[cfe-commits] r86129 - in /cfe/trunk: lib/Sema/Sema.h lib/Sema/SemaCXXCast.cpp lib/Sema/SemaDeclCXX.cpp lib/Sema/SemaOverload.cpp test/SemaTemplate/instantiate-complete.cpp utils/C++Tests/LLVM-Syntax/lit.local.cfg
rjmccall at apple.com
Fri Nov 6 01:24:32 PST 2009
Chris Lattner wrote:
> This last part (known non-negative) involves a bunch of adhoc stuff
> using fold to determine whether something is non-negative, allowing it
> to catch things like 'abs' idioms etc. We don't need to be this smart
> imo :), but it would be nice to catch integer literals.
We actually do catch anything that isIntegerConstantExpression can
resolve to a constant.
Anyway, I've gone ahead and implemented all of these except...
> /* Do not warn if the unsigned quantity is an enumeration
> constant and its maximum value would fit in the result
> if the result were signed. */
...which could easily be done if we care about it.
> Nearby they also have an interesting warning that I've never seen
> /* Warn if two unsigned values are being compared in a size
> larger than their original size, and one (and only one) is the
> result of a `~' operator. This comparison will always fail.
> Also warn if one operand is a constant, and the constant
> does not have all bits set that are set in the ~ operand
> when it is extended. */
> which results in:
> warning (0, "comparison of promoted ~unsigned with constant");
That is indeed a very interesting warning.
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