patch 8.0.0283: mode() does not indicate Insert mode completion

Problem:    The return value of mode() does not indicate that completion is
            active in Replace and Insert mode. (Zhen-Huan (Kenny) Hu)
Solution:   Add "c" or "x" for two kinds of completion. (Yegappan Lakshmanan,
            closes #1397)  Test some more modes.
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 58a61f2..1b3f112 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -5848,9 +5848,13 @@
 			S	Select by line
 			CTRL-S	Select blockwise
 			i	Insert
+			ic	Insert mode completion |compl-generic|
+			ix	Insert mode |i_CTRL-X| completion
 			R	Replace |R|
+			Rc	Replace mode completion |compl-generic|
 			Rv	Virtual Replace |gR|
-			c	Command-line
+			Rx	Replace mode |i_CTRL-X| completion
+			c	Command-line editing
 			cv	Vim Ex mode |gQ|
 			ce	Normal Ex mode |Q|
 			r	Hit-enter prompt
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 7f433a5..5671cf0 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -7783,21 +7783,26 @@
 	}
 	else
 #endif
-	if (State & REPLACE_FLAG)
-	    buf[0] = 'R';
-	else
-	    buf[0] = 'i';
+	{
+	    if (State & REPLACE_FLAG)
+		buf[0] = 'R';
+	    else
+		buf[0] = 'i';
+#ifdef FEAT_INS_EXPAND
+	    if (ins_compl_active())
+		buf[1] = 'c';
+	    else if (ctrl_x_mode == 1)
+		buf[1] = 'x';
+#endif
+	}
     }
-    else if (State & CMDLINE)
+    else if ((State & CMDLINE) || exmode_active)
     {
 	buf[0] = 'c';
-	if (exmode_active)
+	if (exmode_active == EXMODE_VIM)
 	    buf[1] = 'v';
-    }
-    else if (exmode_active)
-    {
-	buf[0] = 'c';
-	buf[1] = 'e';
+	else if (exmode_active == EXMODE_NORMAL)
+	    buf[1] = 'e';
     }
     else
     {
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 38f7723..e2dcb4f 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -304,4 +304,89 @@
   call assert_equal("Ⱥ Ⱦ", toupper("ⱥ ⱦ"))
 endfunc
 
+" Tests for the mode() function
+let current_modes = ''
+func! Save_mode()
+  let g:current_modes = mode(0) . '-' . mode(1)
+  return ''
+endfunc
 
+func! Test_mode()
+  new
+  call append(0, ["Blue Ball Black", "Brown Band Bowl", ""])
+
+  inoremap <F2> <C-R>=Save_mode()<CR>
+
+  normal! 3G
+  exe "normal i\<F2>\<Esc>"
+  call assert_equal('i-i', g:current_modes)
+  exe "normal i\<C-G>uBa\<C-P>\<F2>\<Esc>u"
+  call assert_equal('i-ic', g:current_modes)
+  exe "normal iBro\<C-P>\<F2>\<Esc>u"
+  call assert_equal('i-ic', g:current_modes)
+  exe "normal iBa\<C-X>\<F2>\<Esc>u"
+  call assert_equal('i-ix', g:current_modes)
+  exe "normal iBa\<C-X>\<C-P>\<F2>\<Esc>u"
+  call assert_equal('i-ic', g:current_modes)
+  exe "normal iBro\<C-X>\<C-P>\<F2>\<Esc>u"
+  call assert_equal('i-ic', g:current_modes)
+  exe "normal iBro\<C-X>\<C-P>\<C-P>\<F2>\<Esc>u"
+  call assert_equal('i-ic', g:current_modes)
+  exe "normal iCom\<C-P>\<F2>\<Esc>u"
+  call assert_equal('i-ic', g:current_modes)
+  exe "normal iCom\<C-X>\<C-P>\<F2>\<Esc>u"
+  call assert_equal('i-ic', g:current_modes)
+
+  exe "normal RBa\<C-P>\<F2>\<Esc>u"
+  call assert_equal('R-Rc', g:current_modes)
+  exe "normal RBro\<C-P>\<F2>\<Esc>u"
+  call assert_equal('R-Rc', g:current_modes)
+  exe "normal RBa\<C-X>\<F2>\<Esc>u"
+  call assert_equal('R-Rx', g:current_modes)
+  exe "normal RBa\<C-X>\<C-P>\<F2>\<Esc>u"
+  call assert_equal('R-Rc', g:current_modes)
+  exe "normal RBro\<C-X>\<C-P>\<F2>\<Esc>u"
+  call assert_equal('R-Rc', g:current_modes)
+  exe "normal RBro\<C-X>\<C-P>\<C-P>\<F2>\<Esc>u"
+  call assert_equal('R-Rc', g:current_modes)
+  exe "normal RCom\<C-P>\<F2>\<Esc>u"
+  call assert_equal('R-Rc', g:current_modes)
+  exe "normal RCom\<C-X>\<C-P>\<F2>\<Esc>u"
+  call assert_equal('R-Rc', g:current_modes)
+
+  call assert_equal('n', mode(0))
+  call assert_equal('n', mode(1))
+
+  " How to test operator-pending mode?
+
+  call feedkeys("v", 'xt')
+  call assert_equal('v', mode())
+  call assert_equal('v', mode(1))
+  call feedkeys("\<Esc>V", 'xt')
+  call assert_equal('V', mode())
+  call assert_equal('V', mode(1))
+  call feedkeys("\<Esc>\<C-V>", 'xt')
+  call assert_equal("\<C-V>", mode())
+  call assert_equal("\<C-V>", mode(1))
+  call feedkeys("\<Esc>", 'xt')
+
+  call feedkeys("gh", 'xt')
+  call assert_equal('s', mode())
+  call assert_equal('s', mode(1))
+  call feedkeys("\<Esc>gH", 'xt')
+  call assert_equal('S', mode())
+  call assert_equal('S', mode(1))
+  call feedkeys("\<Esc>g\<C-H>", 'xt')
+  call assert_equal("\<C-S>", mode())
+  call assert_equal("\<C-S>", mode(1))
+  call feedkeys("\<Esc>", 'xt')
+
+  call feedkeys(":echo \<C-R>=Save_mode()\<C-U>\<CR>", 'xt')
+  call assert_equal('c-c', g:current_modes)
+  call feedkeys("gQecho \<C-R>=Save_mode()\<CR>\<CR>vi\<CR>", 'xt')
+  call assert_equal('c-cv', g:current_modes)
+  " How to test Ex mode?
+
+  bwipe!
+  iunmap <F2>
+endfunc
diff --git a/src/testdir/test_mapping.vim b/src/testdir/test_mapping.vim
index 306eb2f..fa8012a 100644
--- a/src/testdir/test_mapping.vim
+++ b/src/testdir/test_mapping.vim
@@ -110,6 +110,8 @@
   call feedkeys(":call append(line('$'), '+')\<CR>", "xt")
   call assert_equal('+', getline('$'))
 
+  iunmap a
+  iunmap c
   set nomodified
 endfunc
 
@@ -120,7 +122,7 @@
   $-1
   call feedkeys("0qqdw.ifoo\<Esc>qj0@q\<Esc>", "xt")
   call assert_equal(['fooc d', 'fooc d'], getline(line('$') - 1, line('$')))
-  unmap .
+  nunmap .
   set nomodified
 endfunc
 
diff --git a/src/version.c b/src/version.c
index daa911c..ef5ddae 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    283,
+/**/
     282,
 /**/
     281,