From fda85b3f4a58d55364b0691445f93bed4ecd0b9d Mon Sep 17 00:00:00 2001
From: Neven Sajko <s@purelymail.com>
Date: Wed, 27 Aug 2025 19:48:46 +0200
Subject: [PATCH] `getindex(::Array, ::Colon)`: typeassert `::Int` to help type
 inference

Fix a regression where abstract return type inference of
`getindex(::Array, ::Colon)` used to produce `Any` after Julia v1.11.
---
 base/array.jl    | 2 +-
 test/arrayops.jl | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/base/array.jl b/base/array.jl
index d62436ca30497..33024aef07a89 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -954,7 +954,7 @@ end
 getindex(a::Array, r::AbstractUnitRange{Bool}) = getindex(a, to_index(r))
 
 function getindex(A::Array, c::Colon)
-    lI = length(A)
+    lI = length(A)::Int
     X = similar(A, lI)
     if lI > 0
         unsafe_copyto!(X, 1, A, 1, lI)
diff --git a/test/arrayops.jl b/test/arrayops.jl
index f9c592e672973..e1588263e3f55 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -221,6 +221,12 @@ end
     end
 end
 
+@testset "return type inference of `getindex(::Array, ::Colon)`" begin
+    f = a -> a[:]
+    @test Vector === Base.infer_return_type(f, Tuple{Array})
+    @test Vector{Float32} === Base.infer_return_type(f, Tuple{Array{Float32}})
+end
+
 struct Z26163 <: AbstractArray{Int,0}; end
 Base.size(::Z26163) = ()
 Base.getindex(::Z26163) = 0