Re: [PATCH v6 1/4] libcpp: reject codepoints above 0x10FFFF

[Jason Merrill via Gcc-patches]

On 6/6/23 16:50, Ben Boeckel wrote:

Unicode does not support such values because they are unrepresentable in
UTF-16.

Pushed.

libcpp/

        * charset.cc: Reject encodings of codepoints above 0x10FFFF.
        UTF-16 does not support such codepoints and therefore all
        Unicode rejects such values.

Signed-off-by: Ben Boeckel <ben.boec...@kitware.com>
---
  libcpp/charset.cc | 7 +++++++
  1 file changed, 7 insertions(+)

diff --git a/libcpp/charset.cc b/libcpp/charset.cc
index d7f323b2cd5..3b34d804cf1 100644
--- a/libcpp/charset.cc
+++ b/libcpp/charset.cc
@@ -1886,6 +1886,13 @@ cpp_valid_utf8_p (const char *buffer, size_t num_bytes)
        int err = one_utf8_to_cppchar (&iter, &bytesleft, &cp);
        if (err)
        return false;
+
+      /* Additionally, Unicode declares that all codepoints above 0010FFFF are
+        invalid because they cannot be represented in UTF-16.
+
+        Reject such values.*/
+      if (cp >= 0x10FFFF)
+       return false;
      }
    /* No problems encountered.  */
    return true;