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/compiler/test/test_lib.erl | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'lib/compiler/test/test_lib.erl') diff --git a/lib/compiler/test/test_lib.erl b/lib/compiler/test/test_lib.erl index d5b79e2357..8954a9f5fb 100644 --- a/lib/compiler/test/test_lib.erl +++ b/lib/compiler/test/test_lib.erl @@ -22,7 +22,10 @@ -include_lib("common_test/include/ct.hrl"). -compile({no_auto_import,[binary_part/2]}). -export([id/1,recompile/1,parallel/0,uniq/0,opt_opts/1,get_data_dir/1, - is_cloned_mod/1,smoke_disasm/1,p_run/2,binary_part/2]). + is_cloned_mod/1,smoke_disasm/1,p_run/2]). + +%% Used by test case that override BIFs. +-export([binary_part/2,binary/1]). id(I) -> I. @@ -151,3 +154,7 @@ p_run_loop(Test, List, N, Refs0, Errors0, Ws0) -> %% This is for the misc_SUITE:override_bif testcase binary_part(_A,_B) -> dummy. + +%% This is for overridden_bif_SUITE. +binary(N) -> + N rem 10 =:= 0. -- cgit v1.2.3