From 999f96be00309bf75534a1491f8ee14b610d6e88 Mon Sep 17 00:00:00 2001
From: Stas Boukarev <stassats@gmail.com>
Date: Wed, 20 Dec 2017 20:06:45 +0300
Subject: [PATCH] Fix the COERCE source transform.

Don't call CSUBTYPEP on NIL which CAREFUL-SPECIFIER-TYPE may return.

Fixes lp#1739450
---
 src/compiler/array-tran.lisp | 3 ++-
 tests/compiler-2.pure.lisp   | 7 +++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/compiler/array-tran.lisp b/src/compiler/array-tran.lisp
index e15554dd2..b6a8d75d0 100644
--- a/src/compiler/array-tran.lisp
+++ b/src/compiler/array-tran.lisp
@@ -582,7 +582,8 @@
       (let* ((type (constant-form-value type env))
              (length (1- (length x)))
              (ctype (careful-values-specifier-type type)))
-        (if (csubtypep ctype (specifier-type '(array * (*))))
+        (if (and ctype
+                 (csubtypep ctype (specifier-type '(array * (*)))))
             (multiple-value-bind (type element-type upgraded had-dimensions)
                 (simplify-vector-type ctype)
               (declare (ignore type upgraded))
diff --git a/tests/compiler-2.pure.lisp b/tests/compiler-2.pure.lisp
index 05b47d83e..0bec9d18b 100644
--- a/tests/compiler-2.pure.lisp
+++ b/tests/compiler-2.pure.lisp
@@ -860,3 +860,10 @@
               (checked-compile
                `(lambda () (the (array abc) #()))
                :allow-style-warnings t))))
+
+(with-test (:name (coerce :bad-type-specifier))
+  (assert
+   (nth-value 1
+              (checked-compile
+               `(lambda () (coerce (list 2) 1))
+               :allow-warnings t))))
-- 
2.11.4.GIT