Merge branch 'anders/diameter/dictionary_make/OTP-11348' into maint

* anders/diameter/dictionary_make/OTP-11348:
  Return compilable forms instead of beam
  Document diameter_make:format/1 and diameter_make:flatten/1
  Fix diameter_make:flatten/1
  Modify type that currently causes dialyzer woe
  Simplify and extend diameter_make interface
  Add diameter_make:flatten/1, remove reformat/1
  Adapt compiler suite to diameter_make
  Remove dead code from codec suite
  Extend diameter_make:codec/2
  Don't pollute process dictionary in diameter_codegen:from_dict/4
  Make forms a separate output from diameter_codegen
  Remove last remnants of "spec"
  Write as last step in code generation
  Change extensions for debug output: .spec/forms -> .D/F

8 files changed, 721 insertions, 371 deletions

diff --git a/lib/diameter/bin/diameterc b/lib/diameter/bin/diameterc
index 2f5834d359..d31f341c36 100755
--- a/lib/diameter/bin/diameterc
+++ b/lib/diameter/bin/diameterc
@@ -50,13 +50,10 @@ usage() ->
       "      -i dir    = set an include directory for inherited beams~n"
       "      -E        = no .erl output~n"
       "      -H        = no .hrl output~n"
-      "      -d        = write intermediate files (.spec and .forms)~n",
+      "      -d        = write intermediate files (.D and .F)~n",
       [?MODULE]).
 
 main(Args) ->
-    %% Add the ebin directory relative to the script path.
-    BinDir = filename:dirname(escript:script_name()),
-    code:add_path(filename:join([BinDir, "..", "ebin"])),
     halt(gen(Args)).
 
 gen(Args) ->
@@ -72,15 +69,12 @@ gen(Args) ->
             1
     end.
 
-compile(#argv{file = File, options = Opts} = A) ->
-    try diameter_dict_util:parse({path, File}, Opts) of
-        {ok, Spec} ->
-            maybe_output(A, Spec, Opts, spec), %% the spec file
-            maybe_output(A, Spec, Opts, erl),  %% the erl file
-            maybe_output(A, Spec, Opts, hrl),  %% The hrl file
+compile(#argv{file = File, options = Opts, output = Out}) ->
+    try diameter_make:codec({path, File}, Opts ++ Out) of
+        ok ->
             0;
         {error, Reason} ->
-            error_msg(diameter_dict_util:format_error(Reason), []),
+            error_msg(Reason, []),
             1
     catch
         error: Reason ->
@@ -88,10 +82,6 @@ compile(#argv{file = File, options = Opts} = A) ->
             2
     end.
 
-maybe_output(#argv{file = File, output = Output}, Spec, Opts, Mode) ->
-    lists:member(Mode, Output)
-        andalso diameter_codegen:from_dict(File, Spec, Opts, Mode).
-
 error_msg({Fmt, Args}) ->
     error_msg(Fmt, Args).
 
@@ -119,8 +109,9 @@ arg(["-o", Dir | Args], #argv{options = Opts} = A) ->
     true = dir_exists(Dir),
     arg(Args, A#argv{options = [{outdir, Dir} | Opts]});
 
-arg(["-i", Dir | Args], #argv{options = Opts} = A) ->
-    arg(Args, A#argv{options = Opts ++ [{include, Dir}]});
+arg(["-i", Dir | Args], #argv{} = A) ->
+    code:add_patha(Dir), %% Set path here instead of passing an include
+    arg(Args, A);        %% option so it's set before calling diameter_make.
 
 arg(["--name", Name | Args], #argv{options = Opts} = A) ->
     arg(Args, A#argv{options = [{name, Name} | Opts]});
@@ -137,9 +128,8 @@ arg(["-E" | Args], #argv{output = Output} = A) ->
 arg(["-H" | Args], #argv{output = Output} = A) ->
     arg(Args, A#argv{output = lists:delete(hrl, Output)});
 
-arg(["-d" | Args], #argv{options = Opts, output = Output} = A) ->
-    arg(Args, A#argv{options = [debug | Opts],
-                     output = [spec | Output]});
+arg(["-d" | Args], #argv{output = Output} = A) ->
+    arg(Args, A#argv{output = [parse, forms | Output -- [parse, forms]]});
 
 arg([[$- = M, C, H | T] | Args], A)  %% clustered options
   when C /= $i, C /= $o, C /= $- ->
diff --git a/lib/diameter/doc/src/diameter_make.xml b/lib/diameter/doc/src/diameter_make.xml
index ec71251be1..68780b1e05 100644
--- a/lib/diameter/doc/src/diameter_make.xml
+++ b/lib/diameter/doc/src/diameter_make.xml
@@ -1,5 +1,7 @@
 <?xml version="1.0" encoding="latin1" ?>
 <!DOCTYPE erlref SYSTEM "erlref.dtd" [
+  <!ENTITY compile_forms2
+  '<seealso marker="compiler:compile#forms-2">compile:forms/2</seealso>'>
   <!ENTITY filename
   '<seealso marker="kernel:file#type-name">file:name()</seealso>'>
   <!ENTITY dictionary
@@ -64,16 +66,47 @@ interface.</p>
 <funcs>
 
 <func>
-<name>codec(Path::string(), [Opt]) -> ok | {error, Reason}</name>
+<name>codec(File :: iolist() | binary(), [Opt]) -> ok
+                                                 | {ok, [Out]}
+                                                 | {error, Reason}</name>
 <fsummary>Compile a dictionary file into Erlang source.</fsummary>
 <desc>
 
 <p>
-Compile a single dictionary file to Erlang source.
-<c>Opt</c> can have the following types.</p>
+Compile a single dictionary file.
+The input <c>File</c> can be either a path or a literal dictionary,
+the occurrence of newline (ascii NL) or carriage return (ascii CR)
+identifying the latter.
+<c>Opt</c> determines the format of the results and whether they are
+written to file or returned, and can have the following types.</p>
 
 <taglist>
 
+<tag><c>parse | forms | erl | hrl</c></tag>
+<item>
+<p>
+Specifies an output format.
+Whether the output is returned or written to file depends on whether
+or not option <c>return</c> is specified.
+When written to file, the resulting file(s) will have extensions
+<c>.D</c>, <c>.F</c>, <c>.erl</c>, and <c>.hrl</c>
+respectively, basenames defaulting to <c>dictionary</c> if the input
+dictionary is literal and does not specify <c>&dict_name;</c>.
+When returned, results are in the order of the corresponding format
+options.
+Format options default to <c>erl</c> and <c>hrl</c> (in this order) if
+unspecified.</p>
+
+<p>
+The <c>parse</c> format is an internal representation that can be
+passed to &flatten; and &format;, while the <c>forms</c> format can be
+passed to &compile_forms2;.
+The <c>erl</c> and <c>hrl</c> formats are returned as
+iolists.</p>
+<!-- That codec/2 can take the parsed format is undocumented, and
+     options name and inherits have no effect in this case. -->
+</item>
+
 <tag><c>{include, string()}</c></tag>
 <item>
 <p>
@@ -90,7 +123,15 @@ Multiple <c>include</c> options can be specified.</p>
 <item>
 <p>
 Write generated source to the specified directory.
-Defaults to the current working directory.</p>
+Defaults to the current working directory.
+Has no effect if option <c>return</c> is specified.</p>
+</item>
+
+<tag><c>return</c></tag>
+<item>
+<p>
+Return results in a <c>{ok, [Out]}</c> tuple instead of writing to
+file and returning <c>ok</c>.</p>
 </item>
 
 <tag><c>{name|prefix, string()}</c></tag>
@@ -108,7 +149,7 @@ Transform the input dictionary before compilation, appending
 <c>&dict_inherits;</c> of the specified string.</p>
 
 <p>
-Two forms of <c>@inherits</c> have special meaning:</p>
+Two forms have special meaning:</p>
 
 <pre>
 {inherits, "-"}
@@ -127,6 +168,41 @@ Multiple <c>inherits</c> options can be specified.</p>
 
 </taglist>
 
+<p>
+Note that a dictionary's <c>&dict_name;</c>, together with the
+<c>outdir</c> option, determine the output paths when the
+<c>return</c> option is not specified.
+The <c>&dict_name;</c> of a literal input dictionary defaults to
+<c>dictionary</c>.</p>
+
+</desc>
+</func>
+
+<!-- ===================================================================== -->
+
+<func>
+<name>format(Parsed) -> iolist()</name>
+<fsummary>Format a parsed dictionary.</fsummary>
+<desc>
+<p>
+Turns a parsed dictionary, as returned by &codec;, back into the
+dictionary format.</p>
+</desc>
+</func>
+
+<!-- ===================================================================== -->
+
+<func>
+<name>flatten(Parsed) -> term()</name>
+<fsummary>Flatten a parsed dictionary.</fsummary>
+<desc>
+
+<p>
+Reconstitute a parsed dictionary, as returned by &codec;, without
+using <c>&dict_inherits;</c>.
+That is, construct an equivalent dictionary in which all AVP's are
+definined in the dictionary itself.
+The return value is also a parsed dictionary.</p>
 </desc>
 </func>
 
@@ -138,11 +214,7 @@ Multiple <c>inherits</c> options can be specified.</p>
 <title>BUGS</title>
 
 <p>
-All options are string-valued.
-In particular, it is not currently possible to specify
-an &dict_inherits; module as an atom(), or a path as an arbitrary
-&filename;</p>
-
+Unrecognized options are silently ignored.</p>
 </section>
 
 <!-- ===================================================================== -->
diff --git a/lib/diameter/doc/src/seealso.ent b/lib/diameter/doc/src/seealso.ent
index 76b9823f79..d3305853af 100644
--- a/lib/diameter/doc/src/seealso.ent
+++ b/lib/diameter/doc/src/seealso.ent
@@ -115,6 +115,8 @@ significant.
 <!-- diameter_make -->
 
 <!ENTITY make_codec '<seealso marker="diameter_make#codec-2">diameter_make:codec/2</seealso>'>
+<!ENTITY make_format '<seealso marker="diameter_make#format-1">diameter_make:format/1</seealso>'>
+<!ENTITY make_flatten '<seealso marker="diameter_make#flatten-1">diameter_make:flatten/1</seealso>'>
 
 <!-- diameter_transport -->
 
diff --git a/lib/diameter/src/compiler/diameter_codegen.erl b/lib/diameter/src/compiler/diameter_codegen.erl
index e687145263..22422f2ef2 100644
--- a/lib/diameter/src/compiler/diameter_codegen.erl
+++ b/lib/diameter/src/compiler/diameter_codegen.erl
@@ -33,11 +33,6 @@
 
 -export([from_dict/4]).
 
-%% Internal exports (for test).
--export([file/1,
-         file/2,
-         file/3]).
-
 -include("diameter_forms.hrl").
 -include("diameter_vsn.hrl").
 
@@ -48,18 +43,61 @@
 
 %% ===========================================================================
 
--spec from_dict(File, Spec, Opts, Mode)
+-spec from_dict(File, ParseD, Opts, Mode)
    -> ok
+    | term()
  when File :: string(),
-      Spec :: orddict:orddict(),
+      ParseD :: orddict:orddict(),
       Opts :: list(),
-      Mode :: spec | erl | hrl.
+      Mode :: parse | forms | erl | hrl.
 
-from_dict(File, Spec, Opts, Mode) ->
+from_dict(File, ParseD, Opts, Mode) ->
     Outdir = proplists:get_value(outdir, Opts, "."),
+    Return = proplists:get_value(return, Opts, false),
+    Mod = mod(File, orddict:find(name, ParseD)),
     putr(verbose, lists:member(verbose, Opts)),
-    putr(debug,   lists:member(debug, Opts)),
-    codegen(File, Spec, Outdir, Mode).
+    try
+        maybe_write(Return, Mode, Outdir, Mod, gen(Mode, ParseD, ?A(Mod)))
+    after
+        eraser(verbose)
+    end.
+
+mod(File, error) ->
+    filename:rootname(filename:basename(File));
+mod(_, {ok, Mod}) ->
+    Mod.
+
+maybe_write(true, _, _, _, T) ->
+    T;
+
+maybe_write(_, Mode, Outdir, Mod, T) ->
+    Path = filename:join(Outdir, Mod),  %% minus extension
+    do_write(Mode, [Path, $., ext(Mode)], T).
+
+ext(parse) ->
+    "D";
+ext(forms) ->
+    "F";
+ext(T) ->
+    ?S(T).
+
+do_write(M, Path, T)
+  when M == parse;
+       M == forms ->
+    write_term(Path, T);
+do_write(_, Path, T) ->
+    write(Path, T).
+
+write(Path, T) ->
+    write(Path, "~s", T).
+
+write_term(Path, T) ->
+    write(Path, "~p.~n", T).
+
+write(Path, Fmt, T) ->
+    {ok, Fd} = file:open(Path, [write]),
+    io:fwrite(Fd, Fmt, [T]),
+    ok = file:close(Fd).
 
 %% Optional reports when running verbosely.
 report(What, Data) ->
@@ -77,20 +115,8 @@ putr(Key, Value) ->
 getr(Key) ->
     get({?MODULE, Key}).
 
-%% ===========================================================================
-%% ===========================================================================
-
-%% Generate from parsed dictionary in a file.
-
-file(F) ->
-    file(F, spec).
-
-file(F, Mode) ->
-    file(F, ".", Mode).
-
-file(F, Outdir, Mode) ->
-    {ok, [Spec]} = file:consult(F),
-    from_dict(F, Spec, Outdir, Mode).
+eraser(Key) ->
+    erase({?MODULE, Key}).
 
 %% ===========================================================================
 %% ===========================================================================
@@ -98,97 +124,68 @@ file(F, Outdir, Mode) ->
 get_value(Key, Plist) ->
     proplists:get_value(Key, Plist, []).
 
-write(Path, Str) ->
-    w(Path, Str, "~s").
-
-write_term(Path, T) ->
-    w(Path, T, "~p.").
-
-w(Path, T, Fmt) ->
-    {ok, Fd} = file:open(Path, [write]),
-    io:fwrite(Fd, Fmt ++ "~n", [T]),
-    file:close(Fd).
-
-codegen(File, Spec, Outdir, Mode) ->
-    Mod = mod(File, orddict:find(name, Spec)),
-    Path = filename:join(Outdir, Mod),  %% minus extension
-    gen(Mode, Spec, ?A(Mod), Path),
-    ok.
-
-mod(File, error) ->
-    filename:rootname(filename:basename(File));
-mod(_, {ok, Mod}) ->
-    Mod.
-
-gen(spec, Spec, _Mod, Path) ->
-    write_term(Path ++ ".spec", [?VERSION | Spec]);
-
-gen(hrl, Spec, Mod, Path) ->
-    gen_hrl(Path ++ ".hrl", Mod, Spec);
-
-gen(erl, Spec, Mod, Path) ->
-    Forms = [{?attribute, module, Mod},
-             {?attribute, compile, {parse_transform, diameter_exprecs}},
-             {?attribute, compile, nowarn_unused_function},
-             {?attribute, export, [{name, 0},
-                                   {id, 0},
-                                   {vendor_id, 0},
-                                   {vendor_name, 0},
-                                   {decode_avps, 2}, %% in diameter_gen.hrl
-                                   {encode_avps, 2}, %%
-                                   {msg_name, 2},
-                                   {msg_header, 1},
-                                   {rec2msg, 1},
-                                   {msg2rec, 1},
-                                   {name2rec, 1},
-                                   {avp_name, 2},
-                                   {avp_arity, 2},
-                                   {avp_header, 1},
-                                   {avp, 3},
-                                   {grouped_avp, 3},
-                                   {enumerated_avp, 3},
-                                   {empty_value, 1},
-                                   {dict, 0}]},
-             %% diameter.hrl is included for #diameter_avp
-             {?attribute, include_lib, "diameter/include/diameter.hrl"},
-             {?attribute, include_lib, "diameter/include/diameter_gen.hrl"},
-             f_name(Mod),
-             f_id(Spec),
-             f_vendor_id(Spec),
-             f_vendor_name(Spec),
-             f_msg_name(Spec),
-             f_msg_header(Spec),
-             f_rec2msg(Spec),
-             f_msg2rec(Spec),
-             f_name2rec(Spec),
-             f_avp_name(Spec),
-             f_avp_arity(Spec),
-             f_avp_header(Spec),
-             f_avp(Spec),
-             f_enumerated_avp(Spec),
-             f_empty_value(Spec),
-             f_dict(Spec),
-             {eof, ?LINE}],
-
-    gen_erl(Path, insert_hrl_forms(Spec, Forms)).
-
-gen_erl(Path, Forms) ->
-    getr(debug) andalso write_term(Path ++ ".forms", Forms),
-    write(Path ++ ".erl",
-          header() ++ erl_prettypr:format(erl_syntax:form_list(Forms))).
-
-insert_hrl_forms(Spec, Forms) ->
-    {H,T} = lists:splitwith(fun is_header/1, Forms),
-    H ++ make_hrl_forms(Spec) ++ T.
-
-is_header({attribute, _, export, _}) ->
-    false;
-is_header(_) ->
-    true.
-
-make_hrl_forms(Spec) ->
+gen(parse, ParseD, _Mod) ->
+    [?VERSION | ParseD];
+
+gen(forms, ParseD, Mod) ->
+    pp(erl_forms(Mod, ParseD));
+
+gen(hrl, ParseD, Mod) ->
+    gen_hrl(Mod, ParseD);
+
+gen(erl, ParseD, Mod) ->
+    [header(), prettypr(erl_forms(Mod, ParseD)), $\n].
+
+erl_forms(Mod, ParseD) ->
+    Forms = [[{?attribute, module, Mod},
+              {?attribute, compile, {parse_transform, diameter_exprecs}},
+              {?attribute, compile, nowarn_unused_function}],
+             make_hrl_forms(ParseD),
+             [{?attribute, export, [{name, 0},
+                                    {id, 0},
+                                    {vendor_id, 0},
+                                    {vendor_name, 0},
+                                    {decode_avps, 2}, %% in diameter_gen.hrl
+                                    {encode_avps, 2}, %%
+                                    {msg_name, 2},
+                                    {msg_header, 1},
+                                    {rec2msg, 1},
+                                    {msg2rec, 1},
+                                    {name2rec, 1},
+                                    {avp_name, 2},
+                                    {avp_arity, 2},
+                                    {avp_header, 1},
+                                    {avp, 3},
+                                    {grouped_avp, 3},
+                                    {enumerated_avp, 3},
+                                    {empty_value, 1},
+                                    {dict, 0}]},
+              %% diameter.hrl is included for #diameter_avp
+              {?attribute, include_lib, "diameter/include/diameter.hrl"},
+              {?attribute, include_lib, "diameter/include/diameter_gen.hrl"},
+              f_name(Mod),
+              f_id(ParseD),
+              f_vendor_id(ParseD),
+              f_vendor_name(ParseD),
+              f_msg_name(ParseD),
+              f_msg_header(ParseD),
+              f_rec2msg(ParseD),
+              f_msg2rec(ParseD),
+              f_name2rec(ParseD),
+              f_avp_name(ParseD),
+              f_avp_arity(ParseD),
+              f_avp_header(ParseD),
+              f_avp(ParseD),
+              f_enumerated_avp(ParseD),
+              f_empty_value(ParseD),
+              f_dict(ParseD),
+              {eof, ?LINE}]],
+
+    lists:append(Forms).
+
+make_hrl_forms(ParseD) ->
     {_Prefix, MsgRecs, GrpRecs, ImportedGrpRecs}
-        = make_record_forms(Spec),
+        = make_record_forms(ParseD),
 
     RecordForms = MsgRecs ++ GrpRecs ++ lists:flatmap(fun({_,Fs}) -> Fs end,
                                                       ImportedGrpRecs),
@@ -199,16 +196,16 @@ make_hrl_forms(Spec) ->
     %% export_records is used by the diameter_exprecs parse transform.
     [{?attribute, export_records, RecNames} | RecordForms].
 
-make_record_forms(Spec) ->
-    Prefix = prefix(Spec),
+make_record_forms(ParseD) ->
+    Prefix = prefix(ParseD),
 
-    MsgRecs = a_record(Prefix, fun msg_proj/1, get_value(messages, Spec)),
-    GrpRecs = a_record(Prefix, fun grp_proj/1, get_value(grouped, Spec)),
+    MsgRecs = a_record(Prefix, fun msg_proj/1, get_value(messages, ParseD)),
+    GrpRecs = a_record(Prefix, fun grp_proj/1, get_value(grouped, ParseD)),
 
     ImportedGrpRecs = [{M, a_record(Prefix, fun grp_proj/1, Gs)}
-                       || {M,Gs} <- get_value(import_groups, Spec)],
+                       || {M,Gs} <- get_value(import_groups, ParseD)],
 
-    {Prefix, MsgRecs, GrpRecs, ImportedGrpRecs}.
+    {to_upper(Prefix), MsgRecs, GrpRecs, ImportedGrpRecs}.
 
 msg_proj({Name, _, _, _, Avps}) ->
     {Name, Avps}.
@@ -246,9 +243,9 @@ f_name(Name) ->
 %%% # id/0
 %%% ------------------------------------------------------------------------
 
-f_id(Spec) ->
+f_id(ParseD) ->
     {?function, id, 0,
-     [c_id(orddict:find(id, Spec))]}.
+     [c_id(orddict:find(id, ParseD))]}.
 
 c_id({ok, Id}) ->
     {?clause, [], [], [?INTEGER(Id)]};
@@ -260,9 +257,9 @@ c_id(error) ->
 %%% # vendor_id/0
 %%% ------------------------------------------------------------------------
 
-f_vendor_id(Spec) ->
+f_vendor_id(ParseD) ->
     {?function, vendor_id, 0,
-     [{?clause, [], [], [b_vendor_id(orddict:find(vendor, Spec))]}]}.
+     [{?clause, [], [], [b_vendor_id(orddict:find(vendor, ParseD))]}]}.
 
 b_vendor_id({ok, {Id, _}}) ->
     ?INTEGER(Id);
@@ -273,9 +270,9 @@ b_vendor_id(error) ->
 %%% # vendor_name/0
 %%% ------------------------------------------------------------------------
 
-f_vendor_name(Spec) ->
+f_vendor_name(ParseD) ->
     {?function, vendor_name, 0,
-     [{?clause, [], [], [b_vendor_name(orddict:find(vendor, Spec))]}]}.
+     [{?clause, [], [], [b_vendor_name(orddict:find(vendor, ParseD))]}]}.
 
 b_vendor_name({ok, {_, Name}}) ->
     ?Atom(Name);
@@ -286,15 +283,15 @@ b_vendor_name(error) ->
 %%% # msg_name/1
 %%% ------------------------------------------------------------------------
 
-f_msg_name(Spec) ->
-    {?function, msg_name, 2, msg_name(Spec)}.
+f_msg_name(ParseD) ->
+    {?function, msg_name, 2, msg_name(ParseD)}.
 
 %% Return the empty name for any unknown command to which
 %% DIAMETER_COMMAND_UNSUPPORTED should be replied.
 
-msg_name(Spec) ->
+msg_name(ParseD) ->
     lists:flatmap(fun c_msg_name/1, proplists:get_value(command_codes,
-                                                        Spec,
+                                                        ParseD,
                                                         []))
         ++ [{?clause, [?VAR('_'), ?VAR('_')], [], [?ATOM('')]}].
 
@@ -310,12 +307,12 @@ c_msg_name({Code, Req, Ans}) ->
 %%% # msg2rec/1
 %%% ------------------------------------------------------------------------
 
-f_msg2rec(Spec) ->
-    {?function, msg2rec, 1, msg2rec(Spec)}.
+f_msg2rec(ParseD) ->
+    {?function, msg2rec, 1, msg2rec(ParseD)}.
 
-msg2rec(Spec) ->
-    Pre = prefix(Spec),
-    lists:map(fun(T) -> c_msg2rec(T, Pre) end, get_value(messages, Spec))
+msg2rec(ParseD) ->
+    Pre = prefix(ParseD),
+    lists:map(fun(T) -> c_msg2rec(T, Pre) end, get_value(messages, ParseD))
         ++ [?BADARG(1)].
 
 c_msg2rec({N,_,_,_,_}, Pre) ->
@@ -325,12 +322,12 @@ c_msg2rec({N,_,_,_,_}, Pre) ->
 %%% # rec2msg/1
 %%% ------------------------------------------------------------------------
 
-f_rec2msg(Spec) ->
-    {?function, rec2msg, 1, rec2msg(Spec)}.
+f_rec2msg(ParseD) ->
+    {?function, rec2msg, 1, rec2msg(ParseD)}.
 
-rec2msg(Spec) ->
-    Pre = prefix(Spec),
-    lists:map(fun(T) -> c_rec2msg(T, Pre) end, get_value(messages, Spec))
+rec2msg(ParseD) ->
+    Pre = prefix(ParseD),
+    lists:map(fun(T) -> c_rec2msg(T, Pre) end, get_value(messages, ParseD))
         ++ [?BADARG(1)].
 
 c_rec2msg({N,_,_,_,_}, Pre) ->
@@ -340,13 +337,13 @@ c_rec2msg({N,_,_,_,_}, Pre) ->
 %%% # name2rec/1
 %%% ------------------------------------------------------------------------
 
-f_name2rec(Spec) ->
-    {?function, name2rec, 1, name2rec(Spec)}.
+f_name2rec(ParseD) ->
+    {?function, name2rec, 1, name2rec(ParseD)}.
 
-name2rec(Spec) ->
-    Pre = prefix(Spec),
-    Groups = get_value(grouped, Spec)
-          ++ lists:flatmap(fun avps/1, get_value(import_groups, Spec)),
+name2rec(ParseD) ->
+    Pre = prefix(ParseD),
+    Groups = get_value(grouped, ParseD)
+          ++ lists:flatmap(fun avps/1, get_value(import_groups, ParseD)),
     lists:map(fun({N,_,_,_}) -> c_name2rec(N, Pre) end, Groups)
         ++ [{?clause, [?VAR('T')], [], [?CALL(msg2rec, [?VAR('T')])]}].
 
@@ -360,8 +357,8 @@ avps({_Mod, Avps}) ->
 %%% # avp_name/1
 %%% ------------------------------------------------------------------------
 
-f_avp_name(Spec) ->
-    {?function, avp_name, 2, avp_name(Spec)}.
+f_avp_name(ParseD) ->
+    {?function, avp_name, 2, avp_name(ParseD)}.
 
 %% 3588, 4.1:
 %%
@@ -372,11 +369,11 @@ f_avp_name(Spec) ->
 %%       field.  AVP numbers 256 and above are used for Diameter, which are
 %%       allocated by IANA (see Section 11.1).
 
-avp_name(Spec) ->
-    Avps = get_value(avp_types, Spec),
-    Imported = get_value(import_avps, Spec),
-    Vid = orddict:find(vendor, Spec),
-    Vs = vendor_id_map(Spec),
+avp_name(ParseD) ->
+    Avps = get_value(avp_types, ParseD),
+    Imported = get_value(import_avps, ParseD),
+    Vid = orddict:find(vendor, ParseD),
+    Vs = vendor_id_map(ParseD),
 
     lists:map(fun(T) -> c_avp_name(T, Vs, Vid) end, Avps)
         ++ lists:flatmap(fun(T) -> c_imported_avp_name(T, Vs) end, Imported)
@@ -407,25 +404,25 @@ c_avp_name_(T, Code, Vid) ->
      [],
      [T]}.
 
-vendor_id_map(Spec) ->
+vendor_id_map(ParseD) ->
     lists:flatmap(fun({V,Ns}) -> [{N,V} || N <- Ns] end,
-                  get_value(avp_vendor_id, Spec))
+                  get_value(avp_vendor_id, ParseD))
         ++ lists:flatmap(fun({_,_,[],_}) -> [];
                             ({N,_,[V],_}) -> [{N,V}]
                          end,
-                         get_value(grouped, Spec)).
+                         get_value(grouped, ParseD)).
 
 %%% ------------------------------------------------------------------------
 %%% # avp_arity/2
 %%% ------------------------------------------------------------------------
 
-f_avp_arity(Spec) ->
-    {?function, avp_arity, 2, avp_arity(Spec)}.
+f_avp_arity(ParseD) ->
+    {?function, avp_arity, 2, avp_arity(ParseD)}.
 
-avp_arity(Spec) ->
-    Msgs = get_value(messages, Spec),
-    Groups = get_value(grouped, Spec)
-          ++ lists:flatmap(fun avps/1, get_value(import_groups, Spec)),
+avp_arity(ParseD) ->
+    Msgs = get_value(messages, ParseD),
+    Groups = get_value(grouped, ParseD)
+          ++ lists:flatmap(fun avps/1, get_value(import_groups, ParseD)),
     c_avp_arity(Msgs ++ Groups)
         ++ [{?clause, [?VAR('_'), ?VAR('_')], [], [?INTEGER(0)]}].
 
@@ -449,15 +446,15 @@ c_arity(Name, Avp) ->
 %%% # avp/3
 %%% ------------------------------------------------------------------------
 
-f_avp(Spec) ->
-    {?function, avp, 3, avp(Spec) ++ [?BADARG(3)]}.
+f_avp(ParseD) ->
+    {?function, avp, 3, avp(ParseD) ++ [?BADARG(3)]}.
 
-avp(Spec) ->
-    Native     = get_value(avp_types, Spec),
-    CustomMods = get_value(custom_types, Spec),
-    TypeMods   = get_value(codecs, Spec),
-    Imported   = get_value(import_avps, Spec),
-    Enums      = get_value(enum, Spec),
+avp(ParseD) ->
+    Native     = get_value(avp_types, ParseD),
+    CustomMods = get_value(custom_types, ParseD),
+    TypeMods   = get_value(codecs, ParseD),
+    Imported   = get_value(import_avps, ParseD),
+    Enums      = get_value(enum, ParseD),
 
     Custom = lists:map(fun({M,As}) -> {M, custom_types, As} end,
                        CustomMods)
@@ -548,14 +545,14 @@ custom(codecs, AvpName, Type) ->
 %%% # enumerated_avp/3
 %%% ------------------------------------------------------------------------
 
-f_enumerated_avp(Spec) ->
-    {?function, enumerated_avp, 3, enumerated_avp(Spec) ++ [?BADARG(3)]}.
+f_enumerated_avp(ParseD) ->
+    {?function, enumerated_avp, 3, enumerated_avp(ParseD) ++ [?BADARG(3)]}.
 
-enumerated_avp(Spec) ->
-    Enums = get_value(enum, Spec),
+enumerated_avp(ParseD) ->
+    Enums = get_value(enum, ParseD),
     lists:flatmap(fun cs_enumerated_avp/1, Enums)
         ++ lists:flatmap(fun({M,Es}) -> enumerated_avp(M, Es, Enums) end,
-                         get_value(import_enums, Spec)).
+                         get_value(import_enums, ParseD)).
 
 enumerated_avp(Mod, Es, Enums) ->
     lists:flatmap(fun({N,_}) ->
@@ -585,16 +582,16 @@ c_enumerated_avp(AvpName, {_,I}) ->
 %%% msg_header/1
 %%% ------------------------------------------------------------------------
 
-f_msg_header(Spec) ->
-    {?function, msg_header, 1, msg_header(Spec) ++ [?BADARG(1)]}.
+f_msg_header(ParseD) ->
+    {?function, msg_header, 1, msg_header(ParseD) ++ [?BADARG(1)]}.
 
-msg_header(Spec) ->
-    msg_header(get_value(messages, Spec), Spec).
+msg_header(ParseD) ->
+    msg_header(get_value(messages, ParseD), ParseD).
 
 msg_header([], _) ->
     [];
-msg_header(Msgs, Spec) ->
-    ApplId = orddict:fetch(id, Spec),
+msg_header(Msgs, ParseD) ->
+    ApplId = orddict:fetch(id, ParseD),
 
     lists:map(fun({M,C,F,_,_}) -> c_msg_header(M, C, F, ApplId) end, Msgs).
 
@@ -616,14 +613,14 @@ emf('ERR', N) -> N bor 2#00100000.
 %%% # avp_header/1
 %%% ------------------------------------------------------------------------
 
-f_avp_header(Spec) ->
-    {?function, avp_header, 1, avp_header(Spec) ++ [?BADARG(1)]}.
+f_avp_header(ParseD) ->
+    {?function, avp_header, 1, avp_header(ParseD) ++ [?BADARG(1)]}.
 
-avp_header(Spec) ->
-    Native = get_value(avp_types, Spec),
-    Imported = get_value(import_avps, Spec),
-    Vid = orddict:find(vendor, Spec),
-    Vs = vendor_id_map(Spec),
+avp_header(ParseD) ->
+    Native = get_value(avp_types, ParseD),
+    Imported = get_value(import_avps, ParseD),
+    Vid = orddict:find(vendor, ParseD),
+    Vs = vendor_id_map(ParseD),
 
     lists:flatmap(fun(A) -> c_avp_header(A, Vs, Vid) end,
                   Native ++ Imported).
@@ -679,14 +676,14 @@ v(false, _, _, _) ->
 %%% # empty_value/0
 %%% ------------------------------------------------------------------------
 
-f_empty_value(Spec) ->
-    {?function, empty_value, 1, empty_value(Spec)}.
+f_empty_value(ParseD) ->
+    {?function, empty_value, 1, empty_value(ParseD)}.
 
-empty_value(Spec) ->
-    Imported = lists:flatmap(fun avps/1, get_value(import_enums, Spec)),
-    Groups = get_value(grouped, Spec)
-        ++ lists:flatmap(fun avps/1, get_value(import_groups, Spec)),
-    Enums = [T || {N,_} = T <- get_value(enum, Spec),
+empty_value(ParseD) ->
+    Imported = lists:flatmap(fun avps/1, get_value(import_enums, ParseD)),
+    Groups = get_value(grouped, ParseD)
+        ++ lists:flatmap(fun avps/1, get_value(import_groups, ParseD)),
+    Enums = [T || {N,_} = T <- get_value(enum, ParseD),
                   not lists:keymember(N, 1, Imported)]
         ++ Imported,
     lists:map(fun c_empty_value/1, Groups ++ Enums)
@@ -706,72 +703,52 @@ c_empty_value({Name, _}) ->
 %%% # dict/0
 %%% ------------------------------------------------------------------------
 
-f_dict(Spec) ->
+f_dict(ParseD) ->
     {?function, dict, 0,
-     [{?clause, [], [], [?TERM([?VERSION | Spec])]}]}.
+     [{?clause, [], [], [?TERM([?VERSION | ParseD])]}]}.
 
 %%% ------------------------------------------------------------------------
-%%% # gen_hrl/3
+%%% # gen_hrl/2
 %%% ------------------------------------------------------------------------
 
-gen_hrl(Path, Mod, Spec) ->
-    {ok, Fd} = file:open(Path, [write]),
-
+gen_hrl(Mod, ParseD) ->
     {Prefix, MsgRecs, GrpRecs, ImportedGrpRecs}
-        = make_record_forms(Spec),
-
-    file:write(Fd, hrl_header(Mod)),
-
-    forms("Message records",     Fd, MsgRecs),
-    forms("Grouped AVP records", Fd, GrpRecs),
-
-    lists:foreach(fun({M,Fs}) ->
-                          forms("Grouped AVP records from " ++ atom_to_list(M),
-                                Fd,
-                                Fs)
-                  end,
-                  ImportedGrpRecs),
-
-    PREFIX = to_upper(Prefix),
-
-    write("ENUM Macros",
-          Fd,
-          m_enums(PREFIX, false, get_value(enum, Spec))),
-    write("DEFINE Macros",
-          Fd,
-          m_enums(PREFIX, false, get_value(define, Spec))),
-
-    lists:foreach(fun({M,Es}) ->
-                          write("ENUM Macros from " ++ atom_to_list(M),
-                                Fd,
-                                m_enums(PREFIX, true, Es))
-                  end,
-                  get_value(import_enums, Spec)),
-
-    file:close(Fd).
-
-forms(_, _, []) ->
-    ok;
-forms(Banner, Fd, Forms) ->
-    write(Banner, Fd, prettypr(Forms)).
-
-write(_, _, []) ->
-    ok;
-write(Banner, Fd, Str) ->
-    banner(Fd, Banner),
-    io:fwrite(Fd, "~s~n", [Str]).
+        = make_record_forms(ParseD),
+
+    [hrl_header(Mod),
+     forms("Message records",     MsgRecs),
+     forms("Grouped AVP records", GrpRecs),
+     lists:map(fun({M,Fs}) ->
+                       forms("Grouped AVP records from " ++ atom_to_list(M),
+                             Fs)
+               end,
+               ImportedGrpRecs),
+     format("ENUM Macros", m_enums(Prefix, false, get_value(enum, ParseD))),
+     format("DEFINE Macros", m_enums(Prefix, false, get_value(define, ParseD))),
+     lists:map(fun({M,Es}) ->
+                       format("ENUM Macros from " ++ atom_to_list(M),
+                              m_enums(Prefix, true, Es))
+               end,
+               get_value(import_enums, ParseD))].
+
+forms(_, [] = No) ->
+    No;
+forms(Banner, Forms) ->
+    format(Banner, prettypr(Forms)).
+
+format(_, [] = No) ->
+    No;
+format(Banner, Str) ->
+    [banner(Banner), Str, $\n].
 
 prettypr(Forms) ->
     erl_prettypr:format(erl_syntax:form_list(Forms)).
 
-banner(Fd, Heading) ->
-    file:write(Fd, banner(Heading)).
-
 banner(Heading) ->
-    ("\n\n"
+    ["\n\n"
      "%%% -------------------------------------------------------\n"
-     "%%% " ++ Heading ++ ":\n"
-     "%%% -------------------------------------------------------\n\n").
+     "%%% ", Heading, ":\n"
+     "%%% -------------------------------------------------------\n\n"].
 
 z(S) ->
     string:join(string:tokens(S, "\s\t"), "\s").
@@ -845,8 +822,8 @@ arity([_],   '*' = Inf) -> {0, Inf};
 arity({_},   '*' = Inf) -> {1, Inf};
 arity(_,   {_,_} = Q)   -> Q.
 
-prefix(Spec) ->
-    case orddict:find(prefix, Spec) of
+prefix(ParseD) ->
+    case orddict:find(prefix, ParseD) of
         {ok, P} ->
             P ++ "_";
         error ->
@@ -855,3 +832,70 @@ prefix(Spec) ->
 
 rec_name(Name, Prefix) ->
     Prefix ++ Name.
+
+%% ===========================================================================
+%% pp/1
+%%
+%% Preprocess forms as generated by 'forms' option. In particular,
+%% replace the include_lib attributes in generated forms by the
+%% corresponding forms, extracting the latter from an existing
+%% dictionary (diameter_gen_relay). The resulting forms can be
+%% compiled to beam using compile:forms/2 (which does no preprocessing
+%% or it's own; DiY currently appears to be the only way to preprocess
+%% a forms list).
+
+pp(Forms) ->
+    {_, Beam, _} = code:get_object_code(diameter_gen_relay),
+    pp(Forms, abstract_code(Beam)).
+
+pp(Forms, {ok, Code}) ->
+    Files = files(Code, []),
+    lists:flatmap(fun(T) -> include(T, Files) end, Forms);
+
+pp(Forms, {error, Reason}) ->
+    erlang:error({forms, Reason, Forms}).
+
+include({attribute, _, include_lib, Path}, Files) ->
+    Inc = filename:basename(Path),
+    [{Inc, Forms}] = [T || {F, _} = T <- Files, F == Inc], %% expect one
+    lists:flatmap(fun filter/1, Forms);
+
+include(T, _) ->
+    [T].
+
+abstract_code(Beam) ->
+    case beam_lib:chunks(Beam, [abstract_code]) of
+        {ok, {_Mod, [{abstract_code, {_Vsn, Code}}]}} ->
+            {ok, Code};
+        {ok, {_Mod, [{abstract_code, no_abstract_code = No}]}} ->
+            {error, No};
+        {error = E, beam_lib, Reason} ->
+            {E, Reason}
+    end.
+
+files([{attribute, _, file, {Path, _}} | T], Acc) ->
+    {Body, Rest} = lists:splitwith(fun({attribute, _, file, _}) -> false;
+                                      (_) -> true
+                                   end,
+                                   T),
+    files(Rest, [{filename:basename(Path), Body} | Acc]);
+
+files([], Acc) ->
+    Acc.
+
+%% Only retain record diameter_avp and functions not generated by
+%% diameter_exprecs.
+
+filter({attribute, _, record, {diameter_avp, _}} = T) ->
+    [T];
+
+filter({function, _, Name, _, _} = T) ->
+    case ?S(Name) of
+        [$#|_] ->  %% generated by diameter_exprecs
+            [];
+        _ ->
+            [T]
+    end;
+
+filter(_) ->
+    [].
diff --git a/lib/diameter/src/compiler/diameter_dict_util.erl b/lib/diameter/src/compiler/diameter_dict_util.erl
index 36a6efa294..3941f30e03 100644
--- a/lib/diameter/src/compiler/diameter_dict_util.erl
+++ b/lib/diameter/src/compiler/diameter_dict_util.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2011. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2013. All Rights Reserved.
 %%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -46,7 +46,7 @@
 -spec parse(File, Opts)
    -> {ok, orddict:orddict()}
     | {error, term()}
- when File :: {path, string()}
+ when File :: {path, file:name_all()}
             | iolist()
             | binary(),
       Opts :: list().
@@ -265,6 +265,9 @@ io(K, Id)
 io(vendor = K, {Id, Name}) ->
     [?NL, section(K) | [[?SP, tok(X)] || X <- [Id, Name]]];
 
+io(_, []) ->
+    [];
+
 io(avp_types = K, Body) ->
     [?NL, ?NL, section(K), ?NL, [body(K,A) || A <- Body]];
 
diff --git a/lib/diameter/src/compiler/diameter_make.erl b/lib/diameter/src/compiler/diameter_make.erl
index 16e30c1ffb..2f314b7e57 100644
--- a/lib/diameter/src/compiler/diameter_make.erl
+++ b/lib/diameter/src/compiler/diameter_make.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2010-2011. All Rights Reserved.
+%% Copyright Ericsson AB 2010-2013. All Rights Reserved.
 %%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -30,102 +30,231 @@
 
 -module(diameter_make).
 
--export([codec/1,
-         codec/2,
-         dict/1,
-         dict/2,
+-export([codec/2,
+         codec/1,
          format/1,
-         reformat/1]).
+         flatten/1]).
 
 -export_type([opt/0]).
 
+-include("diameter_vsn.hrl").
+
+%% Options passed to codec/2.
 -type opt() :: {include|outdir|name|prefix|inherits, string()}
+             | return
              | verbose
-             | debug.
+             | parse  %% internal parsed form
+             | forms  %% abstract format for compile:forms/1,2
+             | erl
+             | hrl.
+
+%% Internal parsed format with a version tag.
+-type parsed() :: list().
+
+%% Literal dictionary or path. A NL of CR identifies the former.
+-type dict() :: iolist()
+              | binary()
+              | parsed().  %% as returned by codec/2
+
+%% Name of a literal dictionary if otherwise unspecified.
+-define(DEFAULT_DICT_FILE, "dictionary.dia").
 
 %% ===========================================================================
 
 %% codec/1-2
 %%
-%% Parse a dictionary file and generate a codec module.
+%% Parse a dictionary file and generate a codec module. Input
+%% dictionary can be either a path or the dictionary itself: the
+%% occurrence of \n or \r in the argument is used to distinguish the
+%% two.
 
--spec codec(Path, [opt()])
+-spec codec(File, [opt()])
    -> ok
+    | {ok, list()}   %% with option 'return', one element for each output
     | {error, Reason}
- when Path :: string(),
+ when File :: dict()
+            | {path, file:name_all()},
       Reason :: string().
 
 codec(File, Opts) ->
-    case dict(File, Opts) of
-        {ok, Dict} ->
-            make(File,
-                 Opts,
-                 Dict,
-                 [spec || _ <- [1], lists:member(debug, Opts)] ++ [erl, hrl]);
-        {error, _} = E ->
-            E
+    {Dict, Path} = identify(File),
+    case parse(Dict, Opts) of
+        {ok, ParseD} ->
+            make(Path, default(Opts), ParseD);
+        {error = E, Reason} ->
+            {E, diameter_dict_util:format_error(Reason)}
     end.
 
 codec(File) ->
     codec(File, []).
 
-%% dict/2
+%% format/1
 %%
-%% Parse a dictionary file and return the orddict that a codec module
-%% returns from dict/0.
-
--spec dict(string(), [opt()])
-   -> {ok, orddict:orddict()}
-    | {error, string()}.
+%% Turn an orddict returned by dict/1-2 back into a dictionary.
 
-dict(Path, Opts) ->
-    case diameter_dict_util:parse({path, Path}, Opts) of
-        {ok, _} = Ok ->
-            Ok;
-        {error = E, Reason} ->
-            {E, diameter_dict_util:format_error(Reason)}
-    end.
+-spec format(parsed())
+   -> iolist().
 
-dict(File) ->
-    dict(File, []).
+format([?VERSION | Dict]) ->
+    diameter_dict_util:format(Dict).
 
-%% format/1
+%% flatten/1
 %%
-%% Turn an orddict returned by dict/1-2 back into a dictionary file
-%% in the form of an iolist().
+%% Reconstitute a dictionary without @inherits.
 
--spec format(orddict:orddict())
-   -> iolist().
+-spec flatten(parsed())
+   -> parsed().
 
-format(Dict) ->
-    diameter_dict_util:format(Dict).
+flatten([?VERSION = V | Dict]) ->
+    [V | lists:foldl(fun flatten/2,
+                     Dict,
+                     [avp_vendor_id,
+                      custom_types,
+                      codecs,
+                      [avp_types, import_avps],
+                      [grouped, import_groups],
+                      [enum, import_enums]])].
+
+%% ===========================================================================
+
+%% flatten/2
+
+flatten([_,_] = Keys, Dict) ->
+    [Values, Imports] = [orddict:fetch(K, Dict) || K <- Keys],
+    Vs = lists:append([Values | [V || {_Mod, V} <- Imports]]),
+    lists:foldl(fun({K,V},D) -> orddict:store(K,V,D) end,
+                Dict,
+                lists:zip([inherits | Keys], [[], Vs, []]));
+
+%% Inherited avp's setting the 'V' flag get their value either from
+%% @avp_vendor_id in the inheriting dictionary or from @vendor in the
+%% *inherited* (not inheriting) dictionary: add the latter to
+%% @avp_vendor_id as required.
+flatten(avp_vendor_id = Key, Dict) ->
+    Def = orddict:find(vendor, Dict),
+    ModD = imports(Dict),
+    Vids = orddict:fetch(Key, Dict),
+    Avps = lists:append([As || {_,As} <- Vids]),
+    orddict:store(Key,
+                  dict:fold(fun(M, As, A) -> vid(M, As -- Avps, Def, A) end,
+                            Vids,
+                            ModD),
+                  Dict);
+
+%% Import @codecs and @custom_types from inherited dictionaries as
+%% required.
+flatten(Key, Dict) ->
+    ImportAvps = orddict:fetch(import_avps, Dict),
+    ImportItems = [{M, As}
+                   || {Mod, Avps} <- ImportAvps,
+                      [_|D] <- [Mod:dict()],
+                      {M,As0} <- orddict:fetch(Key, D),
+                      F <- [fun(A) -> lists:keymember(A, 1, Avps) end],
+                      [_|_] = As <- [lists:filter(F, As0)]],
+    orddict:store(Key,
+                  lists:foldl(fun merge/2,
+                              orddict:fetch(Key, Dict),
+                              ImportItems),
+                  Dict).
 
-%% reformat/1
+%% merge/2
+
+merge({Mod, _Avps} = T, Acc) ->
+    merge(lists:keyfind(Mod, 1, Acc), T, Acc).
+
+merge({Mod, Avps}, {Mod, As}, Acc) ->
+    lists:keyreplace(Mod, 1, Acc, {Mod, Avps ++ As});
+merge(false, T, Acc) ->
+    [T | Acc].
+
+%% imports/1
 %%
-%% Parse a dictionary file and return its formatted equivalent.
+%% Return a module() -> [AVP] dict of inherited AVP's setting the V flag.
 
--spec reformat(File)
-   -> {ok, iolist()}
-    | {error, Reason}
- when File :: string(),
-      Reason :: string().
+imports(Dict) ->
+    lists:foldl(fun imports/2,
+                dict:new(),
+                orddict:fetch(import_avps, Dict)).
+
+imports({Mod, Avps}, Dict) ->
+    dict:store(Mod,
+               [A || {A,_,_,Fs} <- Avps, lists:member($V, Fs)],
+               Dict).
 
-reformat(File) ->
-    case dict(File) of
-        {ok, Dict} ->
-            {ok, format(Dict)};
-        {error, _} = No ->
-            No
+%% vid/4
+
+vid(_, [], _, Acc) ->
+    Acc;
+vid(Mod, Avps, Def, Acc) ->
+    v(Mod:vendor_id(), Avps, Def, Acc).
+
+v(Vid, _, {ok, {Vid, _}}, Acc) -> %% same id as inheriting dictionary's
+    Acc;
+v(Vid, Avps, _, Acc) ->
+    case lists:keyfind(Vid, 1, Acc) of
+        {Vid, As} ->
+            lists:keyreplace(Vid, 1, Acc, {Vid, As ++ Avps});
+        false ->
+            [{Vid, Avps} | Acc]
     end.
 
 %% ===========================================================================
 
-make(_, _, _, []) ->
+parse({dict, ParseD}, _) ->
+    {ok, ParseD};
+parse(File, Opts) ->
+    diameter_dict_util:parse(File, Opts).
+
+default(Opts) ->
+    def(modes(Opts), Opts).
+
+def([], Opts) ->
+    [erl, hrl | Opts];
+def(_, Opts) ->
+    Opts.
+
+modes(Opts) ->
+    lists:filter(fun is_mode/1, Opts).
+
+is_mode(T) ->
+    lists:member(T, [erl, hrl, parse, forms]).
+
+identify([Vsn | [T|_] = ParseD])
+  when is_tuple(T) ->
+    ?VERSION == Vsn orelse erlang:error({version, {Vsn, ?VERSION}}),
+    {{dict, ParseD}, ?DEFAULT_DICT_FILE};
+identify({path, File} = T) ->
+    {T, File};
+identify(File) ->
+    Bin = iolist_to_binary([File]),
+    case is_path(Bin) of
+        true  -> {{path, File}, File};
+        false -> {Bin, ?DEFAULT_DICT_FILE}
+    end.
+
+%% Interpret anything containing \n or \r as a literal dictionary,
+%% otherwise a path. (Which might be the wrong guess in the worst case.)
+is_path(Bin) ->
+    try
+        [throw(C) || <<C>> <= Bin, $\n == C orelse $\r == C],
+        true
+    catch
+        throw:_ -> false
+    end.
+
+make(File, Opts, Dict) ->
+    ok(lists:foldl(fun(M,A) -> [make(File, Opts, Dict, M) | A] end,
+                   [],
+                   modes(Opts))).
+
+ok([ok|_]) ->
     ok;
-make(File, Opts, Dict, [Mode | Rest]) ->
+ok([_|_] = L) ->
+    {ok, lists:reverse(L)}.
+
+make(File, Opts, Dict, Mode) ->
     try
-        ok = diameter_codegen:from_dict(File, Dict, Opts, Mode),
-        make(File, Opts, Dict, Rest)
+        diameter_codegen:from_dict(File, Dict, Opts, Mode)
     catch
         error: Reason ->
             erlang:error({Reason, Mode, erlang:get_stacktrace()})
diff --git a/lib/diameter/test/diameter_codec_test.erl b/lib/diameter/test/diameter_codec_test.erl
index 295d23912b..0b4568a9e5 100644
--- a/lib/diameter/test/diameter_codec_test.erl
+++ b/lib/diameter/test/diameter_codec_test.erl
@@ -473,9 +473,6 @@ pack(true, Arity, Avp, Value, Acc) ->
 pack(false, Arity, Avp, Value, Acc) ->
     min(Arity, Avp, Value, Acc).
 
-all(Mod, Name, Avp, V) ->
-    all(Mod:avp_arity(Name, Avp), Avp, V).
-
 all(1, Avp, V) ->
     {Avp, V};
 all({0,'*'}, Avp, V) ->
@@ -489,9 +486,6 @@ a(N, Avp, V)
   when N /= 0 ->
     {Avp, lists:duplicate(N,V)}.
 
-min(Mod, Name, Avp, V, Acc) ->
-    min(Mod:avp_arity(Name, Avp), Avp, V, Acc).
-
 min(1, Avp, V, Acc) ->
     [{Avp, V} | Acc];
 min({0,_}, _, _, Acc) ->
diff --git a/lib/diameter/test/diameter_compiler_SUITE.erl b/lib/diameter/test/diameter_compiler_SUITE.erl
index 81722c8dca..ed369e8af3 100644
--- a/lib/diameter/test/diameter_compiler_SUITE.erl
+++ b/lib/diameter/test/diameter_compiler_SUITE.erl
@@ -31,10 +31,15 @@
 %% testcases
 -export([format/1,    format/2,
          replace/1,   replace/2,
-         generate/1,  generate/4]).
+         generate/1,  generate/4,
+         flatten1/1,  flatten1/3,
+         flatten2/1]).
 
 -export([dict/0]).  %% fake dictionary module
 
+%% dictionary callbacks for flatten2/1
+-export(['A1'/3, 'Unsigned32'/3]).
+
 -define(base, "base_rfc3588.dia").
 -define(util, diameter_util).
 -define(S, atom_to_list).
@@ -45,7 +50,7 @@
 %% RE/Replacement (in the sense of re:replace/4) pairs for morphing
 %% base_rfc3588.dia. The key is 'ok' or the the expected error as
 %% returned in the first element of the error tuple returned by
-%% diameter_dict_util:parse/2.
+%% diameter_make:codec/2.
 -define(REPLACE,
         [{ok,
           "",
@@ -335,7 +340,9 @@ suite() ->
 all() ->
     [format,
      replace,
-     generate].
+     generate,
+     flatten1,
+     flatten2].
 
 %% Error handling testcases will make an erroneous dictionary out of
 %% the base dictionary and check that the expected error results.
@@ -361,10 +368,18 @@ format(Config) ->
 
 format(Mods, Bin) ->
     B = modify(Bin, Mods),
-    {ok, Dict} = diameter_dict_util:parse(B, []),
-    {ok, D} = diameter_dict_util:parse(diameter_dict_util:format(Dict), []),
+    {ok, Dict} = parse(B, []),
+    {ok, D} = parse(diameter_make:format(Dict), []),
     {Dict, Dict} = {Dict, D}.
 
+parse(File, Opts) ->
+    case diameter_make:codec(File, [parse, hrl, return | Opts]) of
+        {ok, [Dict, _]} ->
+            {ok, Dict};
+        {error, _} = E ->
+            E
+    end.
+
 %% ===========================================================================
 %% replace/1
 %%
@@ -379,13 +394,10 @@ replace(Config) ->
 
 replace({E, Mods}, Bin) ->
     B = modify(Bin, Mods),
-    case {E, diameter_dict_util:parse(B, [{include, here()}]), Mods} of
+    case {E, parse(B, [{include, here()}]), Mods} of
         {ok, {ok, Dict}, _} ->
             Dict;
-        {_, {error, {E,_} = T}, _} ->
-            S = diameter_dict_util:format_error(T),
-            true = nochar($", S, E),
-            true = nochar($', S, E),
+        {_, {error, S}, _} ->
             S
     end.
 
@@ -403,20 +415,127 @@ generate(Config) ->
     [] = ?util:run([{?MODULE, [generate, M, Bin, N, T]}
                     || {E,N} <- Rs,
                        {ok, M} <- [norm(E)],
-                       T <- [erl, hrl, spec]]).
+                       T <- [erl, hrl, parse, forms]]).
 
 generate(Mods, Bin, N, Mode) ->
     B = modify(Bin, Mods ++ [{"@name .*", "@name dict" ++ ?L(N)}]),
-    {ok, Dict} = diameter_dict_util:parse(B, []),
+    {ok, Dict} = parse(B, []),
     File = "dict" ++ integer_to_list(N),
-    {_, ok} = {Dict, diameter_codegen:from_dict("dict",
-                                                Dict,
-                                                [{name, File},
-                                                 {prefix, "base"},
-                                                 debug],
-                                                Mode)},
-    Mode == erl
-        andalso ({ok, _} = compile:file(File ++ ".erl", [return_errors])).
+    {_, ok} = {Dict, diameter_make:codec(Dict,
+                                         [{name, File},
+                                          {prefix, "base"},
+                                          Mode])},
+    generate(Mode, File, Dict).
+
+generate(erl, File, _) ->
+    {ok, _} = compile:file(File ++ ".erl", [return_errors]);
+
+generate(forms, File, _) ->
+    {ok, [_]} = file:consult(File ++ ".F");
+
+generate(parse, File, Dict) ->
+    {ok, [Dict]} = file:consult(File ++ ".D"),  %% assert
+    {ok, [F]} = diameter_make:codec(Dict, [forms, return]),
+    {ok, _, _, _} = compile:forms(F, [return]);
+
+generate(hrl, _, _) ->
+    ok.
+
+%% ===========================================================================
+%% flatten1/1
+
+flatten1(_Config) ->
+    [Vsn | BaseD] = diameter_gen_base_rfc6733:dict(),
+    {ok, I} = parse("@inherits diameter_gen_base_rfc6733\n", []),
+    [Vsn | FlatD] = diameter_make:flatten(I),
+    [] = ?util:run([{?MODULE, [flatten1, K, BaseD, FlatD]}
+                    || K <- [avp_types, grouped, enum]]).
+
+flatten1(Key, BaseD, FlatD) ->
+    Vs = orddict:fetch(Key, BaseD),
+    Vs = orddict:fetch(Key, FlatD).
+
+%% ===========================================================================
+%% flatten2/1
+
+flatten2(_Config) ->
+    Dict1 =
+        "@name diameter_test1\n"
+        "@prefix diameter_test1\n"
+        "@vendor 666 test\n"
+        "@avp_vendor_id 111 A1 A3\n"
+        "@avp_vendor_id 222 A4 A6\n"
+        "@custom_types " ++ ?S(?MODULE) ++ " A1 A4\n"
+        "@codecs " ++ ?S(?MODULE) ++ " A3 A6\n"
+        "@avp_types\n"
+        "A1 1001 Unsigned32 V\n"
+        "A2 1002 Unsigned32 V\n"
+        "A3 1003 Unsigned32 V\n"
+        "A4 1004 Unsigned32 V\n"
+        "A5 1005 Unsigned32 V\n"
+        "A6 1006 Unsigned32 V\n"
+        "@end ignored\n",
+    Dict2 =
+        "@name diameter_test2\n"
+        "@prefix diameter_test2\n"
+        "@vendor 777 test\n"
+        "@inherits diameter_test1 A1 A2 A3\n"
+        "@inherits diameter_gen_base_rfc6733\n"
+        "@avp_vendor_id 333 A1\n",
+
+    {ok, [E1, F1]}
+        = diameter_make:codec(Dict1, [erl, forms, return]),
+    ct:pal("~s", [E1]),
+    diameter_test1 = M1 = load_forms(F1),
+
+    {ok, [D2, E2, F2]}
+        = diameter_make:codec(Dict2, [parse, erl, forms, return]),
+    ct:pal("~s", [E2]),
+    diameter_test2 = M2 = load_forms(F2),
+
+    Flat = lists:flatten(diameter_make:format(diameter_make:flatten(D2))),
+    ct:pal("~s", [Flat]),
+    {ok, [E3, F3]}
+        = diameter_make:codec(Flat, [erl, forms, return,
+                                     {name, "diameter_test3"}]),
+    ct:pal("~s", [E3]),
+    diameter_test3 = M3 = load_forms(F3),
+
+    [{1001, 111, M1, 'A1'},  %% @avp_vendor_id
+     {1002, 666, M1, 'A2'},  %% @vendor
+     {1003, 111, M1, 'A3'},  %% @avp_vendor_id
+     {1004, 222, M1, 'A4'},  %% @avp_vendor_id
+     {1005, 666, M1, 'A5'},  %% @vendor
+     {1006, 222, M1, 'A6'},  %% @avp_vendor_id
+     {1001, 333, M2, 'A1'},  %% M2 @avp_vendor_id
+     {1002, 666, M2, 'A2'},  %% M1 @vendor
+     {1003, 666, M2, 'A3'},  %% M1 @vendor
+     {1001, 333, M3, 'A1'},  %% (as for M2)
+     {1002, 666, M3, 'A2'},  %%   "
+     {1003, 666, M3, 'A3'}]  %%   "
+        = [{Code, Vid, Mod, Name}
+           || Mod <- [M1, M2, M3],
+              Code <- lists:seq(1001, 1006),
+              Vid <- [666, 111, 222, 777, 333],
+              {Name, 'Unsigned32'} <- [Mod:avp_name(Code, Vid)]],
+
+    [] = [{A,T,M,RC} || A <- ['A1', 'A3'],
+                        T <- [encode, decode],
+                        M <- [M2, M3],
+                        Ref <- [make_ref()],
+                        RC <- [M:avp(T, Ref, A)],
+                        RC /= {T, Ref}].
+
+'A1'(T, 'Unsigned32', Ref) ->
+    {T, Ref}.
+
+'Unsigned32'(T, 'A3', Ref) ->
+    {T, Ref}.
+
+load_forms(Forms) ->
+    {ok, Mod, Bin, _} = compile:forms(Forms, [return]),
+    {module, Mod} = code:load_binary(Mod, ?S(Mod), Bin),
+    Mod.
 
 %% ===========================================================================
 
@@ -428,9 +547,6 @@ norm({E, RE, Repl}) ->
 norm({_,_} = T) ->
     T.
 
-nochar(Char, Str, Err) ->
-    Err == parse orelse not lists:member(Char, Str) orelse Str.
-
 here() ->
     filename:dirname(code:which(?MODULE)).