diff options
Diffstat (limited to 'lib/compiler/src')
| -rw-r--r-- | lib/compiler/src/beam_ssa_type.erl | 14 | ||||
| -rw-r--r-- | lib/compiler/src/beam_validator.erl | 12 |
2 files changed, 17 insertions, 9 deletions
diff --git a/lib/compiler/src/beam_ssa_type.erl b/lib/compiler/src/beam_ssa_type.erl index 06b42f1928..fe229d25df 100644 --- a/lib/compiler/src/beam_ssa_type.erl +++ b/lib/compiler/src/beam_ssa_type.erl @@ -896,11 +896,15 @@ type(call, [#b_remote{mod=#b_literal{val=Mod}, {_,_} -> #t_tuple{} end; - {erlang,'++',[List1,List2]} -> - case get_type(List1, Ts) =:= cons orelse - get_type(List2, Ts) =:= cons of - true -> cons; - false -> list + {erlang,'++',[LHS,RHS]} -> + LType = get_type(LHS, Ts), + RType = get_type(RHS, Ts), + case LType =:= cons orelse RType =:= cons of + true -> + cons; + false -> + %% `[] ++ RHS` yields RHS, even if RHS is not a list. + join(list, RType) end; {erlang,'--',[_,_]} -> list; diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl index 09a5a6c104..ebe9631e09 100644 --- a/lib/compiler/src/beam_validator.erl +++ b/lib/compiler/src/beam_validator.erl @@ -2844,10 +2844,14 @@ call_return_type_1(erlang, setelement, 3, Vst) -> setelement(3, TupleType, #{}) end; call_return_type_1(erlang, '++', 2, Vst) -> - case get_term_type({x,0}, Vst) =:= cons orelse - get_term_type({x,1}, Vst) =:= cons of - true -> cons; - false -> list + LType = get_term_type({x,0}, Vst), + RType = get_term_type({x,1}, Vst), + case LType =:= cons orelse RType =:= cons of + true -> + cons; + false -> + %% `[] ++ RHS` yields RHS, even if RHS is not a list + join(list, RType) end; call_return_type_1(erlang, '--', 2, _Vst) -> list; |