From 0824c1bca3f7b1e770178086f4991896cfcc291b Mon Sep 17 00:00:00 2001
From: Martin Holters <martin.holters@hsu-hh.de>
Date: Wed, 1 Sep 2021 19:43:37 +0200
Subject: [PATCH] Avoid impossible unionall normalization (#42003)

If the unionall bounds are inconsistent with the wrapper's bound, avoid
throwing due to an impossible type instantiation.

(cherry picked from commit b5b0684ec0a66c1bd50e75c25c724c20526bb702)
---
 src/jltypes.c | 11 +++++++++--
 test/core.jl  |  3 +++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/jltypes.c b/src/jltypes.c
index c4f5a1aff88bd..43171ee332e87 100644
--- a/src/jltypes.c
+++ b/src/jltypes.c
@@ -1326,8 +1326,15 @@ jl_value_t *normalize_unionalls(jl_value_t *t)
             u = (jl_unionall_t*)t;
         }
 
-        if (u->var->lb == u->var->ub || may_substitute_ub(body, u->var))
-            t = jl_instantiate_unionall(u, u->var->ub);
+        if (u->var->lb == u->var->ub || may_substitute_ub(body, u->var)) {
+            JL_TRY {
+                t = jl_instantiate_unionall(u, u->var->ub);
+            }
+            JL_CATCH {
+                // just skip normalization
+                // (may happen for bounds inconsistent with the wrapper's bounds)
+            }
+        }
     }
     JL_GC_POP();
     return t;
diff --git a/test/core.jl b/test/core.jl
index 56ddfb42e10f1..74edc7cddf7f4 100644
--- a/test/core.jl
+++ b/test/core.jl
@@ -7584,3 +7584,6 @@ let S = Tuple{Tuple{Tuple{K, UInt128} where K<:Tuple{Int64}, Int64}},
     @test pointer_from_objref(T) === pointer_from_objref(S)
     @test isbitstype(T)
 end
+
+# avoid impossible normalization (don't try to form Tuple{Complex{String}} here)
+@test Tuple{Complex{T} where String<:T<:String} == Tuple{Complex{T} where String<:T<:String}