0.8.1.34:

[sbcl.git] / src / compiler / knownfun.lisp

diff --git a/src/compiler/knownfun.lisp b/src/compiler/knownfun.lisp
index bd35c93..d28f79e 100644 (file)
--- a/src/compiler/knownfun.lisp
+++ b/src/compiler/knownfun.lisp
@@ -262,7 +262,7 @@
                (when (csubtypep type ltype)
                  ltype))))))))
 
-;;; Derive the type to be the type specifier which is the N'th arg.
+;;; Derive the type to be the type specifier which is the Nth arg.
 (defun result-type-specifier-nth-arg (n)
   (lambda (call)
     (declare (type combination call))
@@ -270,4 +270,29 @@
       (when (and cont (constant-continuation-p cont))
        (careful-specifier-type (continuation-value cont))))))
 
+;;; Derive the type to be the type specifier which is the Nth arg,
+;;; with the additional restriptions noted in the CLHS for STRING and
+;;; SIMPLE-STRING.
+(defun creation-result-type-specifier-nth-arg (n)
+  (lambda (call)
+    (declare (type combination call))
+    (let ((cont (nth (1- n) (combination-args call))))
+      (when (and cont (constant-continuation-p cont))
+       (let* ((specifier (continuation-value cont))
+              (lspecifier (if (atom specifier) (list specifier) specifier)))
+         (cond
+           ((eq (car lspecifier) 'string)
+            (destructuring-bind (string &rest size)
+                lspecifier
+              (declare (ignore string))
+              (careful-specifier-type
+               `(vector character ,@(when size size)))))
+           ((eq (car lspecifier) 'simple-string)
+            (destructuring-bind (simple-string &rest size)
+                lspecifier
+              (declare (ignore simple-string))
+              (careful-specifier-type
+               `(simple-array character ,@(if size (list size) '((*)))))))
+           (t (careful-specifier-type specifier))))))))
+
 (/show0 "knownfun.lisp end of file")