diff options
Diffstat (limited to 'lib/compiler/src/sys_core_fold.erl')
-rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index 068478496b..6202f07479 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -1,19 +1,19 @@ %% %% %CopyrightBegin% -%% -%% Copyright Ericsson AB 1999-2009. All Rights Reserved. -%% +%% +%% Copyright Ericsson AB 1999-2010. All Rights Reserved. +%% %% The contents of this file are subject to the Erlang Public License, %% Version 1.1, (the "License"); you may not use this file except in %% compliance with the License. You should have received a copy of the %% Erlang Public License along with this software. If not, it can be %% retrieved online at http://www.erlang.org/. -%% +%% %% Software distributed under the License is distributed on an "AS IS" %% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See %% the License for the specific language governing rights and limitations %% under the License. -%% +%% %% %CopyrightEnd% %% %% Purpose : Constant folding optimisation for Core @@ -602,15 +602,23 @@ count_bits_1(Int, Bits) -> count_bits_1(Int bsr 64, Bits+64). %% a rewritten expression consisting of a sequence of %% the arguments only is returned. -useless_call(effect, #c_call{module=#c_literal{val=Mod}, +useless_call(effect, #c_call{anno=Anno, + module=#c_literal{val=Mod}, name=#c_literal{val=Name}, args=Args}=Call) -> A = length(Args), case erl_bifs:is_safe(Mod, Name, A) of false -> case erl_bifs:is_pure(Mod, Name, A) of - true -> add_warning(Call, result_ignored); - false -> ok + true -> + case member(result_not_wanted, Anno) of + false -> + add_warning(Call, result_ignored); + true -> + ok + end; + false -> + ok end, no; true -> @@ -2806,7 +2814,8 @@ format_error({no_effect,{erlang,F,A}}) -> end, flatten(io_lib:format(Fmt, Args)); format_error(result_ignored) -> - "the result of the expression is ignored"; + "the result of the expression is ignored " + "(suppress the warning by assigning the expression to the _ variable)"; format_error(useless_building) -> "a term is constructed, but never used"; format_error(bin_opt_alias) -> |