Fix multiline ternary expression formatting with tabs

internal/format/span.go

@@ -1055,9 +1055,12 @@ func (w *formatSpanWorker) consumeTokenAndAdvanceScanner(currentTokenInfo tokenI
 		indentNextTokenOrTrivia := true
 		if len(currentTokenInfo.leadingTrivia) > 0 {
 			commentIndentation := dynamicIndenation.getIndentationForComment(currentTokenInfo.token.Kind, tokenIndentation, container)
-			indentNextTokenOrTrivia = w.indentTriviaItems(currentTokenInfo.leadingTrivia, commentIndentation, indentNextTokenOrTrivia, func(item TextRangeWithKind) {
-				w.insertIndentation(item.Loc.Pos(), commentIndentation, false)
-			})
+			// Only indent comments if we have a valid indentation value
+			if commentIndentation != -1 {
+				indentNextTokenOrTrivia = w.indentTriviaItems(currentTokenInfo.leadingTrivia, commentIndentation, indentNextTokenOrTrivia, func(item TextRangeWithKind) {
+					w.insertIndentation(item.Loc.Pos(), commentIndentation, false)
+				})
+			}
 		}
 
 		// indent token only if is it is in target range and does not overlap with any error ranges
@@ -1091,6 +1094,10 @@ func (i *dynamicIndenter) getIndentationForComment(kind ast.Kind, tokenIndentati
 	//     // comment
 	// }
 	case ast.KindCloseBraceToken, ast.KindCloseBracketToken, ast.KindCloseParenToken:
+		// If indentation is -1 (Unknown), we should not add delta to it
+		if i.indentation == -1 {
+			return -1
+		}
 		return i.indentation + i.getDelta(container)
 	}
 	if tokenIndentation != -1 {
@@ -1113,6 +1120,10 @@ func (i *dynamicIndenter) getIndentationForComment(kind ast.Kind, tokenIndentati
 //
 //	> yValue;
 func (i *dynamicIndenter) getIndentationForToken(line int, kind ast.Kind, container *ast.Node, suppressDelta bool) int {
+	// If indentation is -1 (Unknown), we should not add delta to it
+	if i.indentation == -1 {
+		return -1
+	}
 	if !suppressDelta && i.shouldAddDelta(line, kind, container) {
 		return i.indentation + i.getDelta(container)
 	}

internal/format/ternary_test.go

@@ -0,0 +1,77 @@
+package format_test
+
+import (
+	"testing"
+
+	"github.com/microsoft/typescript-go/internal/ast"
+	"github.com/microsoft/typescript-go/internal/core"
+	"github.com/microsoft/typescript-go/internal/format"
+	"github.com/microsoft/typescript-go/internal/parser"
+)
+
+func TestTernaryWithTabs(t *testing.T) {
+	t.Parallel()
+
+	// This is the original code with tabs for indentation
+	// Using literal tab characters
+	text := "const test = (a: string) => (\n\ta === '1' ? (\n\t\t10\n\t) : (\n\t\t12\n\t)\n)"
+
+	ctx := format.WithFormatCodeSettings(t.Context(), &format.FormatCodeSettings{
+		EditorSettings: format.EditorSettings{
+			TabSize:                4,
+			IndentSize:             4,
+			BaseIndentSize:         0,
+			NewLineCharacter:       "\n",
+			ConvertTabsToSpaces:    false, // Use tabs
+			IndentStyle:            format.IndentStyleSmart,
+			TrimTrailingWhitespace: true,
+		},
+	}, "\n")
+
+	sourceFile := parser.ParseSourceFile(ast.SourceFileParseOptions{
+		FileName: "/test.ts",
+		Path:     "/test.ts",
+	}, text, core.ScriptKindTS)
+
+	edits := format.FormatDocument(ctx, sourceFile)
+	newText := applyBulkEdits(text, edits)
+
+	// Check that we don't have mixed tabs and spaces
+	// The formatted text should only use tabs for indentation
+	lines := splitLines(newText)
+	for i, line := range lines {
+		if len(line) == 0 {
+			continue
+		}
+		// Check that the line doesn't have spaces for indentation followed by tabs
+		hasLeadingSpaces := false
+		for j := range len(line) {
+			if line[j] == ' ' {
+				hasLeadingSpaces = true
+			} else if line[j] == '\t' {
+				// If we already saw spaces and now see a tab, that's a problem
+				if hasLeadingSpaces {
+					t.Errorf("Line %d has mixed tabs and spaces: %q", i, line)
+				}
+			} else {
+				// Hit non-whitespace
+				break
+			}
+		}
+	}
+}
+
+func splitLines(text string) []string {
+	var lines []string
+	start := 0
+	for i := range len(text) {
+		if text[i] == '\n' {
+			lines = append(lines, text[start:i])
+			start = i + 1
+		}
+	}
+	if start < len(text) {
+		lines = append(lines, text[start:])
+	}
+	return lines
+}