Fix #62143. Indentation guess may not be too eager with alignment.

src/vs/editor/common/model/indentationGuesser.ts

@@ -158,8 +158,19 @@ export function guessIndentation(source: ITextBuffer, defaultTabSize: number, de
 		spacesDiff(previousLineText, previousLineIndentation, currentLineText, currentLineIndentation, tmp);
 
 		if (tmp.looksLikeAlignment) {
-			// skip this line entirely
-			continue;
+			// if defaultInsertSpaces === true && the spaces count == tabSize, we may want to count it as valid indentation
+			//
+			// - item1
+			//   - item2
+			//
+			// otherwise skip this line entirely
+			//
+			// const a = 1,
+			//       b = 2;
+
+			if (!(defaultInsertSpaces && defaultTabSize === tmp.spacesDiff)) {
+				continue;
+			}
 		}
 
 		let currentSpacesDiff = tmp.spacesDiff;

src/vs/editor/test/common/model/textModel.test.ts

@@ -608,6 +608,46 @@ suite('Editor Model - TextModel', () => {
 		]);
 	});
 
+	test('issue #62143: Broken indentation detection', () => {
+		// works before the fix
+		assertGuess(true, 2, [
+			'x',
+			'x',
+			'  x',
+			'  x'
+		]);
+
+		// works before the fix
+		assertGuess(true, 2, [
+			'x',
+			'  - item2',
+			'  - item3'
+		]);
+
+		// works before the fix
+		testGuessIndentation(true, 2, true, 2, [
+			'x x',
+			'  x',
+			'  x',
+		]);
+
+		// fails before the fix
+		// empty space inline breaks the indentation guess
+		testGuessIndentation(true, 2, true, 2, [
+			'x x',
+			'  x',
+			'  x',
+			'    x'
+		]);
+
+		testGuessIndentation(true, 2, true, 2, [
+			'<!--test1.md -->',
+			'- item1',
+			'  - item2',
+			'    - item3'
+		]);
+	});
+
 	test('validatePosition', () => {
 
 		let m = TextModel.createFromString('line one\nline two');