Fix Chinese character display by matching TypeScript's printer selection logic (#1559)

Co-authored-by: Copilot <[email protected]>
Co-authored-by: jakebailey <[email protected]>

Author: Copilot

internal/checker/printer.go

@@ -22,8 +22,10 @@ func createPrinterWithRemoveCommentsOmitTrailingSemicolon(emitContext *printer.E
 }
 
 func createPrinterWithRemoveCommentsNeverAsciiEscape(emitContext *printer.EmitContext) *printer.Printer {
-	// TODO: NeverAsciiEscape support
-	return printer.NewPrinter(printer.PrinterOptions{RemoveComments: true}, printer.PrintHandlers{}, emitContext)
+	return printer.NewPrinter(printer.PrinterOptions{
+		RemoveComments:   true,
+		NeverAsciiEscape: true,
+	}, printer.PrintHandlers{}, emitContext)
 }
 
 type semicolonRemoverWriter struct {
@@ -256,6 +258,7 @@ func (c *Checker) symbolToStringEx(symbol *ast.Symbol, enclosingDeclaration *ast
 		sourceFile = ast.GetSourceFileOfNode(enclosingDeclaration)
 	}
 	var printer_ *printer.Printer
+	// add neverAsciiEscape for GH#39027
 	if enclosingDeclaration != nil && enclosingDeclaration.Kind == ast.KindSourceFile {
 		printer_ = createPrinterWithRemoveCommentsNeverAsciiEscape(nodeBuilder.EmitContext())
 	} else {

internal/fourslash/tests/chineseCharacterDisplay_test.go

@@ -0,0 +1,50 @@
+package fourslash_test
+
+import (
+	"testing"
+
+	"github.com/microsoft/typescript-go/internal/fourslash"
+	"github.com/microsoft/typescript-go/internal/testutil"
+)
+
+func TestChineseCharacterDisplayInHover(t *testing.T) {
+	t.Parallel()
+	defer testutil.RecoverAndFail(t, "Panic on fourslash test")
+	const content = `
+interface 中文界面 {
+    上居中: string;
+    下居中: string;
+}
+
+class 中文类 {
+    获取中文属性(): 中文界面 {
+        return {
+            上居中: "上居中",
+            下居中: "下居中"
+        };
+    }
+}
+
+let /*instanceHover*/实例 = new 中文类();
+let 属性对象 = 实例./*methodHover*/获取中文属性();`
+	f := fourslash.NewFourslash(t, nil /*capabilities*/, content)
+	f.VerifyQuickInfoAt(t, "instanceHover", "let 实例: 中文类", "")
+	f.VerifyQuickInfoAt(t, "methodHover", "(method) 中文类.获取中文属性(): 中文界面", "")
+}
+
+func TestChineseCharacterDisplayInUnionTypes(t *testing.T) {
+	t.Parallel()
+	defer testutil.RecoverAndFail(t, "Panic on fourslash test")
+	const content = `
+// Test the original issue: Chinese characters in method parameters should display correctly
+class TSLine {
+    setLengthTextPositionPreset(/*methodParam*/preset: "上居中" | "下居中" | "右居中" | "左居中"): void {}
+}
+
+let lines = new TSLine();
+lines./*method*/setLengthTextPositionPreset;`
+	f := fourslash.NewFourslash(t, nil /*capabilities*/, content)
+
+	// Verify that the method displays Chinese characters correctly in hover (this was the original problem)
+	f.VerifyQuickInfoAt(t, "method", `(method) TSLine.setLengthTextPositionPreset(preset: "上居中" | "下居中" | "右居中" | "左居中"): void`, "")
+}

internal/printer/printer.go

@@ -45,7 +45,7 @@ type PrinterOptions struct {
 	OmitBraceSourceMapPositions bool
 	// ExtendedDiagnostics           bool
 	OnlyPrintJSDocStyle bool
-	// NeverAsciiEscape              bool
+	NeverAsciiEscape    bool
 	// StripInternal                 bool
 	PreserveSourceNewlines bool
 	// TerminateUnterminatedLiterals bool
@@ -974,7 +974,11 @@ func (p *Printer) emitTokenNodeEx(node *ast.TokenNode, flags tokenEmitFlags) {
 //	SyntaxKindTemplateMiddle
 //	SyntaxKindTemplateTail
 func (p *Printer) emitLiteral(node *ast.LiteralLikeNode, flags getLiteralTextFlags) {
-	// !!! Printer option to control whether to escape non-ASCII characters
+	// Add NeverAsciiEscape flag if the printer option is set
+	if p.Options.NeverAsciiEscape {
+		flags |= getLiteralTextFlagsNeverAsciiEscape
+	}
+
 	text := p.getLiteralTextOfNode(node, nil /*sourceFile*/, flags)
 
 	// !!! Printer option to control source map emit, which causes us to use a different write method on the