[PATCH] D71714: [Sema] Fix -Warray-bounds false negative when casting an out-of-bounds array item

[Ilya Mirsky via Phabricator via cfe-commits]

ilya marked 4 inline comments as done.
ilya added inline comments.


================
Comment at: clang/lib/Sema/SemaChecking.cpp:13384
       case Stmt::MemberExprClass: {
         expr = cast<MemberExpr>(expr)->getBase();
         break;
----------------
rsmith wrote:
> ilya wrote:
> > rsmith wrote:
> > > Hmm, don't we need to do different things for dot and arrow in this case?
> > There are several test cases for an out of bounds access on an array member using dot and arrow operators in array-bounds.cpp. Do you have a specific test case for which you think the code is broken?
> > There are several test cases for an out of bounds access on an array member using dot and arrow operators in array-bounds.cpp. Do you have a specific test case for which you think the code is broken?
> 
> Sure. There's a false negative for this:
> 
> ```
> struct A { int n; };
> A *a[4];
> int *n = &a[4]->n;
> ```
> 
> ... because we incorrectly visit the left-hand side of the `->` with `AllowOnePastEnd == 1`. The left-hand side of `->` is subject to lvalue-to-rvalue conversion, so can't be one-past-the-end regardless of the context in which the `->` appears.
> ... because we incorrectly visit the left-hand side of the -> with AllowOnePastEnd == 1. The left-hand side of -> is subject to lvalue-to-rvalue conversion, so can't be one-past-the-end regardless of the context in which the -> appears.

Thanks for clarifying. So basically we don't want to allow one-past-end for MemberExpr?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71714/new/

https://reviews.llvm.org/D71714