On Sat, Jan 21, 2012 at 11:38 PM, Aaron Ballman <[email protected]> wrote: > On Thu, Jan 19, 2012 at 12:00 AM, Eli Friedman <[email protected]> wrote: >> On Mon, Jan 16, 2012 at 8:38 PM, Aaron Ballman <[email protected]> >> wrote: >>> On Sun, Jan 15, 2012 at 9:05 PM, Eli Friedman <[email protected]> >>> wrote: >>>> On Sun, Jan 15, 2012 at 1:45 PM, Aaron Ballman <[email protected]> >>>> wrote: >>>>> This is a patch for fixing 11747, allowing reinterpret_cast to "cast" >>>>> where the source and destination types are the same as per >>>>> [expr.reinterpret.cast]p2. The fix itself is fairly simple -- the >>>>> code was already there, it just needed to be moved up slightly since >>>>> the previous check was for source and dest being pointers. >>>> >>>> C++11 [expr.reinterpret.cast]p2 is as follows: >>>> >>>> The reinterpret_cast operator shall not cast away constness (5.2.11). >>>> An expression of integral, enumeration, pointer, or pointer-to-member >>>> type can be explicitly converted to its own type; such a cast yields >>>> the value of its operand. >>> >>> Attached is a new patch to hopefully better address this, as well as >>> some additional test cases. >> >> + // C++ 5.2.10p2 has a note that mentions that, subject to all other >> + // restrictions, a cast to the same type is allowed so long as it does >> not >> + // cast away constness. The intent is not entirely clear here, since all >> + // other paragraphs explicitly forbid casts to the same type. >> + // >> + // The only allowed types are: integral, enumeration, pointer, or >> + // pointer-to-member types. >> >> This comment is really unclear... you should really explicitly state >> that the C++98 version is unclear, and C++11 clarifies this case. > > I've clarified now, thanks for pointing out the confusion! > >> + } else if (SrcType->isPointerType() || >> + SrcType->isMemberPointerType()) { >> >> The original code allowed "DestType->isAnyPointerType() || >> DestType->isBlockPointerType()". I don't see any reason to restrict >> Objective-C or block pointers. > > Nor do I, I've added this in as well. > >> + if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, >> + /*CheckObjCLifetime=*/CStyle)) { >> >> How could a cast where the source and destination types are identical >> cast away constness? > > From my testing, the equality test does not take cv qualifiers into > account. Is there another way I should be testing for equality that > does?
"==" should definitely be taking qualifiers into account. Do you have a testcase? -Eli _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
