Properly report unknown parse transforms

We don't want undef errors coming from the parse transform itself to be confused
with undef errors caused by the absence of the parse transform.

Reported-by: Klas Johansson

2 files changed, 39 insertions, 24 deletions

diff --git a/lib/compiler/src/compile.erl b/lib/compiler/src/compile.erl
index c7d91070f6..60311ef002 100644
--- a/lib/compiler/src/compile.erl
+++ b/lib/compiler/src/compile.erl
@@ -906,28 +906,35 @@ transform_module(#compile{options=Opt,code=Code0}=St0) ->
 
 foldl_transform(St, [T|Ts]) ->
     Name = "transform " ++ atom_to_list(T),
-    Fun = fun(S) -> T:parse_transform(S#compile.code, S#compile.options) end,
-    Run = case member(time, St#compile.options) of
-	      true  -> fun run_tc/2;
-	      false -> fun({_Name,F}, S) -> catch F(S) end
-	  end,
-    case Run({Name, Fun}, St) of
-	{error,Es,Ws} ->
-	    {error,St#compile{warnings=St#compile.warnings ++ Ws,
-			      errors=St#compile.errors ++ Es}};
-	{'EXIT',{undef,_}} ->
-	    Es = [{St#compile.ifile,[{none,compile,
-				      {undef_parse_transform,T}}]}],
-	    {error,St#compile{errors=St#compile.errors ++ Es}};
-	{'EXIT',R} ->
-	    Es = [{St#compile.ifile,[{none,compile,{parse_transform,T,R}}]}],
-	    {error,St#compile{errors=St#compile.errors ++ Es}};
-	{warning, Forms, Ws} ->
-	    foldl_transform(
-	      St#compile{code=Forms,
-			 warnings=St#compile.warnings ++ Ws}, Ts);
-	Forms ->
-	    foldl_transform(St#compile{code=Forms}, Ts)
+    case code:ensure_loaded(T) =:= {module,T} andalso
+                erlang:function_exported(T, parse_transform, 2) of
+        true ->
+            Fun = fun(S) ->
+                         T:parse_transform(S#compile.code, S#compile.options)
+                  end,
+            Run = case member(time, St#compile.options) of
+                      true  -> fun run_tc/2;
+                      false -> fun({_Name,F}, S) -> catch F(S) end
+                  end,
+            case Run({Name, Fun}, St) of
+                {error,Es,Ws} ->
+                    {error,St#compile{warnings=St#compile.warnings ++ Ws,
+                                      errors=St#compile.errors ++ Es}};
+                {'EXIT',R} ->
+                    Es = [{St#compile.ifile,[{none,compile,
+                                              {parse_transform,T,R}}]}],
+                    {error,St#compile{errors=St#compile.errors ++ Es}};
+                {warning, Forms, Ws} ->
+                    foldl_transform(
+                      St#compile{code=Forms,
+                                 warnings=St#compile.warnings ++ Ws}, Ts);
+                Forms ->
+                    foldl_transform(St#compile{code=Forms}, Ts)
+            end;
+        false ->
+            Es = [{St#compile.ifile,[{none,compile,
+                                      {undef_parse_transform,T}}]}],
+            {error,St#compile{errors=St#compile.errors ++ Es}}
     end;
 foldl_transform(St, []) -> {ok,St}.
 
diff --git a/lib/compiler/test/error_SUITE.erl b/lib/compiler/test/error_SUITE.erl
index bd877bb528..8e79b88821 100644
--- a/lib/compiler/test/error_SUITE.erl
+++ b/lib/compiler/test/error_SUITE.erl
@@ -235,10 +235,18 @@ transforms(Config) ->
              ">>,
     {error,[{none,compile,{parse_transform,?MODULE,{too_bad,_}}}],[]} =
 	run_test(Ts2, test_filename(Config), [], dont_write_beam),
+    Ts3 = <<"
+              -compile({parse_transform,",?MODULE_STRING,"}).
+             ">>,
+    {error,[{none,compile,{parse_transform,?MODULE,{undef,_}}}],[]} =
+        run_test(Ts3, test_filename(Config), [call_undef], dont_write_beam),
     ok.
 
-parse_transform(_, _) ->
-    error(too_bad).
+parse_transform(_, Opts) ->
+    case lists:member(call_undef, Opts) of
+        false -> error(too_bad);
+        true -> camembert:délicieux()
+    end.
 
 
 forbidden_maps(Config) when is_list(Config) ->