consider `ERL_COMPILER_OPTIONS` when recompiling

on 19.x forward the compiler should now take into consideration the value
of the environment variable `ERL_COMPILER_OPTIONS` when deciding whether
or not to recompile a module

src/rebar_erlc_compiler.erl

@@ -322,6 +322,10 @@ needed_files(G, ErlOpts, RebarOpts, Dir, OutDir, SourceFiles) ->
                          AllOpts = [{outdir, filename:dirname(Target)}
                                    ,{i, filename:join(Dir, "include")}
                                    ,{i, Dir}] ++ PrivIncludes ++ ErlOpts,
+                         %% necessary for erlang:function_exported/3 to work as expected
+                         %% called here for clarity as it's required by both opts_changed/2
+                         %% and erl_compiler_opts_set/0
+                         _ = code:ensure_loaded(compile),
                          digraph:vertex(G, Source) > {Source, filelib:last_modified(Target)}
                               orelse opts_changed(AllOpts, TargetBase)
                               orelse erl_compiler_opts_set()
@@ -342,8 +346,12 @@ maybe_rm_beam_and_edge(G, OutDir, Source) ->
     end.
 
 opts_changed(NewOpts, Target) ->
+    TotalOpts = case erlang:function_exported(compile, env_compiler_options, 0) of
+        true  -> NewOpts ++ compile:env_compiler_options();
+        false -> NewOpts
+    end,
     case compile_info(Target) of
-        {ok, Opts} -> lists:sort(Opts) =/= lists:sort(NewOpts);
+        {ok, Opts} -> lists:sort(Opts) =/= lists:sort(TotalOpts);
         _          -> true
     end.
 
@@ -358,10 +366,12 @@ compile_info(Target) ->
     end.
 
 erl_compiler_opts_set() ->
-    case os:getenv("ERL_COMPILER_OPTIONS") of
+    EnvSet = case os:getenv("ERL_COMPILER_OPTIONS") of
         false -> false;
         _     -> true
-    end.
+    end,
+    %% return false if changed env opts would have been caught in opts_changed/2
+    EnvSet andalso not erlang:function_exported(compile, env_compiler_options, 0).
 
 erlcinfo_file(Dir) ->
     filename:join(rebar_dir:local_cache_dir(Dir), ?ERLCINFO_FILE).

test/rebar_compile_SUITE.erl

@@ -44,6 +44,8 @@
          include_file_in_src/1,
          include_file_relative_to_working_directory_test/1,
          include_file_in_src_test/1,
+         dont_recompile_when_erl_compiler_options_env_does_not_change/1,
+         recompile_when_erl_compiler_options_env_changes/1,
          always_recompile_when_erl_compiler_options_set/1,
          recompile_when_parse_transform_inline_changes/1,
          recompile_when_parse_transform_as_opt_changes/1,
@@ -74,10 +76,20 @@ all() ->
      include_file_relative_to_working_directory_test, include_file_in_src_test,
      recompile_when_parse_transform_as_opt_changes,
      recompile_when_parse_transform_inline_changes,
-     recursive, no_recursive] ++
-     case erlang:function_exported(os, unsetenv, 1) of
-         true  -> [always_recompile_when_erl_compiler_options_set];
-         false -> []
+     %% recompile behaviour when `ERL_COMPILER_OPTIONS` differs prior to 19.x
+     recursive, no_recursive] ++ recompile_when_env_changes_test().
+
+recompile_when_env_changes_test() ->
+     _ = code:ensure_loaded(os),
+     UnSetEnv = erlang:function_exported(os, unsetenv, 1),
+     _ = code:ensure_loaded(compile),
+     EnvOpts = erlang:function_exported(compile, env_compiler_options, 0),
+     case {UnSetEnv, EnvOpts} of
+         {true, true}  ->
+           [dont_recompile_when_erl_compiler_options_env_does_not_change,
+            recompile_when_erl_compiler_options_env_changes];
+         {true, false} -> [always_recompile_when_erl_compiler_options_set];
+         {false, _}    -> []
      end.
 
 groups() ->
@@ -1385,7 +1397,45 @@ include_file_in_src_test(Config) ->
                                    ["as", "test", "compile"],
                                    {ok, [{app, Name}]}).
 
-always_recompile_when_erl_compiler_options_set(Config) ->
+dont_recompile_when_erl_compiler_options_env_does_not_change(Config) ->
+    %% save existing env to restore after test
+    ExistingEnv = os:getenv("ERL_COMPILER_OPTIONS"),
+
+    AppDir = ?config(apps, Config),
+
+    Name = rebar_test_utils:create_random_name("erl_compiler_options_"),
+    Vsn = rebar_test_utils:create_random_vsn(),
+    rebar_test_utils:create_app(AppDir, Name, Vsn, [kernel, stdlib]),
+
+    true = os:unsetenv("ERL_COMPILER_OPTIONS"),
+
+    true = os:putenv("ERL_COMPILER_OPTIONS", "[{d, some_macro}]"),
+
+    rebar_test_utils:run_and_check(Config, [], ["compile"], {ok, [{app, Name}]}),
+
+    EbinDir = filename:join([AppDir, "_build", "default", "lib", Name, "ebin"]),
+
+    {ok, Files} = rebar_utils:list_dir(EbinDir),
+    ModTime = [filelib:last_modified(filename:join([EbinDir, F]))
+               || F <- Files, filename:extension(F) == ".beam"],
+
+    timer:sleep(1000),
+
+    rebar_test_utils:run_and_check(Config, [], ["compile"], {ok, [{app, Name}]}),
+
+    {ok, NewFiles} = rebar_utils:list_dir(EbinDir),
+    NewModTime = [filelib:last_modified(filename:join([EbinDir, F]))
+                  || F <- NewFiles, filename:extension(F) == ".beam"],
+
+    ?assert(ModTime == NewModTime),
+
+    %% restore existing env
+    case ExistingEnv of
+        false -> ok;
+        _     -> os:putenv("ERL_COMPILER_OPTIONS", ExistingEnv)
+    end.
+
+recompile_when_erl_compiler_options_env_changes(Config) ->
     %% save existing env to restore after test
     ExistingEnv = os:getenv("ERL_COMPILER_OPTIONS"),
 
@@ -1423,6 +1473,44 @@ always_recompile_when_erl_compiler_options_set(Config) ->
         _     -> os:putenv("ERL_COMPILER_OPTIONS", ExistingEnv)
     end.
 
+always_recompile_when_erl_compiler_options_set(Config) ->
+    %% save existing env to restore after test
+    ExistingEnv = os:getenv("ERL_COMPILER_OPTIONS"),
+
+    AppDir = ?config(apps, Config),
+
+    Name = rebar_test_utils:create_random_name("erl_compiler_options_"),
+    Vsn = rebar_test_utils:create_random_vsn(),
+    rebar_test_utils:create_app(AppDir, Name, Vsn, [kernel, stdlib]),
+
+    true = os:unsetenv("ERL_COMPILER_OPTIONS"),
+
+    true = os:putenv("ERL_COMPILER_OPTIONS", "[{d, some_macro}]"),
+
+    rebar_test_utils:run_and_check(Config, [], ["compile"], {ok, [{app, Name}]}),
+
+    EbinDir = filename:join([AppDir, "_build", "default", "lib", Name, "ebin"]),
+
+    {ok, Files} = rebar_utils:list_dir(EbinDir),
+    ModTime = [filelib:last_modified(filename:join([EbinDir, F]))
+               || F <- Files, filename:extension(F) == ".beam"],
+
+    timer:sleep(1000),
+
+    rebar_test_utils:run_and_check(Config, [], ["compile"], {ok, [{app, Name}]}),
+
+    {ok, NewFiles} = rebar_utils:list_dir(EbinDir),
+    NewModTime = [filelib:last_modified(filename:join([EbinDir, F]))
+                  || F <- NewFiles, filename:extension(F) == ".beam"],
+
+    ?assert(ModTime =/= NewModTime),
+
+    %% restore existing env
+    case ExistingEnv of
+        false -> ok;
+        _     -> os:putenv("ERL_COMPILER_OPTIONS", ExistingEnv)
+    end.
+
 recompile_when_parse_transform_inline_changes(Config) ->
     AppDir = ?config(apps, Config),