[cfe-commits] [patch] Better diagnostics in for-range expressions.

[Sam Panzer]

Ah. Yes. It's actually attached now :)

On Fri, Jun 8, 2012 at 11:16 AM, Matt Beaumont-Gay <matthewbg at google.com>wrote:

> ENOPATCH
>
> On Fri, Jun 8, 2012 at 11:13 AM, Sam Panzer <panzer at google.com> wrote:
> > Hi,
> >
> > Richard Smith suggested that I try to improve the diagnostic emitted when
> > Clang encounters certain kinds of invalid C+11 ranged-based for loops.
> >
> >> When a pointer to a container is used as the range in a range-based for,
> >> Clang's diagnostic is not awesome:
> >>
> >>> struct S { int *begin(); int *end(); };
> >>> void f(S *p) {
> >>>  for (auto i : p) {}
> >>> }
> >>> tmp.cpp:3:15: error: use of undeclared identifier 'begin'
> >>>  for (auto i : p) {} }
> >>>              ^
> >>> tmp.cpp:3:15: note: range has type 'S *'
> >>
> >>
> >> We should do better than that, and suggest inserting the missing '*'.
> >
> >
> > This patch replaces the errors complaining about undeclared identifiers
> with
> > an error specific to ranged-for loops, along with an explanatory note. I
> > also updated the existing test cases to reflect the change. For example,
> the
> > above code now generates this:
> >
> >> test.cpp:3:15: error: invalid range expression of type 'S *'
> >>  for (auto i : p) {}
> >>              ^ ~
> >> test.cpp:3:16: note: range expression is of type 'S *'; did you
> >>       mean to dereference it with '*'?
> >>  for (auto i : p) {}
> >>                ^
> >>                *
> >> test.cpp:3:14: note: no viable 'end' function for range of type
> >>       'S *'
> >>  for (auto i : p) {}
> >
> >
> > I hope that this is helpful, and comments are always welcome.
> >
> > -Sam
> >
> > _______________________________________________
> > cfe-commits mailing list
> > cfe-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
> >
>
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