fix #23685, incorrect empty intersection with identity convert meth…

…od (#23700)
JuliaLang · Sep 14, 2017 · 1001320 · 1001320
1 parent 6153f97
commit 1001320
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Showing 3 changed files with 31 additions and 0 deletions.
diff --git a/src/subtype.c b/src/subtype.c
@@ -1773,6 +1773,14 @@ static jl_value_t *intersect_invariant(jl_value_t *x, jl_value_t *y, jl_stenv_t
         flip_vars(e);
         return ii;
     }
+    /*
+      TODO: This is a band-aid for issue #23685. A better solution would be to
+      first normalize types so that all `where` expressions in covariant position
+      are pulled out to the top level.
+    */
+    if ((jl_is_typevar(x) && !jl_is_typevar(y) && lookup(e, (jl_tvar_t*)x) == NULL) ||
+        (jl_is_typevar(y) && !jl_is_typevar(x) && lookup(e, (jl_tvar_t*)y) == NULL))
+        return ii;
     jl_value_t *root=NULL;
     jl_savedenv_t se;
     JL_GC_PUSH2(&ii, &root);

diff --git a/test/inference.jl b/test/inference.jl
@@ -1202,3 +1202,13 @@ g23024(TT::Tuple{DataType}) = f23024(TT[1], v23024)
 
 @test !Core.Inference.isconstType(Type{typeof(Union{})}) # could be Core.TypeofBottom or Type{Union{}} at runtime
 @test Base.return_types(supertype, (Type{typeof(Union{})},)) == Any[Any]
+
+# issue #23685
+struct Node23685{T}
+end
+@inline function update23685!(::Node23685{T}) where T
+    convert(Node23685{T}, Node23685{Float64}())
+end
+h23685 = Node23685{Float64}()
+f23685() = update23685!(h23685)
+@test f23685() === h23685
diff --git a/test/subtype.jl b/test/subtype.jl
@@ -271,6 +271,8 @@ function test_3()
     @test !issub(Tuple{Type{Vector{T}} where T, Vector{Float64}}, Tuple{Type{T}, T} where T)
     @test !issub(Tuple{Vector{Float64}, Type{Vector{T}} where T}, Tuple{T, Type{T}} where T)
     @test !issub(Tuple{Type{Ref{T}} where T, Vector{Float64}}, Tuple{Ref{T}, T} where T)
+
+    @test !issub(Tuple{Type{Ref{T}} where T, Ref{Float64}}, Tuple{Type{T},T} where T)
 end
 
 # level 4: Union
@@ -930,6 +932,17 @@ 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 #23685
+    @testintersect(Pair{Type{Z},Z} where Z,
+                   Pair{Type{Ref{T}} where T, Ref{Float64}},
+                   Bottom)
+    @testintersect(Tuple{Type{Z},Z} where Z,
+                   Tuple{Type{Ref{T}} where T, Ref{Float64}},
+                   !Bottom)
+    @test_broken typeintersect(Tuple{Type{Z},Z} where Z,
+                               Tuple{Type{Ref{T}} where T, Ref{Float64}}) ==
+        Tuple{Type{Ref{Float64}},Ref{Float64}}
 end
 
 function test_intersection_properties()