Avoid setting circular var's bounds during intersection.

This fixes the MWE reported in #47874 (comment) And this fixes the remaining internal error in `Healpix.jl`'s test. gc fix
JuliaLang · Jan 3, 2023 · 36cd9c6 · 36cd9c6
1 parent 2901f0e
commit 36cd9c6
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Showing 2 changed files with 18 additions and 4 deletions.
diff --git a/src/subtype.c b/src/subtype.c
@@ -605,6 +605,8 @@ static int var_outside(jl_stenv_t *e, jl_tvar_t *x, jl_tvar_t *y)
 
 static jl_value_t *intersect_aside(jl_value_t *x, jl_value_t *y, jl_stenv_t *e, int R, int d);
 
+static int reachable_var(jl_value_t *x, jl_tvar_t *y, jl_stenv_t *e);
+
 // check that type var `b` is <: `a`, and update b's upper bound.
 static int var_lt(jl_tvar_t *b, jl_value_t *a, jl_stenv_t *e, int param)
 {
@@ -622,8 +624,10 @@ static int var_lt(jl_tvar_t *b, jl_value_t *a, jl_stenv_t *e, int param)
     // since otherwise the issub(a, bb.ub) check in var_gt becomes vacuous.
     if (e->intersection) {
         jl_value_t *ub = intersect_aside(bb->ub, a, e, 0, bb->depth0);
-        if (ub != (jl_value_t*)b)
+        JL_GC_PUSH1(&ub);
+        if (ub != (jl_value_t*)b && (!jl_is_typevar(ub) || !reachable_var(ub, b, e)))
             bb->ub = ub;
+        JL_GC_POP();
     }
     else {
         bb->ub = simple_meet(bb->ub, a);
@@ -640,8 +644,6 @@ static int var_lt(jl_tvar_t *b, jl_value_t *a, jl_stenv_t *e, int param)
     return 1;
 }
 
-static int subtype_by_bounds(jl_value_t *x, jl_value_t *y, jl_stenv_t *e) JL_NOTSAFEPOINT;
-
 // check that type var `b` is >: `a`, and update b's lower bound.
 static int var_gt(jl_tvar_t *b, jl_value_t *a, jl_stenv_t *e, int param)
 {
@@ -660,8 +662,10 @@ static int var_gt(jl_tvar_t *b, jl_value_t *a, jl_stenv_t *e, int param)
     if (!((bb->ub == (jl_value_t*)jl_any_type && !jl_is_type(a) && !jl_is_typevar(a)) || subtype_ccheck(a, bb->ub, e)))
         return 0;
     jl_value_t *lb = simple_join(bb->lb, a);
-    if (!e->intersection || !subtype_by_bounds(lb, (jl_value_t*)b, e))
+    JL_GC_PUSH1(&lb);
+    if (!e->intersection || !jl_is_typevar(lb) || !reachable_var(lb, b, e))
         bb->lb = lb;
+    JL_GC_POP();
     // this bound should not be directly circular
     assert(bb->lb != (jl_value_t*)b);
     if (jl_is_typevar(a)) {

diff --git a/test/subtype.jl b/test/subtype.jl
@@ -2304,6 +2304,16 @@ let S = Tuple{Val{T}, T} where {S1,T<:Val{Union{Nothing,S1}}},
     @test_broken testintersect(S, T) == Tuple{Val{Val{Union{Nothing, S1}}}, Val{Union{Nothing, S1}}} where S1<:(Union{Nothing, S2} where S2)
 end
 
+#issue #47874:case1
+let S1 = Tuple{Int, Any, Union{Val{C1}, C1}} where {R1<:Real, C1<:Union{Complex{R1}, R1}},
+    S2 = Tuple{Int, Any, Union{Val{C1}, C1} where {R1<:Real, C1<:Union{Complex{R1}, R1}}},
+    T1 = Tuple{Any, Int, Union{Val{C2}, C2}} where {R2<:Real, C2<:Union{Complex{R2}, R2}},
+    T2 = Tuple{Any, Int, V} where {R2<:Real, C2<:Union{Complex{R2}, R2}, V<:Union{Val{C2}, C2}}
+    for S in (S1, S2), T in (T1, T2)
+        @testintersect(S, T, !Union{})
+    end
+end
+
 @testset "known subtype/intersect issue" begin
     #issue 45874
     # Causes a hang due to jl_critical_error calling back into malloc...