`read': give fuller error message for errors following "#".

This solves bug#70702.

* src/lread.c (READ_AND_BUFFER, INVALID_SYNTAX_WITH_BUFFER):
New macros.
(read0): For errors in characters sequences beginning with "#",
output the entire character sequence rather than just "#".

* test/src/lread-tests.el (lread-test-bug70702): New test.

1 files changed, 11 insertions, 0 deletions

diff --git a/test/src/lread-tests.el b/test/src/lread-tests.el
index 4d7f8b71838..cc17f7eb3fa 100644
--- a/test/src/lread-tests.el
+++ b/test/src/lread-tests.el
@@ -174,6 +174,17 @@ literals (Bug#20852)."
     (load "somelib" nil t)
     (should (string-suffix-p "/somelib.el" (caar load-history)))))
 
+(ert-deftest lread-test-bug70702 ()
+  "Test for certain wholesome error messages from `read'."
+  (setq eval-expression-debug-on-error nil)
+  (setq ert-debug-on-error nil)
+  (with-temp-buffer
+    (goto-char (point-min))
+    (insert "#<symbol lambda at 10>")
+    (goto-char (point-min))
+    (should (equal (should-error (read (current-buffer)))
+                   '(invalid-read-syntax "#<" 1 2)))))
+
 (ert-deftest lread-lread--substitute-object-in-subtree ()
   (let ((x (cons 0 1)))
     (setcar x x)