[clang] [clang] Migrate away from PointerUnion::dyn_cast (NFC) (PR #228673)

[Kazu Hirata via cfe-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/228673

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>

Literal migration would result in dyn_cast_if_present (see the
definition of PointerUnion::dyn_cast), but this patch uses dyn_cast.
Note that:

    assert(ClassTemplSpec->getSpecializedTemplate() && ...);

a few lines above guarantees that
ClassTemplSpec->getSpecializedTemplateOrPartial() is nonnull.

Assisted-by: Antigravity


>From 4e07c9e9c90691f43826e594b01249fa9548b816 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Sun, 20 Sep 2026 15:29:53 -0700
Subject: [PATCH] [clang] Migrate away from PointerUnion::dyn_cast (NFC)

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>

Literal migration would result in dyn_cast_if_present (see the
definition of PointerUnion::dyn_cast), but this patch uses dyn_cast.
Note that:

    assert(ClassTemplSpec->getSpecializedTemplate() && ...);

a few lines above guarantees that
ClassTemplSpec->getSpecializedTemplateOrPartial() is nonnull.

Assisted-by: Antigravity
---
 clang/lib/Sema/SemaTemplateInstantiate.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 06ea12ca7bd73b..036642f22bd8cb 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -257,8 +257,8 @@ HandleClassTemplateSpec(const ClassTemplateSpecializationDecl *ClassTemplSpec,
     // specialization, as the ClassTemplateSpecializationDecl's
     // DeclContext/LexicalDeclContext will be for the primary template.
     if (auto *InstFromPartialTempl =
-            ClassTemplSpec->getSpecializedTemplateOrPartial()
-                .dyn_cast<ClassTemplatePartialSpecializationDecl *>())
+            dyn_cast<ClassTemplatePartialSpecializationDecl *>(
+                ClassTemplSpec->getSpecializedTemplateOrPartial()))
       return Response::ChangeDecl(
           InstFromPartialTempl->getLexicalDeclContext());
   }