[cfe-dev] Quirky diagnostic/fixit when using insertions

[David Blaikie]

>
> > /tmp/webcompile/_934_0.cc:8:3: error: switch condition type 'foo'
> requires
> > explicit conversion to 'int'
> >   switch(foo())
> >   ^
> >          stati)_cast<int>(
> >
> > Which shows two problems:
> >
> > 1) Multiple carets points don't seem to be shown, only the first one (in
> > this case, the location of the diagnostic, not the location of either of
> the
> > suggested FixIts)
> > 2) If two FixIts overlap, in this case causing the second (")") to be
> > embedded inside the first (replacing the "c" in "static")
> >
> > Are these known issues? Has there been any thought/discussion on how they
> > should be fixed? (I imagine fixing (1) shouldn't be terribly hard, but I
> > haven't looked. Though (2) will presumably require slightly more work to
> > shift the fixits across and make it clear which piece is to be inserted
> > where)
> >
> > - David
>
> Hi,
> Yes I also noticed this problem last week.
> I filled a bugzilla:
> http://llvm.org/bugs/show_bug.cgi?id=10696
>

Thanks - that's (2) at least. Following on from the bug discussion I think
it'd be a pity to drop the fixit entirely - though better than having it
broken like that, sure.

Could we toss around some alternative syntax options & see what people
think?

A var = { b};
          ^
          s)atic_cast<unsigned int>(

One option would be to just suggest the whole replacement (not by
changing the FixIt emitted - that should remain the same so it's fully
descriptive for other tools. But just to change the way its rendered):

A var = { b};
          ^
          static_cast<unsigned int>(b)

or somehow attach the start & end separately:

A var = { b};
          ^^-------------------------\
          static_cast<unsigned int>( )

Though that doesn't really scale up to more than one overlap. (which
might be sufficient to cover more/most cases like this)

A simple separated list (could benefit from color highlighting, but we
wouldn't want to depend on that)

A var = { b};
          ^^
          static_cast<unsigned int>( )

Is there any good separator we could use in this list that wouldn't
get confused with the actual replacement text?

(could we even render fixits completely differently in the presence of
terminal colors?

A var = { *static_cast<unsigned int>(*b*)*};

Though I suppose this doesn't account for replacements (where we'd
want to show the old & the new text) in which case we could pad the
original text:

A var = { foo   (b)};
          foobar

)
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