From 93f5844185a459cbf9efc3843919c463a2eef0fe Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Thu, 8 Oct 2015 13:04:40 +0200 Subject: Teach erlang:is_builtin/3 that erlang:apply/3 is built-in erlang:is_builtin(erlang, apply, 3) returns 'false'. That seems to be an oversight in the implementation of erlang:is_builtin/3 rather than a conscious design decision. Part of apply/3 is implemented in C (as a special instruction), and part of it in Erlang (only used if apply/3 is used recursively). That makes apply/3 special compared to all other BIFs. From the viewpoint of the user, apply/3 is a built-in function, since it cannot possibly be implemented in pure Erlang. Noticed-by: Stavros Aronis --- erts/emulator/beam/beam_emu.c | 9 +++++++++ erts/emulator/test/bif_SUITE.erl | 21 +++++++++++++++++++-- 2 files changed, 28 insertions(+), 2 deletions(-) (limited to 'erts/emulator') diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c index a42ce1c9f1..faf496a030 100644 --- a/erts/emulator/beam/beam_emu.c +++ b/erts/emulator/beam/beam_emu.c @@ -6752,6 +6752,15 @@ erts_is_builtin(Eterm Mod, Eterm Name, int arity) Export e; Export* ep; + if (Mod == am_erlang && Name == am_apply && arity == 3) { + /* + * Special case. apply/3 is built-in (implemented in C), + * but implemented in a different way than all other + * BIFs. + */ + return 1; + } + e.code[0] = Mod; e.code[1] = Name; e.code[2] = arity; diff --git a/erts/emulator/test/bif_SUITE.erl b/erts/emulator/test/bif_SUITE.erl index d6a771e7b9..ebc4db53c4 100644 --- a/erts/emulator/test/bif_SUITE.erl +++ b/erts/emulator/test/bif_SUITE.erl @@ -32,7 +32,8 @@ specs/1,improper_bif_stubs/1,auto_imports/1, t_list_to_existing_atom/1,os_env/1,otp_7526/1, binary_to_atom/1,binary_to_existing_atom/1, - atom_to_binary/1,min_max/1, erlang_halt/1]). + atom_to_binary/1,min_max/1, erlang_halt/1, + is_builtin/1]). suite() -> [{ct_hooks,[ts_install_cth]}]. @@ -42,7 +43,7 @@ all() -> t_list_to_existing_atom, os_env, otp_7526, display, atom_to_binary, binary_to_atom, binary_to_existing_atom, - min_max, erlang_halt]. + min_max, erlang_halt, is_builtin]. groups() -> []. @@ -716,6 +717,22 @@ wait_until_stable_size(File,PrevSz) -> wait_until_stable_size(File,NewSz) end. +is_builtin(_Config) -> + Exp0 = [{M,F,A} || {M,_} <- code:all_loaded(), + {F,A} <- M:module_info(exports)], + Exp = ordsets:from_list(Exp0), + + %% erlang:apply/3 is considered to be built-in, but is not + %% implemented as other BIFs. + + Builtins0 = [{erlang,apply,3}|erlang:system_info(snifs)], + Builtins = ordsets:from_list(Builtins0), + NotBuiltin = ordsets:subtract(Exp, Builtins), + _ = [true = erlang:is_builtin(M, F, A) || {M,F,A} <- Builtins], + _ = [false = erlang:is_builtin(M, F, A) || {M,F,A} <- NotBuiltin], + + ok. + %% Helpers -- cgit v1.2.3