[PATCH] D103938: Diagnose -Wunused-value in constant evaluation context

[Richard Smith - zygoloid via Phabricator via cfe-commits]

rsmith added a comment.

This will diagnose unused values in unreachable code in constant-evaluated contexts; that doesn't seem quite right. For example, in:

  void f() {
    new double[false ? (1, 2) : 3][false ? (1, 2) : 3];
  }

... we'll diagnose that the `1` is unused in only one of the two array bounds, because one of them is a constant-evaluated context and the other is not.

I'd suggest we start by adding a separate `DiagIfReachable` function that does the same thing as `DiagRuntimeBehavior` except without the context check, with the intent to eventually refine it to check for reachability even in expressions for which we don't build a CFG (eg, in the initializer of a global or in a constant expression).


Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D103938