+char *
+Perl_grok_bslash_o(pTHX_ const char *s, UV *uv, STRLEN *len, const bool output_warning)
+{
+
+/* Documentation to be supplied when interface nailed down finally
+ * This returns NULL on success, otherwise a pointer to an internal constant
+ * error message. On input:
+ * s points to a string that begins with o, and the previous character was
+ * a backslash.
+ * uv points to a UV that will hold the output value
+ * len will point to the next character in the string past the end of this
+ * construct
+ * output_warning says whether to output any warning messages, or suppress
+ * them
+ */
+ char* e;
+ STRLEN numbers_len;
+ I32 flags = PERL_SCAN_ALLOW_UNDERSCORES
+ | PERL_SCAN_DISALLOW_PREFIX
+ /* XXX Until the message is improved in grok_oct, handle errors
+ * ourselves */
+ | PERL_SCAN_SILENT_ILLDIGIT;
+
+ PERL_ARGS_ASSERT_GROK_BSLASH_O;
+
+
+ assert(*s == 'o');
+ s++;
+
+ if (*s != '{') {
+ *len = 1; /* Move past the o */
+ return "Missing braces on \\o{}";
+ }
+
+ e = strchr(s, '}');
+ if (!e) {
+ *len = 2; /* Move past the o{ */
+ return "Missing right brace on \\o{";
+ }
+
+ /* Return past the '}' no matter what is inside the braces */
+ *len = e - s + 2; /* 2 = 1 for the o + 1 for the '}' */
+
+ s++; /* Point to first digit */
+
+ numbers_len = e - s;
+ if (numbers_len == 0) {
+ return "Number with no digits";
+ }
+
+ *uv = NATIVE_TO_UNI(grok_oct(s, &numbers_len, &flags, NULL));
+ /* Note that if has non-octal, will ignore everything starting with that up
+ * to the '}' */
+
+ if (output_warning && numbers_len != (STRLEN) (e - s)) {
+ Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
+ /* diag_listed_as: Non-octal character '%c'. Resolved as "%s" */
+ "Non-octal character '%c'. Resolved as \"\\o{%.*s}\"",
+ *(s + numbers_len),
+ (int) numbers_len,
+ s);
+ }
+
+ return NULL;
+}
+