[AST] Migrate away from PointerUnion::dyn_cast (NFC) (#125379)
Note that PointerUnion::dyn_cast has been soft deprecated in
PointerUnion.h:
// FIXME: Replace the uses of is(), get() and dyn_cast() with
// isa<T>, cast<T> and the llvm::dyn_cast<T>
This patch migrates the use of PointerUnion::dyn_cast to
dyn_cast_if_present because the non-const variant of
getInitializedFieldInUnion is known to encounter null in
ArrayFillerOrUnionFieldInit. See:
commit
563c7c5539f05e7f8cbb42565c1f24466019f38b
Author: Kazu Hirata <kazu@google.com>
Date: Sat Jan 25 14:05:01 2025 -0800
FWIW, I am not aware of any test case in check-clang that triggers
null here.