[PATCH] D33672: [analyzer] INT50-CPP. Do not cast to an out-of-range enumeration checker

[Umann Kristóf via Phabricator via cfe-commits]

Szelethus added inline comments.


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Comment at: lib/StaticAnalyzer/Checkers/EnumCastOutOfRangeChecker.cpp:96
+  // Get the value of the expression to cast.
+  const auto ValueToCastOptional =
+      C.getSVal(CE->getSubExpr()).getAs<DefinedOrUnknownSVal>();
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Szelethus wrote:
> ZaMaZaN4iK wrote:
> > lebedev.ri wrote:
> > > ZaMaZaN4iK wrote:
> > > > lebedev.ri wrote:
> > > > > ZaMaZaN4iK wrote:
> > > > > > lebedev.ri wrote:
> > > > > > > ZaMaZaN4iK wrote:
> > > > > > > > aaron.ballman wrote:
> > > > > > > > > `const auto *`
> > > > > > > > Why do we need this change here? If I understand correctly, with `const auto*` we also need change initializer to `C.getSVal(CE->getSubExpr()).getAs<DefinedOrUnknownSVal>().getPointer()`. But I don't understand why we need this.
> > > > > > > Is `ValueToCastOptional` a pointer, a reference, or just an actual `DefinedOrUnknownSVal`? I can't tell.
> > > > > > > (sidenote: would be great to have a clang-tidy check for this.)
> > > > > > `ValueToCastOptional` is `llvm::Optional<DefinedOrUnknownSVal>`
> > > > > See, all my guesses were wrong. That is why it should not be `auto` at all.
> > > > I don't agree with you for this case. Honestly it's like a yet another holywar question. If we are talking only about this case - here you can see `getAs<DefinedOrUnknownSVal>` part of the expression. this means clearly (at least for me) that we get something like `DefinedOrUnknownSVal`. What we get? I just press hotkey in my favourite IDE/text editor and see that `getAs` returns `llvm::Optional<DefinedOrUnknownSVal>`. From my point of view it's clear enough here.
> > > > 
> > > > If we are talking more generally about question "When should we use `auto` at all? " - we can talk, but not here, I think :)
> > > https://llvm.org/docs/CodingStandards.html#use-auto-type-deduction-to-make-code-more-readable comes to mind.
> > > > What we get? I just press hotkey in my favourite IDE/text editor and see that getAs returns llvm::Optional<DefinedOrUnknownSVal>
> > > Which hotkey do i need to press to see this here, in the phabricator?
> > > 
> > > This really shouldn't be `auto`, if you have to explain that in the variable's name, justify it in review comments.
> > Ok, didn't know about such LLVM coding standard. Of course, with this information I will fix using `auto` here. Thank you.
> Actually, I disagree. In the Static Analyzer we use `auto` if the return type is in the name of the expression, and `getAs` may fail, so it returns an `Optional`. In the case where a nullptr may be returned to signal failure, `auto *` is used, so I believe that `auto` is appropriate here.
But don't change it back now, it doesn't matter a whole lot :D


https://reviews.llvm.org/D33672