linux-kernel - Re: [PATCH] kernel-doc: Let backtick and backslash escape percent sign

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Message-ID: <20190405231024.GR22763@bombadil.infradead.org>
Date:   Fri, 5 Apr 2019 16:10:26 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Jonathan Corbet <corbet@....net>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kernel-doc: Let backtick and backslash escape percent
 sign

On Fri, Apr 05, 2019 at 02:18:20PM -0700, Sean Christopherson wrote:
> There are a handful of instances where kernel doc comments want an
> actual '%' in the final output, e.g. vsnprintf() wants to display "%n"
> and "%p" to document format specifiers, and assembly functions that use
> a custom call ABI may want to document their register usage, e.g. %eax.
> 
> Because kernel-doc unconditionally interprets '%' followed by a word
> character as a constant definition, i.e. %CONST, it's impossible to get
> an actual '%\w' when kernel-doc is used to translate comments into rst
> format.  Treat backtick and backlash as escaping '%', the former to
> handle '%' in a ``LITERAL``, and the latter to allow '%' when using
> standard formatting.
> 
> An alternative option would be to define a fancier set of rules for
> interpreting '%' so that explicit escaping would not be required.  For
> example, require "%CONST" to be preceded by a recognized set of
> characters, e.g. whitespace, opening parenthesis, etc...  But the list
> of recognized characters is quite large even in the current code base,
> and using '\' to escape is more common and intuitive, i.e. most people
> will naturally try doing "\%..." to get the desired formatting, whereas
> losing %CONST formatting because of an unrecognized character is likely
> to cause confusion.

Would it make sense to have %% turn into % rather than forcing quotation
marks?