File 3503-Add-a-poor-man-s-implementation-of-enable_feature-Fe.patch of Package erlang
From e025971d73273476e88e4bff385275b7f14ddc39 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Tue, 2 Nov 2021 07:08:54 +0100
Subject: [PATCH 03/12] Add a poor man's implementation of
`{enable_feature,Feature}`
There is ongoing work, which will result in an EEP and a pull request,
for a way to conditionally enable new or experimental features in
the compiler and runtime system.
This commit implements this feature in a crude way, to allow us to
selectively make `maybe` and `else` keywords instead of atoms. That
will allow us to compile source code that use `maybe` and `else`
as atoms. (They are quite a lot of code in OTP that uses `maybe` as
an atom.)
Note that as implemented in this commit, for the
`{enable_feature,maybe_expr}` to have any effect, it must be given as an
option to the compiler, **not** in the source code for the module.
---
lib/compiler/src/compile.erl | 13 +++++++++++++
lib/stdlib/src/epp.erl | 14 ++++++++++----
2 files changed, 23 insertions(+), 4 deletions(-)
diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index ec0414cdda..847ea484ba 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -1018,12 +1018,25 @@ do_parse_module(DefEncoding, #compile{ifile=File,options=Opts,dir=Dir}=St) ->
false ->
1
end,
+
+ %% FIXME: Rewrite this when the enable feature EEP has been implemented.
+ ResWordFun = case proplists:get_value(enable_feature, Opts, []) of
+ maybe_expr ->
+ fun('maybe') -> true;
+ ('else') -> true;
+ (Other) -> erl_scan:reserved_word(Other)
+ end;
+ _ ->
+ fun erl_scan:reserved_word/1
+ end,
+
R = epp:parse_file(File,
[{includes,[".",Dir|inc_paths(Opts)]},
{source_name, SourceName},
{macros,pre_defs(Opts)},
{default_encoding,DefEncoding},
{location,StartLocation},
+ {reserved_word_fun,ResWordFun},
extra]),
case R of
{ok,Forms0,Extra} ->
diff --git a/lib/stdlib/src/epp.erl b/lib/stdlib/src/epp.erl
index 185deaf7b4..1f14133039 100644
--- a/lib/stdlib/src/epp.erl
+++ b/lib/stdlib/src/epp.erl
@@ -73,7 +73,8 @@
:: #{name() => [{argspec(), [used()]}]},
default_encoding = ?DEFAULT_ENCODING :: source_encoding(),
pre_opened = false :: boolean(),
- fname = [] :: function_name_type()
+ fname = [] :: function_name_type(),
+ erl_scan_opts = [] :: erl_scan:options()
}).
%% open(Options)
@@ -604,11 +605,16 @@ init_server(Pid, FileName, Options, St0) ->
%% first in path
Path = [filename:dirname(FileName) |
proplists:get_value(includes, Options, [])],
+
+ ResWordFun = proplists:get_value(reserved_word_fun, Options,
+ fun erl_scan:reserved_word/1),
+
%% the default location is 1 for backwards compatibility, not {1,1}
AtLocation = proplists:get_value(location, Options, 1),
St = St0#epp{delta=0, name=SourceName, name2=SourceName,
path=Path, location=AtLocation, macs=Ms1,
- default_encoding=DefEncoding},
+ default_encoding=DefEncoding,
+ erl_scan_opts=[{reserved_word_fun,ResWordFun}]},
From = wait_request(St),
Anno = erl_anno:new(AtLocation),
enter_file_reply(From, file_name(SourceName), Anno,
@@ -806,7 +812,7 @@ leave_file(From, St) ->
%% scan_toks(Tokens, From, EppState)
scan_toks(From, St) ->
- case io:scan_erl_form(St#epp.file, '', St#epp.location) of
+ case io:scan_erl_form(St#epp.file, '', St#epp.location, St#epp.erl_scan_opts) of
{ok,Toks,Cl} ->
scan_toks(Toks, From, St#epp{location=Cl});
{error,E,Cl} ->
@@ -1322,7 +1328,7 @@ new_location(Ln, {Le,_}, {Lf,_}) ->
%% nested conditionals and repeated 'else's.
skip_toks(From, St, [I|Sis]) ->
- case io:scan_erl_form(St#epp.file, '', St#epp.location) of
+ case io:scan_erl_form(St#epp.file, '', St#epp.location, St#epp.erl_scan_opts) of
{ok,[{'-',_Ah},{atom,_Ai,ifdef}|_Toks],Cl} ->
skip_toks(From, St#epp{location=Cl}, [ifdef,I|Sis]);
{ok,[{'-',_Ah},{atom,_Ai,ifndef}|_Toks],Cl} ->
--
2.34.1
