Fix some more C string handling issues in Cython 3.0.

src/lxml/apihelpers.pxi

@@ -1016,8 +1016,8 @@ cdef inline bint _nsTagMatchesExactly(const_xmlChar* c_node_href,
     if c_qname.href is NULL:
         return 1
     c_href = python.__cstr(c_qname.href)
-    if c_href[0] == '\0':
-        return c_node_href is NULL or c_node_href[0] == '\0'
+    if c_href[0] == b'\0':
+        return c_node_href is NULL or c_node_href[0] == b'\0'
     elif c_node_href is NULL:
         return 0
     else:

src/lxml/parser.pxi

@@ -221,8 +221,8 @@ cdef const_char* _findEncodingName(const_xmlChar* buffer, int size):
     cdef tree.xmlCharEncoding enc
     enc = tree.xmlDetectCharEncoding(buffer, size)
     if enc == tree.XML_CHAR_ENCODING_UTF16LE:
-        if size >= 4 and (buffer[0] == <const_xmlChar>'\xFF' and
-                          buffer[1] == <const_xmlChar>'\xFE' and
+        if size >= 4 and (buffer[0] == <const_xmlChar> b'\xFF' and
+                          buffer[1] == <const_xmlChar> b'\xFE' and
                           buffer[2] == 0 and buffer[3] == 0):
             return "UTF-32LE"  # according to BOM
         else:
@@ -1106,13 +1106,13 @@ cdef class _BaseParser:
                 c_encoding = NULL
                 # libxml2 (at least 2.9.3) does not recognise UTF-32 BOMs
                 # NOTE: limit to problematic cases because it changes character offsets
-                if c_len >= 4 and (c_text[0] == '\xFF' and c_text[1] == '\xFE' and
+                if c_len >= 4 and (c_text[0] == b'\xFF' and c_text[1] == b'\xFE' and
                                    c_text[2] == 0 and c_text[3] == 0):
                     c_encoding = "UTF-32LE"
                     c_text += 4
                     c_len -= 4
                 elif c_len >= 4 and (c_text[0] == 0 and c_text[1] == 0 and
-                                     c_text[2] == '\xFE' and c_text[3] == '\xFF'):
+                                     c_text[2] == b'\xFE' and c_text[3] == b'\xFF'):
                     c_encoding = "UTF-32BE"
                     c_text += 4
                     c_len -= 4

src/lxml/serializer.pxi

@@ -408,11 +408,11 @@ cdef unsigned char *xmlSerializeHexCharRef(unsigned char *out, int val) noexcept
     cdef xmlChar *ptr
     cdef const xmlChar* hexdigits = b"0123456789ABCDEF"
 
-    out[0] = '&'
+    out[0] = b'&'
     out += 1
-    out[0] = '#'
+    out[0] = b'#'
     out += 1
-    out[0] = 'x'
+    out[0] = b'x'
     out += 1
 
     if val < 0x10:
@@ -434,7 +434,7 @@ cdef unsigned char *xmlSerializeHexCharRef(unsigned char *out, int val) noexcept
         ptr -= 1
         val >>= 4
 
-    out[0] = ';'
+    out[0] = b';'
     out += 1
     out[0] = 0
 
@@ -488,7 +488,7 @@ cdef _write_attr_string(tree.xmlOutputBuffer* buf, const char *string):
             cur += 1
             base = cur
 
-        elif cur[0] == '<':
+        elif cur[0] == b'<':
             if base != cur:
                 tree.xmlOutputBufferWrite(buf, cur - base, base)
 

src/lxml/xmlerror.pxi

@@ -144,7 +144,7 @@ cdef class _LogEntry:
         if self._c_message is NULL:
             return None
         size = cstring_h.strlen(self._c_message)
-        if size > 0 and self._c_message[size-1] == '\n':
+        if size > 0 and self._c_message[size-1] == b'\n':
             size -= 1  # strip EOL
         # cannot use funicode() here because the message may contain
         # byte encoded file paths etc.