[clang] [clang] Replace X && isa<Y>(X) with isa_and_nonnull<Y>(X). NFC (PR #94987)

[Donát Nagy via cfe-commits]

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@@ -302,7 +302,7 @@ void MangleContext::mangleBlock(const DeclContext *DC, const BlockDecl *BD,
     assert((isa<NamedDecl>(DC) || isa<BlockDecl>(DC)) &&
            "expected a NamedDecl or BlockDecl");
     if (isa<BlockDecl>(DC))
-      for (; DC && isa<BlockDecl>(DC); DC = DC->getParent())
+      for (; isa_and_nonnull<BlockDecl>(DC); DC = DC->getParent())
         (void) getBlockId(cast<BlockDecl>(DC), true);
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NagyDonat wrote:

Could you remove the line `if (isa<BlockDecl>(DC))` as well? It's completely redundant with the loop condition.

Although I see that this is a big automatic change, so perhaps it should be left for a separate change.

https://github.com/llvm/llvm-project/pull/94987