bug#51529: 27.1; keyword impure is not recognized for highlighting

[Bastiaan Braams]

I am using GNU Emacs 27.1, major mode F.90. The keyword 'impure'
(introduced in fortran 2008 and used in connection with 'elemental') is
not recognized for highlighting. To reproduce, type the line
> elemental impure subroutine foo ()
Keywords elemental and subroutine are highlighted, but impure is not.

In GNU Emacs 27.1 (build 1, x86_64-redhat-linux-gnu, GTK+ Version
3.24.21, cairo version 1.16.0)
of 2020-08-20 built on buildvm-x86-24.iad2.fedoraproject.org
Windowing system distributor 'Fedora Project', version 11.0.12011000
System Description: Fedora 32 (Thirty Two)

Recent messages:
Wrote /ufs/braams/DoubleMC/Tests.f90
Saving file /ufs/braams/DoubleMC/Tests.f90...
Wrote /ufs/braams/DoubleMC/Tests.f90
Saving file /ufs/braams/DoubleMC/Tests.f90...
Wrote /ufs/braams/DoubleMC/Tests.f90
Saving file /ufs/braams/DoubleMC/Tests.f90...
Wrote /ufs/braams/DoubleMC/Tests.f90
Making completion list...
Quit [2 times]
Making completion list...

Configured using:
'configure --build=x86_64-redhat-linux-gnu
--host=x86_64-redhat-linux-gnu --program-prefix=
--disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
--bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
--datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
--libexecdir=/usr/libexec --localstatedir=/var
--sharedstatedir=/var/lib --mandir=/usr/share/man
--infodir=/usr/share/info --with-dbus --with-gif --with-jpeg --with-png
--with-rsvg --with-tiff --with-xft --with-xpm --with-x-toolkit=gtk3
--with-gpm=no --with-xwidgets --with-modules --with-harfbuzz
--with-cairo --with-json build_alias=x86_64-redhat-linux-gnu
host_alias=x86_64-redhat-linux-gnu 'CFLAGS=-DMAIL_USE_LOCKF -O2 -g
-pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2
-Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong
-grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1
-specs=/usr/lib/rpm/redhat/redhat-annobin-cc1 -m64 -mtune=generic
-fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection'
LDFLAGS=-Wl,-z,relro
PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'

Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND DBUS GSETTINGS GLIB NOTIFY
INOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF
ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS XWIDGETS
LIBSYSTEMD JSON PDUMPER GMP

Important settings:
value of $LANG: en_US.UTF-8
value of $XMODIFIERS: @im=ibus
locale-coding-system: utf-8-unix

Major mode: F90

Minor modes in effect:
shell-dirtrack-mode: t
tooltip-mode: t
global-eldoc-mode: t
electric-indent-mode: t
mouse-wheel-mode: t
tool-bar-mode: t
menu-bar-mode: t
file-name-shadow-mode: t
global-font-lock-mode: t
font-lock-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
line-number-mode: t
transient-mark-mode: t

Load-path shadows:
/usr/share/emacs/site-lisp/goodies/emacs-goodies-loaddefs hides
/usr/share/emacs/site-lisp/site-start.d/emacs-goodies-loaddefs
/usr/share/emacs/site-lisp/site-start.d/slime hides
/usr/share/emacs/site-lisp/slime/slime
/usr/share/emacs/site-lisp/site-start.d/slime-tests hides
/usr/share/emacs/site-lisp/slime/slime-tests
/usr/share/emacs/site-lisp/site-start.d/slime-autoloads hides
/usr/share/emacs/site-lisp/slime/slime-autoloads
/usr/share/emacs/site-lisp/vm/tapestry hides
/usr/share/emacs/site-lisp/emacspeak/lisp/tapestry
/usr/share/emacs/site-lisp/ddskk/ccc hides
/usr/share/emacs/site-lisp/proofgeneral/ccc/ccc
/usr/share/emacs/site-lisp/emacspeak/sounds/3d/define-theme hides
/usr/share/emacs/site-lisp/emacspeak/sounds/classic/define-theme
/usr/share/emacs/site-lisp/emacspeak/sounds/3d/define-theme hides
/usr/share/emacs/site-lisp/emacspeak/sounds/pan-chimes/define-theme
/usr/share/emacs/site-lisp/emacspeak/lisp/dom hides
/usr/share/emacs/27.1/lisp/dom
/usr/share/emacs/site-lisp/rinari/util/jump/which-func hides
/usr/share/emacs/27.1/lisp/progmodes/which-func
/usr/share/emacs/site-lisp/rinari/util/ruby-mode hides
/usr/share/emacs/27.1/lisp/progmodes/ruby-mode
/usr/share/emacs/site-lisp/emacspeak/lisp/subr-x hides
/usr/share/emacs/27.1/lisp/emacs-lisp/subr-x
/usr/share/emacs/27.1/lisp/emacs-lisp/cl-lib hides
/usr/share/emacs/site-lisp/slime/lib/cl-lib
/usr/share/emacs/27.1/lisp/emacs-lisp/ert hides
/usr/share/emacs/site-lisp/slime/lib/ert
/usr/share/emacs/27.1/lisp/emacs-lisp/ert-x hides
/usr/share/emacs/site-lisp/slime/lib/ert-x

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec password-cache epa epg epg-config gnus-util rmail
rmail-loaddefs text-property-search mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils time-date f90 cus-edit
cus-start cus-load ccc u-vm-color vm-autoloads vm-version vm-vars
slime-tests mule-util ert ewoc debug backtrace find-func slime cl-extra
help-mode edmacro kmacro lisp-mnt gud apropos etags fileloop generator
arc-mode archive-mode pp hyperspec slime-autoloads preview-latex
proof-site proof-autoloads pg-vars haskell-mode-autoloads ess-site
ess-toolbar ess-mouse mouseme browse-url ess-swv ess-noweb
ess-noweb-font-lock-mode ess-jags-d ess-bugs-l essd-els ess-xls-d
ess-vst-d ess-stata-mode ess-stata-lang make-regexp ess-sp6w-d ess-sp5-d
ess-sp4-d ess-sas-d ess-sas-l ess-sas-a ess-s4-d ess-s3-d ess-omg-d
ess-omg-l ess-arc-d ess-lsp-l ess-sp6-d ess-dde ess-sp3-d ess-julia
julia-mode ess-r-mode ess-r-flymake flymake-proc flymake warnings
thingatpt ess-r-xref xref cl-seq project eieio eieio-core eieio-loaddefs
ess-trns ess-r-package shell ess-r-syntax ess-r-completion ess-roxy
ess-rd essddr noutline outline easy-mmode hideshow ess-s-lang ess-help
ess-mode ess ess-noweb-mode ess-inf ess-tracebug format-spec
ess-generics ess-utils ido ess-custom executable erlang-start epix
derived info-look info cc-mode cc-fonts cc-guess cc-menus cc-cmds
cc-styles cc-align cc-engine cc-vars cc-defs rinari jump inflections
findr ruby-compilation which-func imenu pcomplete inf-ruby compile
comint ansi-color ring ruby-mode 50magit emacs-goodies-loaddefs
color-theme easymenu wid-edit skk-leim clang-rename clang-include-fixer
let-alist json subr-x pcase map seq byte-opt bytecomp byte-compile cconv
clang-format cl-macs xml cl gv cl-loaddefs cl-lib bbdb-loaddefs
auto-loads tex-site advice skk-setup skk-autoloads tooltip eldoc
electric uniquify ediff-hook vc-hooks lisp-float-type mwheel term/x-win
x-win term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame minibuffer cl-generic cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms
cp51932 hebrew greek romanian slovak czech european ethiopic indian
cyrillic chinese composite charscript charprop case-table epa-hook
jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote threads dbusbind inotify dynamic-setting system-font-setting
font-render-setting xwidget-internal cairo move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 246856 15883)
(symbols 48 24472 1)
(strings 32 74309 3811)
(string-bytes 1 2312267)
(vectors 16 28370)
(vector-slots 8 363328 8690)
(floats 8 107 23)
(intervals 56 451 0)
(buffers 1000 16))