Fix error positions on tokenizing a literal terminated with a newline (#187)

Author: makenowjust

lexer.go

@@ -512,7 +512,7 @@ func (l *Lexer) consumeQuotedContent(q string, raw, unicode bool, name string) s
 		}
 
 		if c == '\n' && len(q) != 3 {
-			l.panicfAtPosition(token.Pos(l.pos), token.Pos(l.pos+i+1), "unclosed %s: newline appears in non triple-quoted", name)
+			l.panicfAtPosition(token.Pos(l.pos), token.Pos(l.pos+i), "unclosed %s: newline appears in non triple-quoted", name)
 		}
 
 		content = append(content, c)

lexer_test.go

@@ -149,8 +149,8 @@ var lexerWrongTestCase = []struct {
 	{"\b", 0, 0, "illegal input character: '\\b'"},
 	{`"foo`, 0, 4, "unclosed string literal"},
 	{`R"foo`, 1, 5, "unclosed raw string literal"},
-	{"'foo\n", 0, 5, "unclosed string literal: newline appears in non triple-quoted"},
-	{"R'foo\n", 1, 6, "unclosed raw string literal: newline appears in non triple-quoted"},
+	{"'foo\n", 0, 4, "unclosed string literal: newline appears in non triple-quoted"},
+	{"R'foo\n", 1, 5, "unclosed raw string literal: newline appears in non triple-quoted"},
 	{"R'foo\\", 5, 6, "invalid escape sequence: \\<eof>"},
 	{`"\400"`, 1, 3, "invalid escape sequence: \\4"},
 	{`"\3xx"`, 1, 4, "invalid escape sequence: octal escape sequence must be follwed by 3 octal digits"},