syntax_tools: Fix pretty-printing of type funs

See also ERL-815.

3 files changed, 54 insertions, 5 deletions

diff --git a/lib/syntax_tools/src/erl_prettypr.erl b/lib/syntax_tools/src/erl_prettypr.erl
index 6906ef1553..6ad9bec2e6 100644
--- a/lib/syntax_tools/src/erl_prettypr.erl
+++ b/lib/syntax_tools/src/erl_prettypr.erl
@@ -1101,8 +1101,9 @@ lay_2(Node, Ctxt) ->
             Ctxt1 = reset_prec(Ctxt),
             D1 = lay(erl_syntax:constrained_function_type_body(Node),
                      Ctxt1),
+            Ctxt2 = Ctxt1#ctxt{clause = undefined},
             D2 = lay(erl_syntax:constrained_function_type_argument(Node),
-                     Ctxt1),
+                     Ctxt2),
             beside(D1,
                    beside(floating(text(" when ")), D2));
 
@@ -1113,7 +1114,7 @@ lay_2(Node, Ctxt) ->
                                   _ ->
                                       {"fun(", ")"}
                               end,
-            Ctxt1 = reset_prec(Ctxt),
+            Ctxt1 = (reset_prec(Ctxt))#ctxt{clause = undefined},
             D1 = case erl_syntax:function_type_arguments(Node) of
                      any_arity ->
                          text("(...)");
diff --git a/lib/syntax_tools/test/syntax_tools_SUITE.erl b/lib/syntax_tools/test/syntax_tools_SUITE.erl
index 9dbd0e302a..6b42f7a0a1 100644
--- a/lib/syntax_tools/test/syntax_tools_SUITE.erl
+++ b/lib/syntax_tools/test/syntax_tools_SUITE.erl
@@ -26,14 +26,14 @@
 -export([app_test/1,appup_test/1,smoke_test/1,revert/1,revert_map/1,
          revert_map_type/1,
 	t_abstract_type/1,t_erl_parse_type/1,t_type/1, t_epp_dodger/1,
-	t_comment_scan/1,t_igor/1,t_erl_tidy/1]).
+	t_comment_scan/1,t_igor/1,t_erl_tidy/1,t_prettypr/1]).
 
 suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() -> 
     [app_test,appup_test,smoke_test,revert,revert_map,revert_map_type,
     t_abstract_type,t_erl_parse_type,t_type,t_epp_dodger,
-    t_comment_scan,t_igor,t_erl_tidy].
+    t_comment_scan,t_igor,t_erl_tidy,t_prettypr].
 
 groups() -> 
     [].
@@ -300,6 +300,14 @@ t_comment_scan(Config) when is_list(Config) ->
     ok = test_comment_scan(Filenames,DataDir),
     ok.
 
+t_prettypr(Config) when is_list(Config) ->
+    DataDir   = ?config(data_dir, Config),
+    PrivDir   = ?config(priv_dir, Config),
+    Filenames = ["type_specs.erl",
+                 "specs_and_funs.erl"],
+    ok = test_prettypr(Filenames,DataDir,PrivDir),
+    ok.
+
 test_files(Config) ->
     DataDir = ?config(data_dir, Config),
     [ filename:join(DataDir,Filename) || Filename <- test_files() ].
@@ -307,7 +315,8 @@ test_files(Config) ->
 test_files() ->
     ["syntax_tools_SUITE_test_module.erl",
      "syntax_tools_test.erl",
-     "type_specs.erl"].
+     "type_specs.erl",
+     "specs_and_funs.erl"].
 
 t_igor(Config) when is_list(Config) ->
     DataDir   = ?config(data_dir, Config),
@@ -359,6 +368,27 @@ test_comment_scan([File|Files],DataDir) ->
     test_comment_scan(Files,DataDir).
 
 
+test_prettypr([],_,_) -> ok;
+test_prettypr([File|Files],DataDir,PrivDir) ->
+    Filename  = filename:join(DataDir,File),
+    io:format("Parsing ~p~n", [Filename]),
+    {ok, Fs0} = epp:parse_file(Filename, [], []),
+    Fs = erl_syntax:form_list(Fs0),
+    PP = erl_prettypr:format(Fs, [{paper,  120}, {ribbon, 110}]),
+    io:put_chars(PP),
+    OutFile = filename:join(PrivDir, File),
+    ok = file:write_file(OutFile,iolist_to_binary(PP)),
+    io:format("Parsing OutFile: ~s~n", [OutFile]),
+    {ok, Fs2} = epp:parse_file(OutFile, [], []),
+    case [Error || {error, _} = Error <- Fs2] of
+        [] ->
+            ok;
+        Errors ->
+            ?t:fail(Errors)
+    end,
+    test_prettypr(Files,DataDir,PrivDir).
+
+
 test_epp_dodger([], _, _) -> ok;
 test_epp_dodger([Filename|Files],DataDir,PrivDir) ->
     io:format("Parsing ~p~n", [Filename]),
diff --git a/lib/syntax_tools/test/syntax_tools_SUITE_data/specs_and_funs.erl b/lib/syntax_tools/test/syntax_tools_SUITE_data/specs_and_funs.erl
new file mode 100644
index 0000000000..8dfeaf5a6b
--- /dev/null
+++ b/lib/syntax_tools/test/syntax_tools_SUITE_data/specs_and_funs.erl
@@ -0,0 +1,18 @@
+-module(specs_and_funs).
+
+-export([my_apply/3, two/1]).
+
+%% OTP-15519, ERL-815
+
+-spec my_apply(Fun, Arg, fun((A) -> A)) -> Result when
+      Fun :: fun((Arg) -> Result),
+      Arg :: any(),
+      Result :: any().
+
+my_apply(Fun, Arg, _) ->
+    Fun(Arg).
+
+-spec two(fun((A) -> A)) -> fun((B) -> B).
+
+two(F) ->
+    F(fun(X) -> X end).