Merge pull request #5446 from bjorng/bjorn/parsetools/robustify-yecctoken2string/OTP-17721

yeccpre.hrl: Never crash when printing non-standard tokens

2 files changed, 43 insertions, 13 deletions

diff --git a/lib/parsetools/include/yeccpre.hrl b/lib/parsetools/include/yeccpre.hrl
index 6cfdb60078..e0b132c180 100644
--- a/lib/parsetools/include/yeccpre.hrl
+++ b/lib/parsetools/include/yeccpre.hrl
@@ -148,19 +148,28 @@ yecctoken_location(Token) ->
     end.
 
 -compile({nowarn_unused_function, yecctoken2string/1}).
-yecctoken2string({atom, _, A}) -> io_lib:write_atom(A);
-yecctoken2string({integer,_,N}) -> io_lib:write(N);
-yecctoken2string({float,_,F}) -> io_lib:write(F);
-yecctoken2string({char,_,C}) -> io_lib:write_char(C);
-yecctoken2string({var,_,V}) -> io_lib:format("~s", [V]);
-yecctoken2string({string,_,S}) -> io_lib:write_string(S);
-yecctoken2string({reserved_symbol, _, A}) -> io_lib:write(A);
-yecctoken2string({_Cat, _, Val}) -> io_lib:format("~tp", [Val]);
-yecctoken2string({dot, _}) -> "'.'";
-yecctoken2string({'$end', _}) -> [];
-yecctoken2string({Other, _}) when is_atom(Other) ->
+yecctoken2string(Token) ->
+    try
+        yecctoken2string1(Token)
+    catch
+        _:_ ->
+            io_lib:format("~tp", [Token])
+    end.
+
+-compile({nowarn_unused_function, yecctoken2string1/1}).
+yecctoken2string1({atom, _, A}) -> io_lib:write_atom(A);
+yecctoken2string1({integer,_,N}) -> io_lib:write(N);
+yecctoken2string1({float,_,F}) -> io_lib:write(F);
+yecctoken2string1({char,_,C}) -> io_lib:write_char(C);
+yecctoken2string1({var,_,V}) -> io_lib:format("~s", [V]);
+yecctoken2string1({string,_,S}) -> io_lib:write_string(S);
+yecctoken2string1({reserved_symbol, _, A}) -> io_lib:write(A);
+yecctoken2string1({_Cat, _, Val}) -> io_lib:format("~tp", [Val]);
+yecctoken2string1({dot, _}) -> "'.'";
+yecctoken2string1({'$end', _}) -> [];
+yecctoken2string1({Other, _}) when is_atom(Other) ->
     io_lib:write_atom(Other);
-yecctoken2string(Other) ->
+yecctoken2string1(Other) ->
     io_lib:format("~tp", [Other]).
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
diff --git a/lib/parsetools/test/yecc_SUITE.erl b/lib/parsetools/test/yecc_SUITE.erl
index cfdb3e4458..83daa91535 100644
--- a/lib/parsetools/test/yecc_SUITE.erl
+++ b/lib/parsetools/test/yecc_SUITE.erl
@@ -1218,8 +1218,29 @@ yeccpre(Config) when is_list(Config) ->
                 ok.
            ">>,
            default,
+           ok},
+
+          {error_3, <<"
+            Nonterminals statement.
+            Terminals keyword string.
+            Rootsymbol statement.
+
+            statement -> keyword string.
+
+            Erlang code.
+
+            -export([t/0]).
+
+            t() ->
+                %% Never crash in yecctoken_to_string/1 or its helpers,
+                %% even if when tokens are not in the format that erl_scan
+                %% produces.
+                {error, _} = parse([{string, 1, <<\"foo\">>}]),
+                ok.
+           ">>,
+           default,
            ok}],
-       
+
     run(Config, Ts),
     ok.