+/**
+ * Parse an escape sequence.
+ */
+static utf32 parse_escape_sequence(void)
+{
+ eat('\\');
+
+ utf32 const ec = c;
+ next_char();
+
+ switch (ec) {
+ case '"': return '"';
+ case '\'': return '\'';
+ case '\\': return '\\';
+ case '?': return '\?';
+ case 'a': return '\a';
+ case 'b': return '\b';
+ case 'f': return '\f';
+ case 'n': return '\n';
+ case 'r': return '\r';
+ case 't': return '\t';
+ case 'v': return '\v';
+ case 'x':
+ return parse_hex_sequence();
+ case '0':
+ case '1':
+ case '2':
+ case '3':
+ case '4':
+ case '5':
+ case '6':
+ case '7':
+ return parse_octal_sequence(ec);
+ case EOF:
+ parse_error("reached end of file while parsing escape sequence");
+ return EOF;
+ /* \E is not documented, but handled, by GCC. It is acceptable according
+ * to §6.11.4, whereas \e is not. */
+ case 'E':
+ case 'e':
+ if (c_mode & _GNUC)
+ return 27; /* hopefully 27 is ALWAYS the code for ESCAPE */
+ break;
+ case 'u':
+ case 'U':
+ parse_error("universal character parsing not implemented yet");
+ return EOF;
+ default:
+ break;
+ }
+ /* §6.4.4.4:8 footnote 64 */
+ parse_error("unknown escape sequence");
+ return EOF;
+}
+
+/**
+ * Concatenate two strings.
+ */
+string_t concat_strings(const string_t *const s1, const string_t *const s2)
+{
+ const size_t len1 = s1->size - 1;
+ const size_t len2 = s2->size - 1;
+
+ char *const concat = obstack_alloc(&symbol_obstack, len1 + len2 + 1);
+ memcpy(concat, s1->begin, len1);
+ memcpy(concat + len1, s2->begin, len2 + 1);
+
+ return identify_string(concat, len1 + len2 + 1);
+}
+
+string_t make_string(const char *string)
+{
+ size_t len = strlen(string) + 1;
+ char *const space = obstack_alloc(&symbol_obstack, len);
+ memcpy(space, string, len);
+
+ return identify_string(space, len);
+}
+
+static void grow_symbol(utf32 const tc)
+{
+ struct obstack *const o = &symbol_obstack;
+ if (tc < 0x80U) {
+ obstack_1grow(o, tc);
+ } else if (tc < 0x800) {
+ obstack_1grow(o, 0xC0 | (tc >> 6));
+ obstack_1grow(o, 0x80 | (tc & 0x3F));
+ } else if (tc < 0x10000) {
+ obstack_1grow(o, 0xE0 | ( tc >> 12));
+ obstack_1grow(o, 0x80 | ((tc >> 6) & 0x3F));
+ obstack_1grow(o, 0x80 | ( tc & 0x3F));
+ } else {
+ obstack_1grow(o, 0xF0 | ( tc >> 18));
+ obstack_1grow(o, 0x80 | ((tc >> 12) & 0x3F));
+ obstack_1grow(o, 0x80 | ((tc >> 6) & 0x3F));
+ obstack_1grow(o, 0x80 | ( tc & 0x3F));
+ }
+}
+
+/**
+ * Parse a string literal and set lexer_token.
+ */
+static void parse_string_literal(void)
+{
+ eat('"');
+
+ while (true) {
+ switch (c) {
+ case '\\': {
+ utf32 const tc = parse_escape_sequence();
+ if (tc >= 0x100) {
+ warningf(WARN_OTHER, &lexer_pos, "escape sequence out of range");
+ }
+ obstack_1grow(&symbol_obstack, tc);