Re: cc-mode: Make all parameters introduced in Emacs 26 optional

[Ergus <spacibba@aol.com>]

Hi Stefan:

Sorry, maybe my question is a bit orthogonal to this thread, but somehow
I feel it is related.

In CC mode is there a way (when activating a high level for
font-lock-mode) to highlight escape sequences, and numbers as in default
vim?

I am talking about something simple like the packages:

highlight-escape-sequences and highlight-numbers.

But maybe simpler and that doesn't rely on an external package for a
simpler functionality like this?

This is just a question, you can ignore it.

Thanks in advance Ergus

On Sat, Mar 30, 2019 at 04:17:25PM -0400, Stefan Monnier wrote:
>>>     (modify-syntax-entry ?' "\"" st)
>>
>> Maybe, but that doesn't give you the facilities that CC Mode offers,
>> namely that the delimiters of invalid constructs (such as unterminated
>> strings, or invalid character constants) get fontified with warning face.
>
>... or quotes-in-numbers, indeed.
>
>> One question which has just occurred to me is why am I doing this in CC
>> Mode rather than the syntax and font-lock functionality handling it
>> directly?  Languages where strings don't extend over unescaped newlines
>> aren't exactly a rarity.
>
>I think doing it in the syntax part is not necessary: the design of the
>syntax is made simpler and more efficient by assuming that the behavior
>on invalid code is largely irrelevant.  And efficiency is important
>there when we need to parse-partial-sexp a large buffer.
>
>But providing support for highlighting such errors in font-lock
>(e.g. within font-lock-fontify-syntactically-region) would make a lot of
>sense, yes.
>
>Or maybe the simplest would be to provide
>a `font-lock-flag-multiline-strings` function that modes can add to
>font-lock-keywords.
>
>>> But the above sounds surprisingly complex&scary,
>> It only looks like that because I've spelled it out so laboriously.  There
>> are two hook variables, each of which needs one function and the lack of
>> another.
>
>After re-reading the description I wonder if it couldn't be made simpler
>by making those hook functions check c-single-quotes-quote-strings
>instead (or have separate code in the cc-mode setup which adds/removes
>those hooks as needed based on c-single-quotes-quote-strings,
>essentially replacing the docstring text with executable code)?
>
>Also I still wonder why c-has-quoted-numbers is incompatible with
>c-single-quotes-quote-strings.  I guess c-has-quoted-numbers only
>exists in C++, so in practice no language needs both features, but
>I can't see any reason why the CC-mode code wouldn't work just as
>well when both features are set.  While both have to do with ' they seem
>fundamentally orthogonal.
>
>
>        Stefan
>
>