[clang] [C2y] Add octal prefixes, deprecate unprefixed octals (PR #131626)

[via cfe-commits]

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@@ -120,6 +120,10 @@ C2y Feature Support
 - Implemented `WG14 N3411 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3411.pdf>`_
   which allows a source file to not end with a newline character. This is still
   reported as a conforming extension in earlier language modes.
+- Implemented `WG14 N3353 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3353.htm>_`
+  which adds the new ``0o`` and ``0O`` ocal literal prefixes and deprecates
+  octal literals other than ``0`` which do not start with the new prefix. This
+  feature is exposed in earlier language modes and in C++ as an extension.
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cor3ntin wrote:

Maybe you want to mention delimited escape sequences

https://github.com/llvm/llvm-project/pull/131626