Re-sending with patch inline, without typo in test case, but with typo in subject line because why not.

From 8ebb3839798b720d895b4d17eddc1649a14caabc Mon Sep 17 00:00:00 2001
From: Douglas Katzman <dougk@google.com>
Date: Thu, 10 Oct 2013 11:56:32 -0400
Subject: [PATCH] Mustn't forget an undefined-function check on fopcompilable
 TLFs

---
 src/compiler/fopcompile.lisp        |    2 ++
 tests/fopcompiler.impure-cload.lisp |   11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/src/compiler/fopcompile.lisp b/src/compiler/fopcompile.lisp
index 2ac2385..2711525 100644
--- a/src/compiler/fopcompile.lisp
+++ b/src/compiler/fopcompile.lisp
@@ -362,6 +362,8 @@
                        (sb!fasl::dump-fop 'sb!fasl::fop-package
                                           *compile-object*))
                       (t
+                       (when (eq (info :function :where-from operator) :assumed)
+                          (note-undefined-reference operator :function))
                        (fopcompile-constant operator t)
                        (dolist (arg args)
                          (fopcompile arg path t))
diff --git a/tests/fopcompiler.impure-cload.lisp b/tests/fopcompiler.impure-cload.lisp
index 25fc8e7..71c6dc0 100644
--- a/tests/fopcompiler.impure-cload.lisp
+++ b/tests/fopcompiler.impure-cload.lisp
@@ -94,3 +94,14 @@
          (y (bar (x foo))))
     (bar (y x foo))))
 
+;; Ensure that fopcompiling a call to an assumed function style-warns.
+(defvar *file* #p"compile-temp.lisp")
+(with-test (:name (:fopcompiler :undefined-warning))
+  (with-open-file (stream *file* :direction :output :if-exists :supersede)
+    ;; protect in case 'UNKNOWN-FN is the name of a function some day...
+    (write `(defvar *foo* (,(make-symbol "UNKNOWN-FN"))) :stream stream))
+  (multiple-value-bind (output warningp errorp) (compile-file *file*)
+    (when output
+      (delete-file output))
+    (assert (and warningp (not errorp)))))
+(delete-file *file*)
-- 
1.7.10.2 (Apple Git-33)

On Thu, Oct 10, 2013 at 12:40 PM, Douglas Katzman <dougk@google.com> wrote:
fopcompiler was too forgiving. See attached.