[PATCH] D24507: Add attribute for return values that shouldn't be cast to bool

Anna Zaks via cfe-commits cfe-commits at lists.llvm.org
Tue Sep 20 11:14:14 PDT 2016

zaks.anna added inline comments.

Comment at: test/Analysis/ReturnNonBoolTest.c:67
@@ +66,3 @@
+  if (rc < 0)
+    // error handling
How about addressing this as follows: in checkBranchCondition, you check for any comparisons of the tracked value other than comparisons to bool. If you see such a comparison, you assume that the error handling has occurred and remove the symbol from the set of tracked symbols. This will ensure that any code after the cleansing condition (error handling) can cast the return value to bool. 

The warning will still get triggered if the error handling is **after** the comparison to bool. That could be avoided as well, but the solution would be more complicated. I am thinking something along the lines of tracking all comparisons until the symbol goes out of scope. For each symbol, you'd track it's state (for example, "performedErrorHandling  | comparedToBoolAndNoErrorHandling | notSeen"). You can draw the automaton to see what the transitions should be. When the symbol goes out of scope, you'd check if it's state is "comparedToBoolAndNoErrorHandling". Further, we'd need to walk up the path to find the location where we compared the symbol and use that for error reporting.



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