File 5841-Eliminate-false-warning-for-re-defined-and-unused-ty.patch of Package erlang

From f7c11e4e4c4e9c11bf0c319fe24c5491de30120e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Mon, 13 Mar 2023 14:02:41 +0100
Subject: [PATCH] Eliminate false warning for re-defined and unused type

Closes #6997
---
 lib/stdlib/src/erl_lint.erl        |  7 +++++-
 lib/stdlib/test/erl_lint_SUITE.erl | 34 +++++++++++++++++++++++++++++-
 2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/lib/stdlib/src/erl_lint.erl b/lib/stdlib/src/erl_lint.erl
index 728f82b518..959c04184a 100644
--- a/lib/stdlib/src/erl_lint.erl
+++ b/lib/stdlib/src/erl_lint.erl
@@ -3066,7 +3066,12 @@ check_type_2({type, Anno, TypeName, Args}, SeenVars, St) ->
                           add_warning(Anno, W, St)
                   end;
               _ ->
-                  St
+                  case is_default_type(TypePair) of
+                      true ->
+                          used_type(TypePair, Anno, St);
+                      false ->
+                          St
+                  end
           end,
     check_type_2({type, nowarn(), product, Args}, SeenVars, St1);
 check_type_2({user_type, A, TypeName, Args}, SeenVars, St) ->
diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl
index 93595459d4..3d5f081cc5 100644
--- a/lib/stdlib/test/erl_lint_SUITE.erl
+++ b/lib/stdlib/test/erl_lint_SUITE.erl
@@ -5095,7 +5095,39 @@ redefined_builtin_type(Config) ->
                       {{5,16},erl_lint,{redefine_builtin_type,{port,0}}},
                       {{6,16},erl_lint,{redefine_builtin_type,{float,0}}},
                       {{7,16},erl_lint,{redefine_builtin_type,{iodata,0}}}
-                     ]}}
+                     ]}},
+          {redef6,
+           <<"-spec bar(function()) -> bar().
+              bar({function, F}) -> F().
+              -type function() :: {function, fun(() -> bar())}.
+              -type bar() :: {bar, binary()}.
+             ">>,
+           [],
+           {warnings,[{{3,16},erl_lint,
+                       {redefine_builtin_type,{function,0}}}]}},
+          {redef7,
+           <<"-type function() :: {function, fun(() -> bar())}.
+              -type bar() :: {bar, binary()}.
+              -spec bar(function()) -> bar().
+              bar({function, F}) -> F().
+             ">>,
+           [],
+           {warnings,[{{1,22},erl_lint,
+                       {redefine_builtin_type,{function,0}}}]}},
+          {redef8,
+           <<"-type function() :: {function, fun(() -> atom())}.
+             ">>,
+           [],
+           {warnings,[{{1,22},erl_lint,
+                       {redefine_builtin_type,{function,0}}},
+                      {{1,22},erl_lint,
+                       {unused_type,{function,0}}}]}},
+          {redef9,
+           <<"-spec foo() -> fun().
+              foo() -> fun() -> ok end.
+             ">>,
+           [],
+           []}
          ],
     [] = run(Config, Ts),
     ok.
-- 
2.35.3