcher())
+	ctx.subscriptions.push(new EditorConfigDiagnosticsProvider())
 
 	// register .editorconfig file completion provider
 	const editorConfigFileSelector: DocumentSelector = {

syntaxes/editorconfig.tmLanguage.json

@@ -273,6 +273,10 @@
         }
       ]
     },
+    "inlineComment": {
+      "name": "invalid.illegal.inline-comment.editorconfig",
+      "match": "\\s*[#;].*$"
+    },
     "section": {
       "name": "meta.section.editorconfig",
       "begin": "^\\s*(?=\\[.*?\\])",
@@ -286,6 +290,9 @@
         },
         {
           "include": "#rule"
+        },
+        {
+          "include": "#inlineComment"
         }
       ]
     },
@@ -374,6 +381,9 @@
         },
         {
           "include": "#string"
+        },
+        {
+          "include": "#inlineComment"
         }
       ]
     }