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authorStefan Monnier <monnier@iro.umontreal.ca>2018-04-20 17:22:47 -0400
committerStefan Monnier <monnier@iro.umontreal.ca>2018-04-20 17:22:47 -0400
commit495963cfaf535646350051f47c085b84319572f0 (patch)
tree41cbcf9016d33124ea845c0c352731cf4a49d11c /lisp/emacs-lisp
parent71b108a5d771a5d9a777dd9bdafa082fa6a6384b (diff)
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* lisp/emacs-lisp/bytecomp.el (byte-compile-file-form-defvar-function):
Warn about defvaralias that follows instead of precedes its var.
Diffstat (limited to 'lisp/emacs-lisp')
-rw-r--r--lisp/emacs-lisp/bytecomp.el9
1 files changed, 9 insertions, 0 deletions
diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index ea9e3f06555..50e67046e8b 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -2426,6 +2426,15 @@ list that represents a doc string reference.
(defun byte-compile-file-form-defvar-function (form)
(pcase-let (((or `',name (let name nil)) (nth 1 form)))
(if name (byte-compile--declare-var name)))
+ ;; Variable aliases are better declared before the corresponding variable,
+ ;; since it makes it more likely that only one of the two vars has a value
+ ;; before the `defvaralias' gets executed, which avoids the need to
+ ;; merge values.
+ (pcase form
+ (`(defvaralias ,_ ',newname . ,_)
+ (when (memq newname byte-compile-bound-variables)
+ (byte-compile-warn
+ "Alias for `%S' should be declared before its referent" newname))))
(byte-compile-keep-pending form))
(put 'custom-declare-variable 'byte-hunk-handler