Fix error when processing non-existent include_lib file

Since process_attr/3 searches source code for attributes, it can
happen that it finds an attribute which is eventually not needed
by the compilation, e.g. hidden by ifdef macro - see enclosed test.
Such attribute can reference a file which is not in the path or
which even doesn't exist at all, and current code doesn't expect
such a situation.  We fix things by simply ignoring such files.

inttest/erlc_dep_graph/src/lisp.erl

@@ -5,6 +5,9 @@
 -export([parse_transform/2]).
 
 -include("lambda.hrl").
+-ifdef(NOT_DEFINED).
+-include_lib("include/non/existent.hrl").
+-endif.
 
 parse_transform(Forms, _Options) ->
     Forms.

src/rebar_erlc_compiler.erl

@@ -594,8 +594,7 @@ process_attr(include, Form, Includes) ->
 process_attr(include_lib, Form, Includes) ->
     [FileNode] = erl_syntax:attribute_arguments(Form),
     RawFile = erl_syntax:string_value(FileNode),
-    File = maybe_expand_include_lib_path(RawFile),
-    [File|Includes];
+    maybe_expand_include_lib_path(RawFile) ++ Includes;
 process_attr(behaviour, Form, Includes) ->
     [FileNode] = erl_syntax:attribute_arguments(Form),
     File = module_to_erl(erl_syntax:atom_value(FileNode)),
@@ -631,7 +630,7 @@ module_to_erl(Mod) ->
 maybe_expand_include_lib_path(File) ->
     case filelib:is_regular(File) of
         true ->
-            File;
+            [File];
         false ->
             expand_include_lib_path(File)
     end.
@@ -646,8 +645,10 @@ expand_include_lib_path(File) ->
     Split = filename:split(filename:dirname(File)),
     Lib = hd(Split),
     SubDir = filename:join(tl(Split)),
-    Dir = code:lib_dir(list_to_atom(Lib), list_to_atom(SubDir)),
-    filename:join(Dir, File1).
+    case code:lib_dir(list_to_atom(Lib), list_to_atom(SubDir)) of
+        {error, bad_name} -> [];
+        Dir -> [filename:join(Dir, File1)]
+    end.
 
 %%
 %% Ensure all files in a list are present and abort if one is missing