Warn about lambda expressions in comparisons

Lambda expressions are not comparable; warn about calls such as
(eq x (lambda ...)) etc.

* lisp/emacs-lisp/bytecomp.el (bytecomp--dodgy-eq-arg): Rename to...
(bytecomp--dodgy-eq-arg-p): ...this.  Use pcase.  Add lambda checks.
(bytecomp--value-type-description, bytecomp--arg-type-description)
(bytecomp--check-eq-args, bytecomp--check-memq-args): Add function
checks.  Update calls.  Make compiler-macro arguments optional to
avoid crashes in malformed code.
* test/lisp/emacs-lisp/bytecomp-tests.el
(bytecomp--with-warning-test): Simplify argument.  Run each
compilation with a fresh (empty) warning cache.  Add ert-info for
easier debugging.
(bytecomp-warn-dodgy-args-eq, bytecomp-warn-dodgy-args-memq):
Add lambda tests.

1 files changed, 14 insertions, 6 deletions

diff --git a/test/lisp/emacs-lisp/bytecomp-tests.el b/test/lisp/emacs-lisp/bytecomp-tests.el
index 00361a4286b..3400128759a 100644
--- a/test/lisp/emacs-lisp/bytecomp-tests.el
+++ b/test/lisp/emacs-lisp/bytecomp-tests.el
@@ -833,15 +833,19 @@ byte-compiled.  Run with dynamic binding."
     ;; Should not warn that mt--test2 is not known to be defined.
     (should-not (re-search-forward "my--test2" nil t))))
 
-(defmacro bytecomp--with-warning-test (re-warning &rest form)
+(defmacro bytecomp--with-warning-test (re-warning form)
   (declare (indent 1))
   `(with-current-buffer (get-buffer-create "*Compile-Log*")
      (let ((inhibit-read-only t)) (erase-buffer))
-     (let ((text-quoting-style 'grave))
-       (byte-compile ,@form)
-       (ert-info ((prin1-to-string (buffer-string)) :prefix "buffer: ")
-         (should (re-search-forward
-                  (string-replace " " "[ \n]+" ,re-warning)))))))
+     (let ((text-quoting-style 'grave)
+           (macroexp--warned
+            (make-hash-table :test #'equal :weakness 'key))   ; oh dear
+           (form ,form))
+       (ert-info ((prin1-to-string form) :prefix "form: ")
+         (byte-compile form)
+         (ert-info ((prin1-to-string (buffer-string)) :prefix "buffer: ")
+           (should (re-search-forward
+                    (string-replace " " "[ \n]+" ,re-warning))))))))
 
 (ert-deftest bytecomp-warn-wrong-args ()
   (bytecomp--with-warning-test "remq.*3.*2"
@@ -874,6 +878,8 @@ byte-compiled.  Run with dynamic binding."
       (bytecomp--with-warning-test (msg "list" 1)   `(,fn '(a) 'x))
       (bytecomp--with-warning-test (msg "string" 2) `(,fn 'x "a"))
       (bytecomp--with-warning-test (msg "vector" 2) `(,fn 'x [a]))
+      (bytecomp--with-warning-test (msg "function" 2) `(,fn 'x (lambda () 1)))
+      (bytecomp--with-warning-test (msg "function" 2) `(,fn 'x #'(lambda () 1)))
       (unless (eq fn 'eql)
         (bytecomp--with-warning-test (msg "integer" 2) `(,fn 'x #x10000000000))
         (bytecomp--with-warning-test (msg "float" 2)   `(,fn 'x 1.0))))))
@@ -899,6 +905,8 @@ byte-compiled.  Run with dynamic binding."
     (bytecomp--with-warning-test (msg1 "list")   `(,fn '(a) '(x)))
     (bytecomp--with-warning-test (msg1 "string") `(,fn "a" '(x)))
     (bytecomp--with-warning-test (msg1 "vector") `(,fn [a] '(x)))
+    (bytecomp--with-warning-test (msg1 "function") `(,fn (lambda () 1) '(x)))
+    (bytecomp--with-warning-test (msg1 "function") `(,fn #'(lambda () 1) '(x)))
     (unless (eq fn 'memql)
       (bytecomp--with-warning-test (msg1 "integer") `(,fn #x10000000000 '(x)))
       (bytecomp--with-warning-test (msg1 "float")   `(,fn 1.0 '(x))))