Author:

* lisp/files.el (hack-local-variables--find-variables): Use the
final mode: line (which is the same as having several mode: bits
in the header line.

* etc/NEWS (mode): Fall back on outline-mode in older Emacsen.
* lisp/files.el (hack-local-variables--find-variables): Use the
final mode: line (which is the same as having several mode: bits
in the header line.

* lisp/files.el (hack-local-variables): Fix regression in setting
the major mode when there are mode: cookies in the file (bug#54993).

* doc/emacs/dired.texi (Misc Dired Features): Document it (bug#23812).
* lisp/dired.el (dired-free-space): New user option.
(dired-insert-directory): Use it from here.
(dired--insert-disk-space): New function that uses the user option.

* lisp/files.el (insert-directory): Don't transform "total" here.
* lisp/ls-lisp.el (ls-lisp--insert-directory): Or here.  Instead
just leave the "total <num>" bit alone, and let Dired transform it.

* test/lisp/files-tests.el (files-tests): Move "available" tests
to dired-tests.
* test/lisp/dired-tests.el (data-dir): Moved here.

* test/lisp/files-tests.el: Add 'insert-directory' tests.
* test/lisp/files-resources/insert-directory/: Create directories and files to
use for testing 'insert-directory'.

Add tests for 'insert-directory' base functionality and regression tests for
the issue where free space was reported for the current directory instead of
the target of 'list-directory' (Bug#50630).

* lisp/files.el (set-auto-mode--dir-local-valid-p): New function.
(set-auto-mode--apply-alist): Use it as a stricter test.

* doc/emacs/custom.texi (Directory Variables): Document
auto-mode-alist in .dir-locals.el (Bug#18721)
* doc/emacs/modes.texi (Choosing Modes): Update.
* lisp/files.el (set-auto-mode--apply-alist): New function,
from set-auto-mode.
(set-auto-mode): Check directory locals for auto-mode-alist.
(dir-locals-collect-variables): Add "predicate" parameter.
(hack-dir-local--get-variables): New function, from
hack-dir-local-variables.
(hack-dir-local-variables): Call hack-dir-local--get-variables.
* test/lisp/files-resources/.dir-locals.el: New file.
* test/lisp/files-resources/whatever.quux: New file.
* test/lisp/files-tests.el (files-tests-data-dir): New variable.
(files-test-dir-locals-auto-mode-alist): New test.

* test/data/emacs-module/mod-test.c: Move from here...
* test/src/emacs-module-resources/mod-test.c: ...to here.
* test/src/emacs-module-tests.el (ert-x): Require.
(mod-test-file, module/describe-function-1):
* test/Makefile.in (test_module_dir): Adjust for move.

* test/data/files-bug18141.el.gz: Move from here...
* test/lisp/files-resources/files-bug18141.el.gz: ... to here.
* test/lisp/files-tests.el (ert-x): Require.
(files-test-bug-18141-file): Use ert-resource-file.

* test/data/mailcap/mime.types: Move from here...
* test/lisp/net/mailcap-resources/mime.types: ...to here.
* test/lisp/net/mailcap-tests.el (ert-x): Require.
(mailcap-tests-path): Use ert-resource-file.

* test/data/somelib.el:
* test/data/somelib2.el: Move from here...
* test/src/lread-resources/somelib.el:
* test/src/lread-resources/somelib2.el: ...to here.
* test/src/lread-tests.el (ert, ert-x): Require.
(lread-test-bug26837): Use ert-resource-directory.

* test/data/syntax-comments.txt: Move from here....
* test/src/syntax-resources/syntax-comments.txt: ...to here.
* test/src/syntax-tests.el (ert-x): Require.
(syntax-comments, syntax-br-comments, syntax-pps-comments):
Use ert-resource-file.

* test/data/xref/file1.txt:
* test/data/xref/file2.txt: Move from here...
* test/lisp/progmodes/xref-resources/file1.txt:
* test/lisp/progmodes/xref-resources/file2.txt: ...to here.
* test/lisp/progmodes/xref-tests.el (ert, ert-x): Require.
(xref-tests-data-dir): Use ert-resource-directory.