From f721374321e1a6772d10583ea613b20de75edcc6 Mon Sep 17 00:00:00 2001
From: Badlop <badlop@process-one.net>
Date: Thu, 24 Feb 2022 21:34:40 +0100
Subject: [PATCH] Determine compile definitions based on Erlang version

This gives a clear definition of what erlang versions require each
workaround, instead of depending on the actual workaround details.
The lib module was removed in OTP 21.0,
and the formatting options were moved to erl_error.
The uri_string module was introduced in OTP 21.0.
---
 mix.exs      | 15 +++------------
 rebar.config |  4 ++--
 2 files changed, 5 insertions(+), 14 deletions(-)

diff --git a/mix.exs b/mix.exs
index 00659b346..4e61b0dcd 100644
--- a/mix.exs
+++ b/mix.exs
@@ -50,15 +50,6 @@ defmodule Ejabberd.MixProject do
      ++ cond_apps()]
   end
 
-  defp if_function_exported(mod, fun, arity, okResult) do
-    :code.ensure_loaded(mod)
-    if :erlang.function_exported(mod, fun, arity) do
-      okResult
-    else
-      []
-    end
-  end
-
   defp if_version_above(ver, okResult) do
     if :erlang.system_info(:otp_release) > ver do
       okResult
@@ -82,15 +73,15 @@ defmodule Ejabberd.MixProject do
              cond_options() ++
              Enum.map(includes, fn (path) -> {:i, path} end) ++
              if_version_above('20', [{:d, :DEPRECATED_GET_STACKTRACE}]) ++
+             if_version_above('20', [{:d, :HAVE_URI_STRING}]) ++
+             if_version_above('20', [{:d, :HAVE_ERL_ERROR}]) ++
              if_version_below('21', [{:d, :USE_OLD_HTTP_URI}]) ++
              if_version_below('22', [{:d, :LAGER}]) ++
              if_version_below('21', [{:d, :NO_CUSTOMIZE_HOSTNAME_CHECK}]) ++
              if_version_below('23', [{:d, :USE_OLD_CRYPTO_HMAC}]) ++
              if_version_below('23', [{:d, :USE_OLD_PG2}]) ++
              if_version_below('24', [{:d, :COMPILER_REPORTS_ONLY_LINES}]) ++
-             if_version_below('24', [{:d, :SYSTOOLS_APP_DEF_WITHOUT_OPTIONAL}]) ++
-             if_function_exported(:uri_string, :normalize, 1, [{:d, :HAVE_URI_STRING}]) ++
-             if_function_exported(:erl_error, :format_exception, 6, [{:d, :HAVE_ERL_ERROR}])
+             if_version_below('24', [{:d, :SYSTOOLS_APP_DEF_WITHOUT_OPTIONAL}])
     defines = for {:d, value} <- result, do: {:d, value}
     result ++ [{:d, :ALL_DEFS, defines}]
   end
diff --git a/rebar.config b/rebar.config
index eb51d1295..6343a006c 100644
--- a/rebar.config
+++ b/rebar.config
@@ -107,6 +107,8 @@
 {erl_opts, [nowarn_deprecated_function,
             {i, "include"},
             {if_version_above, "20", {d, 'DEPRECATED_GET_STACKTRACE'}},
+            {if_version_above, "20", {d, 'HAVE_ERL_ERROR'}},
+            {if_version_above, "20", {d, 'HAVE_URI_STRING'}},
             {if_version_below, "21", {d, 'USE_OLD_HTTP_URI'}},
             {if_version_below, "22", {d, 'LAGER'}},
             {if_version_below, "21", {d, 'NO_CUSTOMIZE_HOSTNAME_CHECK'}},
@@ -121,8 +123,6 @@
             {if_var_true, roster_gateway_workaround, {d, 'ROSTER_GATEWAY_WORKAROUND'}},
             {if_var_true, sip, {d, 'SIP'}},
             {if_var_true, stun, {d, 'STUN'}},
-            {if_have_fun, {erl_error, format_exception, 6}, {d, 'HAVE_ERL_ERROR'}},
-            {if_have_fun, {uri_string, normalize, 1}, {d, 'HAVE_URI_STRING'}},
             {src_dirs, [src,
                         {if_rebar3, sql},
                         {if_var_true, tools, tools},