fix zero-dimensional reverse! (#58086)

Also changed the check to compare against the tuple argument, instead of
against the method static parameter for the tuple length. Should be
better when the length isn't known at compile time.

Fixes #58085

Author: nsajko

base/arraymath.jl

@@ -72,12 +72,12 @@ _reverse!(A::AbstractArray{<:Any,N}, ::Colon) where {N} = _reverse!(A, ntuple(id
 _reverse!(A, dim::Integer) = _reverse!(A, (Int(dim),))
 _reverse!(A, dims::NTuple{M,Integer}) where {M} = _reverse!(A, Int.(dims))
 function _reverse!(A::AbstractArray{<:Any,N}, dims::NTuple{M,Int}) where {N,M}
+    dims === () && return A # nothing to reverse
     dimrev = ntuple(k -> k in dims, Val{N}()) # boolean tuple indicating reversed dims
 
     if N < M || M != sum(dimrev)
         throw(ArgumentError("invalid dimensions $dims in reverse!"))
     end
-    M == 0 && return A # nothing to reverse
 
     # swapping loop only needs to traverse ≈half of the array
     halfsz = ntuple(k -> k == dims[1] ? size(A,k) ÷ 2 : size(A,k), Val{N}())

test/arrayops.jl

@@ -1761,6 +1761,12 @@ end
     end
 end
 
+@testset "reverse zero dims" begin
+    a = fill(3)
+    @test a == reverse(a)
+    @test a === reverse!(a)
+end
+
 @testset "isdiag, istril, istriu" begin
     # Scalar
     @test isdiag(3)