Merge pull request #2892 from ferd/prevent-DAG-edge-duplication

Prevent infinite DAG growth

apps/rebar/src/rebar_compiler_dag.erl

@@ -149,12 +149,21 @@ finalise_populate_sources_(G, InDirs, [{Status, {deps, Source, AbsIncls}}|Acc])
  {_, _Src, Path, _Label} <- [digraph:edge(G, Edge)],
  not lists:member(Path, AbsIncls)],
  %% Add the rest
- [digraph:add_edge(G, Source, Incl) || Incl <- AbsIncls],
+ RemainingEdges = [digraph:edge(G, E) || E <- digraph:out_edges(G, Source),
+ AbsIncls =/= []],
+ [digraph:add_edge(G, Source, Incl) || Incl <- AbsIncls,
+ not in_edges(Source, Incl, RemainingEdges)],
  %% mark the digraph dirty when there is any change in
  %% dependencies, for any application in the project
  mark_dirty(G),
  finalise_populate_sources_(G, InDirs, Acc).
 
+%% @private look if two vertices `V1' and `V2' exist in an unsorted set
+%% of DAG edges (in expanded format).
+in_edges(_, _, []) -> false;
+in_edges(V1, V2, [{_, V1, V2, []}|_]) -> true;
+in_edges(V1, V2, [_|T]) -> in_edges(V1, V2, T).
+
 %% @doc this function scans all the source files found and looks into
 %% all the `InDirs' for deps (other source files, or files that aren't source
 %% but still returned by the compiler module) that are related