Fix expand-file-name for names starting with '~'

* src/fileio.c: (file_name_absolute_no_tilde_p):
New static function.
(Fexpand_file_name): If the current buffer's default-directory
starts with "~user" where "user" is not a valid user name, don't
give the '~' a special meaning.  Just treat the value of
default-directory as a relative name.  (Bug#36502)
* test/src/fileio-tests.el
(fileio-tests--relative-default-directory): Add a test.

1 files changed, 5 insertions, 1 deletions

diff --git a/test/src/fileio-tests.el b/test/src/fileio-tests.el
index 0e0230a145d..813ee5f798f 100644
--- a/test/src/fileio-tests.el
+++ b/test/src/fileio-tests.el
@@ -131,4 +131,8 @@ Also check that an encoding error can appear in a symlink."
 (ert-deftest fileio-tests--relative-default-directory ()
   "Test expand-file-name when default-directory is relative."
   (let ((default-directory "some/relative/name"))
-    (should (file-name-absolute-p (expand-file-name "foo")))))
+    (should (file-name-absolute-p (expand-file-name "foo"))))
+  (let* ((default-directory "~foo")
+         (name (expand-file-name "bar")))
+    (should (and (file-name-absolute-p name)
+                 (not (eq (aref name 0) ?~))))))