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intersect: fix a minor soundness issue with supertypes #47813

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Merged
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Dec 16, 2022
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intersect: fix a minor soundness issue with supertypes #47813

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46 changes: 6 additions & 40 deletions src/subtype.c
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Expand Up @@ -2882,48 +2882,14 @@ static void flip_vars(jl_stenv_t *e)
// intersection where xd nominally inherits from yd
static jl_value_t *intersect_sub_datatype(jl_datatype_t *xd, jl_datatype_t *yd, jl_stenv_t *e, int R, int param)
{
// attempt to populate additional constraints into `e`
// if that attempt fails, then return bottom
// otherwise return xd (finish_unionall will later handle propagating those constraints)
jl_value_t *isuper = R ? intersect((jl_value_t*)yd, (jl_value_t*)xd->super, e, param) :
intersect((jl_value_t*)xd->super, (jl_value_t*)yd, e, param);
if (isuper == jl_bottom_type) return jl_bottom_type;
if (jl_nparams(xd) == 0 || jl_nparams(xd->super) == 0 || !jl_has_free_typevars((jl_value_t*)xd))
return (jl_value_t*)xd;
jl_value_t *super_pattern=NULL;
JL_GC_PUSH2(&isuper, &super_pattern);
jl_value_t *wrapper = xd->name->wrapper;
super_pattern = jl_rewrap_unionall_((jl_value_t*)((jl_datatype_t*)jl_unwrap_unionall(wrapper))->super,
wrapper);
int envsz = jl_subtype_env_size(super_pattern);
jl_value_t *ii = jl_bottom_type;
{
jl_value_t **env;
JL_GC_PUSHARGS(env, envsz);
jl_stenv_t tempe;
init_stenv(&tempe, env, envsz);
tempe.intersection = tempe.ignore_free = 1;
if (subtype_in_env(isuper, super_pattern, &tempe)) {
jl_value_t *wr = wrapper;
int i;
for(i=0; i<envsz; i++) {
// if a parameter is not constrained by the supertype, use the original
// parameter value from `x`. this is detected by the value in `env` being
// the exact typevar from the type's `wrapper`, or a free typevar.
jl_value_t *ei = env[i];
if (ei == (jl_value_t*)((jl_unionall_t*)wr)->var ||
(jl_is_typevar(ei) && lookup(e, (jl_tvar_t*)ei) == NULL))
env[i] = jl_tparam(xd,i);
wr = ((jl_unionall_t*)wr)->body;
}
JL_TRY {
ii = jl_apply_type(wrapper, env, envsz);
}
JL_CATCH {
ii = jl_bottom_type;
}
}
JL_GC_POP();
}
JL_GC_POP();
return ii;
if (isuper == jl_bottom_type)
return jl_bottom_type;
return (jl_value_t*)xd;
}

static jl_value_t *intersect_invariant(jl_value_t *x, jl_value_t *y, jl_stenv_t *e)
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1 change: 1 addition & 0 deletions test/docs.jl
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Expand Up @@ -970,6 +970,7 @@ abstract type $(curmod_prefix)Undocumented.at1{T>:Integer, N}

```
$(curmod_prefix)Undocumented.mt6{Integer, N}
$(curmod_prefix)Undocumented.st5{T>:Integer, N}
```

# Supertype Hierarchy
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11 changes: 10 additions & 1 deletion test/subtype.jl
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Expand Up @@ -2188,7 +2188,16 @@ for T in (B46871{Int, N} where {N}, B46871{Int}) # intentional duplication
end
abstract type C38497{e,g<:Tuple,i} end
struct Q38497{o,e<:NTuple{o},g} <: C38497{e,g,Array{o}} end
@testintersect(Q38497{<:Any, Tuple{Int}}, C38497, Q38497{1, Tuple{Int}, <:Tuple})
@testintersect(Q38497{<:Any, Tuple{Int}}, C38497, Q38497{<:Any, Tuple{Int}, <:Tuple})
# n.b. the only concrete instance of this type is Q38497{1, Tuple{Int}, <:Tuple} (since NTuple{o} also adds an ::Int constraint)
# but this abstract type is also part of the intersection abstractly

abstract type X38497{T<:Number} end
abstract type Y38497{T>:Integer} <: X38497{T} end
struct Z38497{T>:Int} <: Y38497{T} end
@testintersect(Z38497, X38497, Z38497{T} where Int<:T<:Number)
@testintersect(Z38497, Y38497, Z38497{T} where T>:Integer)
@testintersect(X38497, Y38497, Y38497{T} where Integer<:T<:Number)

#issue #33138
@test Vector{Vector{Tuple{T,T}} where Int<:T<:Int} <: Vector{Vector{Tuple{S1,S1} where S<:S1<:S}} where S
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