[PATCH] D125318: [analyzer] Add UnarySymExpr

[Gabor Marton via Phabricator via cfe-commits]

martong added inline comments.


================
Comment at: clang/lib/StaticAnalyzer/Core/SimpleSValBuilder.cpp:107
+    return makeNonLoc(X.castAs<nonloc::SymbolVal>().getSymbol(), UO_Not,
+                      X.getType(Context));
   default:
----------------
steakhal wrote:
> martong wrote:
> > steakhal wrote:
> > > I'm not sure if we should rely on `SVal::getType()`. I think the calling context should pass the type along here.
> > Good point. One example where the type of the SVal is different than the type of the UnaryExpr is here:
> > ```
> > void test_x(int x, long y) {
> >   x = y;  // $x has `long` type
> >   -x;     // the UnaryExpr `-x` has `int` type
> > }
> > ```
> > Note that if we use `support-symbolic-integer-casts=true` then there is no such type mismatch because there is in implicit cast modeled at `x = y`, thus $x type is correctly `int`.
> > 
> > Anyway, I am going to update evalMinus and evalComplement to take an additional QualType parameter.
> Please add this test with both scenarios with `support-symbolic-integer-casts`. D125532 will help in demonstrating this.
Ahh, unfortunately, if we use the type of the AST's `UnaryExpr` instead of the operand `SVal` then we will end up crashing the constraint solver, because of the missing SymbolCast below:
```
void crash(int b, long c) {
  b = c;
  if (b > 0)                            // $b  is long
    if(-b) // should not crash here     // $-b is int
      ;
  // SymbolicRangeInferrer
  // takes the negated range of $-b (with type int)
  //     getRangeForNegatedSub
  // and takes the range of $b (with type long) and tries to intersect them.
  //     RangeSet VisitSymExpr(SymbolRef Sym)
}
```
This manifests in the child patch, because that's where we add the support of UnarySymExpr to the solver, so I add a test case there.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D125318/new/

https://reviews.llvm.org/D125318