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[Tinycc-devel] Unicode letter escape


From: Samir Ribić
Subject: [Tinycc-devel] Unicode letter escape
Date: Fri, 5 Aug 2022 13:32:04 +0200

Tcc supports \u escape sequence inside L"" but I have no idea how to overcome this problem:
The code inside parse_escape_string function, in this part

           case 'x':
            case 'u':
            case 'U':
                p++;
                n = 0;
                for(;;) {
                    c = *p;
                    if (c >= 'a' && c <= 'f')
                        c = c - 'a' + 10;
                    else if (c >= 'A' && c <= 'F')
                        c = c - 'A' + 10;
                    else if (isnum(c))
                        c = c - '0';
                    else
                        break;
                    n = n * 16 + c;
                    p++;
                }

does not limit the size of the hexadecimal number written after the \u escape code. Why is this a problem? If the text with an unicode letter is followed by letters a,b, c, d, e or f, it will be part of the code itself. For example L"Mogu\u0107i" will display the word "Mogući" as should be, because the code 0107 is c acute.  However, the word L"Mogu\u0107e" will not display "Moguće" but "Moguၾ" because 107e is  Myanmar Shan Fa

Section 6.4.3 of C99 standard  ISO/IEC 9899:1999(E) -- Programming Languages -- C (uchile.cl) states that \unnnn escape sequence requires exactly four hexadecimal digits, so the code above needs  to be changed.

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