File 0405-erl_eval-Support-the-fun-Name-Arity-syntax-for-creat.patch of Package erlang
From 4ad645d55b2cd25bf7689a0180d84e6dc13de7fc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Fri, 25 Oct 2024 08:50:50 +0200
Subject: [PATCH 1/2] erl_eval: Support the fun Name/Arity syntax for creating
a fun
Attempting to create a fun referering to either an auto-imported
BIF or a local fun defined in shell would fail:
1> fun is_atom/1.
** exception error: undefined function erl_eval:is_atom/1
2> id(I) -> I.
ok
3> fun id/1.
** exception error: undefined function erl_eval:id/1
This commit adds support for defining a fun based on either
an auto-imported BIF:
1> F = fun is_atom/1.
fun erlang:is_atom/1
2> F(a).
true
3> F(42).
false
Or on a local function defined in the shell:
1> I = fun id/1.
#Fun<erl_eval.42.18682967>
2> I(42).
** exception error: undefined shell command id/1
3> id(I) -> I.
ok
4> I(42).
42
As shown in the example, it not necessary that the local fun is
defined at the time the fun is created; only that it is defined when
the fun is called.
Closes #8963
---
lib/debugger/test/erl_eval_SUITE.erl | 1 -
lib/stdlib/src/erl_eval.erl | 21 +++++++++++++++---
lib/stdlib/test/erl_eval_SUITE.erl | 32 +++++++++++++++++++++++++---
3 files changed, 47 insertions(+), 7 deletions(-)
diff --git a/lib/debugger/test/erl_eval_SUITE.erl b/lib/debugger/test/erl_eval_SUITE.erl
index 8907856583..4977b33ee7 100644
--- a/lib/debugger/test/erl_eval_SUITE.erl
+++ b/lib/debugger/test/erl_eval_SUITE.erl
@@ -948,7 +948,6 @@ funs(Config) when is_list(Config) ->
error_check("apply(timer, sleep, [1]).", got_it, none, EFH),
error_check("begin F = fun(T) -> timer:sleep(T) end,F(1) end.",
got_it, none, EFH),
- error_check("fun c/1.", undef),
error_check("fun a:b/0().", undef),
MaxArgs = 20,
diff --git a/lib/stdlib/src/erl_eval.erl b/lib/stdlib/src/erl_eval.erl
index 0989f43ed9..560c56136c 100644
--- a/lib/stdlib/src/erl_eval.erl
+++ b/lib/stdlib/src/erl_eval.erl
@@ -489,9 +489,24 @@ expr({'fun',_Anno,{function,Mod0,Name0,Arity0}}, Bs0, Lf, Ef, RBs, FUVs) ->
{[Mod,Name,Arity],Bs} = expr_list([Mod0,Name0,Arity0], Bs0, Lf, Ef, FUVs),
F = erlang:make_fun(Mod, Name, Arity),
ret_expr(F, Bs, RBs);
-expr({'fun',Anno,{function,Name,Arity}}, Bs0, _Lf, Ef, RBs, _FUVs) -> % R8
- %% Don't know what to do...
- apply_error(undef, [{?MODULE,Name,Arity}|?STACKTRACE], Anno, Bs0, Ef, RBs);
+expr({'fun',Anno,{function,Name,Arity}}, Bs0, Lf, Ef, RBs, FUVs) -> % R8
+ case erl_internal:bif(Name, Arity) of
+ true ->
+ %% Auto-imported BIF. Create an external fun.
+ ret_expr(fun erlang:Name/Arity, Bs0, RBs);
+ false ->
+ %% A local function assumed to be defined in the shell.
+ %% Create a wrapper fun that will call the local fun.
+ %% Calling the fun will succeed if the local fun is
+ %% defined when the call is made.
+ Args = [{var,Anno,list_to_atom("@arg" ++ [V])} ||
+ V <- lists:seq($a, $a+Arity-1)],
+ H = Args,
+ G = [{atom,Anno,true}],
+ B = [{call,Anno,{atom,Anno,Name},Args}],
+ Cs = [{clause,Anno,H,G,B}],
+ expr({'fun',Anno,{clauses,Cs}}, Bs0, Lf, Ef, RBs, FUVs)
+ end;
expr({'fun',Anno,{clauses,Cs}} = Ex, Bs, Lf, Ef, RBs, FUVs) ->
{En,NewFUVs} = fun_used_bindings(Ex, Cs, Bs, FUVs),
Info = {Anno,En,Lf,Ef,NewFUVs,Cs},
diff --git a/lib/stdlib/test/erl_eval_SUITE.erl b/lib/stdlib/test/erl_eval_SUITE.erl
index e28dd788bb..3cecbda635 100644
--- a/lib/stdlib/test/erl_eval_SUITE.erl
+++ b/lib/stdlib/test/erl_eval_SUITE.erl
@@ -68,6 +68,7 @@
-export([count_down/2, count_down_fun/0, do_apply/2,
local_func/3, local_func_value/2]).
-export([simple/0]).
+-export([my_div/2]).
-ifdef(STANDALONE).
-define(config(A,B),config(A,B)).
@@ -1217,8 +1218,6 @@ custom_stacktrace(Config) when is_list(Config) ->
backtrace_check("#unknown.index.", {undef_record,unknown},
[erl_eval, mystack(1)], none, EFH),
- backtrace_check("fun foo/2.", undef,
- [{erl_eval, foo, 2}, erl_eval, mystack(1)], none, EFH),
backtrace_check("foo(1, 2).", undef,
[{erl_eval, foo, 2}, erl_eval, mystack(1)], none, EFH),
@@ -1369,7 +1368,6 @@ funs(Config) when is_list(Config) ->
error_check("begin F = fun(T) -> timer:sleep(T) end,F(1) end.",
got_it, none, AnnEFH),
- error_check("fun c/1.", undef),
error_check("fun a:b/0().", undef),
MaxArgs = 20,
@@ -1387,8 +1385,36 @@ funs(Config) when is_list(Config) ->
%% Test that {M,F} is not accepted as a fun.
error_check("{" ?MODULE_STRING ",module_info}().",
{badfun,{?MODULE,module_info}}),
+
+ %% Test defining and calling a fun based on an auto-imported BIF.
+ check(fun() ->
+ F = fun is_binary/1,
+ true = F(<<>>),
+ false = F(a)
+ end,
+ ~S"""
+ F = fun is_binary/1,
+ true = F(<<>>),
+ false = F(a).
+ """,
+ false, ['F'], lfh(), none),
+
+ %% Test defining and calling a local fun defined in the shell.
+ check(fun() ->
+ D = fun my_div/2,
+ 3 = D(15, 5)
+ end,
+ ~S"""
+ D = fun my_div/2,
+ 3 = D(15, 5).
+ """,
+ 3, ['D'], lfh(), efh()),
+
ok.
+my_div(A, B) ->
+ A div B.
+
run_many_args({S, As}) ->
apply(eval_string(S), As) =:= As.
--
2.43.0
