Make byte-compiler warn about wide docstrings

* lisp/emacs-lisp/bytecomp.el (byte-compile--wide-docstring-p):
(byte-compile-docstring-length-warn): New defuns.
(byte-compile-docstring-max-column): New defcustom.
(byte-compile--wide-docstring-substitution-len): New variable.
(byte-compile-warning-types, byte-compile-warnings): New value
'docstrings'.
(byte-compile-file-form-autoload, byte-compile-file-form-defvar):
(byte-compile-file-form-defvar-function, byte-compile-lambda):
(byte-compile-defvar, byte-compile-file-form-defalias): Warn about too
wide docstrings.  (Bug#44858)

* test/lisp/emacs-lisp/bytecomp-tests.el
(bytecomp-warn-wide-docstring/defconst)
(bytecomp-warn-wide-docstring/defvar): New tests.
(bytecomp--define-warning-file-test): New macro.
(bytecomp/warn-wide-docstring-autoload\.el)
(bytecomp/warn-wide-docstring-custom-declare-variable\.el)
(bytecomp/warn-wide-docstring-defalias\.el)
(bytecomp/warn-wide-docstring-defconst\.el)
(bytecomp/warn-wide-docstring-define-abbrev-table\.el)
(bytecomp/warn-wide-docstring-define-obsolete-function-alias\.el)
(bytecomp/warn-wide-docstring-define-obsolete-variable-alias\.el)
(bytecomp/warn-wide-docstring-defun\.el)
(bytecomp/warn-wide-docstring-defvar\.el)
(bytecomp/warn-wide-docstring-defvaralias\.el)
(bytecomp/warn-wide-docstring-ignore-fill-column\.el)
(bytecomp/warn-wide-docstring-ignore-override\.el)
(bytecomp/warn-wide-docstring-ignore\.el)
(bytecomp/warn-wide-docstring-multiline-first\.el)
(bytecomp/warn-wide-docstring-multiline\.el): New tests.
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-autoload.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-custom-declare-variable.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-defalias.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-defconst.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-define-abbrev-table.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-define-obsolete-function-alias.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-define-obsolete-variable-alias.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-defun.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-defvar.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-defvaralias.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-ignore-fill-column.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-ignore-override.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-ignore.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-multiline-first.el:
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-multiline.el:
New files.

1 files changed, 71 insertions, 0 deletions

diff --git a/test/lisp/emacs-lisp/bytecomp-tests.el b/test/lisp/emacs-lisp/bytecomp-tests.el
index 4a6e28f7c7c..47aab563f6f 100644
--- a/test/lisp/emacs-lisp/bytecomp-tests.el
+++ b/test/lisp/emacs-lisp/bytecomp-tests.el
@@ -540,6 +540,16 @@ Subtests signal errors if something goes wrong."
   (bytecomp--with-warning-test "foo.*lacks a prefix"
     '(defvar foo nil)))
 
+(defvar bytecomp-tests--docstring (make-string 100 ?x))
+
+(ert-deftest bytecomp-warn-wide-docstring/defconst ()
+  (bytecomp--with-warning-test "defconst.*foo.*wider than.*characters"
+    `(defconst foo t ,bytecomp-tests--docstring)))
+
+(ert-deftest bytecomp-warn-wide-docstring/defvar ()
+  (bytecomp--with-warning-test "defvar.*foo.*wider than.*characters"
+    `(defvar foo t ,bytecomp-tests--docstring)))
+
 (defmacro bytecomp--define-warning-file-test (file re-warning &optional reverse)
   `(ert-deftest ,(intern (format "bytecomp/%s" file)) ()
      :expected-result ,(if reverse :failed :passed)
@@ -639,6 +649,67 @@ Subtests signal errors if something goes wrong."
 (bytecomp--define-warning-file-test "warn-variable-set-nonvariable.el"
                             "variable reference to nonvariable")
 
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-autoload.el"
+ "autoload.*foox.*wider than.*characters")
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-custom-declare-variable.el"
+ "custom-declare-variable.*foo.*wider than.*characters")
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-defalias.el"
+ "defalias.*foo.*wider than.*characters")
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-defconst.el"
+ "defconst.*foo.*wider than.*characters")
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-define-abbrev-table.el"
+ "define-abbrev.*foo.*wider than.*characters")
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-define-obsolete-function-alias.el"
+ "defalias.*foo.*wider than.*characters")
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-define-obsolete-variable-alias.el"
+ "defvaralias.*foo.*wider than.*characters")
+
+;; TODO: We don't yet issue warnings for defuns.
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-defun.el"
+ "wider than.*characters" 'reverse)
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-defvar.el"
+ "defvar.*foo.*wider than.*characters")
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-defvaralias.el"
+ "defvaralias.*foo.*wider than.*characters")
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-ignore-fill-column.el"
+ "defvar.*foo.*wider than.*characters" 'reverse)
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-ignore-override.el"
+ "defvar.*foo.*wider than.*characters" 'reverse)
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-ignore.el"
+ "defvar.*foo.*wider than.*characters" 'reverse)
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-multiline-first.el"
+ "defvar.*foo.*wider than.*characters")
+
+(bytecomp--define-warning-file-test
+ "warn-wide-docstring-multiline.el"
+ "defvar.*foo.*wider than.*characters")
+
 
 ;;;; Macro expansion.