[PATCH] D38358: [analyzer] Fix autodetection of getSVal()'s type argument.

[Artem Dergachev via Phabricator via cfe-commits]

NoQ added a comment.

Whoops forgot to submit inline comments.



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Comment at: lib/StaticAnalyzer/Core/RegionStore.cpp:1404
+          // When trying to dereference a void pointer, read the first byte.
+          T = Ctx.CharTy;
+        }
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dcoughlin wrote:
> Nit: It seems a bit odd to read the first byte here since (unless I'm misunderstanding) this would never be triggered by actual C semantics, only by a checker. Did you consider just returning UnknownVal() in this case?
`UnknownVal` seems to be quite similar to assertion failure: in both cases we'd have to force the checker to specify `CharTy` explicitly. But assertions are better because the author of the checker would instantly know that he needs to specify the type, instead of never noticing the problem, or spending a lot of time in the debugger trying to understand why he gets an `UnknownVal`.


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Comment at: lib/StaticAnalyzer/Core/RegionStore.cpp:1408
     }
+    assert(!T.isNull() && "Unable to auto-detect binding type!");
+    assert(!T->isVoidType() && "Attempted to retrieve a void value!");
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dcoughlin wrote:
> I think you missed handling the AllocaRegion case from the old version in your new version. This means the assert will fire on the following when core.alpha is enabled:
> ```
> void foo(void *dest) {
>   void *src = __builtin_alloca(5);
>   memcpy(dest, src, 1);
> }
> ```
Nice one!

Always been that way though. In the old code, if `AllocaRegion` is supplied and no type is explicitly specified, `cast<SymbolicRegion>(MR)` would fail. Also `ElementRegion` is created in both old and new code if the type was specified.


https://reviews.llvm.org/D38358