From 388d82f6c4e6003a9923fb7d02d885d5de3500ec Mon Sep 17 00:00:00 2001
From: N5N3 <2642243996@qq.com>
Date: Fri, 14 Jul 2023 22:27:37 +0800
Subject: [PATCH] Also record chained `innervars`

At present we only record direct `innervars` (`T` -> `S<:Val{T}`). And chained `innervars` might be ignored (`T` -> `S<:Val{V<:T}`\
This commit fix it.
---
 src/subtype.c   | 56 +++++++++++++++++++++++++++++++++++++++++++++++--
 test/subtype.jl |  7 ++++++-
 2 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/src/subtype.c b/src/subtype.c
index 5b05bb288ffc4a..395ac165a0b2bf 100644
--- a/src/subtype.c
+++ b/src/subtype.c
@@ -2770,9 +2770,9 @@ static jl_value_t *omit_bad_union(jl_value_t *u, jl_tvar_t *t)
 // Caller might not have rooted `res`
 static jl_value_t *finish_unionall(jl_value_t *res JL_MAYBE_UNROOTED, jl_varbinding_t *vb, jl_unionall_t *u, jl_stenv_t *e)
 {
-    jl_value_t *varval = NULL;
+    jl_value_t *varval = NULL, *ilb = NULL, *iub = NULL;
     jl_tvar_t *newvar = vb->var;
-    JL_GC_PUSH2(&res, &newvar);
+    JL_GC_PUSH4(&res, &newvar, &ilb, &iub);
     // try to reduce var to a single value
     if (jl_is_long(vb->ub) && jl_is_typevar(vb->lb)) {
         varval = vb->ub;
@@ -2868,6 +2868,58 @@ static jl_value_t *finish_unionall(jl_value_t *res JL_MAYBE_UNROOTED, jl_varbind
                 btemp->ub = jl_new_struct(jl_unionall_type, vb->var, btemp->ub);
             assert((jl_value_t*)btemp->var != btemp->ub);
         }
+        // We have checked direct innervars above.
+        // But `btemp->innervars` might includes tvars depending on vb.
+        // Check them here.
+        if (btemp->innervars != NULL) {
+            for (size_t i = 0; i < jl_array_len(btemp->innervars); i++) {
+                jl_tvar_t *ivar = (jl_tvar_t*)jl_array_ptr_ref(btemp->innervars, i);
+                jl_value_t *ilb = ivar->lb, *iub = ivar->ub;
+                if (jl_has_typevar(btemp->lb, ivar) || jl_has_typevar(btemp->ub, ivar)) {
+                    if (jl_has_typevar(ilb, vb->var)) {
+                        if (varval) {
+                            JL_TRY {
+                                ilb = jl_substitute_var(ilb, vb->var, varval);
+                            }
+                            JL_CATCH {
+                                res = jl_bottom_type;
+                            }
+                        }
+                        else if (btemp->depth0 == vb->depth0 && !jl_has_typevar(vb->lb, btemp->var) && !jl_has_typevar(vb->ub, btemp->var)) {
+                            if (newvar != vb->var)
+                                ilb = jl_substitute_var(ilb, vb->var, (jl_value_t*)newvar);
+                            wrap = btemp;
+                        }
+                        else {
+                            // TODO: This doesn't make any sense.
+                            ilb = jl_new_struct(jl_unionall_type, vb->var, ilb);
+                        }
+                    }
+                    if (jl_has_typevar(iub, vb->var)) {
+                        if (varval) {
+                            JL_TRY {
+                                iub = jl_substitute_var(iub, vb->var, varval);
+                            }
+                            JL_CATCH {
+                                res = jl_bottom_type;
+                            }
+                        }
+                        else if (btemp->depth0 == vb->depth0 && !jl_has_typevar(vb->lb, btemp->var) && !jl_has_typevar(vb->ub, btemp->var)) {
+                            if (newvar != vb->var)
+                                iub = jl_substitute_var(iub, vb->var, (jl_value_t*)newvar);
+                            wrap = btemp;
+                        }
+                        else {
+                            // TODO: This doesn't make any sense.
+                            iub = jl_new_struct(jl_unionall_type, vb->var, iub);
+                        }
+                    }
+                    if (ivar->lb != ilb || ivar->ub != iub) {
+                        jl_array_ptr_set(btemp->innervars, i, (jl_value_t *)jl_new_typevar(ivar->name, ilb, iub));
+                    }
+                }
+            }
+        }
     }
 
     if (wrap) {
diff --git a/test/subtype.jl b/test/subtype.jl
index de11689e9e7c46..19901897ebaaad 100644
--- a/test/subtype.jl
+++ b/test/subtype.jl
@@ -2552,8 +2552,13 @@ end
 @test !<:(Type{Vector{Union{Base.BitInteger, Base.IEEEFloat, StridedArray, Missing, Nothing, Val{T}}}} where {T}, Type{Array{T}} where {T})
 
 #issue 50195
-T50195{S} = Pair{S,Set{S}}
 let a = Tuple{Type{X} where X<:Union{Nothing, Val{X1} where {X4, X1<:(Pair{X2, Val{X2}} where X2<:Val{X4})}}},
     b = Tuple{Type{Y} where Y<:(Val{Y1} where {Y4<:Src, Y1<:(Pair{Y2, Val{Y2}} where Y2<:Union{Val{Y4}, Y4})})} where Src
     @test typeintersect(a, b) <: Any
 end
+
+#issue 50195
+let a = Tuple{Union{Nothing, Type{Pair{T1}} where T1}}
+    b = Tuple{Type{X2} where X2<:(Pair{T2, Y2} where {Src, Z2<:Src, Y2<:Union{Val{Z2}, Z2}})} where T2
+    @test !Base.has_free_typevars(typeintersect(a, b))
+end