llvm-project

1299c87f - fix gh185270 consteval crash (#185511)

fix gh185270 consteval crash (#185511) replace `cast<VarDecl>` with `dyn_cast_or_null<VarDecl>` in `HandleImmediateInvocations` to avoid the crash when `ManglingContextDecl` is a `FunctionDecl` instead of a `VarDecl`. fixes #185270