From 838dde1e27ee6a6debf74cf2370b2284f618b348 Mon Sep 17 00:00:00 2001
From: Hans Bolinder <hasse@erlang.org>
Date: Wed, 17 May 2017 14:08:49 +0200
Subject: stdlib: Warn for bad type variables of parameterized types

The linter emits warnings about using '_' as type variable in
parameterized types.
---
 lib/stdlib/src/erl_parse.yrl | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'lib/stdlib/src')

diff --git a/lib/stdlib/src/erl_parse.yrl b/lib/stdlib/src/erl_parse.yrl
index 2dcddeb8c2..733932e711 100644
--- a/lib/stdlib/src/erl_parse.yrl
+++ b/lib/stdlib/src/erl_parse.yrl
@@ -1052,6 +1052,9 @@ build_typed_attribute({atom,Aa,record},
 build_typed_attribute({atom,Aa,Attr},
                       {type_def, {call,_,{atom,_,TypeName},Args}, Type})
   when Attr =:= 'type' ; Attr =:= 'opaque' ->
+    lists:foreach(fun({var, A, '_'}) -> ret_err(A, "bad type variable");
+                     (_)             -> ok
+                  end, Args),
     case lists:all(fun({var, _, _}) -> true;
                       (_)           -> false
                    end, Args) of
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