\exposid (and similar macros) cause misalignment of columns in code blocks

[burblebee]

See the \expos comments near the beginning of [range.take.while.sentinel] for an example - they don't line up. The comments start on the same column in ranges.tex (after subtracting out the columns taken up by the use of \exposid), so the should line up. This appears to be similar to what I've seen when \placeholder is used instead of \placeholdernc. Do we need a \exposidnc?

In addition to \exposid, the use of other macros should be checked and possibly fixed as well.

[tkoeppe]

Yes, looks like we need \exposidnc there.

(For the purpose of column counting, it'd be nice if we could annotate our macros with the number of characters that the macro invocation takes up and the number of output characters it produces, so support mental arithmetic.)

[burblebee]

(For the purpose of column counting, it'd be nice if we could annotate our macros with the number of characters that the macro invocation takes up and the number of output characters it produces, so support mental arithmetic.)

Yes please!!! Unfortunately, \exposid doesn't take up any space when rendered, so still have to do mental arithmetic to align the // \expos that often follow it.

[burblebee]

This issue has not been resolved.

Using either \exposid or \exposidnc on an exposid in a synopsis causes \expos comments to not line up.

\exposidnc is supposed to be like \exposid but without italic correction.
In #3135 Thomas says:
"The non-correcting spacing is most necessary when horizontal fixed-width alignment is required"
suggesting that we should be using \exposidnc when an exposid is followed by a \expos comment, but doing so doesn't appear to make a visible difference.

For example, see the declarations in the private: section of [range.cartesian.iterator] after applying the resolution to LWG3760 from P2703r0 (branch motions-2022-11-lwg-7). You'll see the \expos comments don't line up. Replacing \exposidnc with \exposid in the branch doesn't appear to make a difference.

Since \exposidnc uses \placeholdernc, will #3135 fix this #4381?
Summary of related github issues/prs:

• #4381 \exposid causes misalignment of columns in code blocks
  status: this issue; was closed but not resolved; closed when pr [macros] Add "\exposidnc", like \exposid without italic correction #4392 merged
• #4392 [macros] Add "\exposidnc", like \exposid without italic correction
  status: pr closed, macro \exposidnc added
• #3135 \placeholder or \placeholdernc?
  status: issue open, supposedly fixed by [lib] Harmonize italics correction after \placeholder #3138 which remains open
• #3138 [lib] Harmonize italics correction after \placeholder
  status: pr open, supposed to fix \placeholder or \placeholdernc? #3135, needs rebase, comment claims rebase is waiting on [index] Add index of concept names. #3159 which has since been closed

Summary of related commits:

• d5e8108 [macros] Add "\exposidnc", like \exposid without italic correction (#4392)
• 475cc82 [macros] Fix spacing of \exposidnc
• f3ff6aa [lib] Use \placeholder with italic correction before <
• b743f3b [lib] Use \placeholdernc before (

[tkoeppe]

Note that italic correction is only applied (and hence only needs to be removed) before certain characters, but not always. E.g. before a whitespace I believe no correction is inserted, so using the "nc" variants doesn't make a difference there.