Merge remote-tracking branch 'upstream/master'

16 files changed, 266 insertions, 151 deletions

diff --git a/README.md b/README.md
index 0442ee61de..4016c9b3c2 100644
--- a/README.md
+++ b/README.md
@@ -48,17 +48,24 @@ and [more](https://github.com/neovim/neovim/wiki/Installing-Neovim)!
 Project layout
 --------------
 
-    ├─ ci/            Build server scripts
-    ├─ cmake/         Build scripts
-    ├─ runtime/       User plugins/docs
-    ├─ src/           Source code
-    ├─ third-party/   CMake subproject to build dependencies 
-    └─ test/          Test code
-
-- `third-party/` is activated if `USE_BUNDLED_DEPS` is undefined or the
-  `USE_BUNDLED` CMake option is true.
-- [Source README](src/nvim/README.md)
-- [Test README](test/README.md)
+    ├─ ci/              build automation
+    ├─ cmake/           build scripts
+    ├─ runtime/         user plugins/docs
+    ├─ src/             application source code (see src/nvim/README.md)
+    │  ├─ api/          API subsystem
+    │  ├─ eval/         VimL subsystem
+    │  ├─ event/        event-loop subsystem
+    │  ├─ generators/   code generation (pre-compilation)
+    │  ├─ lib/          generic data structures
+    │  ├─ lua/          lua subsystem
+    │  ├─ msgpack_rpc/  RPC subsystem
+    │  ├─ os/           low-level platform code
+    │  └─ tui/          built-in UI
+    ├─ third-party/     cmake subproject to build dependencies
+    └─ test/            tests (see test/README.md)
+
+- To disable `third-party/` specify `USE_BUNDLED_DEPS=NO` or `USE_BUNDLED=NO`
+  (CMake option).
 
 Features
 --------
diff --git a/runtime/autoload/health.vim b/runtime/autoload/health.vim
index f875c8b797..bd99a0e104 100644
--- a/runtime/autoload/health.vim
+++ b/runtime/autoload/health.vim
@@ -90,7 +90,7 @@ endfunction
 
 " Changes ':h clipboard' to ':help |clipboard|'.
 function! s:help_to_link(s) abort
-  return substitute(a:s, '\v:h%[elp] ([^|][^"\r\n]+)', ':help |\1|', 'g')
+  return substitute(a:s, '\v:h%[elp] ([^|][^"\r\n ]+)', ':help |\1|', 'g')
 endfunction
 
 " Format a message for a specific report item
diff --git a/runtime/autoload/health/provider.vim b/runtime/autoload/health/provider.vim
index ec20615f69..26db5b77b7 100644
--- a/runtime/autoload/health/provider.vim
+++ b/runtime/autoload/health/provider.vim
@@ -121,14 +121,14 @@ function! s:check_clipboard() abort
   call health#report_start('Clipboard (optional)')
 
   let clipboard_tool = provider#clipboard#Executable()
-  if empty(clipboard_tool)
+  if exists('g:clipboard') && empty(clipboard_tool)
+    call health#report_error(
+          \ provider#clipboard#Error(),
+          \ ["Use the example in :help g:clipboard as a template, or don't set g:clipboard at all."])
+  elseif empty(clipboard_tool)
     call health#report_warn(
-          \ 'No clipboard tool found. Clipboard registers will not work.',
+          \ 'No clipboard tool found. Clipboard registers (`"+` and `"*`) will not work.',
           \ [':help clipboard'])
-  elseif exists('g:clipboard') && (type({}) != type(g:clipboard)
-        \ || !has_key(g:clipboard, 'copy') || !has_key(g:clipboard, 'paste'))
-    call health#report_error(
-          \ 'g:clipboard exists but is malformed. It must be a dictionary with the keys documented at :help g:clipboard')
   else
     call health#report_ok('Clipboard tool found: '. clipboard_tool)
   endif
diff --git a/runtime/autoload/provider.vim b/runtime/autoload/provider.vim
index a4d5241b57..b46ae12b3c 100644
--- a/runtime/autoload/provider.vim
+++ b/runtime/autoload/provider.vim
@@ -10,7 +10,7 @@ function! provider#stderr_collector(chan_id, data, event) dict
 endfunction
 
 function! provider#clear_stderr(chan_id)
-   silent! call delete(s:stderr, a:chan_id)
+   silent! call remove(s:stderr, a:chan_id)
 endfunction
 
 function! provider#get_stderr(chan_id)
diff --git a/runtime/autoload/provider/clipboard.vim b/runtime/autoload/provider/clipboard.vim
index 8eb694e9fa..8fe53c495a 100644
--- a/runtime/autoload/provider/clipboard.vim
+++ b/runtime/autoload/provider/clipboard.vim
@@ -3,6 +3,7 @@
 " available.
 let s:copy = {}
 let s:paste = {}
+let s:clipboard = {}
 
 " When caching is enabled, store the jobid of the xclip/xsel process keeping
 " ownership of the selection, so we know how long the cache is valid.
@@ -23,7 +24,7 @@ function! s:selection.on_exit(jobid, data, event) abort
   call provider#clear_stderr(a:jobid)
 endfunction
 
-let s:selections = { '*': s:selection, '+': copy(s:selection)}
+let s:selections = { '*': s:selection, '+': copy(s:selection) }
 
 function! s:try_cmd(cmd, ...) abort
   let argv = split(a:cmd, " ")
@@ -55,9 +56,15 @@ endfunction
 
 function! provider#clipboard#Executable() abort
   if exists('g:clipboard')
+    if type({}) isnot# type(g:clipboard)
+          \ || type({}) isnot# type(get(g:clipboard, 'copy', v:null))
+          \ || type({}) isnot# type(get(g:clipboard, 'paste', v:null))
+      let s:err = 'clipboard: invalid g:clipboard'
+      return ''
+    endif
     let s:copy = get(g:clipboard, 'copy', { '+': v:null, '*': v:null })
     let s:paste = get(g:clipboard, 'paste', { '+': v:null, '*': v:null })
-    let s:cache_enabled = get(g:clipboard, 'cache_enabled', 1)
+    let s:cache_enabled = get(g:clipboard, 'cache_enabled', 0)
     return get(g:clipboard, 'name', 'g:clipboard')
   elseif has('mac') && executable('pbcopy')
     let s:copy['+'] = 'pbcopy'
@@ -104,16 +111,17 @@ function! provider#clipboard#Executable() abort
     return 'tmux'
   endif
 
-  let s:err = 'clipboard: No clipboard tool available. :help clipboard'
+  let s:err = 'clipboard: No clipboard tool. :help clipboard'
   return ''
 endfunction
 
 if empty(provider#clipboard#Executable())
+  " provider#clipboard#Call() *must not* be defined if the provider is broken.
+  " Otherwise eval_has_provider() thinks the clipboard provider is
+  " functioning, and eval_call_provider() will happily call it.
   finish
 endif
 
-let s:clipboard = {}
-
 function! s:clipboard.get(reg) abort
   if s:selections[a:reg].owner > 0
     return s:selections[a:reg].data
@@ -154,7 +162,9 @@ function! s:clipboard.set(lines, regtype, reg) abort
     echohl WarningMsg
     echomsg 'clipboard: failed to execute: '.(s:copy[a:reg])
     echohl None
+    return 0
   endif
+  return 1
 endfunction
 
 function! provider#clipboard#Call(method, args) abort
diff --git a/runtime/doc/api.txt b/runtime/doc/api.txt
index 7c6b8a3c1a..e12cd1cfa9 100644
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@@ -171,8 +171,8 @@ nvim_replace_termcodes({str}, {from_part}, {do_lt}, {special})
                 Parameters:~
                     {str}        String to be converted.
                     {from_part}  Legacy Vim parameter. Usually true.
-                    {do_lt}      Also translate <lt>. Does nothing if
-                                 `special` is false.
+                    {do_lt}      Also translate <lt>. Ignored if `special` is
+                                 false.
                     {special}    Replace |keycodes|, e.g. <CR> becomes a "\n"
                                  char.
 
@@ -309,20 +309,24 @@ nvim_set_option({name}, {value})                           *nvim_set_option()*
                     {value}  New option value
 
 nvim_out_write({str})                                       *nvim_out_write()*
-                Writes a message to vim output buffer
+                Writes a message to the Vim output buffer. Does not append
+                "\n", the message is buffered (won't display) until a linefeed
+                is written.
 
                 Parameters:~
                     {str}  Message
 
 nvim_err_write({str})                                       *nvim_err_write()*
-                Writes a message to vim error buffer
+                Writes a message to the Vim error buffer. Does not append
+                "\n", the message is buffered (won't display) until a linefeed
+                is written.
 
                 Parameters:~
                     {str}  Message
 
 nvim_err_writeln({str})                                   *nvim_err_writeln()*
-                Writes a message to vim error buffer. Appends a linefeed to
-                ensure all contents are written.
+                Writes a message to the Vim error buffer. Appends "\n", so the
+                buffer is flushed (and displayed).
 
                 Parameters:~
                     {str}  Message
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 29e254b0b3..b37b0e8836 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -1522,14 +1522,16 @@ v:errors	Errors found by assert functions, such as |assert_true()|.
 
 					*v:event* *event-variable*
 v:event		Dictionary of event data for the current |autocommand|.  Valid
-		only during the autocommand lifetime: storing or passing
-		`v:event` is invalid.  Copy it instead: >
+		only during the event lifetime; storing or passing v:event is
+		invalid!  Copy it instead: >
 			au TextYankPost * let g:foo = deepcopy(v:event)
 <		Keys vary by event; see the documentation for the specific
-		event, e.g. |TextYankPost|.
+		event, e.g. |DirChanged| or |TextYankPost|.
 			KEY		DESCRIPTION ~
-			operator	The current |operator|.  Also set for
-					Ex commands (unlike |v:operator|). For
+			cwd		Current working directory
+			scope		Event-specific scope name.
+			operator	Current |operator|.  Also set for Ex
+					commands (unlike |v:operator|). For
 					example if |TextYankPost| is triggered
 					by the |:yank| Ex command then
 					`v:event['operator']` is "y".
@@ -4726,7 +4728,8 @@ input({opts})
 		"-complete=" argument.	Refer to |:command-completion| for
 		more information.  Example: >
 			let fname = input("File: ", "", "file")
-<							*E5400* *E5402*
+
+<					*input()-highlight* *E5400* *E5402*
 		The optional `highlight` key allows specifying function which
 		will be used for highlighting user input.  This function
 		receives user input as its only argument and must return
@@ -4744,6 +4747,30 @@ input({opts})
 		sections must be ordered so that next hl_start_col is greater
 		then or equal to previous hl_end_col.
 
+		Example (try some input with parentheses): >
+			highlight RBP1 guibg=Red ctermbg=red
+			highlight RBP2 guibg=Yellow ctermbg=yellow
+			highlight RBP3 guibg=Green ctermbg=green
+			highlight RBP4 guibg=Blue ctermbg=blue
+			let g:rainbow_levels = 4
+			function! RainbowParens(cmdline)
+			  let ret = []
+			  let i = 0
+			  let lvl = 0
+			  while i < len(a:cmdline)
+			    if a:cmdline[i] is# '('
+			      call add(ret, [i, i + 1, 'RBP' . ((lvl % g:rainbow_levels) + 1)])
+			      let lvl += 1
+			    elseif a:cmdline[i] is# ')'
+			      let lvl -= 1
+			      call add(ret, [i, i + 1, 'RBP' . ((lvl % g:rainbow_levels) + 1)])
+			    endif
+			    let i += 1
+			  endwhile
+			  return ret
+			endfunction
+			call input({'prompt':'>','highlight':'RainbowParens'})
+<
 		Highlight function is called at least once for each new
 		displayed input string, before command-line is redrawn.  It is
 		expected that function is pure for the duration of one input()
diff --git a/runtime/doc/vim_diff.txt b/runtime/doc/vim_diff.txt
index 2f031c0b1f..eb3c4d50ce 100644
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@@ -6,9 +6,8 @@
 
 Differences between Nvim and Vim			       *vim-differences*
 
-Throughout the help files, differences between Nvim and Vim are indicated via
-the "{Nvim}" tag.  This document is a complete and centralized list of all
-these differences.
+Nvim differs from Vim in many ways, big and small.  This document is
+a complete and centralized reference of those differences.
 
 				      Type <M-]> to see the table of contents.
 
@@ -72,12 +71,18 @@ Clipboard integration		|provider-clipboard|
 
 USER EXPERIENCE  ~
 
-Working intuitively and consistently is a major goal of Nvim. Examples:
+Working intuitively and consistently is a major goal of Nvim.
 
-- Nvim does not have `-X`, a platform-specific option "sometimes" available in
-  Vim (with potential surprises: http://stackoverflow.com/q/14635295). Nvim
-  avoids features that cannot be provided on all platforms--instead that is
-  delegated to external plugins/extensions.
+							*feature-compile*
+- Nvim always includes ALL features, in contrast to Vim (which ships with
+  various combinations of 100+ optional features). Think of it as a leaner
+  version of Vim's "HUGE" build. This reduces surface area for bugs, and
+  removes a common source of confusion and friction for users.
+
+- Nvim avoids features that cannot be provided on all platforms; instead that
+  is delegated to external plugins/extensions. E.g. the `-X` platform-specific
+  option is "sometimes" available in Vim (with potential surprises:
+  http://stackoverflow.com/q/14635295).
 
 - Vim's internal test functions (test_autochdir(), test_settime(), etc.) are
   not exposed (nor implemented); instead Nvim has a robust API.
@@ -268,13 +273,12 @@ Lua interface (|if_lua.txt|):
 - Lua has direct access to Nvim |API| via `vim.api`.
 - Lua package.path and package.cpath are automatically updated according to
   'runtimepath': |lua-require|.
-- Currently, most legacy Vim features are missing.
 
-|input()| and |inputdialog()| gained support for each other’s features (return 
-on cancel and completion respectively) via dictionary argument (replaces all 
+|input()| and |inputdialog()| support for each other’s features (return on
+cancel and completion respectively) via dictionary argument (replaces all
 other arguments if used).
 
-|input()| and |inputdialog()| now support user-defined cmdline highlighting.
+|input()| and |inputdialog()| support user-defined cmdline highlighting.
 
 ==============================================================================
 5. Missing legacy features				 *nvim-features-missing*
@@ -282,7 +286,7 @@ other arguments if used).
 Some legacy Vim features are not implemented:
 
 - |if_py|: vim.bindeval() and vim.Function() are not supported
-- |if_lua|: the `vim` object currently only supports `vim.api`
+- |if_lua|: the `vim` object is missing most legacy methods
 - *if_perl*
 - *if_mzscheme*
 - *if_tcl*
@@ -290,7 +294,7 @@ Some legacy Vim features are not implemented:
 ==============================================================================
 6. Removed features					 *nvim-features-removed*
 
-These features are in Vim, but have been intentionally removed from Nvim.
+These Vim features were intentionally removed from Nvim.
 
 			*'cp'* *'nocompatible'* *'nocp'* *'compatible'*
 Nvim is always "non-compatible" with Vi.
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index 2bc31b2812..cfbe34b848 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -484,7 +484,8 @@ void nvim_set_option(String name, Object value, Error *err)
   set_option_to(NULL, SREQ_GLOBAL, name, value, err);
 }
 
-/// Writes a message to vim output buffer
+/// Writes a message to the Vim output buffer. Does not append "\n", the
+/// message is buffered (won't display) until a linefeed is written.
 ///
 /// @param str Message
 void nvim_out_write(String str)
@@ -493,7 +494,8 @@ void nvim_out_write(String str)
   write_msg(str, false);
 }
 
-/// Writes a message to vim error buffer
+/// Writes a message to the Vim error buffer. Does not append "\n", the
+/// message is buffered (won't display) until a linefeed is written.
 ///
 /// @param str Message
 void nvim_err_write(String str)
@@ -502,8 +504,8 @@ void nvim_err_write(String str)
   write_msg(str, true);
 }
 
-/// Writes a message to vim error buffer. Appends a linefeed to ensure all
-/// contents are written.
+/// Writes a message to the Vim error buffer. Appends "\n", so the buffer is
+/// flushed (and displayed).
 ///
 /// @param str Message
 /// @see nvim_err_write()
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index ac22d75a83..d6ee13857a 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -22775,7 +22775,7 @@ typval_T eval_call_provider(char *provider, char *method, list_T *arguments)
 
 bool eval_has_provider(const char *name)
 {
-#define check_provider(name) \
+#define CHECK_PROVIDER(name) \
   if (has_##name == -1) { \
     has_##name = !!find_func((char_u *)"provider#" #name "#Call"); \
     if (!has_##name) { \
@@ -22791,17 +22791,17 @@ bool eval_has_provider(const char *name)
   static int has_python3 = -1;
   static int has_ruby = -1;
 
-  if (!strcmp(name, "clipboard")) {
-    check_provider(clipboard);
+  if (strequal(name, "clipboard")) {
+    CHECK_PROVIDER(clipboard);
     return has_clipboard;
-  } else if (!strcmp(name, "python3")) {
-    check_provider(python3);
+  } else if (strequal(name, "python3")) {
+    CHECK_PROVIDER(python3);
     return has_python3;
-  } else if (!strcmp(name, "python")) {
-    check_provider(python);
+  } else if (strequal(name, "python")) {
+    CHECK_PROVIDER(python);
     return has_python;
-  } else if (!strcmp(name, "ruby")) {
-    check_provider(ruby);
+  } else if (strequal(name, "ruby")) {
+    CHECK_PROVIDER(ruby);
     return has_ruby;
   }
 
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 3f828d7be9..a665ad1de2 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -1878,54 +1878,47 @@ static void usage(void)
   signal_stop();              // kill us with CTRL-C here, if you like
 
   mch_msg(_("Usage:\n"));
-  mch_msg(_("  nvim [arguments] [file ...]      Edit specified file(s)\n"));
-  mch_msg(_("  nvim [arguments] -               Read text from stdin\n"));
-  mch_msg(_("  nvim [arguments] -t <tag>        Edit file where tag is defined\n"));
-  mch_msg(_("  nvim [arguments] -q [errorfile]  Edit file with first error\n"));
-  mch_msg(_("\nArguments:\n"));
+  mch_msg(_("  nvim [options] [file ...]      Edit file(s)\n"));
+  mch_msg(_("  nvim [options] -               Read text from stdin\n"));
+  mch_msg(_("  nvim [options] -t <tag>        Edit file where tag is defined\n"));
+  mch_msg(_("  nvim [options] -q [errorfile]  Edit file with first error\n"));
+  mch_msg(_("\nOptions:\n"));
   mch_msg(_("  --                    Only file names after this\n"));
-#if !defined(UNIX)
-  mch_msg(_("  --literal             Don't expand wildcards\n"));
-#endif
-  mch_msg(_("  -e                    Ex mode\n"));
-  mch_msg(_("  -E                    Improved Ex mode\n"));
-  mch_msg(_("  -s                    Silent (batch) mode (only for ex mode)\n"));
+  mch_msg(_("  +                     Start at end of file\n"));
+  mch_msg(_("  --cmd <cmd>           Execute <cmd> before any config\n"));
+  mch_msg(_("  +<cmd>, -c <cmd>      Execute <cmd> after config and first file\n"));
+  mch_msg("\n");
+  mch_msg(_("  -b                    Binary mode\n"));
   mch_msg(_("  -d                    Diff mode\n"));
-  mch_msg(_("  -R                    Read-only mode\n"));
-  mch_msg(_("  -Z                    Restricted mode\n"));
+  mch_msg(_("  -e, -E                Ex mode, Improved Ex mode\n"));
+  mch_msg(_("  -es                   Silent (batch) mode\n"));
+  mch_msg(_("  -h, --help            Print this help message\n"));
+  mch_msg(_("  -i <shada>            Use this shada file\n"));
   mch_msg(_("  -m                    Modifications (writing files) not allowed\n"));
   mch_msg(_("  -M                    Modifications in text not allowed\n"));
-  mch_msg(_("  -b                    Binary mode\n"));
-  mch_msg(_("  -l                    Lisp mode\n"));
-  mch_msg(_("  -A                    Arabic mode\n"));
-  mch_msg(_("  -F                    Farsi mode\n"));
-  mch_msg(_("  -H                    Hebrew mode\n"));
-  mch_msg(_("  -V[N][file]           Be verbose [level N][log messages to file]\n"));
-  mch_msg(_("  -D                    Debugging mode\n"));
   mch_msg(_("  -n                    No swap file, use memory only\n"));
-  mch_msg(_("  -r, -L                List swap files and exit\n"));
-  mch_msg(_("  -r <file>             Recover crashed session\n"));
-  mch_msg(_("  -u <vimrc>            Use <vimrc> instead of the default\n"));
-  mch_msg(_("  -i <shada>            Use <shada> instead of the default\n"));
-  mch_msg(_("  --noplugin            Don't load plugin scripts\n"));
-  mch_msg(_("  -o[N]                 Open N windows (default: one for each file)\n"));
-  mch_msg(_("  -O[N]                 Like -o but split vertically\n"));
-  mch_msg(_("  -p[N]                 Open N tab pages (default: one for each file)\n"));
-  mch_msg(_("  +                     Start at end of file\n"));
-  mch_msg(_("  +<linenum>            Start at line <linenum>\n"));
-  mch_msg(_("  +/<pattern>           Start at first occurrence of <pattern>\n"));
-  mch_msg(_("  --cmd <command>       Execute <command> before loading any vimrc\n"));
-  mch_msg(_("  -c <command>          Execute <command> after loading the first file\n"));
+  mch_msg(_("  -o[N]                 Open N windows (default: one per file)\n"));
+  mch_msg(_("  -O[N]                 Open N vertical windows (default: one per file)\n"));
+  mch_msg(_("  -p[N]                 Open N tab pages (default: one per file)\n"));
+  mch_msg(_("  -r, -L                List swap files\n"));
+  mch_msg(_("  -r <file>             Recover edit state for this file\n"));
+  mch_msg(_("  -R                    Read-only mode\n"));
   mch_msg(_("  -S <session>          Source <session> after loading the first file\n"));
   mch_msg(_("  -s <scriptin>         Read Normal mode commands from <scriptin>\n"));
-  mch_msg(_("  -w <scriptout>        Append all typed characters to <scriptout>\n"));
-  mch_msg(_("  -W <scriptout>        Write all typed characters to <scriptout>\n"));
-  mch_msg(_("  --startuptime <file>  Write startup timing messages to <file>\n"));
-  mch_msg(_("  --api-info            Dump API metadata serialized to msgpack and exit\n"));
+  mch_msg(_("  -u <config>           Use this config file\n"));
+  mch_msg(_("  -v, --version         Print version information\n"));
+  mch_msg(_("  -V[N][file]           Verbose [level][file]\n"));
+  mch_msg(_("  -Z                    Restricted mode\n"));
+  mch_msg("\n");
+  mch_msg(_("  --api-info            Write msgpack-encoded API metadata to stdout\n"));
   mch_msg(_("  --embed               Use stdin/stdout as a msgpack-rpc channel\n"));
   mch_msg(_("  --headless            Don't start a user interface\n"));
-  mch_msg(_("  -v, --version         Print version information and exit\n"));
-  mch_msg(_("  -h, --help            Print this help message and exit\n"));
+#if !defined(UNIX)
+  mch_msg(_("  --literal             Don't expand wildcards\n"));
+#endif
+  mch_msg(_("  --noplugin            Don't load plugins\n"));
+  mch_msg(_("  --startuptime <file>  Write startup timing messages to <file>\n"));
+  mch_msg(_("\nSee \":help startup-options\" for all options.\n"));
 }
 
 
diff --git a/src/nvim/ops.c b/src/nvim/ops.c
index 5c6f4d0d07..6c873a96c0 100644
--- a/src/nvim/ops.c
+++ b/src/nvim/ops.c
@@ -58,8 +58,8 @@ static yankreg_T *y_previous = NULL; /* ptr to last written yankreg */
 static bool clipboard_didwarn_unnamed = false;
 
 // for behavior between start_batch_changes() and end_batch_changes())
-static bool clipboard_delay_update = false;  // delay clipboard update
 static int batch_change_count = 0;           // inside a script
+static bool clipboard_delay_update = false;  // delay clipboard update
 static bool clipboard_needs_update = false;  // clipboard was updated
 
 /*
@@ -5524,7 +5524,7 @@ int get_default_register_name(void)
 }
 
 /// Determine if register `*name` should be used as a clipboard.
-/// In an unnammed operation, `*name` is `NUL` and will be adjusted to `'*'/'+'` if
+/// In an unnamed operation, `*name` is `NUL` and will be adjusted to */+ if
 /// `clipboard=unnamed[plus]` is set.
 ///
 /// @param name The name of register, or `NUL` if unnamed.
@@ -5535,33 +5535,46 @@ int get_default_register_name(void)
 /// if the register isn't a clipboard or provider isn't available.
 static yankreg_T *adjust_clipboard_name(int *name, bool quiet, bool writing)
 {
-  if (*name == '*' || *name == '+') {
-    if(!eval_has_provider("clipboard")) {
-      if (!quiet) {
-        EMSG("clipboard: No provider. Try \":CheckHealth\" or "
-             "\":h clipboard\".");
-      }
-      return NULL;
-    }
-    return &y_regs[*name == '*' ? STAR_REGISTER : PLUS_REGISTER];
-  } else if ((*name == NUL) && (cb_flags & CB_UNNAMEDMASK)) {
-    if(!eval_has_provider("clipboard")) {
-      if (!quiet && !clipboard_didwarn_unnamed) {
-        msg((char_u *)"clipboard: No provider. Try \":CheckHealth\" or "
-            "\":h clipboard\".");
-        clipboard_didwarn_unnamed = true;
-      }
-      return NULL;
+#define MSG_NO_CLIP "clipboard: No provider. " \
+  "Try \":CheckHealth\" or \":h clipboard\"."
+
+  yankreg_T *target = NULL;
+  bool explicit_cb_reg = (*name == '*' || *name == '+');
+  bool implicit_cb_reg = (*name == NUL) && (cb_flags & CB_UNNAMEDMASK);
+  int save_redir_off = redir_off;
+  if (!explicit_cb_reg && !implicit_cb_reg) {
+    goto end;
+  }
+
+  if (!eval_has_provider("clipboard")) {
+    if (batch_change_count == 1 && explicit_cb_reg && !quiet) {
+      redir_off = true;   // Avoid recursion from :redir + emsg().
+      // Do NOT error (emsg()) here--if it interrupts :redir we get into
+      // a weird state, stuck in "redirect mode".
+      msg((char_u *)MSG_NO_CLIP);
+    } else if (batch_change_count == 1 && implicit_cb_reg
+               && !quiet && !clipboard_didwarn_unnamed) {
+      redir_off = true;  // Avoid recursion from :redir + emsg().
+      msg((char_u *)MSG_NO_CLIP);
+      clipboard_didwarn_unnamed = true;
     }
+    // ... else, be silent (don't flood during :while, :redir, etc.).
+    goto end;
+  }
+
+  if (explicit_cb_reg) {
+    target = &y_regs[*name == '*' ? STAR_REGISTER : PLUS_REGISTER];
+    goto end;
+  } else {  // unnamed register: "implicit" clipboard
     if (writing && clipboard_delay_update) {
+      // For "set" (copy), defer the clipboard call.
       clipboard_needs_update = true;
-      return NULL;
+      goto end;
     } else if (!writing && clipboard_needs_update) {
-      // use the internal value
-      return NULL;
+      // For "get" (paste), use the internal value.
+      goto end;
     }
 
-    yankreg_T *target;
     if (cb_flags & CB_UNNAMEDPLUS) {
       *name = (cb_flags & CB_UNNAMED && writing) ? '"': '+';
       target = &y_regs[PLUS_REGISTER];
@@ -5569,10 +5582,12 @@ static yankreg_T *adjust_clipboard_name(int *name, bool quiet, bool writing)
       *name = '*';
       target = &y_regs[STAR_REGISTER];
     }
-    return target; // unnamed register
+    goto end;
   }
-  // don't do anything for other register names
-  return NULL;
+
+end:
+  redir_off = save_redir_off;
+  return target;
 }
 
 static bool get_clipboard(int name, yankreg_T **target, bool quiet)
@@ -5740,7 +5755,7 @@ static void set_clipboard(int name, yankreg_T *reg)
   (void)eval_call_provider("clipboard", "set", args);
 }
 
-/// Avoid clipboard (slow) during batch operations (i.e., a script).
+/// Avoid slow things (clipboard) during batch operations (while/for-loops).
 void start_batch_changes(void)
 {
   if (++batch_change_count > 1) {
@@ -5750,7 +5765,7 @@ void start_batch_changes(void)
   clipboard_needs_update = false;
 }
 
-/// Update the clipboard after batch changes finished.
+/// Counterpart to start_batch_changes().
 void end_batch_changes(void)
 {
   if (--batch_change_count > 0) {
@@ -5759,6 +5774,7 @@ void end_batch_changes(void)
   }
   clipboard_delay_update = false;
   if (clipboard_needs_update) {
+    // unnamed ("implicit" clipboard)
     set_clipboard(NUL, y_previous);
     clipboard_needs_update = false;
   }
diff --git a/src/nvim/testdir/test_startup.vim b/src/nvim/testdir/test_startup.vim
index 64f7f31294..5a38178bd5 100644
--- a/src/nvim/testdir/test_startup.vim
+++ b/src/nvim/testdir/test_startup.vim
@@ -76,11 +76,11 @@ func Test_help_arg()
     let found = []
     for line in lines
       if line =~ '-R.*Read-only mode'
-	call add(found, 'Readonly mode')
+        call add(found, 'Readonly mode')
       endif
       " Watch out for a second --version line in the Gnome version.
-      if line =~ '--version.*Print version information and exit'
-	call add(found, "--version")
+      if line =~ '--version.*Print version information'
+        call add(found, "--version")
       endif
     endfor
     call assert_equal(['Readonly mode', '--version'], found)
diff --git a/src/nvim/version.c b/src/nvim/version.c
index f5b45caefc..2a3fdbd70d 100644
--- a/src/nvim/version.c
+++ b/src/nvim/version.c
@@ -1089,13 +1089,7 @@ static void list_features(void)
           msg_putchar('\n');
         }
       } else {
-        while (msg_col % width) {
-          int old_msg_col = msg_col;
-          msg_putchar(' ');
-          if (old_msg_col == msg_col) {
-            break;  // XXX: Avoid infinite loop.
-          }
-        }
+        msg_putchar(' ');
       }
     } else {
       if (msg_col > 0) {
@@ -1103,7 +1097,7 @@ static void list_features(void)
       }
     }
   }
-  MSG_PUTS("For differences from Vim, see :help vim-differences\n\n");
+  MSG_PUTS("See \":help feature-compile\"\n\n");
 }
 
 void list_version(void)
@@ -1144,7 +1138,7 @@ void list_version(void)
   }
 #endif  // ifdef HAVE_PATHDEF
 
-  version_msg(_("\n\nOptional features included (+) or not (-): "));
+  version_msg(_("\n\nFeatures: "));
 
   list_features();
 
@@ -1216,7 +1210,6 @@ void intro_message(int colon)
   static char *(lines[]) = {
     N_(NVIM_VERSION_LONG),
     "",
-    N_("by al."),
     N_("Nvim is open source and freely distributable"),
     N_("https://neovim.io/community"),
     "",
diff --git a/test/functional/clipboard/clipboard_provider_spec.lua b/test/functional/clipboard/clipboard_provider_spec.lua
index eb2eeee0da..e6544a8e2e 100644
--- a/test/functional/clipboard/clipboard_provider_spec.lua
+++ b/test/functional/clipboard/clipboard_provider_spec.lua
@@ -4,6 +4,8 @@ local helpers = require('test.functional.helpers')(after_each)
 local Screen = require('test.functional.ui.screen')
 local clear, feed, insert = helpers.clear, helpers.feed, helpers.insert
 local feed_command, expect, eq, eval = helpers.feed_command, helpers.expect, helpers.eq, helpers.eval
+local command = helpers.command
+local meths = helpers.meths
 
 local function basic_register_test(noblock)
   insert("some words")
@@ -80,15 +82,47 @@ local function basic_register_test(noblock)
   expect("two and three and one")
 end
 
-describe('the unnamed register', function()
+describe('clipboard', function()
   before_each(clear)
-  it('works without provider', function()
+
+  it('unnamed register works without provider', function()
     eq('"', eval('v:register'))
     basic_register_test()
   end)
+
+  it('`:redir @+>` with invalid g:clipboard shows error exactly once', function()
+    local screen = Screen.new(72, 5)
+    screen:attach()
+    command("let g:clipboard = 'bogus'")
+    feed_command('redir @+> | :silent echo system("cat CONTRIBUTING.md") | redir END')
+    screen:expect([[
+      ^                                                                        |
+      ~                                                                       |
+      ~                                                                       |
+      ~                                                                       |
+      clipboard: No provider. Try ":CheckHealth" or ":h clipboard".           |
+    ]], nil, {{bold = true, foreground = Screen.colors.Blue}})
+  end)
+
+  it('invalid g:clipboard', function()
+    command("let g:clipboard = 'bogus'")
+    eq('', eval('provider#clipboard#Executable()'))
+    eq('clipboard: invalid g:clipboard', eval('provider#clipboard#Error()'))
+  end)
+
+  it('valid g:clipboard', function()
+    -- provider#clipboard#Executable() only checks the structure.
+    meths.set_var('clipboard', {
+      ['name'] = 'clippy!',
+      ['copy'] = { ['+'] = 'any command', ['*'] = 'some other' },
+      ['paste'] = { ['+'] = 'any command', ['*'] = 'some other' },
+    })
+    eq('clippy!', eval('provider#clipboard#Executable()'))
+    eq('', eval('provider#clipboard#Error()'))
+  end)
 end)
 
-describe('clipboard usage', function()
+describe('clipboard', function()
   local function reset(...)
     clear('--cmd', 'let &rtp = "test/functional/fixtures,".&rtp', ...)
   end
@@ -98,7 +132,23 @@ describe('clipboard usage', function()
     feed_command('call getreg("*")') -- force load of provider
   end)
 
-   it('has independent "* and unnamed registers per default', function()
+  it('`:redir @+>` invokes clipboard once-per-message', function()
+    eq(0, eval("g:clip_called_set"))
+    feed_command('redir @+> | :silent echo system("cat CONTRIBUTING.md") | redir END')
+    -- Assuming CONTRIBUTING.md has >100 lines.
+    assert(eval("g:clip_called_set") > 100)
+  end)
+
+  it('`:redir @">` does NOT invoke clipboard', function()
+    -- :redir to a non-clipboard register, with `:set clipboard=unnamed` does
+    -- NOT propagate to the clipboard. This is consistent with Vim.
+    command("set clipboard=unnamedplus")
+    eq(0, eval("g:clip_called_set"))
+    feed_command('redir @"> | :silent echo system("cat CONTRIBUTING.md") | redir END')
+    eq(0, eval("g:clip_called_set"))
+  end)
+
+  it('has independent "* and unnamed registers by default', function()
     insert("some words")
     feed('^"*dwdw"*P')
     expect('some ')
@@ -139,7 +189,7 @@ describe('clipboard usage', function()
     eq({'some\ntext', '\nvery binary\n'}, eval("getreg('*', 1, 1)"))
   end)
 
-  it('support autodectection of regtype', function()
+  it('autodetects regtype', function()
     feed_command("let g:test_clip['*'] = ['linewise stuff','']")
     feed_command("let g:test_clip['+'] = ['charwise','stuff']")
     eq("V", eval("getregtype('*')"))
@@ -169,7 +219,7 @@ describe('clipboard usage', function()
     eq({{' much', 'ktext', ''}, 'b'}, eval("g:test_clip['+']"))
   end)
 
-  it('supports setreg', function()
+  it('supports setreg()', function()
     feed_command('call setreg("*", "setted\\ntext", "c")')
     feed_command('call setreg("+", "explicitly\\nlines", "l")')
     feed('"+P"*p')
@@ -187,7 +237,7 @@ describe('clipboard usage', function()
         ]])
   end)
 
-  it('supports let @+ (issue #1427)', function()
+  it('supports :let @+ (issue #1427)', function()
     feed_command("let @+ = 'some'")
     feed_command("let @* = ' other stuff'")
     eq({{'some'}, 'v'}, eval("g:test_clip['+']"))
@@ -305,7 +355,7 @@ describe('clipboard usage', function()
 
   end)
 
-  describe('with clipboard=unnamedplus', function()
+  describe('clipboard=unnamedplus', function()
     before_each(function()
       feed_command('set clipboard=unnamedplus')
     end)
@@ -349,6 +399,7 @@ describe('clipboard usage', function()
         really unnamed
         the plus]])
     end)
+
     it('is updated on global changes', function()
       insert([[
 	text
diff --git a/test/functional/fixtures/autoload/provider/clipboard.vim b/test/functional/fixtures/autoload/provider/clipboard.vim
index 411e095c71..6d777255c8 100644
--- a/test/functional/fixtures/autoload/provider/clipboard.vim
+++ b/test/functional/fixtures/autoload/provider/clipboard.vim
@@ -5,7 +5,13 @@ let s:methods = {}
 let g:cliplossy = 0
 let g:cliperror = 0
 
+" Count how many times the clipboard was invoked.
+let g:clip_called_get = 0
+let g:clip_called_set = 0
+
 function! s:methods.get(reg)
+  let g:clip_called_get += 1
+
   if g:cliperror
     return 0
   end
@@ -19,6 +25,8 @@ function! s:methods.get(reg)
 endfunction
 
 function! s:methods.set(lines, regtype, reg)
+  let g:clip_called_set += 1
+
   if a:reg == '"'
     call s:methods.set(a:lines,a:regtype,'+')
     call s:methods.set(a:lines,a:regtype,'*')