Avoid false positives about wide docstrings for key sequences

* lisp/emacs-lisp/bytecomp.el (byte-compile--wide-docstring-p):
Ignore literal key sequence substitutions.
* test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-ignore-substitutions.el:
New file.
* test/lisp/emacs-lisp/bytecomp-tests.el
("warn-wide-docstring-ignore-substitutions.el"): New test.

3 files changed, 27 insertions, 1 deletions

diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el
index 3338c383171..bd74c79d717 100644
--- a/lisp/emacs-lisp/bytecomp.el
+++ b/lisp/emacs-lisp/bytecomp.el
@@ -1674,7 +1674,12 @@ URLs."
     (replace-regexp-in-string
      (rx "\\" (or (seq "[" (* (not "]")) "]")))
      (make-string byte-compile--wide-docstring-substitution-len ?x)
-     docstring))))
+     ;; For literal key sequence substitutions (e.g. "\\`C-h'"), just
+     ;; remove the markup as `substitute-command-keys' would.
+     (replace-regexp-in-string
+      (rx "\\" (seq "`" (group (* (not "]"))) "'"))
+      "\\1"
+      docstring)))))
 
 (defcustom byte-compile-docstring-max-column 80
   "Recommended maximum width of doc string lines.
diff --git a/test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-ignore-substitutions.el b/test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-ignore-substitutions.el
new file mode 100644
index 00000000000..37cfe463bfe
--- /dev/null
+++ b/test/lisp/emacs-lisp/bytecomp-resources/warn-wide-docstring-ignore-substitutions.el
@@ -0,0 +1,17 @@
+;;; -*- lexical-binding: t -*-
+(defalias 'foo #'ignore
+  "None of this should be considered too wide.
+
+; this should be treated as 60 characters - no warning
+\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]\\[quit-window]
+
+; 64 * 'x' does not warn
+\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'\\`x'
+
+; keymaps are just ignored
+\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>\\<foo-bar-map>
+
+\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}\\{foo-bar-map}
+
+bar baz foo bar baz foo bar baz foo bar baz foo bar baz foo bar
+")
diff --git a/test/lisp/emacs-lisp/bytecomp-tests.el b/test/lisp/emacs-lisp/bytecomp-tests.el
index dbc0aa3db42..816f14a18d5 100644
--- a/test/lisp/emacs-lisp/bytecomp-tests.el
+++ b/test/lisp/emacs-lisp/bytecomp-tests.el
@@ -956,6 +956,10 @@ byte-compiled.  Run with dynamic binding."
  "defvar .foo-bar. docstring wider than .* characters" 'reverse)
 
 (bytecomp--define-warning-file-test
+ "warn-wide-docstring-ignore-substitutions.el"
+ "defvar .foo-bar. docstring wider than .* characters" 'reverse)
+
+(bytecomp--define-warning-file-test
  "warn-wide-docstring-ignore.el"
  "defvar .foo-bar. docstring wider than .* characters" 'reverse)