fix #31993, intersection of Type{Vec} and Type{<:Vec{T}}

Author: JeffBezanson

src/subtype.c

@@ -573,6 +573,11 @@ static int var_gt(jl_tvar_t *b, jl_value_t *a, jl_stenv_t *e, int param)
         return 0;
     bb->lb = simple_join(bb->lb, a);
     assert(bb->lb != (jl_value_t*)b);
+    if (jl_is_typevar(a)) {
+        jl_varbinding_t *aa = lookup(e, (jl_tvar_t*)a);
+        if (aa && !aa->right && bb->depth0 != aa->depth0 && param == 2 && var_outside(e, b, (jl_tvar_t*)a))
+            return subtype_left_var(aa->ub, aa->lb, e);
+    }
     return 1;
 }
 
@@ -960,7 +965,7 @@ static int subtype(jl_value_t *x, jl_value_t *y, jl_stenv_t *e, int param)
             if (xr) {
                 if (yy) record_var_occurrence(yy, e, param);
                 if (yr) {
-                    if (xx) record_var_occurrence(xx, e, param);
+                    record_var_occurrence(xx, e, param);
                     return subtype(xx->lb, yy->ub, e, 0);
                 }
                 return var_lt((jl_tvar_t*)x, y, e, param);
@@ -1410,6 +1415,7 @@ static int subtype_in_env(jl_value_t *x, jl_value_t *y, jl_stenv_t *e)
     e2.vars = e->vars;
     e2.intersection = e->intersection;
     e2.ignore_free = e->ignore_free;
+    e2.invdepth = e->invdepth;
     e2.envsz = e->envsz;
     e2.envout = e->envout;
     e2.envidx = e->envidx;
@@ -1624,6 +1630,8 @@ static int subtype_in_env_existential(jl_value_t *x, jl_value_t *y, jl_stenv_t *
 {
     jl_varbinding_t *v = e->vars;
     int len = 0;
+    if (x == jl_bottom_type || y == (jl_value_t*)jl_any_type)
+        return 1;
     while (v != NULL) {
         len++;
         v = v->prev;

test/subtype.jl

@@ -1529,3 +1529,16 @@ end
                Tuple{Type{<:SA{N, L}}, Type{<:SA{N, L}}} where {N,L},
                # TODO: this could be narrower
                Tuple{Type{SA{2, L}}, Type{SA{2, 16}}} where L)
+
+# issue #31993
+@testintersect(Tuple{Type{<:AbstractVector{T}}, Int} where T,
+               Tuple{Type{Vector}, Any},
+               Union{})
+@testintersect(Tuple{Type{<:AbstractVector{T}}, Int} where T,
+               Tuple{Type{Vector{T} where Int<:T<:Int}, Any},
+               Tuple{Type{Vector{Int}}, Int})
+let X = LinearAlgebra.Symmetric{T, S} where S<:(AbstractArray{U, 2} where U<:T) where T,
+    Y = Union{LinearAlgebra.Hermitian{T, S} where S<:(AbstractArray{U, 2} where U<:T) where T,
+              LinearAlgebra.Symmetric{T, S} where S<:(AbstractArray{U, 2} where U<:T) where T}
+    @test X <: Y
+end