[cfe-dev] Ranges for diagnostics

[David Blaikie]

On Fri, Jan 24, 2014 at 10:12 AM, Milian Wolff <mail at milianw.de> wrote:

> On Friday 24 January 2014 08:25:26 David Blaikie wrote:
> > On Fri, Jan 24, 2014 at 6:26 AM, Milian Wolff <mail at milianw.de> wrote:
> > > Hey there,
> > >
> > > integrating clang into KDevelop we noticed that some diagnostics are
> > > lacking
> > > ranges which are in our opinion useful to have. Take this example:
> > >
> > > ~~~~~~~
> > > class foobar {};
> > > class foobar {};
> > >
> > > void foo(double);
> > > void foo(float);
> > >
> > > int main()
> > > {
> > >
> > >   foo(0);
> > >
> > >   "123" + 1;
> > >   return 0;
> > >
> > > }
> > > ~~~~~~~
> > >
> > > If you compile this with clang++ you'll get:
> > >
> > > ~~~~~~~
> > > test.cpp:2:7: error: redefinition of 'foobar'
> > > class foobar {};
> > >
> > >       ^
> > >
> > > test.cpp:1:7: note: previous definition is here
> > > class foobar {};
> > >
> > >       ^
> > >
> > > test.cpp:9:3: error: call to 'foo' is ambiguous
> > >
> > >   foo(0);
> > >   ^~~
> > >
> > > test.cpp:4:6: note: candidate function
> > > void foo(double);
> > >
> > >      ^
> > >
> > > test.cpp:5:6: note: candidate function
> > > void foo(float);
> > >
> > >      ^
> > >
> > > test.cpp:11:9: warning: expression result unused [-Wunused-value]
> > >
> > >   "123" + 1;
> > >   ~~~~~ ^ ~
> > >
> > > 1 warning and 2 errors generated.
> > > ~~~~~~~
> > >
> > > Is there a reason why some diagnostics only have a cursor pointing to
> the
> > > beginning of a token, while others are underlined properly?
> >
> > This isn't a question of "properly" or not - you'll notice that the
> things
> > underlined could actually, in other contexts, be more than one token (eg:
> > (1 + 2) + "foo" the LHS is (1 + 2) is underlined, and in "foo(0)" it's
> > possible that 'foo' could be a more complex expression involving a fully
> > qualified function name, decltype, etc). I suppose arguably the 'foobar'
> > example could involve a fully qualified (nested) name too.
>
> Right, properly is the wrong word.
>
> To rephrase: I propose to add ranges to "top-level" diagnostics. In the
> example above, that would mean adding a range to the "redifinition of
> 'foobar'.
>
> > > For the child diagnostics pointing to the candidate function it's fine
> to
> > > only
> > > get a cursor. But for the redefinition of 'foobar' I'd expect a range.
> > > Similar
> > > for diagnostics related to not-found #include statements.
> > >
> > > Would patches be accepted to add ranges to these diagnostics? Where
> would
> > > I
> > > have to look in the codebase?
> >
> > If we decide that's the right direction (that all diagnostic locations
> > should highlight the entire token, rather than just use a caret to point
> to
> > the start) we should probably just fix the diagnostic printer, rather
> than
> > fixing every diagnostic call site.
>
> Me as a consumer of the clang-c API also need to have that information.
> Thus
> we'll need to store the ranges into the diagnostics anyways - no? The
> printers
> should then just work™.
>
> Or how would you implement this purely on the diagnostic printer side? How
> do
> you get the token at a cursor position with the C-API? We tried
> clang_Cursor_getSpellingNameRange but didn't get good results.
>

I haven't used the C API, but if there's a limitation there that you can't
get the range of a token - we should just fix that.


>
> Thanks
> --
> Milian Wolff
> mail at milianw.de
> http://milianw.de
>
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20140124/8e9a543a/attachment.html>