core tests broken by #39875

[vtjnash]

#39875 broke the core tests (outside of CI), though I don't understand how nobody has noticed since March. We thus must fix these tests and the breakage caused.

core                          (2) |         failed at 2021-11-08T15:28:28.538                                                                                                                                                            
Test Failed at /data/vtjnash/julia1/test/core.jl:3521                                                                                                                                                                                    
  Expression: (Vararg{Int, N} where N <: T) where T                                                                                                                                                                                      
    Expected: ErrorException                                                                                                                                                                                                             
  No exception thrown                                                                                                                                                                                                                    
Test Failed at /data/vtjnash/julia1/test/core.jl:3522                                                                                                                                                                                    
  Expression: Vararg{Int, N} where N <: Integer                                                                                                                                                                                          
    Expected: ErrorException                                                                                                                                                                                                             
  No exception thrown                                                                                                                                                                                                                    
Test Failed at /data/vtjnash/julia1/test/core.jl:3523                                                                                                                                                                                    
  Expression: Vararg{Int, N} where N >: Integer                                                                                                                                                                                          
    Expected: ErrorException                                                                                                                                                                                                             
  No exception thrown                                                                                                                                                                                                                    
                                                                                                                                                                                                                                         

[martinholters]

With --depwarn=error:

julia> Vararg{Int, N} where N>:Integer
ERROR: Wrapping `Vararg` directly in UnionAll is deprecated (wrap the tuple instead).

So that's why this has gone unnoticed.

[DilumAluthge]

One option would be to run these tests in a Julia subprocess that we start with the --depwarn=error flag.

[martinholters]

That's what happens with e.g. make test anyway, making these tests pass under the usual circumstances. But IIUC it's not what they were intended to test. They were testing for this error:

julia> Vararg{Int, N} where N>:Integer
ERROR: TypeVar in Vararg length must have bounds Union{} and Any

Which went away between 1.5 and 1.6. So I guess we can just delete the tests.

[martinholters]

Ah, they've already been deleted in 1.6 by d06bab0, the backport of #39875, which itself did not delete these tests but in retrospect, it probably should have.

[staticfloat]

@JeffBezanson can you confirm that these tests should be deleted?