stdlib: fix a qlc bug introduced in 18.0

As pointed out by roowe, qlc does not handle errors in early compiler
(scanner, parser) well in OTP 18.0.

2 files changed, 21 insertions, 2 deletions

diff --git a/lib/stdlib/src/qlc_pt.erl b/lib/stdlib/src/qlc_pt.erl
index 4e81e2c2dd..9577d17a85 100644
--- a/lib/stdlib/src/qlc_pt.erl
+++ b/lib/stdlib/src/qlc_pt.erl
@@ -428,7 +428,13 @@ compile_errors(FormsNoShadows) ->
     end.
 
 compile_forms(Forms0, Options) ->
-    Forms = [F || F <- Forms0, element(1, F) =/= eof] ++  [{eof,anno0()}],
+    Exclude = fun(eof) -> true;
+                 (warning) -> true;
+                 (error) -> true;
+                 (_) -> false
+              end,
+    Forms = ([F || F <- Forms0, not Exclude(element(1, F))]
+             ++ [{eof,anno0()}]),
     try 
         case compile:noenv_forms(Forms, compile_options(Options)) of
             {ok, _ModName, Ws0} ->
diff --git a/lib/stdlib/test/qlc_SUITE.erl b/lib/stdlib/test/qlc_SUITE.erl
index 72216bfa0d..52fdb69b73 100644
--- a/lib/stdlib/test/qlc_SUITE.erl
+++ b/lib/stdlib/test/qlc_SUITE.erl
@@ -74,6 +74,7 @@
 	  otp_5644/1, otp_5195/1, otp_6038_bug/1, otp_6359/1, otp_6562/1,
 	  otp_6590/1, otp_6673/1, otp_6964/1, otp_7114/1, otp_7238/1,
 	  otp_7232/1, otp_7552/1, otp_6674/1, otp_7714/1, otp_11758/1,
+          otp_12946/1,
 
 	  manpage/1,
 
@@ -143,7 +144,7 @@ groups() ->
      {tickets, [],
       [otp_5644, otp_5195, otp_6038_bug, otp_6359, otp_6562,
        otp_6590, otp_6673, otp_6964, otp_7114, otp_7232,
-       otp_7238, otp_7552, otp_6674, otp_7714, otp_11758]},
+       otp_7238, otp_7552, otp_6674, otp_7714, otp_11758, otp_12946]},
      {compat, [], [backward, forward]}].
 
 init_per_suite(Config) ->
@@ -7154,6 +7155,18 @@ otp_6674(Config) when is_list(Config) ->
 
     ?line run(Config, Ts).
 
+otp_12946(doc) ->
+    ["Syntax error."];
+otp_12946(suite) -> [];
+otp_12946(Config) when is_list(Config) ->
+    Text =
+        <<"-export([init/0]).
+           init() ->
+               ok.
+           y">>,
+    {errors,[{4,erl_parse,_}],[]} = compile_file(Config, Text, []),
+    ok.
+
 manpage(doc) ->
     "Examples from qlc(3).";
 manpage(suite) -> [];