We have discovered a potential small editorial mistake in the wording of marking unprefixed octal-literals (e.g., 07 and 0042) obsolescent in the C2y draft following the WG14 N3353 proposal (Obsolete implicitly octal literals and add delimited escape sequences).

In paragraph 5 in section 6.4.5.2 of the C2y draft, it is stated:

An unprefixed octal literal begins with the digit 0 optionally followed by a sequence of the digits 0
through 7 only. Use of an unprefixed octal literal with digits other than 0 is an obsolescent feature.

While working on the wording for the deprecation of unprefixed literals in WG21 P0085 (Oo... adding a coherent character sequence to begin octal-literals), we noticed that it is unclear whether 000 is obsolescent.

We reached out to some of the authors of the WG14 N3353 paper (Aaron Ballman and Corentin Jabot) and Aaron confirmed that their intent was to make obsolescent all octal literals starting with a 0 instead of 0o, except the literal 0. This means that the octal literal 000 is obsolescent, but 0 is not, as implemented by Aaron for Clang: https://www.godbolt.org/z/jEa4qnaMo

Aaron Ballman has pinged the WG14 reflectors to confirm that WG14 agrees with the authors' design intent.

In our WG21 P0085 paper, we agree with the declared design intent of the authors of N3353, deprecating also 000. It would be good if C and C++ could agree here, and the wording of C be clarified if WG14 believes that is needed.

Best,
Jolly