Use :contiguous in N-index pyarray_offset

The Vararg method ignored the flag, and it is also the one picked for
1-D linear indexing, so sum over a contiguous vector didn't vectorise.

Author: Beforerr

src/Wrap/PyArray.jl

@@ -639,7 +639,13 @@ function pyarray_offset(x::PyArray{T,N,F}, i::Int) where {T,N,F}
 end
 
 function pyarray_offset(x::PyArray{T,N,F}, i::Vararg{Int,N}) where {T,N,F}
-    sum((i .- 1) .* x.strides)
+    # Strides from the size make the unit first stride a compile-time constant, so loops vectorise.
+    # Also matters for N == 1, where this method is picked over `pyarray_offset(x, i::Int)`.
+    if (:contiguous in F)
+        sum((i .- 1) .* Utils.size_to_fstrides(sizeof(pyarray_get_R(T)), x.size))
+    else
+        sum((i .- 1) .* x.strides)
+    end
 end
 
 function pyarray_load(::Type{T}, p::Ptr{R}) where {T,R}

test/Wrap.jl

@@ -100,6 +100,18 @@
         )
         @test_throws Exception PyArray(nd; array = false, buffer = true)
     end
+    @testset "contiguous 2D" begin
+        tb = pyimport("_testbuffer")
+        nd = tb.ndarray(
+            pylist(1:6),
+            shape = pylist([2, 3]),
+            format = "i",
+            flags = tb.ND_FORTRAN,
+        )
+        a = PyArray(nd; array = false)
+        @test a isa PyArray{Cint,2,(:linear,:contiguous)}
+        @test [a[i, j] for i = 1:2, j = 1:3] == reshape(1:6, 2, 3)
+    end
 end
 
 @testitem "PyDict" begin