From fc5470009502d5469fe5dbb58a52f0f659636ca2 Mon Sep 17 00:00:00 2001
From: N5N3 <2642243996@qq.com>
Date: Sat, 24 Sep 2022 22:32:19 +0800
Subject: [PATCH] Set `intersection = 1` during `intersect_sub_datatype`
 (#46882)

(cherry picked from commit e6d99792e6dd0cffe41e98b8d642cf07e64364c5)
---
 src/subtype.c   | 2 +-
 test/subtype.jl | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/subtype.c b/src/subtype.c
index 76fcab4c0a3010..d79185d50f301b 100644
--- a/src/subtype.c
+++ b/src/subtype.c
@@ -2780,7 +2780,7 @@ static jl_value_t *intersect_sub_datatype(jl_datatype_t *xd, jl_datatype_t *yd,
         JL_GC_PUSHARGS(env, envsz);
         jl_stenv_t tempe;
         init_stenv(&tempe, env, envsz);
-        tempe.ignore_free = 1;
+        tempe.intersection = tempe.ignore_free = 1;
         if (subtype_in_env(isuper, super_pattern, &tempe)) {
             jl_value_t *wr = wrapper;
             int i;
diff --git a/test/subtype.jl b/test/subtype.jl
index fd5e3156493f17..2ff887a435cc8e 100644
--- a/test/subtype.jl
+++ b/test/subtype.jl
@@ -1885,3 +1885,10 @@ let A = Tuple{Array{Pair{T, JT} where JT<:Ref{T}, 1} where T, Vector},
     @test_broken I <: A
     @test_broken !Base.has_free_typevars(I)
 end
+
+#issue #46871
+struct A46871{T, N, M} <: AbstractArray{T, N} end
+struct B46871{T, N} <: Ref{A46871{T, N, N}} end
+for T in (B46871{Int, N} where {N}, B46871{Int}) # intentional duplication
+    @testintersect(T, Ref{<:AbstractArray{<:Real, 3}}, B46871{Int, 3})
+end