[AST] Migrate away from PointerUnion::dyn_cast (NFC)

[kazutakahirata]

Note that PointerUnion::dyn_cast has been soft deprecated in
PointerUnion.h:

// FIXME: Replace the uses of is(), get() and dyn_cast() with
// isa, cast and the llvm::dyn_cast

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 563c7c5
Author: Kazu Hirata [email protected]
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.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Kazu Hirata (kazutakahirata)

Changes

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 563c7c5
Author: Kazu Hirata <[email protected]>
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.

---

Full diff: https://github.com/llvm/llvm-project/pull/125379.diff

1 Files Affected:

• (modified) clang/include/clang/AST/ExprCXX.h (+1-1)

diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index 0b6c8cfb163c958..98ba2bb41bb54d9 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -5040,7 +5040,7 @@ class CXXParenListInitExpr final
   }
 
   const FieldDecl *getInitializedFieldInUnion() const {
-    return ArrayFillerOrUnionFieldInit.dyn_cast<FieldDecl *>();
+    return dyn_cast_if_present<FieldDecl *>(ArrayFillerOrUnionFieldInit);
   }
 
   child_range children() {