From 462962ebab154362ac87445550b9590f6f5840ce Mon Sep 17 00:00:00 2001
From: David Kubecka <davidkubecka@seznam.cz>
Date: Wed, 25 Mar 2015 09:57:42 +0100
Subject: [PATCH] Delete existing out-edges before adding new ones in
 modify_erlcinfo

When the source file changes it could happen that some of its
dependecies get removed.  In that case we should remove these
former dependencies from the graph, so that they don't influence
recompilation of the source file anymore.
---
 inttest/erlc_dep_graph/erlc_dep_graph_rt.erl | 19 ++++++++++++++++---
 inttest/erlc_dep_graph/src/java.erl.no_extra | 10 ++++++++++
 src/rebar_erlc_compiler.erl                  |  1 +
 3 files changed, 27 insertions(+), 3 deletions(-)
 create mode 100644 inttest/erlc_dep_graph/src/java.erl.no_extra

diff --git a/inttest/erlc_dep_graph/erlc_dep_graph_rt.erl b/inttest/erlc_dep_graph/erlc_dep_graph_rt.erl
index ee3907e..fb128c6 100644
--- a/inttest/erlc_dep_graph/erlc_dep_graph_rt.erl
+++ b/inttest/erlc_dep_graph/erlc_dep_graph_rt.erl
@@ -40,7 +40,7 @@ files() ->
 run(_Dir) ->
     compile_all(ok, ""),
     check_beams_ok(),
-    check_beams_untouched(),
+    check_beams_untouched(filelib:wildcard("ebin/*.beam")),
     modify_and_recompile_ok("src/lisp.erl", "ebin/lisp.beam"),
 
     clean_all_ok(),
@@ -48,14 +48,27 @@ run(_Dir) ->
     compile_all(ok, ""),
     modify_and_recompile_ok("extra_include/extra.hrl", "ebin/java.beam"),
 
+    Java = "src/java.erl",
+    {ok, OrigContent} = file:read_file(Java),
+    %% Remove header file inclusion
+    {ok, _} = file:copy("src/java.erl.no_extra", Java),
+    %% Ensure recompilation
+    touch([Java]),
+    compile_all(ok, ""),
+    %% Modify that header file
+    touch(["extra_include/extra.hrl"]),
+    %% Ensure we don't have to recompile anything
+    check_beams_untouched(["ebin/java.beam"]),
+    %% Clean up
+    ok = file:write_file(Java, OrigContent),
+
     ok.
 
 check_beams_ok() ->
     F = fun(BeamFile) -> ?assert(filelib:is_regular(BeamFile)) end,
     with_erl_beams(F).
 
-check_beams_untouched() ->
-    Beams = filelib:wildcard("ebin/*.beam"),
+check_beams_untouched(Beams) ->
     compile_all_and_assert_mtimes(Beams, fun erlang:'=:='/2).
 
 modify_and_recompile_ok(TouchFile, CheckFile) ->
diff --git a/inttest/erlc_dep_graph/src/java.erl.no_extra b/inttest/erlc_dep_graph/src/java.erl.no_extra
new file mode 100644
index 0000000..7a8fc04
--- /dev/null
+++ b/inttest/erlc_dep_graph/src/java.erl.no_extra
@@ -0,0 +1,10 @@
+%% -*- mode: erlang;erlang-indent-level: 4;indent-tabs-mode: nil -*-
+%% ex: ts=4 sw=4 ft=erlang et
+-module(java).
+
+-export([factory/0]).
+
+-include("lambda.hrl").
+
+factory() ->
+	?FUN.
diff --git a/src/rebar_erlc_compiler.erl b/src/rebar_erlc_compiler.erl
index 19dc40a..7c3f6db 100644
--- a/src/rebar_erlc_compiler.erl
+++ b/src/rebar_erlc_compiler.erl
@@ -448,6 +448,7 @@ modify_erlcinfo(G, Source, Dirs) ->
     ok = file:close(Fd),
     LastUpdated = {date(), time()},
     digraph:add_vertex(G, Source, LastUpdated),
+    digraph:del_edges(G, digraph:out_edges(G, Source)),
     lists:foreach(
       fun(Incl) ->
               update_erlcinfo(G, Dirs, Incl),