Port TypeScript PR #60303: Fix template string escaping (microsoft#1142)

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: andrewbranch <[email protected]>
Co-authored-by: jakebailey <[email protected]>

Author: 3 people

internal/printer/printer_test.go

@@ -28,6 +28,8 @@ func TestEmit(t *testing.T) {
 		{title: "BooleanLiteral#1", input: `true`, output: `true;`},
 		{title: "BooleanLiteral#2", input: `false`, output: `false;`},
 		{title: "NoSubstitutionTemplateLiteral", input: "``", output: "``;"},
+		{title: "NoSubstitutionTemplateLiteral#2", input: "`\n`", output: "`\n`;"},
+
 		{title: "RegularExpressionLiteral#1", input: `/a/`, output: `/a/;`},
 		{title: "RegularExpressionLiteral#2", input: `/a/g`, output: `/a/g;`},
 		{title: "NullLiteral", input: `null`, output: `null;`},

internal/printer/utilities.go

@@ -103,7 +103,7 @@ func escapeStringWorker(s string, quoteChar QuoteChar, flags getLiteralTextFlags
 				escape = true
 			}
 		default:
-			if ch < '\u001f' || flags&getLiteralTextFlagsNeverAsciiEscape == 0 && ch > '\u007f' {
+			if ch <= '\u001f' || flags&getLiteralTextFlagsNeverAsciiEscape == 0 && ch > '\u007f' {
 				escape = true
 			}
 		}

internal/printer/utilities_test.go

@@ -25,6 +25,7 @@ func TestEscapeString(t *testing.T) {
 		{s: "ab'c", quoteChar: QuoteCharSingleQuote, expected: `ab\'c`},
 		{s: "ab\"c", quoteChar: QuoteCharSingleQuote, expected: `ab"c`},
 		{s: "ab`c", quoteChar: QuoteCharBacktick, expected: "ab\\`c"},
+		{s: "\u001f", quoteChar: QuoteCharBacktick, expected: "\\u001F"},
 	}
 	for i, rec := range data {
 		t.Run(fmt.Sprintf("[%d] escapeString(%q, %v)", i, rec.s, rec.quoteChar), func(t *testing.T) {

testdata/baselines/reference/submodule/conformance/templateStringControlCharacterEscapes03.types

@@ -3,5 +3,5 @@
 === templateStringControlCharacterEscapes03.ts ===
 var x = `\x1F\u001f 1F 1f`;
 >x : string
->`\x1F\u001f 1F 1f` : " 1F 1f"
+>`\x1F\u001f 1F 1f` : "\u001F\u001F 1F 1f"
 

testdata/baselines/reference/submodule/conformance/templateStringControlCharacterEscapes03.types.diff

@@ -3,5 +3,5 @@
 === templateStringControlCharacterEscapes03_ES6.ts ===
 var x = `\x1F\u001f 1F 1f`;
 >x : string
->`\x1F\u001f 1F 1f` : " 1F 1f"
+>`\x1F\u001f 1F 1f` : "\u001F\u001F 1F 1f"