Package: cc-mode

Hi Alan,
Thanks for all your recent work on CC mode.
It isn't much fun to use, currently, on master. For example, from "emacs
-Q":

Add this text to a buffer in C or C++ mode (<<END):
int main ()
{
}
END

Add a double quote, inside main() or before it. (The double quote is
highlighted as an error. IIUC this is as expected now.)
Add another double quote. (Actual: both quotes and what comes after are
highlighted as a string. Expected: just the quotes are highlighted as a
string.)
Add a semicolon. (Actual: the semicolon is not highlighted but everything
after it is still highlighted as a string. Expected: just the quotes.)

Emacs  : GNU Emacs 27.0.50 (build 2, x86_64-w64-mingw32)
 of 2019-06-26
Package: CC Mode 5.34 (C++//l)
Buffer Style: gnu
c-emacs-features: (pps-extended-state col-0-paren posix-char-classes
gen-string-delim gen-comment-delim syntax-properties 1-bit)

current state:
==============
(setq
 c-basic-offset 2
 c-comment-only-line-offset '(0 . 0)
 c-indent-comment-alist '((anchored-comment column . 0) (end-block space .
1)
 (cpp-end-block space . 2))
 c-indent-comments-syntactically-p nil
 c-block-comment-prefix ""
 c-comment-prefix-regexp '((pike-mode . "//+!?\\|\\**") (awk-mode . "#+")
  (other . "//+\\|\\**"))
 c-doc-comment-style '((java-mode . javadoc) (pike-mode . autodoc)
      (c-mode . gtkdoc))
 c-cleanup-list '(scope-operator)
 c-hanging-braces-alist '((substatement-open before after)
 (arglist-cont-nonempty))
 c-hanging-colons-alist nil
 c-hanging-semi&comma-criteria '(c-semi&comma-inside-parenlist)
 c-backslash-column 48
 c-backslash-max-column 72
 c-special-indent-hook '(c-gnu-impose-minimum)
 c-label-minimum-indentation 1
 c-offsets-alist '((inexpr-class . +)
  (inexpr-statement . +)
  (lambda-intro-cont . +)
  (inlambda . 0)
  (template-args-cont c-lineup-template-args +)
  (incomposition . +)
  (inmodule . +)
  (innamespace . +)
  (inextern-lang . +)
  (composition-close . 0)
  (module-close . 0)
  (namespace-close . 0)
  (extern-lang-close . 0)
  (composition-open . 0)
  (module-open . 0)
  (namespace-open . 0)
  (extern-lang-open . 0)
  (objc-method-call-cont
   c-lineup-ObjC-method-call-colons
   c-lineup-ObjC-method-call
   +
   )
  (objc-method-args-cont . c-lineup-ObjC-method-args)
  (objc-method-intro . [0])
  (friend . 0)
  (cpp-define-intro c-lineup-cpp-define +)
  (cpp-macro-cont . +)
  (cpp-macro . [0])
  (inclass . +)
  (stream-op . c-lineup-streamop)
  (arglist-cont-nonempty
   c-lineup-gcc-asm-reg
   c-lineup-arglist
   )
  (arglist-cont c-lineup-gcc-asm-reg 0)
  (comment-intro
   c-lineup-knr-region-comment
   c-lineup-comment
   )
  (catch-clause . 0)
  (else-clause . 0)
  (do-while-closure . 0)
  (access-label . -)
  (case-label . 0)
  (substatement . +)
  (statement-case-intro . +)
  (statement . 0)
  (brace-entry-open . 0)
  (brace-list-entry . 0)
  (brace-list-close . 0)
  (block-close . 0)
  (block-open . 0)
  (inher-cont . c-lineup-multi-inher)
  (inher-intro . +)
  (member-init-cont . c-lineup-multi-inher)
  (member-init-intro . +)
  (annotation-var-cont . +)
  (annotation-top-cont . 0)
  (topmost-intro . 0)
  (knr-argdecl . 0)
  (func-decl-cont . +)
  (inline-close . 0)
  (class-close . 0)
  (class-open . 0)
  (defun-block-intro . +)
  (defun-close . 0)
  (defun-open . 0)
  (c . c-lineup-C-comments)
  (string . c-lineup-dont-change)
  (topmost-intro-cont
   first
   c-lineup-topmost-intro-cont
   c-lineup-gnu-DEFUN-intro-cont
   )
  (brace-list-intro
   first
   c-lineup-2nd-brace-entry-in-arglist
   c-lineup-class-decl-init-+
   +
   )
  (brace-list-open . +)
  (inline-open . 0)
  (arglist-close . c-lineup-arglist)
  (arglist-intro . c-lineup-arglist-intro-after-paren)
  (statement-cont . +)
  (statement-case-open . +)
  (label . 0)
  (substatement-label . 0)
  (substatement-open . +)
  (knr-argdecl-intro . 5)
  (statement-block-intro . +)
  )
 c-buffer-is-cc-mode 'c++-mode
 c-tab-always-indent t
 c-syntactic-indentation t
 c-syntactic-indentation-in-macros t
 c-ignore-auto-fill '(string cpp code)
 c-auto-align-backslashes t
 c-backspace-function 'backward-delete-char-untabify
 c-delete-function 'delete-char
 c-electric-pound-behavior nil
 c-default-style '((java-mode . "java") (awk-mode . "awk") (other . "gnu"))
 c-enable-xemacs-performance-kludge-p nil
 c-old-style-variable-behavior nil
 defun-prompt-regexp nil
 tab-width 8
 comment-column 32
 parse-sexp-ignore-comments t
 parse-sexp-lookup-properties t
 auto-fill-function nil
 comment-multi-line t
 comment-start-skip "\\(//+\\|/\\*+\\)\\s *"
 fill-prefix nil
 fill-column 70
 paragraph-start "[ ]*\\(//+\\|\\**\\)[ ]*$\\|^\f"
 adaptive-fill-mode t
 adaptive-fill-regexp "[ ]*\\(//+\\|\\**\\)[ ]*\\([ ]*\\([-–!|#%;>*·•‣⁃◦]+[
]*\\)*\\)"
 )