From 332cd2c6c03c32bd60b95757f4fc9b419033c644 Mon Sep 17 00:00:00 2001
From: Jeff Bezanson <jeff.bezanson@gmail.com>
Date: Fri, 25 Aug 2017 10:54:04 -0400
Subject: [PATCH] fix #23430, counter overflow in subtyping

Ref #23447
(cherry picked from commit 4d4b9ce06de296df3d51646c66192681ca1a8788)
---
 src/subtype.c   |  5 +++--
 test/subtype.jl | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/subtype.c b/src/subtype.c
index 98b44bc6d54980..b636d77bba83dd 100644
--- a/src/subtype.c
+++ b/src/subtype.c
@@ -420,9 +420,10 @@ static int subtype_ufirst(jl_value_t *x, jl_value_t *y, jl_stenv_t *e)
 static void record_var_occurrence(jl_varbinding_t *vb, jl_stenv_t *e, int param)
 {
     if (vb != NULL && param) {
-        if (param == 2 && e->invdepth > vb->depth0)
+        // saturate counters at 2; we don't need values bigger than that
+        if (param == 2 && e->invdepth > vb->depth0 && vb->occurs_inv < 2)
             vb->occurs_inv++;
-        else
+        else if (vb->occurs_cov < 2)
             vb->occurs_cov++;
     }
 }
diff --git a/test/subtype.jl b/test/subtype.jl
index 0f391208f98922..3e2fcab5d01d12 100644
--- a/test/subtype.jl
+++ b/test/subtype.jl
@@ -1130,3 +1130,22 @@ end
 @testintersect(Tuple{DataType, Any},
                Tuple{Type{T}, Int} where T,
                Tuple{DataType, Int})
+
+# issue #23430
+@test [0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.;
+       0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.;
+       0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.;
+       0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.;
+       0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.; 0 0.;
+       0 0.; 0 0.; 0 0.; 0 0.] isa Matrix{Float64}
+@test !(Tuple{Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,
+              Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,
+              Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,
+              Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,
+              Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,
+              Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,
+              Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,
+              Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,
+              Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,
+              Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64,
+              Int64,Float64,Int64,Float64,Int64,Float64,Int64,Float64} <: (Tuple{Vararg{T}} where T<:Number))