Fix handling of latin1 characters in false ifdef branches

The fallback to latin-1 encoding would not work if the invalid
UTF-8 characters occurred in a skipped branch in an -ifdef/-ifndef.

2 files changed, 28 insertions, 2 deletions

diff --git a/lib/compiler/test/warnings_SUITE.erl b/lib/compiler/test/warnings_SUITE.erl
index ad4ad91f74..0637041873 100644
--- a/lib/compiler/test/warnings_SUITE.erl
+++ b/lib/compiler/test/warnings_SUITE.erl
@@ -662,6 +662,20 @@ latin1_fallback(Conf) when is_list(Conf) ->
 	    {warnings,[{1,compile,reparsing_invalid_unicode}]}
 	   }],
     [] = run(Conf, Ts2),
+
+    Ts3 = [{latin1_fallback3,
+	    %% Test that the compiler fall backs to latin-1 with
+	    %% a warning if a file has no encoding and does not
+	    %% contain correct UTF-8 sequences.
+	    <<"-ifdef(NOTDEFINED).
+              t(_) -> \"",246,"\";
+              t(x) -> ok.
+              -endif.
+              ">>,
+	    [],
+	    {warnings,[{2,compile,reparsing_invalid_unicode}]}}],
+    [] = run(Conf, Ts3),
+
     ok.
 
 %%%
diff --git a/lib/stdlib/src/epp.erl b/lib/stdlib/src/epp.erl
index 9b506b0a44..5f8637c118 100644
--- a/lib/stdlib/src/epp.erl
+++ b/lib/stdlib/src/epp.erl
@@ -1121,8 +1121,20 @@ skip_toks(From, St, [I|Sis]) ->
 	    skip_toks(From, St#epp{location=Cl}, Sis);
 	{ok,_Toks,Cl} ->
 	    skip_toks(From, St#epp{location=Cl}, [I|Sis]);
-	{error,_E,Cl} ->
-	    skip_toks(From, St#epp{location=Cl}, [I|Sis]);
+	{error,E,Cl} ->
+	    case E of
+		{_,file_io_server,invalid_unicode} ->
+		    %% The compiler needs to know that there was
+		    %% invalid unicode characters in the file
+		    %% (and there is no point in continuing anyway
+		    %% since io server process has terminated).
+		    epp_reply(From, {error,E}),
+		    leave_file(wait_request(St), St);
+		_ ->
+		    %% Some other invalid token, such as a bad floating
+		    %% point number. Just ignore it.
+		    skip_toks(From, St#epp{location=Cl}, [I|Sis])
+	    end;
 	{eof,Cl} ->
 	    leave_file(From, St#epp{location=Cl,istk=[I|Sis]});
 	{error,_E} ->