[Lldb-commits] [PATCH] D26883: Demonstrate proposed new Args API

[Zachary Turner via lldb-commits]

Assuming we do that, what interface do you think would be simpler? We still
need easy access to both a StringRef and a c_str(), since StringRef::data
is not guaranteed to be null terminated, so the entry thing is still nice.
On Sat, Nov 19, 2016 at 5:44 AM Zachary Turner <zturner at google.com> wrote:

> The quote char is only exposed as a means to not break existing code which
> depends on it (most of which, not surprisingly, is in the Args class itself.
>
> We could try to come up with a way to kill it, but that seems like a
> separate refactor (and perhaps quite difficult since different platforms
> have different rules)
> On Sat, Nov 19, 2016 at 5:23 AM Pavel Labath <labath at google.com> wrote:
>
> labath added a comment.
>
> I don't know how deep do you want this refactor to be, but there is one
> issue I would like us to consider, if only to decide it is out of scope of
> this change. I am talking about the `quote_char` thingy. The main problem
> for me is that I don't think it's possible to sanely define the meaning of
> that field. According to POSIX quoting rules (which our command line
> more-or-less follows) a single argument can be quoted in a great many ways,
> using various combinations of quote characters. For example, these are all
> valid ways to represent the argument `asdf` in a POSIX shell:
>
>   asdf
>   "asdf"
>   'asdf'
>   a"sd"f
>   "as"df
>   "as""df"
>   "as"'df'
>   "a"s'd'"f"
>   ... (you get my point)
>
> I don't think there is a self-consistent way to define what the
> `quote_char` field will be for each of these options. Moreover, I don't see
> why one would ever need to use that field. It can only encourage someone to
> try to "quote" the argument by doing `quote_char+value+quote_char`, which
> is absolutely wrong if you ever want that result to be machine parsable.(*)
> For proper quoting I think we should just have a free-standing `std::string
> quote_for_posix_shell(llvm::StringRef)` function (and maybe
> `quote_for_windows_cmd`, and whatever else quoting scheme we need), and
> then the user can decide which one to use based on who is going to be
> consuming it. Then we can just kill the `quote` field. The only thing is...
> I have no idea how much work that will be (but I am ready to chip in to
> make it happen).
>
> So, yea, if we decide not to do that, then I think the interface looks
> great. Otherwise, I think we can design a slightly simpler (and more
> consistent) one.
>
> (*) Bonus question: Try to start an executable under lldb, so that in
> enters `main()` with `argc=2` and `argv[1]="'"` I.e.,  as if it had been
> started this way via bash:
>
>   $ /bin/cat \'
>
>
> https://reviews.llvm.org/D26883
>
>
>
>
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