Fixing duplicate macro definition in umbrella edoc

When in umbrella mode (or through multiple profiles), users can specify
macros for EDocs based on either the {def, ...} or the {macros, ...}
arguments.

This patch replaces the prior options merging for umbrellas to use the
rebar3 tup_umerge utils to remove identical duplicates while preserving
correct ordering, and manually merges the {macros, ...} definitions
while ke eping the correct precedence rules since these appear (given
their behaviour) to be all individually extracted and passed as `{d,
...}` to  the compiler so that epp expands them. This compiler
function freaks out on any re-defined macros and explodes.

Do note that the macros with `{def, ...}` are edoc macros and do not
suffer from that issue, safely deduplicating multiple definitions.

src/rebar_prv_edoc.erl

@@ -47,7 +47,7 @@ do(State) ->
                     AppDir = rebar_app_info:dir(AppInfo),
                     AppOpts = rebar_app_info:opts(AppInfo),
                     %% order of the merge is important to allow app opts overrides
-                    AppEdocOpts = rebar_opts:get(AppOpts, edoc_opts, []) ++ EdocOptsAcc,
+                    AppEdocOpts = merge_opts(rebar_opts:get(AppOpts, edoc_opts, []), EdocOptsAcc),
                     AppRes = (catch edoc:application(list_to_atom(AppName), AppDir, AppEdocOpts)),
                     rebar_hooks:run_all_hooks(Cwd, post, ?PROVIDER, Providers, AppInfo, State),
                     case {AppRes, ShouldAccPaths} of
@@ -93,3 +93,27 @@ add_to_paths([{doc_path, Paths}|T], Path) ->
     [{doc_path, [Path | Paths]} | T];
 add_to_paths([H|T], Path) ->
     [H | add_to_paths(T, Path)].
+
+merge_opts(AppOpts, BaseOpts) ->
+    merge_epp_macros(rebar_utils:tup_umerge(AppOpts, BaseOpts)).
+
+%% @private the `{macros, ...}' definitions for epp can't be
+%% containing duplicate definitions even if multiple macro lists
+%% are supported, so we need to manually remove duplicates
+%% and merge the many lists into a single one.
+merge_epp_macros([]) ->
+    [];
+merge_epp_macros([{macros, M1}, {macros, M2} | Rest]) ->
+    NewMacros = dedupe_macros(lists:usort(M1), lists:usort(M2)),
+    merge_epp_macros( [{macros, NewMacros} | Rest]);
+merge_epp_macros([H | T]) ->
+    [H | merge_epp_macros(T)].
+
+dedupe_macros([], Bs) -> Bs;
+dedupe_macros(As, []) -> As;
+dedupe_macros([{K, V1} | As], [{K, _} | Bs]) ->
+    [{K, V1} | dedupe_macros(As, Bs)];
+dedupe_macros([{KA, VA} | As], [{KB, VB} | Bs]) ->
+    if KA < KB -> [{KA, VA} | dedupe_macros(As, [{KB, VB} | Bs])];
+       KA > KB -> [{KB, VB} | dedupe_macros([{KA, VA} | As], Bs)]
+    end.

test/rebar_edoc_SUITE.erl

@@ -3,7 +3,7 @@
 -include_lib("eunit/include/eunit.hrl").
 -compile(export_all).
 
-all() -> [multiapp, error_survival].
+all() -> [multiapp, multiapp_macros, error_survival].
 
 init_per_testcase(multiapp, Config) ->
     application:load(rebar),
@@ -17,6 +17,19 @@ init_per_testcase(multiapp, Config) ->
     State = rebar_state:new([{base_dir, filename:join([AppsDir, "_build"])}
                             ,{root_dir, AppsDir}]),
     [{apps, AppsDir}, {state, State}, {name, Name} | Config];
+init_per_testcase(multiapp_macros, Config) ->
+    application:load(rebar),
+    DataDir = ?config(data_dir, Config),
+    PrivDir = ?config(priv_dir, Config),
+    Name = rebar_test_utils:create_random_name("multiapp_macros"),
+    AppsDir = filename:join([PrivDir, rebar_test_utils:create_random_name(Name)]),
+    ec_file:copy(filename:join([DataDir, "foo"]), AppsDir, [recursive]),
+    ok = ec_file:remove(filename:join([AppsDir, "apps", "foo"]), [recursive]),
+    %Verbosity = rebar3:log_level(),
+    %rebar_log:init(command_line, Verbosity),
+    State = rebar_state:new([{base_dir, filename:join([AppsDir, "_build"])}
+                            ,{root_dir, AppsDir}]),
+    [{apps, AppsDir}, {state, State}, {name, Name} | Config];
 init_per_testcase(error_survival, Config) ->
     application:load(rebar),
     DataDir = ?config(data_dir, Config),
@@ -61,6 +74,48 @@ multiapp(Config) ->
     )),
     ok.
 
+multiapp_macros(Config) ->
+    RebarConfig = [{edoc_opts, [
+        preprocess,
+        {macros, [{m1, x1}, {m2, x2}]},
+        {def, [{d1, "1"}, {d2, "1"}]}
+    ]}],
+    AppConfig = {edoc_opts, [
+        {preprocess, true},
+        {macros, [{m2, f2}, {m3, f3}]},
+        {def, [{d2, "2"}, {d3, "2"}]}
+    ]},
+    DebugModule = "
+    -module(debug).
+    -ifndef(m1). -define(m1,z1). -endif.
+    -ifndef(m2). -define(m2,z2). -endif.
+    -ifndef(m3). -define(m3,z3). -endif.
+    -export([?m1 /0, ?m2 /0, ?m3 /0]).
+
+    %% @doc
+    %% d1:{@d1}
+    %% d2:{@d2}
+    %% d3:{@d3}
+    %% @end
+    ?m1 () -> ok.
+    ?m2 () -> ok.
+    ?m3 () -> ok.
+    ",
+    AppsDir = ?config(apps, Config),
+    ct:pal("AppsDir: ~s", [AppsDir]),
+    ok = file:write_file(filename:join([AppsDir, "apps", "bar1", "rebar.config"]),
+                         io_lib:format("~p.~n", [AppConfig])),
+    ok = file:write_file(filename:join([AppsDir, "apps", "bar1", "src", "debug.erl"]),
+                         DebugModule),
+    rebar_test_utils:run_and_check(Config, RebarConfig, ["edoc"], {ok, []}),
+    DocFile = filename:join([AppsDir, "apps", "bar1", "doc", "debug.html"]),
+    ?assert(file_content_matches(DocFile, "d1:1")), % config layered
+    ?assert(file_content_matches(DocFile, "d2:2")),
+    ?assert(file_content_matches(DocFile, "d3:2")),
+    ?assert(file_content_matches(DocFile, "x1/0")), % elided in config drop
+    ?assert(file_content_matches(DocFile, "f2/0")),
+    ?assert(file_content_matches(DocFile, "f3/0")),
+    ok.
 
 error_survival(Config) ->
     RebarConfig = [],