[PATCH] D45601: Warn on bool* to bool conversion

[Arthur O'Dwyer via Phabricator via cfe-commits]

Quuxplusone added inline comments.


================
Comment at: lib/Sema/SemaChecking.cpp:2623
+                QualType QT = Pointer->getType()->getPointeeType();
+                if (!QT.isNull() && QT->isBooleanType())
+                  // Warn on bool* to bool conversion.
----------------
efriedma wrote:
> Have you considered skipping the isBooleanType() check?  Passing any pointer to a function which expects a boolean parameter seems fundamentally suspicious.
We already know that LLVM itself passes pointers to functions in many places, and they're not bugs. I mean, this isn't the first time someone's proposed that pointer->bool conversions are evil. :)

I know this just came up on a mailing list somewhere recently (rsmith was involved in the rebuttal, as was I), but all I can find on Google is:
https://groups.google.com/a/isocpp.org/d/msg/std-proposals/a3g9qXFVGCs/Wj40qj48H3wJ
Anyway, the punch line I'm thinking of is something like
```
    FooBar *FB = ...;
    LLVMAssert(FB, "expected fb to be set");
```
but with whatever the real names are. Found a bunch of those when I wrote the diagnostic. And they're fairly solidly in the "not bugs" category.


https://reviews.llvm.org/D45601