fix #29208, incorrect Union{} result from type intersection (#29380)

also fixes #29357 (cherry picked from commit 6794778)
JuliaLang · Sep 30, 2018 · 8cc9136 · 8cc9136
1 parent 63384f3
commit 8cc9136
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Showing 2 changed files with 19 additions and 7 deletions.
diff --git a/src/subtype.c b/src/subtype.c
@@ -1379,13 +1379,15 @@ static jl_value_t *intersect_var(jl_tvar_t *b, jl_value_t *a, jl_stenv_t *e, int
     if (param == 2) {
         jl_value_t *ub = R ? intersect_ufirst(a, bb->ub, e, d) : intersect_ufirst(bb->ub, a, e, d);
         JL_GC_PUSH2(&ub, &root);
-        save_env(e, &root, &se);
-        int issub = subtype_in_env(bb->lb, ub, e);
-        restore_env(e, root, &se);
-        free(se.buf);
-        if (!issub) {
-            JL_GC_POP();
-            return jl_bottom_type;
+        if (!jl_has_free_typevars(ub) && !jl_has_free_typevars(bb->lb)) {
+            save_env(e, &root, &se);
+            int issub = subtype_in_env(bb->lb, ub, e);
+            restore_env(e, root, &se);
+            free(se.buf);
+            if (!issub) {
+                JL_GC_POP();
+                return jl_bottom_type;
+            }
         }
         if (ub != (jl_value_t*)b) {
             if (jl_has_free_typevars(ub)) {

diff --git a/test/subtype.jl b/test/subtype.jl
@@ -955,6 +955,16 @@ function test_intersection()
     @testintersect(Tuple{Ref{Ref{T}} where T, Ref},
                    Tuple{Ref{T}, Ref{T}} where T,
                    Tuple{Ref{Ref{T}}, Ref{Ref{T}}} where T)
+    # issue #29208
+    @testintersect(Tuple{Ref{Ref{T}} where T, Ref{Ref{Int}}},
+                   Tuple{Ref{T}, Ref{T}} where T,
+                   Tuple{Ref{Ref{Int}}, Ref{Ref{Int}}})
+    @testintersect(Tuple{Vector{Pair{K,V}}, Vector{Pair{K,V}}} where K where V,
+                   Tuple{(Array{Pair{Ref{_2},_1},1} where _2 where _1),
+                         Array{Pair{Ref{Int64},Rational{Int64}},1}},
+                   Tuple{Vector{Pair{Ref{Int64},Rational{Int64}}},
+                         Vector{Pair{Ref{Int64},Rational{Int64}}}})
+    @testintersect(Vector{>:Missing}, Vector{Int}, Union{})
 
     # issue #23685
     @testintersect(Pair{Type{Z},Z} where Z,