From 0baa07cdf2754748bbc2d969bf83f08c0976fb78 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Mon, 15 Aug 2016 15:34:06 +0200 Subject: Fix overridden BIFs The filters in a list comprehension can be guard expressions or an ordinary expressions. If a guard expression is used as a filter, an exception will basically mean the same as 'false': t() -> L = [{some_tag,42},an_atom], [X || X <- L, element(1, X) =:= some_tag] %% Returns [{some_tag,42}] On the other hand, if an ordinary expression is used as a filter, there will be an exception: my_element(N, T) -> element(N, T). t() -> L = [{some_tag,42},an_atom], [X || X <- L, my_element(1, X) =:= some_tag] %% Causes a 'badarg' exception when element(1, an_atom) is evaluated It has been allowed for several releases to override a BIF with a local function. Thus, if we define a function called element/2, it will be called instead of the BIF element/2 within the module. We must use the "erlang:" prefix to call the BIF. Therefore, the following code is expected to work the same way as in our second example above: -compile({no_auto_import,[element/2]}). element(N, T) -> erlang:element(N, T). t() -> L = [{some_tag,42},an_atom], [X || X <- L, element(1, X) =:= some_tag]. %% Causes a 'badarg' exception when element(1, an_atom) is evaluated But the compiler refuses to compile the code with the following diagnostic: call to local/imported function element/2 is illegal in guard --- lib/stdlib/src/erl_expand_records.erl | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'lib/stdlib/src/erl_expand_records.erl') diff --git a/lib/stdlib/src/erl_expand_records.erl b/lib/stdlib/src/erl_expand_records.erl index ab47f05320..2280464bff 100644 --- a/lib/stdlib/src/erl_expand_records.erl +++ b/lib/stdlib/src/erl_expand_records.erl @@ -507,9 +507,16 @@ lc_tq(Line, [{b_generate,Lg,P0,G0} | Qs0], St0) -> {P1,St2} = pattern(P0, St1), {Qs1,St3} = lc_tq(Line, Qs0, St2), {[{b_generate,Lg,P1,G1} | Qs1],St3}; -lc_tq(Line, [F0 | Qs0], St0) -> +lc_tq(Line, [F0 | Qs0], #exprec{calltype=Calltype}=St0) -> %% Allow record/2 and expand out as guard test. - case erl_lint:is_guard_test(F0) of + IsOverriden = fun(FA) -> + case Calltype of + #{FA := local} -> true; + #{FA := {imported,_}} -> true; + _ -> false + end + end, + case erl_lint:is_guard_test(F0, [], IsOverriden) of true -> {F1,St1} = guard_test(F0, St0), {Qs1,St2} = lc_tq(Line, Qs0, St1), -- cgit v1.2.3