[cfe-commits] [PATCH] Fix bad highlight range when diagnosing non-class friend usage

[Magee, Josh]

Attached is a new patch that (a) fixes the assertion when emitting the
warning dialogue in C++98 mode, and (b) implements C++11
[class.friend]p3 (PR9834).

For (a) I removed FriendLoc from the highlight range.  As noted, the
caret is pointing to FriendLoc anyway.

For (b): During parsing, I flagged whether or not the friend keyword
appears first in friend declarations.  Unfortunately, since the standard
only requires friend to be the first token in non-function friend
declarations, it isn't possible to generate an error at this point.
Instead, in Semantic Analysis, generate an error if the FriendFirst flag
is not set when checking a friend type (i.e., non-function) declaration.


Thanks,
Josh


At 1346342316 seconds past the Epoch, Richard Smith wrote:
> I wonder if we should even get as far as producing that diagnostic in this
> case. The code is ill-formed: for a non-function friend declaration,
> 'friend' must be the first token in the declaration (see C++11
> [class.friend]p3).
> 
> +  // Check whether the "friend" specifier is before or after the
> +  // type specifiers to determine the highlighted range.
> +  SourceRange HighlightRange = TypeRange.getEnd() < FriendLoc ?
> +         SourceRange(TypeRange.getBegin(),
> PP.getLocForEndOfToken(FriendLoc)) :
> +         SourceRange(FriendLoc, TypeRange.getEnd());
> 
> operator< on SourceLocation does not do what you expect here, and this
> doesn't form the correct range in cases where the 'friend' keyword is
> neither at the start nor at the end of the range, for instance "unsigned
> friend int;". How about just not including FriendLoc in the highlighted
> range at all? We're already pointing the caret at it.
> 
> On Wed, Aug 29, 2012 at 5:50 PM, Magee, Josh <Joshua.Magee at am.sony.com>wrote:
> 
> > Hi,
> >
> > Attached is a patch to fix an assertion that occurs when printing
> > diagnostic
> > warnings for non-class friend usage.
> >
> > Example:
> > This case prints fine:
> > struct { friend int; } a;
> >   warning: non-class friend type 'int' is a C++11 extension
> > [-Wc++11-extensions]
> >   friend int;
> >   ^~~~~~~~~~
> >
> > This case causes an assertion:
> > struct {int friend; } a;
> >   warning: non-class friend type 'int' is a C++11 extension
> > [-Wc++11-extensions]
> > ...
> > Assertion `StartColNo <= EndColNo && "Invalid range!"' failed.
> >
> > The problem is that when printing the diagnostic the possibility that the
> > friend specifier may appear after the type specifier is not considered.
> >  The
> > fix is to check whether the friend specifier appears after the type and
> > adjust
> > the highlight range accordingly.
> >
> >
> > Can someone review and, if everything is OK, commit?
> >
> > Thanks!
> > Josh
> > _______________________________________________
> > cfe-commits mailing list
> > cfe-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
> >
> >
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