Fix firstindex in replace_ref_begin_end (fixes #41630) (#41695)

Author: phipsgabler

base/views.jl

@@ -42,7 +42,7 @@ function replace_ref_begin_end_!(ex, withex)
                 n = 1
                 J = lastindex(ex.args)
                 for j = 2:J
-                    exj, used = replace_ref_begin_end_!(ex.args[j], (:($firstindex($S)),:($lastindex($S,$n))))
+                    exj, used = replace_ref_begin_end_!(ex.args[j], (:($firstindex($S,$n)),:($lastindex($S,$n))))
                     used_S |= used
                     ex.args[j] = exj
                     if isa(exj,Expr) && exj.head === :...

test/offsetarray.jl

@@ -801,3 +801,24 @@ end
     @test reshape(a, :) === a
     @test reshape(a, (:,)) === a
 end
+
+@testset "issue #41630: replace_ref_begin_end!/@view on offset-like arrays" begin
+    x = OffsetArray([1 2; 3 4], -10:-9, 9:10)  # 2×2 OffsetArray{...} with indices -10:-9×9:10
+
+    # begin/end with offset indices
+    @test (@view x[begin, 9])[] == 1
+    @test (@view x[-10, end])[] == 2
+    @test (@view x[-9, begin])[] == 3
+    @test (@view x[end, 10])[] == 4
+    @test (@view x[begin, begin])[] == 1
+    @test (@view x[begin, end])[] == 2
+    @test (@view x[end, begin])[] == 3
+    @test (@view x[end, end])[] == 4
+
+    # nested usages of begin/end
+    y = OffsetArray([-10, -9], (5,))
+    @test (@view x[begin, -y[end]])[] == 1
+    @test (@view x[y[begin], end])[] == 2
+    @test (@view x[end, -y[end]])[] == 3
+    @test (@view x[y[end], end])[] == 4
+end