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 +++
 lib/stdlib/test/erl_lint_SUITE.erl | 6 +++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

(limited to 'lib')

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
diff --git a/lib/stdlib/test/erl_lint_SUITE.erl b/lib/stdlib/test/erl_lint_SUITE.erl
index 02524679fa..cc3d605840 100644
--- a/lib/stdlib/test/erl_lint_SUITE.erl
+++ b/lib/stdlib/test/erl_lint_SUITE.erl
@@ -3978,7 +3978,11 @@ otp_14323(Config) ->
                     {13,erl_lint,{undefined_function,{a,1}}},
                     {14,erl_lint,{bad_dialyzer_attribute,
                                   {nowarn_function,{a,-1}}}}],
-            []}}],
+            []}},
+          {otp_14323_2,
+           <<"-type t(_) :: atom().">>,
+           [],
+           {errors,[{1,erl_parse,"bad type variable"}],[]}}],
     [] = run(Config, Ts),
     ok.
 
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