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Make sure reachable_var not falls into infinite recusion. #48135

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merged 2 commits into from
Jan 7, 2023
Merged

Make sure reachable_var not falls into infinite recusion. #48135

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9ae6051
make sure `reachable_var` not falls into infinite recusion.
N5N3 Jan 5, 2023
f84566a
add `current_env_length`.
N5N3 Jan 5, 2023
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30 changes: 27 additions & 3 deletions src/subtype.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2302,16 +2302,40 @@ static int subtype_in_env_existential(jl_value_t *x, jl_value_t *y, jl_stenv_t *
}

// See if var y is reachable from x via bounds; used to avoid cycles.
static int reachable_var(jl_value_t *x, jl_tvar_t *y, jl_stenv_t *e)
static int _reachable_var(jl_value_t *x, jl_tvar_t *y, jl_stenv_t *e)
{
if (in_union(x, (jl_value_t*)y))
return 1;
if (!jl_is_typevar(x))
return 0;
jl_varbinding_t *xv = lookup(e, (jl_tvar_t*)x);
if (xv == NULL)
if (xv == NULL || xv->right)
return 0;
return reachable_var(xv->ub, y, e) || reachable_var(xv->lb, y, e);
xv->right = 1;
return _reachable_var(xv->ub, y, e) || _reachable_var(xv->lb, y, e);
}

static int reachable_var(jl_value_t *x, jl_tvar_t *y, jl_stenv_t *e)
{
int len = current_env_length(e);
int8_t *rs = (int8_t*)malloc_s(len);
int n = 0;
jl_varbinding_t *v = e->vars;
while (n < len) {
assert(v != NULL);
rs[n++] = v->right;
v->right = 0;
v = v->prev;
}
int res = _reachable_var(x, y, e);
n = 0; v = e->vars;
while (n < len) {
assert(v != NULL);
v->right = rs[n++];
v = v->prev;
}
free(rs);
return res;
}

// check whether setting v == t implies v == SomeType{v}, which is unsatisfiable.
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5 changes: 5 additions & 0 deletions test/subtype.jl
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Expand Up @@ -2314,6 +2314,11 @@ let S1 = Tuple{Int, Any, Union{Val{C1}, C1}} where {R1<:Real, C1<:Union{Complex{
end
end

let S = Tuple{T2, V2} where {T2, N2, V2<:(Array{S2, N2} where {S2 <: T2})},
T = Tuple{V1, T1} where {T1, N1, V1<:(Array{S1, N1} where {S1 <: T1})}
@testintersect(S, T, !Union{})
end

@testset "known subtype/intersect issue" begin
#issue 45874
# Causes a hang due to jl_critical_error calling back into malloc...
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