From ed3a0c8336f3b7e2a72fb2b2ba80b7a40f639d41 Mon Sep 17 00:00:00 2001
From: Jeff Bezanson <jeff.bezanson@gmail.com>
Date: Mon, 29 Jul 2019 22:05:07 -0400
Subject: [PATCH] fix #32703, bad ambiguity error

caused by 52838478aabe93120a0152ec5da733c9d8f0c39a
---
 src/subtype.c   |  8 ++++++++
 test/subtype.jl | 16 ++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/src/subtype.c b/src/subtype.c
index b4ddb8f0c1de5..153eed2648c70 100644
--- a/src/subtype.c
+++ b/src/subtype.c
@@ -3032,6 +3032,14 @@ static jl_value_t *intersect_types(jl_value_t *x, jl_value_t *y, int emptiness_o
     jl_stenv_t e;
     if (obviously_disjoint(x, y, 0))
         return jl_bottom_type;
+    if (jl_is_dispatch_tupletype(x) || jl_is_dispatch_tupletype(y)) {
+        if (jl_subtype(x, y))
+            return x;
+        else if (jl_subtype(y, x))
+            return y;
+        else
+            return jl_bottom_type;
+    }
     init_stenv(&e, NULL, 0);
     e.intersection = e.ignore_free = 1;
     e.emptiness_only = emptiness_only;
diff --git a/test/subtype.jl b/test/subtype.jl
index a8b00b57cc2f1..1fbe442774665 100644
--- a/test/subtype.jl
+++ b/test/subtype.jl
@@ -1632,3 +1632,19 @@ end
 @testintersect(Tuple{Type{T} where T<:(S32488{Tuple{_A}, Int64, 1, _A} where _A), Tuple{Vararg{Int64, D}} where D},
                Tuple{Type{S32488{S, T, N, L}}, Tuple{Vararg{T, L}}} where L where N where T where S,
                Tuple{Type{S32488{Tuple{L},Int64,1,L}},Tuple{Vararg{Int64,L}}} where L)
+
+# issue #32703
+struct Str{C} <: AbstractString
+end
+struct CSE{X}
+end
+const UTF16CSE = CSE{1}
+const UTF16Str = Str{UTF16CSE}
+const ASCIIStr = Str{CSE{2}}
+c32703(::Type{<:Str{UTF16CSE}}, str::AbstractString) = 42
+c32703(::Type{<:Str{C}}, str::Str{C}) where {C<:CSE} = str
+
+@testintersect(Tuple{Type{UTF16Str},ASCIIStr},
+               Tuple{Type{<:Str{C}}, Str{C}} where {C<:CSE},
+               Union{})
+@test c32703(UTF16Str, ASCIIStr()) == 42