Re-add a fast-path to obviously_unequal to re-fix #22624

Author: martinholters

src/subtype.c

@@ -220,6 +220,9 @@ static int obviously_unequal(jl_value_t *a, jl_value_t *b)
     if ((jl_is_concrete_type(a) || jl_is_concrete_type(b)) &&
         jl_type_equality_is_identity(a, b))
         return 1;
+    if ((jl_is_concrete_type(a) && jl_is_typevar(b)) ||
+        (jl_is_concrete_type(b) && jl_is_typevar(a)))
+        return 1;
     if (jl_is_unionall(a)) a = jl_unwrap_unionall(a);
     if (jl_is_unionall(b)) b = jl_unwrap_unionall(b);
     if (jl_is_datatype(a)) {

test/core.jl

@@ -218,7 +218,6 @@ struct D21923{T,N}; v::D21923{T}; end
 @test fieldtype(D21923, 1) == D21923
 
 # issue #22624, more circular definitions
-#= broken again :-(
 struct T22624{A,B,C}; v::Vector{T22624{Int64,A}}; end
 let elT = T22624.body.body.body.types[1].parameters[1]
     @test elT == T22624{Int64, T22624.var, C} where C
@@ -227,7 +226,6 @@ let elT = T22624.body.body.body.types[1].parameters[1]
     @test elT2.body.types[1].parameters[1] === elT2
     @test Base.isconcretetype(elT2.body.types[1])
 end
-=#
 
 # issue #3890
 mutable struct A3890{T1}