[cfe-commits] r135222 - in /cfe/trunk: lib/Sema/SemaExpr.cpp test/SemaCXX/expressions.cpp

[Douglas Gregor]

On Jul 14, 2011, at 5:19 PM, Chandler Carruth wrote:

> On Thu, Jul 14, 2011 at 5:04 PM, Douglas Gregor <dgregor at apple.com> wrote:
> IMO, the right approach would be to suppress this warning when the constant value itself was instantiated from something... although that's rather trickier to implement.
> 
> I don't disagree with your premise.... but it does seem much trickier to implement. We don't have the nice type sugar in non-types to indicate that substitution took place. Is it worth adding that for this? Are there other good reasons to add it?

Yes, there are other reasons to add it. For one, it helps us track the correlation between instantiation and definition, but it also leads to a more sane AST for instantiations that's also consistent with the way we handle substitutions of template type and template template parameters. See, for example, the FIXME in Sema::BuildExpressionFromIntegralTemplateArgument regarding enumeration values.

> (Also, this patch seems a strict improvement, and we can add the refined checking you're mentioning as a second step? I'd like to avoid the false positives we were seeing with the previous incarnation)


Unless I misunderstood the effect, it also eliminates some true positives as well, in code like

	if (dependent-thing && 0)

so it's not strictly an improvement. I'm not asking to revert it---the patch probably does more good than harm---but I do believe that there is a better solution.
	- Doug
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