rebar_base_compiler: replace fixed size list with a tuple

src/rebar_base_compiler.erl

@@ -161,7 +161,7 @@ compile_queue(Config, Pids, Targets) ->
                     compile_queue(Config, Pids, Rest)
             end;
 
-        {fail, [_, {source, Source}}=Error] ->
+        {fail, {_, {source, Source}}=Error} ->
             ?CONSOLE("Compiling ~s failed:\n",
                      [maybe_absname(Config, Source)]),
             maybe_report(Error),
@@ -206,8 +206,7 @@ compile_worker(QueuePid, Config, CompileFn) ->
                     QueuePid ! {skipped, Source},
                     compile_worker(QueuePid, Config, CompileFn);
                 Error ->
-                    QueuePid ! {fail, [{error, Error},
-                                       {source, Source}]},
+                    QueuePid ! {fail, {{error, Error}, {source, Source}}},
                     ok
             end;
 
@@ -228,7 +227,7 @@ format_warnings(Config, Source, Warnings, Opts) ->
              end,
     format_errors(Config, Source, Prefix, Warnings).
 
-maybe_report([{error, {error, _Es, _Ws}=ErrorsAndWarnings}, {source, _}]) ->
+maybe_report({{error, {error, _Es, _Ws}=ErrorsAndWarnings}, {source, _}}) ->
     maybe_report(ErrorsAndWarnings);
 maybe_report([{error, E}, {source, S}]) ->
     report(["unexpected error compiling " ++ S, io_lib:fwrite("~n~p~n", [E])]);