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authorJosé Valim <[email protected]>2017-07-03 14:16:13 +0200
committerJosé Valim <[email protected]>2017-07-04 15:26:05 +0200
commitf2b332186a8cdb90b199b7121881b2ae8a454b8c (patch)
treea95506e4815dcabac660336bc010caacaf8896f2 /lib
parentf52748254f17ba42e344798e8c787a1e3361fa33 (diff)
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Make tuple calls opt-in
Tuple calls is the ability to invoke a function on a tuple as first argument: 1> Var = dict:new(). {dict,0,16,16,8,80,48, {[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]}, {{[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],[]}}} 2> Var:size(). 0 This behaviour is considered by most to be undesired and confusing, especially when it comes to errors. For example, imagine you invoke "Mod:new()" where a Mod is an atom and you accidentally pass {ok, dict}. It raises: {undef,[{ok,new,[{ok,dict}],[]},...]} As it attempts to invoke ok:new/1, which is really hard to debug as there is no call to new/1 on the source code. Furthemore, this behaviour is implemented at the VM level, which imposes such semantics on all languages running on BEAM. Since we cannot remove the behaviour above, this proposal makes the behaviour opt-in with a compiler flag: -compile(tuple_calls). This means that, if a codebase relies on this functionality, they can keep compatibility by adding configuring their build tool to always use the 'tuple_calls' flag or explicitly on each module. As long as the compile attribute above is listed, the codebase will work on old and new Erlang versions alike. The only downside of the current implementation is that modules compiled on OTP 20 that rely on 'tuple_calls' will have to be recompiled to run with 'tuple_calls' on OTP 21+.
Diffstat (limited to 'lib')
-rw-r--r--lib/compiler/src/v3_core.erl45
-rw-r--r--lib/compiler/test/compile_SUITE.erl35
2 files changed, 76 insertions, 4 deletions
diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl
index ae650546e5..20cb3343fb 100644
--- a/lib/compiler/src/v3_core.erl
+++ b/lib/compiler/src/v3_core.erl
@@ -2505,8 +2505,46 @@ cexpr(#ifun{anno=#a{us=Us0}=A0,name={named,Name},fc=#iclause{pats=Ps}}=Fun0,
end;
cexpr(#iapply{anno=A,op=Op,args=Args}, _As, St) ->
{#c_apply{anno=A#a.anno,op=Op,args=Args},[],A#a.us,St};
-cexpr(#icall{anno=A,module=Mod,name=Name,args=Args}, _As, St) ->
- {#c_call{anno=A#a.anno,module=Mod,name=Name,args=Args},[],A#a.us,St};
+cexpr(#icall{anno=A,module=Mod,name=Name,args=Args}, _As, St0) ->
+ Anno = A#a.anno,
+ case (not cerl:is_c_atom(Mod)) andalso member(tuple_calls, St0#core.opts) of
+ true ->
+ GenAnno = [compiler_generated|Anno],
+
+ %% Generate the clause that matches on the tuple
+ {TupleVar,St1} = new_var(GenAnno, St0),
+ {TupleSizeVar, St2} = new_var(GenAnno, St1),
+ {TupleModVar, St3} = new_var(GenAnno, St2),
+ {TupleArgsVar, St4} = new_var(GenAnno, St3),
+ TryVar = cerl:c_var('Try'),
+
+ TupleGuardExpr =
+ cerl:c_let([TupleSizeVar],
+ c_call_erl(tuple_size, [TupleVar]),
+ c_call_erl('>', [TupleSizeVar, cerl:c_int(0)])),
+
+ TupleGuard =
+ cerl:c_try(TupleGuardExpr, [TryVar], TryVar,
+ [cerl:c_var('T'),cerl:c_var('R')], cerl:c_atom(false)),
+
+ TupleApply =
+ cerl:c_let([TupleModVar],
+ c_call_erl(element, [cerl:c_int(1),TupleVar]),
+ cerl:c_let([TupleArgsVar],
+ cerl:make_list(Args ++ [TupleVar]),
+ c_call_erl(apply, [TupleModVar,Name,TupleArgsVar]))),
+
+ TupleClause = cerl:ann_c_clause(GenAnno, [TupleVar], TupleGuard, TupleApply),
+
+ %% Generate the fallback clause
+ {OtherVar,St5} = new_var(GenAnno, St4),
+ OtherApply = cerl:ann_c_call(GenAnno, OtherVar, Name, Args),
+ OtherClause = cerl:ann_c_clause(GenAnno, [OtherVar], OtherApply),
+
+ {cerl:ann_c_case(GenAnno, Mod, [TupleClause,OtherClause]),[],A#a.us,St5};
+ false ->
+ {#c_call{anno=Anno,module=Mod,name=Name,args=Args},[],A#a.us,St0}
+ end;
cexpr(#iprimop{anno=A,name=Name,args=Args}, _As, St) ->
{#c_primop{anno=A#a.anno,name=Name,args=Args},[],A#a.us,St};
cexpr(#iprotect{anno=A,body=Es}, _As, St0) ->
@@ -2536,6 +2574,9 @@ cfun(#ifun{anno=A,id=Id,vars=Args,clauses=Lcs,fc=Lfc}, _As, St0) ->
clauses=Ccs ++ [Cfc]}},
[],A#a.us,St2}.
+c_call_erl(Fun, Args) ->
+ cerl:c_call(cerl:c_atom(erlang), cerl:c_atom(Fun), Args).
+
%% lit_vars(Literal) -> [Var].
lit_vars(Lit) -> lit_vars(Lit, []).
diff --git a/lib/compiler/test/compile_SUITE.erl b/lib/compiler/test/compile_SUITE.erl
index f647a4030d..aaa2005e73 100644
--- a/lib/compiler/test/compile_SUITE.erl
+++ b/lib/compiler/test/compile_SUITE.erl
@@ -32,7 +32,7 @@
binary/1, makedep/1, cond_and_ifdef/1, listings/1, listings_big/1,
other_output/1, kernel_listing/1, encrypted_abstr/1,
strict_record/1, utf8_atoms/1, utf8_functions/1, extra_chunks/1,
- cover/1, env/1, core_pp/1,
+ cover/1, env/1, core_pp/1, tuple_calls/1,
core_roundtrip/1, asm/1, optimized_guards/1,
sys_pre_attributes/1, dialyzer/1,
warnings/1, pre_load_check/1, env_compiler_options/1,
@@ -49,7 +49,7 @@ all() ->
test_lib:recompile(?MODULE),
[app_test, appup_test, file_1, forms_2, module_mismatch, big_file, outdir,
binary, makedep, cond_and_ifdef, listings, listings_big,
- other_output, kernel_listing, encrypted_abstr,
+ other_output, kernel_listing, encrypted_abstr, tuple_calls,
strict_record, utf8_atoms, utf8_functions, extra_chunks,
cover, env, core_pp, core_roundtrip, asm, optimized_guards,
sys_pre_attributes, dialyzer, warnings, pre_load_check,
@@ -781,6 +781,37 @@ extra_chunks(Config) when is_list(Config) ->
{ok,{extra_chunks,[{"ExCh",<<"Contents">>}]}} =
beam_lib:chunks(ExtraChunksBinary, ["ExCh"]).
+tuple_calls(Config) when is_list(Config) ->
+ Anno = erl_anno:new(1),
+ Forms = [{attribute,Anno,export,[{size,1},{store,1}]},
+ {function,Anno,size,1,
+ [{clause,Anno,[{var,[],mod}],[],
+ [{call,[],{remote,[],{var,[],mod},{atom,[],size}},[]}]}]},
+ {function,Anno,store,1,
+ [{clause,Anno,[{var,[],mod}],[],
+ [{call,[],{remote,[],{var,[],mod},{atom,[],store}},[{atom,[],key},{atom,[],value}]}]}]}],
+
+ TupleCallsFalse = [{attribute,Anno,module,tuple_calls_false}|Forms],
+ {ok,_,TupleCallsFalseBinary} = compile:forms(TupleCallsFalse, [binary]),
+ code:load_binary(tuple_calls_false, "compile_SUITE.erl", TupleCallsFalseBinary),
+ {'EXIT',{badarg,_}} = (catch tuple_calls_false:store(dict())),
+ {'EXIT',{badarg,_}} = (catch tuple_calls_false:size(dict())),
+ {'EXIT',{badarg,_}} = (catch tuple_calls_false:size(empty_tuple())),
+
+ TupleCallsTrue = [{attribute,Anno,module,tuple_calls_true}|Forms],
+ {ok,_,TupleCallsTrueBinary} = compile:forms(TupleCallsTrue, [binary,tuple_calls]),
+ code:load_binary(tuple_calls_true, "compile_SUITE.erl", TupleCallsTrueBinary),
+ Dict = tuple_calls_true:store(dict()),
+ 1 = tuple_calls_true:size(Dict),
+ {'EXIT',{badarg,_}} = (catch tuple_calls_true:size(empty_tuple())),
+
+ ok.
+
+dict() ->
+ dict:new().
+empty_tuple() ->
+ {}.
+
env(Config) when is_list(Config) ->
{Simple,Target} = get_files(Config, simple, env),
{ok,Cwd} = file:get_cwd(),