Fix merl:compile_and_load/1 with comments

Use erl_syntax:revert_forms/1 instead of manually reverting each form
to properly handle syntax trees containing comments. The manual approach
failed when comment nodes were passed to the compiler.

Add test case to verify compile_and_load works with various comment
placements in quoted code.

Author: williamthome

lib/syntax_tools/src/merl.erl

@@ -429,7 +429,7 @@ compile(Code, Options) when not is_list(Code)->
         _ -> compile([Code], Options)
     end;
 compile(Code, Options0) when is_list(Options0) ->
-    Forms = [erl_syntax:revert(F) || F <- Code],
+    Forms = erl_syntax:revert_forms(Code),
     Options = [verbose, report_errors, report_warnings, binary | Options0],
     compile:noenv_forms(Forms, Options).
 

lib/syntax_tools/test/merl_SUITE.erl

@@ -25,19 +25,21 @@
 -include_lib("eunit/include/eunit.hrl").
 
 %% Test server specific exports
--export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, 
+-export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1,
 	 init_per_group/2,end_per_group/2]).
 
 %% Test cases
 -export([merl_smoke_test/1,
-         transform_parse_error_test/1, otp_15291/1]).
+         transform_parse_error_test/1, otp_15291/1,
+         compile_and_load_with_comments/1]).
 
 suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() ->
     [merl_smoke_test,
      transform_parse_error_test,
-     otp_15291].
+     otp_15291,
+     compile_and_load_with_comments].
 
 groups() -> 
     [].
@@ -112,6 +114,18 @@ otp_15291(_Config) ->
     {clause,A1,[{var,A1,'_'}],[],[{atom,A1,ok}]} = C1,
     ok.
 
+compile_and_load_with_comments(_Config) ->
+    ?assertMatch({ok, _},
+                 merl:compile_and_load(merl:quote(
+                     ~"-module(merl_test_module_1)."))),
+    ?assertMatch({ok, _},
+                 merl:compile_and_load(merl:quote(
+                     ~"-module(merl_test_module_2). % comment"))),
+    ?assertMatch({ok, _},
+                 merl:compile_and_load(merl:quote(
+                     ~"\n-module(merl_test_module_3).\n% comment"))),
+    ok.
+
 %% utilities
 
 f(Ts) when is_list(Ts) ->