r177137 - [analyzer] Teach trackNullOrUndef to look through ternary operators

[Jordan Rose]

On Mar 14, 2013, at 18:15 , Anna Zaks <ganna at apple.com> wrote:

> +  // Peel off the ternary operator.
> +  if (const ConditionalOperator *CO = dyn_cast<ConditionalOperator>(S)) {
> +    ProgramStateRef State = N->getState();
> +    SVal CondVal = State->getSVal(CO->getCond(), N->getLocationContext());
> +    if (State->isNull(CondVal).isConstrainedTrue()) {
> +      S = CO->getTrueExpr();
> +    } else {
> +      assert(State->isNull(CondVal).isConstrainedFalse());
> +      S =  CO->getFalseExpr();
> +    }
> +  }

I'm not sure this is good enough; we don't know that the CO->getCond() is still live if the ternary operator is, say, inside of a cast (which would make the assertion fire). The "right" way to do this is to back up along the graph until we (a) get to the ternary operator node, or (b) get to the block edge that tells us which path was chosen.

Jordan
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