From 634dd378030292abeec98e7f332e57c5d36e13ef Mon Sep 17 00:00:00 2001 From: Patrik Nyblom Date: Wed, 26 May 2010 12:22:50 +0200 Subject: Return nowarn_bif_clash functionality but with warning Wrote and changed some tests in stdlib:erl_lint_SUITE nowarn_bif_clash is obsoleted but will remove warnings and errors about bif clashes. The recommended way is to use no_auto_import directives instead. Hopefully erlang.erl is the only user in the world of nowarn_bif_clash. --- lib/compiler/test/error_SUITE.erl | 22 ++-- lib/stdlib/src/erl_lint.erl | 133 +++++++++++++++------- lib/stdlib/test/erl_lint_SUITE.erl | 170 +++++++++++++++++++++++++--- system/doc/reference_manual/expressions.xml | 97 ++++++++++++++-- 4 files changed, 347 insertions(+), 75 deletions(-) diff --git a/lib/compiler/test/error_SUITE.erl b/lib/compiler/test/error_SUITE.erl index c34dacb1bf..0874225a62 100644 --- a/lib/compiler/test/error_SUITE.erl +++ b/lib/compiler/test/error_SUITE.erl @@ -29,7 +29,7 @@ all(suite) -> bif_clashes(Config) when is_list(Config) -> - Ts = [{bif_clashes, + Ts = [{bif_clashes1, <<" -export([t/0]). t() -> @@ -40,9 +40,9 @@ bif_clashes(Config) when is_list(Config) -> ">>, [return_warnings], {error, - [{4, erl_lint,{redefine_old_bif,{length,1}}}], []} }], + [{4, erl_lint,{call_to_redefined_old_bif,{length,1}}}], []} }], ?line [] = run(Config, Ts), - Ts1 = [{bif_clashes, + Ts1 = [{bif_clashes2, <<" -export([t/0]). -import(x,[length/1]). @@ -53,7 +53,7 @@ bif_clashes(Config) when is_list(Config) -> {error, [{3, erl_lint,{redefine_old_bif_import,{length,1}}}], []} }], ?line [] = run(Config, Ts1), - Ts00 = [{bif_clashes, + Ts00 = [{bif_clashes3, <<" -export([t/0]). -compile({no_auto_import,[length/1]}). @@ -66,7 +66,7 @@ bif_clashes(Config) when is_list(Config) -> [return_warnings], []}], ?line [] = run(Config, Ts00), - Ts11 = [{bif_clashes, + Ts11 = [{bif_clashes4, <<" -export([t/0]). -compile({no_auto_import,[length/1]}). @@ -77,7 +77,7 @@ bif_clashes(Config) when is_list(Config) -> [return_warnings], []}], ?line [] = run(Config, Ts11), - Ts000 = [{bif_clashes, + Ts000 = [{bif_clashes5, <<" -export([t/0]). t() -> @@ -88,9 +88,9 @@ bif_clashes(Config) when is_list(Config) -> ">>, [return_warnings], {warning, - [{4, erl_lint,{redefine_bif,{binary_part,3}}}]} }], + [{4, erl_lint,{call_to_redefined_bif,{binary_part,3}}}]} }], ?line [] = run(Config, Ts000), - Ts111 = [{bif_clashes, + Ts111 = [{bif_clashes6, <<" -export([t/0]). -import(x,[binary_part/3]). @@ -101,7 +101,7 @@ bif_clashes(Config) when is_list(Config) -> {warning, [{3, erl_lint,{redefine_bif_import,{binary_part,3}}}]} }], ?line [] = run(Config, Ts111), - Ts2 = [{bif_clashes, + Ts2 = [{bif_clashes7, <<" -export([t/0]). -compile({no_auto_import,[length/1]}). @@ -116,7 +116,7 @@ bif_clashes(Config) when is_list(Config) -> [{7,erl_lint,{define_import,{length,1}}}], []} }], ?line [] = run2(Config, Ts2), - Ts3 = [{bif_clashes, + Ts3 = [{bif_clashes8, <<" -export([t/1]). -compile({no_auto_import,[length/1]}). @@ -130,7 +130,7 @@ bif_clashes(Config) when is_list(Config) -> [{4,erl_lint,illegal_guard_expr}], []} }], ?line [] = run2(Config, Ts3), - Ts4 = [{bif_clashes, + Ts4 = [{bif_clashes9, <<" -export([t/1]). -compile({no_auto_import,[length/1]}). diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl index acb9165ead..631ad0c1e3 100644 --- a/lib/stdlib/src/erl_lint.erl +++ b/lib/stdlib/src/erl_lint.erl @@ -163,6 +163,9 @@ format_error({bad_nowarn_unused_function,{F,A}}) -> io_lib:format("function ~w/~w undefined", [F,A]); format_error({bad_nowarn_bif_clash,{F,A}}) -> io_lib:format("function ~w/~w undefined", [F,A]); +format_error(deprecated_nowarn_bif_clash) -> + io_lib:format("compile directive nowarn_bif_clash is deprecated,~n" + " - use explicit module names or -compile({no_auto_import, [F/A]})", []); format_error({bad_nowarn_deprecated_function,{M,F,A}}) -> io_lib:format("~w:~w/~w is not a deprecated function", [M,F,A]); format_error({bad_on_load,Term}) -> @@ -188,11 +191,11 @@ format_error({define_import,{F,A}}) -> io_lib:format("defining imported function ~w/~w", [F,A]); format_error({unused_function,{F,A}}) -> io_lib:format("function ~w/~w is unused", [F,A]); -format_error({redefine_bif,{F,A}}) -> +format_error({call_to_redefined_bif,{F,A}}) -> io_lib:format("ambiguous call of redefined auto-imported BIF ~w/~w~n" " - use erlang:~w/~w or \"-compile({no_auto_import,[~w/~w]}).\" " "to resolve name clash", [F,A,F,A,F,A]); -format_error({redefine_old_bif,{F,A}}) -> +format_error({call_to_redefined_old_bif,{F,A}}) -> io_lib:format("ambiguous call of redefined pre R14 auto-imported BIF ~w/~w~n" " - use erlang:~w/~w or \"-compile({no_auto_import,[~w/~w]}).\" " "to resolve name clash", [F,A,F,A,F,A]); @@ -549,9 +552,11 @@ loc(L) -> forms(Forms0, St0) -> Forms = eval_file_attribute(Forms0, St0), Locals = local_functions(Forms), - AutoImportSupressed = auto_import_supressed(St0#lint.compile), + AutoImportSuppressed = auto_import_suppressed(St0#lint.compile), + StDeprecated = deprecated_compile_flags(Forms,St0), %% Line numbers are from now on pairs {File,Line}. - St1 = includes_qlc_hrl(Forms, St0#lint{locals = Locals, no_auto = AutoImportSupressed}), + St1 = includes_qlc_hrl(Forms, StDeprecated#lint{locals = Locals, + no_auto = AutoImportSuppressed}), St2 = bif_clashes(Forms, St1), St3 = not_deprecated(Forms, St2), St4 = foldl(fun form/2, pre_scan(Forms, St3), Forms), @@ -757,6 +762,23 @@ not_deprecated(Forms, St0) -> St1 = func_line_warning(bad_nowarn_deprecated_function, Bad, St0), St1#lint{not_deprecated = ordsets:from_list(Nowarn)}. +deprecated_compile_flags(Forms, St0) -> + %% There are (still) no line numbers in St0#lint.compile. + Warnings0 = [ {St0#lint.file,{L,erl_lint,deprecated_nowarn_bif_clash}} || + {attribute,[{line,{_,L}}],compile,nowarn_bif_clash} <- Forms ], + Warnings1 = [ {St0#lint.file,{L,erl_lint,deprecated_nowarn_bif_clash}} || + {attribute,[{line,{_,L}}],compile,{nowarn_bif_clash, {_,_}}} <- Forms ], + Disabled = (not is_warn_enabled(bif_clash, St0)), + Warnings = if + Disabled andalso Warnings0 =:= [] -> + [{St0#lint.file,{erl_lint,deprecated_nowarn_bif_clash}} | St0#lint.warnings]; + Disabled -> + Warnings0 ++ Warnings1 ++ St0#lint.warnings; + true -> + Warnings1 ++ St0#lint.warnings + end, + St0#lint{warnings=Warnings}. + %% post_traversal_check(Forms, State0) -> State. %% Do some further checking after the forms have been traversed and %% data about calls etc. have been collected. @@ -1015,7 +1037,8 @@ check_option_functions(Forms, Tag0, Type, St0) -> {Tag, FAs0} <- lists:flatten([Args]), Tag0 =:= Tag, FA <- lists:flatten([FAs0])], - DefFunctions = gb_sets:to_list(St0#lint.defined) -- pseudolocals(), + DefFunctions = (gb_sets:to_list(St0#lint.defined) -- pseudolocals()) ++ + [{F,A} || {{F,A},_} <- orddict:to_list(St0#lint.imports)], Bad = [{FA,L} || {FA,L} <- FAsL, not member(FA, DefFunctions)], func_line_error(Type, Bad, St0). @@ -1108,8 +1131,10 @@ import(Line, {Mod,Fs}, St) -> Efs -> {Err, St1} = foldl(fun ({bif,{F,A},_}, {Err,St0}) -> - Warn = is_warn_enabled(bif_clash, St0), %% PaN -> import directive - AutoImpSup = is_autoimport_supressed(St0#lint.no_auto,{F,A}), + %% BifClash - import directive + Warn = is_warn_enabled(bif_clash, St0) + and (not bif_clash_specifically_disabled(St0,{F,A})), + AutoImpSup = is_autoimport_suppressed(St0#lint.no_auto,{F,A}), OldBif = erl_internal:old_bif(F,A), {Err,if Warn and (not AutoImpSup) and OldBif -> @@ -1123,7 +1148,7 @@ import(Line, {Mod,Fs}, St) -> {redefine_bif_import, {F,A}}, St0); true -> - St0 + St0 end}; (Ef, {_Err,St0}) -> {true,add_error(Line, @@ -1249,14 +1274,6 @@ define_function(Line, Name, Arity, St0) -> add_error(Line, {redefine_function,NA}, St1); false -> St2 = St1#lint{defined=gb_sets:add_element(NA, St1#lint.defined)}, -%% St = case erl_internal:bif(Name, Arity) andalso %% PaN - Function definitions -%% (not is_function_exported(Name, Arity, St2)) andalso -%% is_warn_enabled(bif_clash, St2) andalso -%% is_bif_clash(Name,Arity,St2) andalso -%% (not is_autoimport_supressed(St0#lint.no_auto,NA)) of -%% true -> add_warning(Line, {redefine_bif,NA}, St2); -%% false -> St2 -%% end, case imported(Name, Arity, St2) of {yes,_M} -> add_error(Line, {define_import,NA}, St2); no -> St2 @@ -1762,17 +1779,16 @@ gexpr({call,Line,{remote,_,{atom,_,erlang},{atom,_,is_record}=Isr},[_,_,_]=Args} gexpr({call,Line,{atom,_La,F},As}, Vt, St0) -> {Asvt,St1} = gexpr_list(As, Vt, St0), A = length(As), - case (not is_local_function(St1#lint.locals,{F,A})) andalso %% PaN -> Function called in guard - (not is_imported_function(St1#lint.imports,{F,A})) andalso - erl_internal:guard_bif(F, A) andalso - (not is_autoimport_supressed(St1#lint.no_auto, {F,A})) of + %% BifClash - Function called in guard + case erl_internal:guard_bif(F, A) andalso no_guard_bif_clash(St1,{F,A}) of true -> %% Also check that it is auto-imported. case erl_internal:bif(F, A) of true -> {Asvt,St1}; false -> {Asvt,add_error(Line, {explicit_export,F,A}, St1)} end; - false -> {Asvt,add_error(Line, illegal_guard_expr, St1)} + false -> + {Asvt,add_error(Line, illegal_guard_expr, St1)} end; gexpr({call,Line,{remote,_Lr,{atom,_Lm,erlang},{atom,_Lf,F}},As}, Vt, St0) -> {Asvt,St1} = gexpr_list(As, Vt, St0), @@ -1998,10 +2014,11 @@ expr({'fun',Line,Body}, Vt, St) -> {Bvt, St1} = fun_clauses(Cs, Vt, St), {vtupdate(Bvt, Vt), St1}; {function,F,A} -> + %% BifClash - Fun expression %% N.B. Only allows BIFs here as well, NO IMPORTS!! - case ((not is_local_function(St#lint.locals,{F,A})) andalso %% PaN - Fun expression + case ((not is_local_function(St#lint.locals,{F,A})) andalso (erl_internal:bif(F, A) andalso - (not is_autoimport_supressed(St#lint.no_auto,{F,A})))) of + (not is_autoimport_suppressed(St#lint.no_auto,{F,A})))) of true -> {[],St}; false -> {[],call_function(Line, F, A, St)} end; @@ -2036,8 +2053,9 @@ expr({call,Line,{atom,La,F},As}, Vt, St0) -> A = length(As), IsLocal = is_local_function(St2#lint.locals,{F,A}), IsAutoBif = erl_internal:bif(F, A), - AutoSupressed = is_autoimport_supressed(St2#lint.no_auto,{F,A}), - case ((not IsLocal) andalso IsAutoBif andalso (not AutoSupressed)) of %% PaN - function call + AutoSuppressed = is_autoimport_suppressed(St2#lint.no_auto,{F,A}), + Warn = is_warn_enabled(bif_clash, St2) and (not bif_clash_specifically_disabled(St2,{F,A})), + case ((not IsLocal) andalso IsAutoBif andalso (not AutoSuppressed)) of true -> St3 = deprecated_function(Line, erlang, F, As, St2), {Asvt,St3}; @@ -2052,27 +2070,33 @@ expr({call,Line,{atom,La,F},As}, Vt, St0) -> case {F,A} of {record_info,2} -> check_record_info_call(Line,La,As,St2); - N when N =:= St2#lint.func -> - St2; - _ -> + N -> + %% BifClash - function call + %% Issue these warnings/errors even if it's a recursive call St3 = if - (not AutoSupressed) andalso IsAutoBif -> + (not AutoSuppressed) andalso IsAutoBif andalso Warn -> case erl_internal:old_bif(F,A) of true -> add_error (Line, - {redefine_old_bif, {F,A}}, + {call_to_redefined_old_bif, {F,A}}, St2); false -> add_warning (Line, - {redefine_bif, {F,A}}, + {call_to_redefined_bif, {F,A}}, St2) end; true -> St2 end, - call_function(Line, F, A, St3) + %% ...but don't lint recursive calls + if + N =:= St3#lint.func -> + St3; + true -> + call_function(Line, F, A, St3) + end end end} end; @@ -3502,22 +3526,55 @@ expand_package(M, St0) -> end end. + +%% Prebuild set of local functions (to override auto-import) local_functions(Forms) -> gb_sets:from_list([ {Func,Arity} || {function,_,Func,Arity,_} <- Forms ]). - +%% Predicate to find out if the function is locally defined is_local_function(LocalSet,{Func,Arity}) -> gb_sets:is_element({Func,Arity},LocalSet). - +%% Predicate to see if a function is explicitly imported is_imported_function(ImportSet,{Func,Arity}) -> case orddict:find({Func,Arity}, ImportSet) of {ok,_Mod} -> true; error -> false end. - -auto_import_supressed(CompileFlags) -> +%% Predicate to see if a function is explicitly imported from the erlang module +is_imported_from_erlang(ImportSet,{Func,Arity}) -> + case orddict:find({Func,Arity}, ImportSet) of + {ok,erlang} -> true; + _ -> false + end. +%% Build set of functions where auto-import is explicitly supressed +auto_import_suppressed(CompileFlags) -> L0 = [ X || {no_auto_import,X} <- CompileFlags ], L1 = [ {Y,Z} || {Y,Z} <- lists:flatten(L0), is_atom(Y), is_integer(Z) ], gb_sets:from_list(L1). - -is_autoimport_supressed(NoAutoSet,{Func,Arity}) -> +%% Predicate to find out if autoimport is explicitly supressed for a function +is_autoimport_suppressed(NoAutoSet,{Func,Arity}) -> gb_sets:is_element({Func,Arity},NoAutoSet). +%% Predicate to find out if a function specific bif-clash supression (old deprecated) is present +bif_clash_specifically_disabled(St,{F,A}) -> + Nowarn = nowarn_function(nowarn_bif_clash, St#lint.compile), + lists:member({F,A},Nowarn). + +%% Predicate to find out if an autoimported guard_bif is not overriden in some way +%% Guard Bif without module name is disallowed if +%% * It is overridden by local function +%% * It is overridden by -import and that import is not of itself (i.e. from module erlang) +%% * The autoimport is suppressed or it's not reimported by -import directive +%% Otherwise it's OK (given that it's actually a guard bif and actually is autoimported) +no_guard_bif_clash(St,{F,A}) -> + ( + (not is_local_function(St#lint.locals,{F,A})) + andalso + ( + (not is_imported_function(St#lint.imports,{F,A})) orelse + is_imported_from_erlang(St#lint.imports,{F,A}) + ) + andalso + ( + (not is_autoimport_suppressed(St#lint.no_auto, {F,A})) orelse + is_imported_from_erlang(St#lint.imports,{F,A}) + ) + ). diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl index 8581b496aa..4a366f6a28 100644 --- a/lib/stdlib/test/erl_lint_SUITE.erl +++ b/lib/stdlib/test/erl_lint_SUITE.erl @@ -1784,6 +1784,9 @@ otp_5362(Config) when is_list(Config) -> {15,erl_lint,{undefined_field,ok,nix}}, {16,erl_lint,{field_name_is_variable,ok,'Var'}}]}}, + %% Nowarn_bif_clash has changed behaviour as local functions + %% nowdays supersede auto-imported BIFs, why nowarn_bif_clash in itself generates a warning + %% (OTP-8579) /PaN {otp_5362_4, <<"-compile(nowarn_deprecated_function). -compile(nowarn_bif_clash). @@ -1795,9 +1798,8 @@ otp_5362(Config) when is_list(Config) -> warn_deprecated_function, warn_bif_clash]}, {error, - [{5,erl_lint,{call_to_redefined_bif,{spawn,1}}}], - [{3,erl_lint,{redefine_bif,{spawn,1}}}, - {4,erl_lint,{deprecated,{erlang,hash,2},{erlang,phash2,2}, + [{5,erl_lint,{call_to_redefined_old_bif,{spawn,1}}}], + [{4,erl_lint,{deprecated,{erlang,hash,2},{erlang,phash2,2}, "in a future release"}}]}}, {otp_5362_5, @@ -1809,7 +1811,7 @@ otp_5362(Config) when is_list(Config) -> ">>, {[nowarn_unused_function]}, {warnings, - [{3,erl_lint,{redefine_bif,{spawn,1}}}]}}, + [{2,erl_lint,deprecated_nowarn_bif_clash}]}}, %% The special nowarn_X are not affected by general warn_X. {otp_5362_6, @@ -1823,7 +1825,7 @@ otp_5362(Config) when is_list(Config) -> warn_deprecated_function, warn_bif_clash]}, {warnings, - [{3,erl_lint,{redefine_bif,{spawn,1}}}]}}, + [{2,erl_lint,deprecated_nowarn_bif_clash}]}}, {otp_5362_7, <<"-export([spawn/1]). @@ -1839,7 +1841,9 @@ otp_5362(Config) when is_list(Config) -> ">>, {[nowarn_unused_function]}, {error,[{4,erl_lint,{bad_nowarn_bif_clash,{spawn,2}}}], - [{5,erl_lint,{bad_nowarn_deprecated_function,{3,hash,-1}}}, + [{3,erl_lint,deprecated_nowarn_bif_clash}, + {4,erl_lint,deprecated_nowarn_bif_clash}, + {5,erl_lint,{bad_nowarn_deprecated_function,{3,hash,-1}}}, {5,erl_lint,{bad_nowarn_deprecated_function,{erlang,hash,-1}}}, {5,erl_lint,{bad_nowarn_deprecated_function,{{a,b,c},hash,-1}}}]} }, @@ -1865,7 +1869,21 @@ otp_5362(Config) when is_list(Config) -> t() -> #a{}. ">>, {[]}, - []} + []}, + + {otp_5362_10, + <<"-compile({nowarn_deprecated_function,{erlang,hash,2}}). + -compile({nowarn_bif_clash,{spawn,1}}). + -import(x,[spawn/1]). + spin(A) -> + erlang:hash(A, 3000), + spawn(A). + ">>, + {[nowarn_unused_function, + warn_deprecated_function, + warn_bif_clash]}, + {warnings, + [{2,erl_lint,deprecated_nowarn_bif_clash}]}} ], @@ -2389,7 +2407,7 @@ bif_clash(Config) when is_list(Config) -> N. ">>, [], - {errors,[{2,erl_lint,{call_to_redefined_bif,{size,1}}}],[]}}, + {errors,[{2,erl_lint,{call_to_redefined_old_bif,{size,1}}}],[]}}, %% Verify that (some) warnings can be turned off. {clash2, @@ -2400,17 +2418,141 @@ bif_clash(Config) when is_list(Config) -> size({N,_}) -> N. - %% My own abs/1 function works on lists too. - %% Unfortunately, it is not exported, so there will - %% be a warning that can't be turned off. + %% My own abs/1 function works on lists too. From R14 this really works. abs([H|T]) when $a =< H, H =< $z -> [H-($a-$A)|abs(T)]; abs([H|T]) -> [H|abs(T)]; abs([]) -> []; abs(X) -> erlang:abs(X). ">>, - {[nowarn_bif_clash]}, - {warnings,[{11,erl_lint,{redefine_bif,{abs,1}}}, - {11,erl_lint,{unused_function,{abs,1}}}]}}], + {[nowarn_unused_function,nowarn_bif_clash]}, + {warnings,[{erl_lint,deprecated_nowarn_bif_clash}]}}, + %% As long as noone calls an overridden BIF, it's totally OK + {clash3, + <<"-export([size/1]). + size({N,_}) -> + N; + size(X) -> + erlang:size(X). + ">>, + [], + []}, + %% But this is totally wrong - meaning of the program changed in R14, so this is an error + {clash4, + <<"-export([size/1]). + size({N,_}) -> + N; + size(X) -> + size(X). + ">>, + [], + {errors,[{5,erl_lint,{call_to_redefined_old_bif,{size,1}}}],[]}}, + %% For a post R14 bif, its only a warning + {clash5, + <<"-export([binary_part/2]). + binary_part({B,_},{X,Y}) -> + binary_part(B,{X,Y}); + binary_part(B,{X,Y}) -> + binary:part(B,X,Y). + ">>, + [], + {warnings,[{3,erl_lint,{call_to_redefined_bif,{binary_part,2}}}]}}, + %% If you really mean to call yourself here, you can "unimport" size/1 + {clash6, + <<"-export([size/1]). + -compile({no_auto_import,[size/1]}). + size([]) -> + 0; + size({N,_}) -> + N; + size([_|T]) -> + 1+size(T). + ">>, + [], + []}, + %% Same for the post R14 autoimport warning + {clash7, + <<"-export([binary_part/2]). + -compile({no_auto_import,[binary_part/2]}). + binary_part({B,_},{X,Y}) -> + binary_part(B,{X,Y}); + binary_part(B,{X,Y}) -> + binary:part(B,X,Y). + ">>, + [], + []}, + %% but this doesn't mean the local function is allowed in a guard... + {clash8, + <<"-export([x/1]). + -compile({no_auto_import,[binary_part/2]}). + x(X) when binary_part(X,{1,2}) =:= <<1,2>> -> + hej. + binary_part({B,_},{X,Y}) -> + binary_part(B,{X,Y}); + binary_part(B,{X,Y}) -> + binary:part(B,X,Y). + ">>, + [], + {errors,[{3,erl_lint,illegal_guard_expr}],[]}}, + %% no_auto_import is not like nowarn_bif_clash, it actually removes the autoimport + {clash9, + <<"-export([x/1]). + -compile({no_auto_import,[binary_part/2]}). + x(X) -> + binary_part(X,{1,2}) =:= <<1,2>>. + ">>, + [], + {errors,[{4,erl_lint,{undefined_function,{binary_part,2}}}],[]}}, + %% but we could import it again... + {clash10, + <<"-export([x/1]). + -compile({no_auto_import,[binary_part/2]}). + -import(erlang,[binary_part/2]). + x(X) -> + binary_part(X,{1,2}) =:= <<1,2>>. + ">>, + [], + []}, + %% and actually use it in a guard... + {clash11, + <<"-export([x/1]). + -compile({no_auto_import,[binary_part/2]}). + -import(erlang,[binary_part/2]). + x(X) when binary_part(X,{0,1}) =:= <<0>> -> + binary_part(X,{1,2}) =:= <<1,2>>. + ">>, + [], + []}, + %% but for non-obvious historical reasons, imported functions cannot be used in + %% fun construction without the module name... + {clash12, + <<"-export([x/1]). + -compile({no_auto_import,[binary_part/2]}). + -import(erlang,[binary_part/2]). + x(X) when binary_part(X,{0,1}) =:= <<0>> -> + binary_part(X,{1,2}) =:= fun binary_part/2. + ">>, + [], + {errors,[{5,erl_lint,{undefined_function,{binary_part,2}}}],[]}}, + %% Not from erlang and not from anywhere else + {clash13, + <<"-export([x/1]). + -compile({no_auto_import,[binary_part/2]}). + -import(x,[binary_part/2]). + x(X) -> + binary_part(X,{1,2}) =:= fun binary_part/2. + ">>, + [], + {errors,[{5,erl_lint,{undefined_function,{binary_part,2}}}],[]}}, + %% ...while real auto-import is OK. + {clash14, + <<"-export([x/1]). + x(X) when binary_part(X,{0,1}) =:= <<0>> -> + binary_part(X,{1,2}) =:= fun binary_part/2. + ">>, + [], + []} + + ], ?line [] = run(Config, Ts), ok. diff --git a/system/doc/reference_manual/expressions.xml b/system/doc/reference_manual/expressions.xml index b56b8acbf0..714ecccaf6 100644 --- a/system/doc/reference_manual/expressions.xml +++ b/system/doc/reference_manual/expressions.xml @@ -217,12 +217,16 @@ lists:keysearch(Name, 1, List)

In the second form of function calls, ExprF(Expr1,...,ExprN), ExprF must be an atom or evaluate to a fun.

+

If ExprF is an atom the function is said to be called by - using the implicitly qualified function name. If - ExprF/N is the name of a function explicitly or - automatically imported from module M, then the call is - short for M:ExprF(Expr1,...,ExprN). Otherwise, - ExprF/N must be a locally defined function. Examples:

+ using the implicitly qualified function name. If the + function ExprF is locally defined, it is called. + Alternatively if ExprF is explicitly imported from module + M, M:ExprF(Expr1,...,ExprN) is called. If + ExprF is neither declared locally nor explicitly + imported, ExprF must be the name of an automatically + imported BIF. Examples:

+ handle(Msg, State) spawn(m, init, []) @@ -238,16 +242,85 @@ Fun2([1,2], [3,4]) fun lists:append/2([1,2], [3,4]) => [1,2,3,4] -

To avoid possible ambiguities, the fully qualified function - name must be used when calling a function with the same name as - a BIF, and the compiler does not allow defining a function with - the same name as an explicitly imported function.

+

Note that when calling a local function, there is a difference - between using the implicitly or fully qualified function name, as - the latter always refers to the latest version of the module. See - Compilation and Code Loading.

+ between using the implicitly or fully qualified function name, as + the latter always refers to the latest version of the module. See + Compilation and Code Loading.

+

See also the chapter about Function Evaluation.

+ +
+ Local Function Names Clashing With Auto-imported BIFs +

If a local function has the same name as an auto-imported BIF, + the semantics is that implicitly qualified function calls are + directed to the locally defined function, not to the BIF. To avoid + confusion, there is a compiler directive available, + -compile({no_auto_import,[F/A]}), that makes a BIF not + being auto-imported. In certain situations, such a compile-directive + is mandatory.

+ +

Before OTP R14A (ERTS version 5.8), an implicitly + qualified function call to a function having the same name as an + auto-imported BIF always resulted in the BIF being called. In + newer versions of the compiler the local function is instead + called. The change is there to avoid that future additions to the + set of auto-imported BIFs does not silently change the behavior + of old code.

+ +

However, to avoid that old (pre R14) code changed it's + behavior when compiled with OTP version R14A or later, the + following restriction applies: If you override the name of a BIF + that was auto-imported in OTP versions prior to R14A (ERTS version + 5.8) and have an implicitly qualified call to that function in + your code, you either need to explicitly remove the auto-import + using a compiler directive, or replace the call with a fully + qualified function call, otherwise you will get a compilation + error. See example below:

 + + +-export([length/1,f/1]). + +-compile({no_auto_import,[length/1]}). % erlang:length/1 no longer autoimported + +length([]) -> + 0; +length([H|T]) -> + 1 + length(T). %% Calls the local funtion length/1 + +f(X) when erlang:length(X) > 3 -> %% Calls erlang:length/1, + %% which is allowed in guards + long. + +

The same logic applies to explicitly imported functions from + other modules as to locally defined functions. To both import a + function from another module and have the function declared in the + module at the same time is not allowed.

+ + +-export([f/1]). + +-compile({no_auto_import,[length/1]}). % erlang:length/1 no longer autoimported + +-import(mod,[length/1]). + +f(X) when erlang:length(X) > 33 -> %% Calls erlang:lenght/1, + %% which is allowed in guards + + erlang:length(X); %% Explicit call to erlang:length in body + +f(X) -> + length(X). %% mod:length/1 is called + + +

For auto-imported BIFs added to Erlang in release R14A and thereafter, + overriding the name with a local function or explicit import is always + allowed. However, if the -compile({no_auto_import,[F/A]) + directive is not used, the compiler will issue a warning whenever + the function is called in the module using the implicitly qualified + function name.

+
-- cgit v1.2.3