Re: [BUG] groff: inconsistent behavior of " to separate arguments

[Ingo Schwarze]

Hi Alex,

Alejandro Colomar (man-pages) wrote on Sun, Mar 20, 2022 at 01:29:32AM +0100:

> I've met some undocumented (or I couldn't find it) behavior
> of double quotes ("),

I did not check the authoritative GNU troff documentation yet,
but the roff(7) manual in the mandoc package says this:

  MACRO SYNTAX
    Macros are provided by the mdoc(7) and man(7) languages and can be
    defined by the de request.  When called, they follow the same syntax
    as requests, except that macro arguments may optionally be quoted
    by enclosing them in double quote characters (`"').  Quoted text,
    even if it contains whitespace or would cause a macro invocation when
    unquoted, is always considered literal text.  Inside quoted text,
    pairs of double quote characters (`""') resolve to single double
    quote characters.

    To be recognised as the beginning of a quoted argument, the opening
    quote character must be preceded by a space character.  A quoted
    argument extends to the next double quote character that is not part
    of a pair, or to the end of the input line, whichever comes earlier.
    Leaving out the terminating double quote character at the end of the
    line is discouraged.  For clarity, if more arguments follow on the
    same input line, it is recommended to follow the terminating double
    quote character by a space character; in case the next character
    after the terminating double quote character is anything else,
    it is regarded as the beginning of the next, unquoted argument.

This text is also available here:

  https://man.openbsd.org/roff#MACRO_SYNTAX

While the mandoc roff(7) manual is neither authoritative with respect
to groff (it merely describes the most important parts of mandoc(1)'s
roff(7) implementation, but that is designed to be compatible with groff)
nor complete, that manual is designed to explain those facts about the
roff language that are most relevant for manual pages, in a form that
is as compact as possible, so it might sometimes be helpful for your
particular purposes.

> which might be a bug in groff(1):

Consequently, i agree with Ralph and doubt that this is a bug
in groff.  I believe it works as intended.

> .IR "foo"bar
> .IR foo"bar"
> .IR "foo"bar"baz"

The first and third lines are bad style and are better written as

  .IR "foo" bar
  .IR "foo" bar"baz"

[...]
>        foobar foo"bar" foobar"baz"

That output seems correct to me.  In any case, the mandoc(1) program 
produces the same output.

> When a double-quoted word is not space-separated from an adjacent word,
> it's not considered a different argument _except_ if if is the first
> argument.

That description is inaccurate.  It has nothing to do with whether
or not it is the first argument.

> Could you please improve the documentation regarding '"'?
> I've also seen """ to mean \(dq in some manual pages.

That seems like bad style to me.  If you really want to use the
quoted argument syntax to provide an argument containing nothing
but a single quote, than that argument should better be written
as four quotes (""""), not three.  Then again, i believe \(dq
is more readable than """" to the average reader.

> I guess the behavior is related to this report,
> but I'd like to understand why it works that way.

Yours,
  Ingo