Fix logic for empty sets and fast any.

Now logic in the Manopt universe is fixed again.

Author: kellertuer

src/plans/stopping_criterion.jl

@@ -1169,8 +1169,11 @@ end
 
 # `_fast_any(f, tup::Tuple)`` is functionally equivalent to `any(f, tup)`` but on Julia 1.10
 # this implementation is faster on heterogeneous tuples
+# for length zero -> return false
 @inline _fast_any(f, tup::Tuple{}) = false
+# for one-element tuples, evaluate that one element
 @inline _fast_any(f, tup::Tuple{T}) where {T} = f(tup[1])
+# for more than that -> finish fast, if the first is true end checks, otherwise continue with tail
 @inline function _fast_any(f, tup::Tuple)
     if f(tup[1])
         return true

test/plans/test_stopping_criteria.jl

@@ -48,7 +48,8 @@ end
         @test get_reason(sn) == ""
         @test !Manopt.indicates_convergence(sn) # since it might stop after 10 iterations
         @test repr(sn) == "StopWhenAny([$(repr(sn1)), $(repr(s3))])"
-        @test_broken Manopt._fast_any(x -> false, ())
+        # or over an empty set has to be false for any function
+        @test !Manopt._fast_any(x -> false, ())
 
         sn2 = StopAfterIteration(10) | s3
         @test get_stopping_criteria(sn)[1].max_iterations ==