Warn about bad face specs in `defface` at compile time

* lisp/emacs-lisp/bytecomp.el (byte-compile--custom-declare-face):
Byte-compile `defface` forms, or the byte-compile handler won't
be called.
(bytecomp--check-cus-face-spec): New.
(bytecomp--custom-declare): Call it.
* test/lisp/emacs-lisp/bytecomp-tests.el (bytecomp-test-defface-spec):
New tests.

1 files changed, 26 insertions, 0 deletions

diff --git a/test/lisp/emacs-lisp/bytecomp-tests.el b/test/lisp/emacs-lisp/bytecomp-tests.el
index e3ce87cc9af..cce6b1221fc 100644
--- a/test/lisp/emacs-lisp/bytecomp-tests.el
+++ b/test/lisp/emacs-lisp/bytecomp-tests.el
@@ -1985,6 +1985,32 @@ EXPECTED-POINT BINDINGS (MODES \\='\\='(ruby-mode js-mode python-mode)) \
      (dc 'integerp))
     ))
 
+(ert-deftest bytecomp-test-defface-spec ()
+  (cl-flet ((df (spec) `(defface mytest ',spec "doc" :group 'test)))
+    (bytecomp--with-warning-test
+     (rx "Bad face display condition `max-colors'")
+     (df '((((class color grayscale) (max-colors 75) (background light))
+            :foreground "cyan"))))
+    (bytecomp--with-warning-test
+     (rx "Bad face display `defualt'")
+     (df '((defualt :foreground "cyan"))))
+    (bytecomp--with-warning-test
+     (rx "`:inverse' is not a valid face attribute keyword")
+     (df '((t :background "blue" :inverse t))))
+    (bytecomp--with-warning-test
+     (rx "`:inverse' is not a valid face attribute keyword")
+     (df '((t (:background "blue" :inverse t)))))  ; old attr list syntax
+    (bytecomp--with-warning-test
+     (rx "Value for face attribute `:inherit' should not be quoted")
+     (df '((t :inherit 'other))))
+    (bytecomp--with-warning-test
+     (rx "Missing face attribute `:extend' value")
+     (df '((t :foundry "abc" :extend))))
+    (bytecomp--with-warning-test
+     (rx "Non-keyword in face attribute list: `\"green\"'")
+     (df '((t :foreground "white" "green"))))
+    ))
+
 (ert-deftest bytecomp-function-attributes ()
   ;; Check that `byte-compile' keeps the declarations, interactive spec and
   ;; doc string of the function (bug#55830).