From d59bdfa4e0d74a69f700b516f143fe0176dc84ca Mon Sep 17 00:00:00 2001
From: Stas Boukarev <stassats@gmail.com>
Date: Mon, 8 Apr 2013 14:12:55 +0400
Subject: [PATCH] Don't signal an error on (setf (documentation nil 'function)
 "doc").

Signal a style-warning instead when trying to set documentation of NIL
for all other documentation types (except TYPE).

Reported by Zach Beane. Regression since 2e52fa05.
---
 NEWS                        |    6 +++++-
 src/pcl/documentation.lisp  |   43 +++++++++++++++++++++++++++++++++++--------
 tests/interface.impure.lisp |    9 +++++++++
 3 files changed, 49 insertions(+), 9 deletions(-)

diff --git a/NEWS b/NEWS
index 0450bf6..91ec2be 100644
--- a/NEWS
+++ b/NEWS
@@ -4,9 +4,13 @@ changes relative to sbcl-1.1.6
     anymore. (Minimal test case provided by James M. Lawrence on sbcl-devel)
   * bug fix: no more bogus ## references when pretty printing backquoted
     forms with non-trivial structure sharing. (lp#1161218)
+  * bug fix: Don't signal an error on (setf (documentation nil 'function) "doc").
+    Signal a style-warning instead when trying to set documentation of NIL
+    for all other documentation types.
+    Reported by Zach Beane. Regression since 2e52fa05.
 
 changes in sbcl-1.1.6 relative to sbcl-1.1.5:
-  * enhancement: the continuable error when defknown-ing over extant 
+  * enhancement: the continuable error when defknown-ing over extant
     fndb entries can be ignored by passing :overwrite-fndb-silently t
     as a keyword argument to sb-c:defknown (after attributes). Useful
     to allow defknown to be re-loaded. Use with :allow-other-keys t
diff --git a/src/pcl/documentation.lisp b/src/pcl/documentation.lisp
index 65d9485..a382b9d 100644
--- a/src/pcl/documentation.lisp
+++ b/src/pcl/documentation.lisp
@@ -44,8 +44,14 @@
         (t
          (fun-name (fdefinition name)))))
 
+(defun ignore-nil-doc (type)
+  (style-warn "Ignoring documentation of type ~a for ~a."
+              type nil))
+
 (defun set-function-name-documentation (name documentation)
-  (cond ((not (legal-fun-name-p name))
+  (cond ((not name)
+         (ignore-nil-doc 'function))
+        ((not (legal-fun-name-p name))
          nil)
         ((not (equal (real-function-name name) name))
          (setf (random-documentation name 'function) documentation))
@@ -53,7 +59,8 @@
          (setf (fun-doc (or (and (symbolp name)
                                  (macro-function name))
                             (fdefinition name)))
-               documentation))))
+               documentation)))
+  documentation)
 
 ;;; functions, macros, and special forms
 (defmethod documentation ((x function) (doc-type (eql 't)))
@@ -109,11 +116,19 @@
   (set-function-name-documentation x new-value))
 
 (defmethod (setf documentation) (new-value (x symbol) (doc-type (eql 'compiler-macro)))
-  (awhen (compiler-macro-function x)
-    (setf (documentation it t) new-value)))
+  (cond (x
+         (awhen (compiler-macro-function x)
+           (setf (documentation it t) new-value)))
+        (t
+         (ignore-nil-doc 'compiler-macro)
+         new-value)))
 
 (defmethod (setf documentation) (new-value (x symbol) (doc-type (eql 'setf)))
-  (setf (fdocumentation x 'setf) new-value))
+  (cond (x
+         (setf (fdocumentation x 'setf) new-value))
+        (t
+         (ignore-nil-doc 'setf)
+         new-value)))
 
 ;;; method combinations
 (defmethod documentation ((x method-combination) (doc-type (eql 't)))
@@ -136,7 +151,11 @@
 
 (defmethod (setf documentation)
     (new-value (x symbol) (doc-type (eql 'method-combination)))
-  (setf (random-documentation x 'method-combination) new-value))
+  (cond (x
+         (setf (random-documentation x 'method-combination) new-value))
+        (t
+         (ignore-nil-doc 'method-combination)
+         new-value)))
 
 ;;; methods
 (defmethod documentation ((x standard-method) (doc-type (eql 't)))
@@ -235,7 +254,11 @@
 (defmethod (setf documentation) (new-value
                                  (x symbol)
                                  (doc-type (eql 'structure)))
-  (setf (fdocumentation x 'structure) new-value))
+  (cond (x
+         (setf (fdocumentation x 'structure) new-value))
+        (t
+         (ignore-nil-doc 'structure)
+         new-value)))
 
 ;;; variables
 (defmethod documentation ((x symbol) (doc-type (eql 'variable)))
@@ -244,7 +267,11 @@
 (defmethod (setf documentation) (new-value
                                  (x symbol)
                                  (doc-type (eql 'variable)))
-  (setf (fdocumentation x 'variable) new-value))
+  (cond (x
+         (setf (fdocumentation x 'variable) new-value))
+        (t
+         (ignore-nil-doc 'variable)
+         new-value)))
 
 ;;; default if DOC-TYPE doesn't match one of the specified types
 (defmethod documentation (object doc-type)
diff --git a/tests/interface.impure.lisp b/tests/interface.impure.lisp
index 52b5fc2..ad10e6d 100644
--- a/tests/interface.impure.lisp
+++ b/tests/interface.impure.lisp
@@ -310,5 +310,14 @@
            (equal (documentation 'test 'function)
                   (documentation 'test2 'function)))))
 
+(with-test (:name :setf-documentation-on-nil)
+  (assert
+   (handler-case
+       (assert (equal (setf (documentation nil 'function) "foo") "foo"))
+     (style-warning () t)
+     (:no-error (x)
+       (declare (ignore x))
+       nil))))
+
 
 ;;;; success
-- 
1.7.10.4