[lldb-dev] LLDB Evolution - Final Form

[Zachary Turner via lldb-dev]

The =delete overload of StringRef is also a great idea.  It just helped me
catch all the places where we were initializing global option tables from
const char *s

On Wed, Sep 21, 2016 at 2:28 PM Zachary Turner <zturner at google.com> wrote:

> On Wed, Sep 21, 2016 at 2:20 PM Greg Clayton <gclayton at apple.com> wrote:
>
>
> > On Sep 21, 2016, at 1:55 PM, Zachary Turner <zturner at google.com> wrote:
> >
> > :-/  The same thing happens if you write Foo &f = *nullptr;   It's a
> reference.
>
> I might be a good idea to add an overloaded constructor for nullptr and
> void * and delete them so that we can't implicitly create a StringRef from
> nullptr or NULL and cause as crash as it wouldn't compile in the first
> place.
>
> >
> > Did you try StringRef::withNullAsEmpty()?
>
> I am still catching code conversion issues with things like:
>
> if (name == nullptr)
>
>
> Yea you have to handle it on a case by case basis.  What I've been doing
> is to look around the surrounding code.  If it's obvious that it's not null
> (because it was just checked above, or because it's .c_str() of something,
> or it came from a string literal, or whatever, then i just call
> llvm::StringRef(name);  If I don't know, even if I can probably guess, I do
> one of two things.  If it seems like a rabbit hole you don't want to
> venture into, just do withNullAsEmpty.  If it's a trivial utility function
> that doesn't pass the string through many layers of nested calls, go change
> that function to return a StringRef, then come back.
>
> Another thing that's helped me a lot (although it will make the code
> slightly verbose in the short term) is that any function I'm changing the
> signature of from const char* to StringRef, copy the declaration and
> =delete the const char* version.  This way the compiler won't allow the
> implicit conversion, and you'll be forced to fix up every callsite.  This
> is annoying because 99% of the time you end up explicitly constructing
> StringRefs from literals, which will obviously work, but it's the only way
> to guarantee that the conversion won't introduce null pointer errors.
>
> Once the code is more or less done, we can go back and remove all the
> =delete functions we added so you don't have to write explicit conversions
> anymore.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/lldb-dev/attachments/20160921/8db26acf/attachment.html>