Merge pull request #2905 from bfredl/utf8

Only allow encoding=utf-8 and simplify multibyte code
2025-02-25 18:55:25 -06:00 · 2016-11-05 18:12:14 +01:00 · 2016-11-05 18:12:14 +01:00 · 9147331e21
commit 9147331e21
parent 32d9c19e29 4ab3fe8eaa
21 changed files with 263 additions and 1064 deletions
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@ -1029,8 +1029,8 @@ A string constant accepts these special characters:
 \x.	byte specified with one hex number (must be followed by non-hex char)
 \X..	same as \x..
 \X.	same as \x.
-\u....	character specified with up to 4 hex numbers, stored according to the
+\u....	character specified with up to 4 hex numbers, stored as UTF-8
-	current value of 'encoding' (e.g., "\u02a4")
+	(e.g., "\u02a4")
 \U....	same as \u but allows up to 8 hex numbers.
 \b	backspace <BS>
 \e	escape <Esc>
@ -1045,8 +1045,7 @@ A string constant accepts these special characters:
 	utf-8 character, use \uxxxx as mentioned above.
 Note that "\xff" is stored as the byte 255, which may be invalid in some
-encodings.  Use "\u00ff" to store character 255 according to the current value
+encodings.  Use "\u00ff" to store character 255 correctly as UTF-8.
 of 'encoding'.
 Note that "\000" and "\x00" force the end of the string.
@ -2532,8 +2531,6 @@ byteidxcomp({expr}, {nr})					*byteidxcomp()*
 <		The first and third echo result in 3 ('e' plus composing
 		character is 3 bytes), the second echo results in 1 ('e' is
 		one byte).
 		Only works different from byteidx() when 'encoding' is set to
 		a Unicode encoding.
 call({func}, {arglist} [, {dict}])			*call()* *E699*
 		Call function {func} with the items in |List| {arglist} as
@ -2568,11 +2565,11 @@ char2nr({expr}[, {utf8}])					*char2nr()*
 		Return number value of the first char in {expr}.  Examples: >
 			char2nr(" ")		returns 32
 			char2nr("ABC")		returns 65
 <		When {utf8} is omitted or zero, the current 'encoding' is used.
 		Example for "utf-8": >
 			char2nr("á")		returns 225
 			char2nr("á"[0])		returns 195
-<		With {utf8} set to 1, always treat as utf-8 characters.
+<		Non-ASCII characters are always treated as UTF-8 characters.
 		{utf8} has no effect, and exists only for
 		backwards-compatibility.
 		A combining character is a separate character.
 		|nr2char()| does the opposite.
@ -4225,11 +4222,7 @@ iconv({expr}, {from}, {to})				*iconv()*
 		Most conversions require Vim to be compiled with the |+iconv|
 		feature.  Otherwise only UTF-8 to latin1 conversion and back
 		can be done.
-		This can be used to display messages with special characters,
+		Note that Vim uses UTF-8 for all Unicode encodings, conversion
 		no matter what 'encoding' is set to.  Write the message in
 		UTF-8 and use: >
 			echo iconv(utf8_str, "utf-8", &enc)
 <		Note that Vim uses UTF-8 for all Unicode encodings, conversion
 		from/to UCS-2 is automatically changed to use UTF-8.  You
 		cannot use UCS-2 in a string anyway, because of the NUL bytes.
 		{only available when compiled with the |+multi_byte| feature}
@ -4513,9 +4506,7 @@ join({list} [, {sep}])					*join()*
 json_decode({expr})					*json_decode()*
 		Convert {expr} from JSON object.  Accepts |readfile()|-style 
 		list as the input, as well as regular string.  May output any 
-		Vim value.  When 'encoding' is not UTF-8 string is converted 
+		Vim value. In the following cases it will output
 		from UTF-8 to 'encoding', failing conversion fails 
 		json_decode().  In the following cases it will output 
 		|msgpack-special-dict|:
 		1. Dictionary contains duplicate key.
 		2. Dictionary contains empty key.
@ -4523,33 +4514,22 @@ json_decode({expr})					*json_decode()*
 		   dictionary and for string will be emitted in case string 
 		   with NUL byte was a dictionary key.
-		Note: function treats its input as UTF-8 always regardless of 
+		Note: function treats its input as UTF-8 always.  The JSON
-		'encoding' value.  This is needed because JSON source is 
+		standard allows only a few encodings, of which UTF-8 is
-		supposed to be external (e.g. |readfile()|) and JSON standard 
+		recommended and the only one required to be supported.
-		allows only a few encodings, of which UTF-8 is recommended and 
+		Non-UTF-8 characters are an error.
 		the only one required to be supported.  Non-UTF-8 characters 
 		are an error.
 json_encode({expr})					*json_encode()*
 		Convert {expr} into a JSON string.  Accepts 
-		|msgpack-special-dict| as the input.  Converts from 'encoding' 
+		|msgpack-special-dict| as the input.  Will not convert |Funcref|s, 
 		to UTF-8 when encoding strings.  Will not convert |Funcref|s, 
 		mappings with non-string keys (can be created as 
 		|msgpack-special-dict|), values with self-referencing 
 		containers, strings which contain non-UTF-8 characters, 
 		pseudo-UTF-8 strings which contain codepoints reserved for 
 		surrogate pairs (such strings are not valid UTF-8 strings).  
 		When converting 'encoding' is taken into account, if it is not 
 		"utf-8", then conversion is performed before encoding strings.  
 		Non-printable characters are converted into "\u1234" escapes 
 		or special escapes like "\t", other are dumped as-is.
 		Note: all characters above U+0079 are considered non-printable 
 		when 'encoding' is not UTF-8.  This function always outputs 
 		UTF-8 strings as required by the standard thus when 'encoding' 
 		is not unicode resulting string will look incorrect if 
 		"\u1234" notation is not used.
 keys({dict})						*keys()*
 		Return a |List| with all the keys of {dict}.  The |List| is in
 		arbitrary order.
@ -4651,9 +4631,9 @@ line2byte({lnum})					*line2byte()*
 		Return the byte count from the start of the buffer for line
 		{lnum}.  This includes the end-of-line character, depending on
 		the 'fileformat' option for the current buffer.  The first
-		line returns 1. 'encoding' matters, 'fileencoding' is ignored.
+		line returns 1. UTF-8 encoding is used, 'fileencoding' is
-		This can also be used to get the byte count for the line just
+		ignored.  This can also be used to get the byte count for the
-		below the last line: >
+		line just below the last line: >
 			line2byte(line("$") + 1)
 <		This is the buffer size plus one.  If 'fileencoding' is empty
 		it is the file size plus one.
@ -5172,10 +5152,10 @@ nr2char({expr}[, {utf8}])				*nr2char()*
 		value {expr}.  Examples: >
 			nr2char(64)		returns "@"
 			nr2char(32)		returns " "
-<		When {utf8} is omitted or zero, the current 'encoding' is used.
+<		Example for "utf-8": >
 		Example for "utf-8": >
 			nr2char(300)		returns I with bow character
-<		With {utf8} set to 1, always return utf-8 characters.
+<		UTF-8 encoding is always used, {utf8} option has no effect,
 		and exists only for backwards-compatibility.
 		Note that a NUL character in the file is specified with
 		nr2char(10), because NULs are represented with newline
 		characters.  nr2char(0) is a real NUL and terminates the
@ -5417,7 +5397,7 @@ py3eval({expr})						*py3eval()*
 		converted to Vim data structures.
 		Numbers and strings are returned as they are (strings are 
 		copied though, Unicode strings are additionally converted to 
-		'encoding').
+		UTF-8).
 		Lists are represented as Vim |List| type.
 		Dictionaries are represented as Vim |Dictionary| type with 
 		keys converted to strings.
@ -5467,8 +5447,7 @@ readfile({fname} [, {binary} [, {max}]])
 		Otherwise:
 		- CR characters that appear before a NL are removed.
 		- Whether the last line ends in a NL or not does not matter.
-		- When 'encoding' is Unicode any UTF-8 byte order mark is
+		- Any UTF-8 byte order mark is removed from the text.
 		  removed from the text.
 		When {max} is given this specifies the maximum number of lines
 		to be read.  Useful if you only want to check the first ten
 		lines of a file: >
@ -6621,8 +6600,7 @@ string({expr})	Return {expr} converted to a String.  If {expr} is a Number,
 		for infinite and NaN floating-point values representations 
 		which use |str2float()|.  Strings are also dumped literally, 
 		only single quote is escaped, which does not allow using YAML 
-		for parsing back binary strings (including text when 
+		for parsing back binary strings.  |eval()| should always work for 
 		'encoding' is not UTF-8).  |eval()| should always work for 
 		strings and floats though and this is the only official 
 		method, use |msgpackdump()| or |json_encode()| if you need to 
 		share data with other application.
--- a/runtime/doc/mbyte.txt
+++ b/runtime/doc/mbyte.txt
@ -70,29 +70,24 @@ See |mbyte-locale| for details.
 ENCODING
-If your locale works properly, Vim will try to set the 'encoding' option
+Nvim always uses UTF-8 internally. Thus 'encoding' option is always set
-accordingly.  If this doesn't work you can overrule its value: >
+to "utf-8" and cannot be changed.
-	:set encoding=utf-8
+All the text that is used inside Vim will be in UTF-8. Not only the text in
 the buffers, but also in registers, variables, etc.
-See |encoding-values| for a list of acceptable values.
+You can edit files in different encodings than UTF-8.  Nvim
 The result is that all the text that is used inside Vim will be in this
 encoding.  Not only the text in the buffers, but also in registers, variables,
 etc. 'encoding' is read-only after startup because changing it would make the
 existing text invalid.
 You can edit files in another encoding than what 'encoding' is set to.  Vim
 will convert the file when you read it and convert it back when you write it.
 See 'fileencoding', 'fileencodings' and |++enc|.
 DISPLAY AND FONTS
-If you are working in a terminal (emulator) you must make sure it accepts the
+If you are working in a terminal (emulator) you must make sure it accepts
-same encoding as which Vim is working with.
+UTF-8, the encoding which Vim is working with. Otherwise only ASCII can
 be displayed and edited correctly.
-For the GUI you must select fonts that work with the current 'encoding'.  This
+For the GUI you must select fonts that work with UTF-8.  This
 is the difficult part.  It depends on the system you are using, the locale and
 a few other things.  See the chapters on fonts: |mbyte-fonts-X11| for
 X-Windows and |mbyte-fonts-MSwin| for MS-Windows.
@ -216,10 +211,9 @@ You could make a small shell script for this.
 ==============================================================================
 3.  Encoding				*mbyte-encoding*
-Vim uses the 'encoding' option to specify how characters are identified and
+In Nvim UTF-8 is always used internally to encode characters.
-encoded when they are used inside Vim.  This applies to all the places where
+ This applies to all the places where text is used, including buffers (files
-text is used, including buffers (files loaded into memory), registers and
+ loaded into memory), registers and variables.
 variables.
 							*charset* *codeset*
 Charset is another name for encoding.  There are subtle differences, but these
@ -240,7 +234,7 @@ matter what language is used.  Thus you might see the right text even when the
 encoding was set wrong.
 							*encoding-names*
-Vim can use many different character encodings.  There are three major groups:
+Vim can edit files in different character encodings.  There are three major groups:
 1   8bit	Single-byte encodings, 256 different characters.  Mostly used
 		in USA and Europe.  Example: ISO-8859-1 (Latin1).  All
@ -255,11 +249,10 @@ u   Unicode	Universal encoding, can replace all others.  ISO 10646.
 		Millions of different characters.  Example: UTF-8.  The
 		relation between bytes and screen cells is complex.
-Other encodings cannot be used by Vim internally.  But files in other
+Only UTF-8 is used by Vim internally.  But files in other
 encodings can be edited by using conversion, see 'fileencoding'.
 Note that all encodings must use ASCII for the characters up to 128.
-Supported 'encoding' values are:			*encoding-values*
+Recognized 'fileencoding' values include:		*encoding-values*
 1   latin1	8-bit characters (ISO 8859-1, also used for cp1252)
 1   iso-8859-n	ISO_8859 variant (n = 2 to 15)
 1   koi8-r	Russian
@ -311,11 +304,11 @@ u   ucs-4	32 bit UCS-4 encoded Unicode (ISO/IEC 10646-1)
 u   ucs-4le	like ucs-4, little endian
 The {name} can be any encoding name that your system supports.  It is passed
-to iconv() to convert between the encoding of the file and the current locale.
+to iconv() to convert between UTF-8 and the encoding of the file.
 For MS-Windows "cp{number}" means using codepage {number}.
 Examples: >
-		:set encoding=8bit-cp1252
+		:set fileencoding=8bit-cp1252
-		:set encoding=2byte-cp932
+		:set fileencoding=2byte-cp932
 The MS-Windows codepage 1252 is very similar to latin1.  For practical reasons
 the same encoding is used and it's called latin1.  'isprint' can be used to
@ -337,8 +330,7 @@ u   ucs-2be	same as ucs-2 (big endian)
 u   ucs-4be	same as ucs-4 (big endian)
 u   utf-32	same as ucs-4
 u   utf-32le	same as ucs-4le
-    default     stands for the default value of 'encoding', depends on the
+    default     the encoding of the current locale.
 		environment
 For the UCS codes the byte order matters.  This is tricky, use UTF-8 whenever
 you can.  The default is to use big-endian (most significant byte comes
@ -363,13 +355,12 @@ or when conversion is not possible:
 CONVERSION						*charset-conversion*
 Vim will automatically convert from one to another encoding in several places:
- When reading a file and 'fileencoding' is different from 'encoding'
+- When reading a file and 'fileencoding' is different from "utf-8"
- When writing a file and 'fileencoding' is different from 'encoding'
+- When writing a file and 'fileencoding' is different from "utf-8"
 - When displaying messages and the encoding used for LC_MESSAGES differs from
-  'encoding' (requires a gettext version that supports this).
+  "utf-8" (requires a gettext version that supports this).
 - When reading a Vim script where |:scriptencoding| is different from
-  'encoding'.
+  "utf-8".
 - When reading or writing a |shada| file.
 Most of these require the |+iconv| feature.  Conversion for reading and
 writing files may also be specified with the 'charconvert' option.
@ -408,11 +399,11 @@ Useful utilities for converting the charset:
 							*mbyte-conversion*
-When reading and writing files in an encoding different from 'encoding',
+When reading and writing files in an encoding different from "utf-8",
 conversion needs to be done.  These conversions are supported:
 - All conversions between Latin-1 (ISO-8859-1), UTF-8, UCS-2 and UCS-4 are
  handled internally.
- For MS-Windows, when 'encoding' is a Unicode encoding, conversion from and
+- For MS-Windows, conversion from and
  to any codepage should work.
 - Conversion specified with 'charconvert'
 - Conversion with the iconv library, if it is available.
@ -468,8 +459,6 @@ and you will have a working UTF-8 terminal emulator.  Try both >
 with the demo text that comes with ucs-fonts.tar.gz in order to see
 whether there are any problems with UTF-8 in your xterm.
 For Vim you may need to set 'encoding' to "utf-8".
 ==============================================================================
 5.  Fonts on X11					*mbyte-fonts-X11*
@ -864,11 +853,11 @@ between two keyboard settings.
 The value of the 'keymap' option specifies a keymap file to use.  The name of
 this file is one of these two:
-	keymap/{keymap}_{encoding}.vim
+	keymap/{keymap}_utf-8.vim
 	keymap/{keymap}.vim
-Here {keymap} is the value of the 'keymap' option and {encoding} of the
+Here {keymap} is the value of the 'keymap' option.
-'encoding' option.  The file name with the {encoding} included is tried first.
+The file name with "utf-8" included is tried first.
 'runtimepath' is used to find these files.  To see an overview of all
 available keymap files, use this: >
@ -950,7 +939,7 @@ this is unusual.  But you can use various ways to specify the character: >
 	A	<char-0141>	octal value
 	x	<Space>		special key name
-The characters are assumed to be encoded for the current value of 'encoding'.
+The characters are assumed to be encoded in UTF-8.
 It's possible to use ":scriptencoding" when all characters are given
 literally.  That doesn't work when using the <char-> construct, because the
 conversion is done on the keymap file, not on the resulting character.
@ -1170,21 +1159,13 @@ Useful commands:
  message is truncated, use ":messages").
 - "g8" shows the bytes used in a UTF-8 character, also the composing
  characters, as hex numbers.
- ":set encoding=utf-8 fileencodings=" forces using UTF-8 for all files.  The
+- ":set fileencodings=" forces using UTF-8 for all files.  The
-  default is to use the current locale for 'encoding' and set 'fileencodings'
+  default is to automatically detect the encoding of a file.
  to automatically detect the encoding of a file.
 STARTING VIM
-If your current locale is in an utf-8 encoding, Vim will automatically start
+You might want to select the font used for the menus.  Unfortunately this
 in utf-8 mode.
 If you are using another locale: >
 	set encoding=utf-8
 You might also want to select the font used for the menus.  Unfortunately this
 doesn't always work.  See the system specific remarks below, and 'langmenu'.
@ -1245,10 +1226,9 @@ not everybody is able to type a composing character.
 These options are relevant for editing multi-byte files.  Check the help in
 options.txt for detailed information.
-'encoding'	Encoding used for the keyboard and display.  It is also the
+'encoding'	Internal text encoding, always "utf-8".
 		default encoding for files.
-'fileencoding'	Encoding of a file.  When it's different from 'encoding'
+'fileencoding'	Encoding of a file.  When it's different from "utf-8"
 		conversion is done when reading or writing the file.
 'fileencodings'	List of possible encodings of a file.  When opening a file
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@ -52,7 +52,6 @@ achieve special effects.  These options come in three forms:
 :se[t] all&		Set all options to their default value.  The values of
 			these options are not changed:
 			  'columns'
 			  'encoding'
 			  'lines'
 			Warning: This may have a lot of side effects.
@ -615,7 +614,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 			global
 			{only available when compiled with the |+multi_byte|
 			feature}
 	Only effective when 'encoding' is "utf-8" or another Unicode encoding.
 	Tells Vim what to do with characters with East Asian Width Class
 	Ambiguous (such as Euro, Registered Sign, Copyright Sign, Greek
 	letters, Cyrillic letters).
@ -668,7 +666,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 	- Set the 'keymap' option to "arabic"; in Insert mode CTRL-^ toggles
 	  between typing English and Arabic key mapping.
 	- Set the 'delcombine' option
 	Note that 'encoding' must be "utf-8" for working with Arabic text.
 	Resetting this option will:
 	- Reset the 'rightleft' option.
@ -1078,8 +1075,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 			{not available when compiled without the |+linebreak|
 			feature}
 	This option lets you choose which characters might cause a line
-	break if 'linebreak' is on.  Only works for ASCII and also for 8-bit
+	break if 'linebreak' is on.  Only works for ASCII characters.
 	characters when 'encoding' is an 8-bit encoding.
 						*'breakindent'* *'bri'*
 'breakindent' 'bri'	boolean (default off)
@ -1214,11 +1210,9 @@ A jump table for the options with a short description can be found at |Q_op|.
 	Specifies details about changing the case of letters.  It may contain
 	these words, separated by a comma:
 	internal	Use internal case mapping functions, the current
-			locale does not change the case mapping.  This only
+			locale does not change the case mapping. When
-			matters when 'encoding' is a Unicode encoding,
+			"internal" is omitted, the towupper() and towlower()
-			"latin1" or "iso-8859-15".  When "internal" is
+			system library functions are used when available.
 			omitted, the towupper() and towlower() system library
 			functions are used when available.
 	keepascii	For the ASCII characters (0x00 to 0x7f) use the US
 			case mapping, the current locale is not effective.
 			This probably only matters for Turkish.
@ -1271,13 +1265,12 @@ A jump table for the options with a short description can be found at |Q_op|.
 	file to convert from.  You will have to save the text in a file first.
 	The expression must return zero or an empty string for success,
 	non-zero for failure.
-	The possible encoding names encountered are in 'encoding'.
+	See |encoding-names| for possible encoding names.
 	Additionally, names given in 'fileencodings' and 'fileencoding' are
 	used.
 	Conversion between "latin1", "unicode", "ucs-2", "ucs-4" and "utf-8"
 	is done internally by Vim, 'charconvert' is not used for this.
-	'charconvert' is also used to convert the shada file, if 'encoding' is 
+	Also used for Unicode conversion.
 	not "utf-8".  Also used for Unicode conversion.
 	Example: >
 		set charconvert=CharConvert()
 		fun CharConvert()
@ -1292,8 +1285,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 		v:fname_in		name of the input file
 		v:fname_out		name of the output file
 	Note that v:fname_in and v:fname_out will never be the same.
 	Note that v:charconvert_from and v:charconvert_to may be different
 	from 'encoding'.  Vim internally uses UTF-8 instead of UCS-2 or UCS-4.
 	This option cannot be set from a |modeline| or in the |sandbox|, for
 	security reasons.
@ -2140,44 +2131,14 @@ A jump table for the options with a short description can be found at |Q_op|.
 					*'encoding'* *'enc'* *E543*
-'encoding' 'enc'	string (default: "utf-8")
+'encoding' 'enc'	Removed. |vim-differences| {Nvim}
-			global
+	Nvim always uses UTF-8 internally. RPC communication
-			{only available when compiled with the |+multi_byte|
+	(remote plugins/GUIs) must use UTF-8 strings.
 			feature}
 	Sets the character encoding used inside Vim.  It applies to text in
 	the buffers, registers, Strings in expressions, text stored in the
 	shada file, etc.  It sets the kind of characters which Vim can work
 	with.  See |encoding-names| for the possible values.
-	'encoding' cannot be changed after startup, because (1) it causes
+	The character encoding of files can be different than UTF-8.
 	non-ASCII text inside Vim to become invalid, and (2) it complicates
 	runtime logic.  The recommended 'encoding' is "utf-8".  Remote plugins
 	and GUIs only support utf-8. See |multibyte|.
 	The character encoding of files can be different from 'encoding'.
 	This is specified with 'fileencoding'.  The conversion is done with
 	iconv() or as specified with 'charconvert'.
 	If you need to know whether 'encoding' is a multi-byte encoding, you
 	can use: >
 		if has("multi_byte_encoding")
 <
 	When you set this option, it fires the |EncodingChanged| autocommand
 	event so that you can set up fonts if necessary.
 	When the option is set, the value is converted to lowercase.  Thus
 	you can set it with uppercase values too.  Underscores are translated
 	to '-' signs.
 	When the encoding is recognized, it is changed to the standard name.
 	For example "Latin-1" becomes "latin1", "ISO_88592" becomes
 	"iso-8859-2" and "utf8" becomes "utf-8".
 	When "unicode", "ucs-2" or "ucs-4" is used, Vim internally uses utf-8.
 	You don't notice this while editing, but it does matter for the
 	|shada-file|.  And Vim expects the terminal to use utf-8 too.  Thus
 	setting 'encoding' to one of these values instead of utf-8 only has
 	effect for encoding used for files when 'fileencoding' is empty.
 			*'endofline'* *'eol'* *'noendofline'* *'noeol'*
 'endofline' 'eol'	boolean	(default on)
 			local to buffer
@ -2304,20 +2265,14 @@ A jump table for the options with a short description can be found at |Q_op|.
 			feature}
 	Sets the character encoding for the file of this buffer.
-	When 'fileencoding' is different from 'encoding', conversion will be
+	When 'fileencoding' is different from "utf-8", conversion will be
 	done when writing the file.  For reading see below.
-	When 'fileencoding' is empty, the same value as 'encoding' will be
+	When 'fileencoding' is empty, the file will be saved with utf-8
-	used (no conversion when reading or writing a file).
+	encoding.  (no conversion when reading or writing a file).
-	Conversion will also be done when 'encoding' and 'fileencoding' are
+		WARNING: Conversion to a non-Unicode encoding can cause loss of
-	both a Unicode encoding and 'fileencoding' is not utf-8.  That's
+		information! 
 	because internally Unicode is always stored as utf-8.
 		WARNING: Conversion can cause loss of information!  When
 		'encoding' is "utf-8" or another Unicode encoding, conversion
 		is most likely done in a way that the reverse conversion
 		results in the same text.  When 'encoding' is not "utf-8" some
 		characters may be lost!
-	See 'encoding' for the possible values.  Additionally, values may be
+	See |encoding-names| for the possible values.  Additionally, values may be
 	specified that can be handled by the converter, see
 	|mbyte-conversion|.
@ -2330,8 +2285,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	Prepending "8bit-" and "2byte-" has no meaning here, they are ignored.
 	When the option is set, the value is converted to lowercase.  Thus
 	you can set it with uppercase values too.  '_' characters are
-	replaced with '-'.  If a name is recognized from the list for
+	replaced with '-'.  If a name is recognized from the list at
-	'encoding', it is replaced by the standard name.  For example
+	|encoding-names|, it is replaced by the standard name.  For example
 	"ISO8859-2" becomes "iso-8859-2".
 	When this option is set, after starting to edit a file, the 'modified'
@ -2354,12 +2309,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 	mentioned character encoding.  If an error is detected, the next one
 	in the list is tried.  When an encoding is found that works,
 	'fileencoding' is set to it.  If all fail, 'fileencoding' is set to
-	an empty string, which means the value of 'encoding' is used.
+	an empty string, which means that UTF-8 is used.
-		WARNING: Conversion can cause loss of information!  When
+		WARNING: Conversion can cause loss of information! You can use
 		'encoding' is "utf-8" (or one of the other Unicode variants)
 		conversion is most likely done in a way that the reverse
 		conversion results in the same text.  When 'encoding' is not
 		"utf-8" some non-ASCII characters may be lost!  You can use
 		the |++bad| argument to specify what is done with characters
 		that can't be converted.
 	For an empty file or a file with only ASCII characters most encodings
@ -2385,11 +2336,11 @@ A jump table for the options with a short description can be found at |Q_op|.
 	because Vim cannot detect an error, thus the encoding is always
 	accepted.
 	The special value "default" can be used for the encoding from the
-	environment.  It is useful when 'encoding' is set to "utf-8" and
+	environment.  It is useful when your environment uses a non-latin1
-	your environment uses a non-latin1 encoding, such as Russian.
+	encoding, such as Russian.
-	When 'encoding' is "utf-8" and a file contains an illegal byte
+	When a file contains an illegal UTF-8 byte sequence it won't be
-	sequence it won't be recognized as UTF-8.  You can use the |8g8|
+	recognized as "utf-8".  You can use the |8g8| command to find the
-	command to find the illegal byte sequence.
+	illegal byte sequence.
 	WRONG VALUES:			WHAT'S WRONG:
 		latin1,utf-8		"latin1" will always be used
 		utf-8,ucs-bom,latin1	BOM won't be recognized in an utf-8
@ -3048,8 +2999,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	Note: The size of these fonts must be exactly twice as wide as the one
 	specified with 'guifont' and the same height.
-	'guifontwide' is only used when 'encoding' is set to "utf-8" and
+	'guifontwide' is only used when 'guifontset' is empty or invalid.
 	'guifontset' is empty or invalid.
 	When 'guifont' is set and a valid font is found in it and
 	'guifontwide' is empty Vim will attempt to find a matching
 	double-width font and set 'guifontwide' to it.
@ -3702,7 +3652,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 		128 - 159	"~@" - "~_"
 		160 - 254	"| " - "|~"
 		   255		"~?"
-	When 'encoding' is a Unicode one, illegal bytes from 128 to 255 are
+	Illegal bytes from 128 to 255 (invalid UTF-8) are
 	displayed as <xx>, with the hexadecimal value of the byte.
 	When 'display' contains "uhex" all unprintable characters are
 	displayed as <xx>.
@ -3980,8 +3930,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 			omitted.
 	The characters ':' and ',' should not be used.  UTF-8 characters can
-	be used when 'encoding' is "utf-8", otherwise only printable
+	be used.  All characters must be single width.
 	characters are allowed.  All characters must be single width.
 	Examples: >
 	    :set lcs=tab:>-,trail:-
@ -4078,7 +4027,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 			{only available when compiled with the |+multi_byte|
 			feature}
 	The maximum number of combining characters supported for displaying.
 	Only used when 'encoding' is "utf-8".
 	The default is OK for most languages.  Hebrew may require 4.
 	Maximum value is 6.
 	Even when this option is set to 2 you can still edit text with more
@ -5825,9 +5773,6 @@ A jump table for the options with a short description can be found at |Q_op|.
 	(_xx is an underscore, two letters and followed by a non-letter).
 	This is mainly for testing purposes.  You must make sure the correct
 	encoding is used, Vim doesn't check it.
 	When 'encoding' is set the word lists are reloaded.  Thus it's a good
 	idea to set 'spelllang' after setting 'encoding' to avoid loading the
 	files twice.
 	How the related spell files are found is explained here: |spell-load|.
 	If the |spellfile.vim| plugin is active and you use a language name
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@ -40,7 +40,6 @@ these differences.
 - 'complete' doesn't include "i"
 - 'directory' defaults to ~/.local/share/nvim/swap// (|xdg|), auto-created
 - 'display' defaults to "lastline"
 - 'encoding' defaults to "utf-8"
 - 'formatoptions' defaults to "tcqj"
 - 'history' defaults to 10000 (the maximum)
 - 'hlsearch' is set by default
@ -159,7 +158,7 @@ are always available and may be used simultaneously in separate plugins.  The
   'p')) mkdir() will silently exit. In Vim this was an error.
 3. mkdir() error messages now include strerror() text when mkdir fails.
-'encoding' cannot be changed after startup.
+'encoding' is always "utf-8".
 |string()| and |:echo| behaviour changed:
 1. No maximum recursion depth limit is applied to nested container
@ -266,6 +265,7 @@ Highlight groups:
 Other options:
  'antialias'
  'cpoptions' ("g", "w", "H", "*", "-", "j", and all POSIX flags were removed)
  'encoding' ("utf-8" is always used)
  'guioptions' "t" flag was removed
  *'guipty'* (Nvim uses pipes and PTYs consistently on all platforms.)
  *'imactivatefunc'* *'imaf'*
--- a/src/nvim/charset.c
+++ b/src/nvim/charset.c
@ -1612,9 +1612,7 @@ bool vim_islower(int c)
      return false;
    }
-    if (enc_latin1like) {
+    return (latin1flags[c] & LATIN1LOWER) == LATIN1LOWER;
      return (latin1flags[c] & LATIN1LOWER) == LATIN1LOWER;
    }
  }
  return islower(c);
 }
@ -1643,9 +1641,7 @@ bool vim_isupper(int c)
      return false;
    }
-    if (enc_latin1like) {
+    return (latin1flags[c] & LATIN1UPPER) == LATIN1UPPER;
      return (latin1flags[c] & LATIN1UPPER) == LATIN1UPPER;
    }
  }
  return isupper(c);
 }
@ -1670,9 +1666,7 @@ int vim_toupper(int c)
      return c;
    }
-    if (enc_latin1like) {
+    return latin1upper[c];
      return latin1upper[c];
    }
  }
  return TOUPPER_LOC(c);
 }
@ -1697,9 +1691,7 @@ int vim_tolower(int c)
      return c;
    }
-    if (enc_latin1like) {
+    return latin1lower[c];
      return latin1lower[c];
    }
  }
  return TOLOWER_LOC(c);
 }
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@ -4165,9 +4165,8 @@ static bool need_conversion(const char_u *fenc)
    same_encoding = (enc_flags != 0 && fenc_flags == enc_flags);
  }
  if (same_encoding) {
-    /* Specified encoding matches with 'encoding'.  This requires
+    // Specified file encoding matches UTF-8.
-     * conversion when 'encoding' is Unicode but not UTF-8. */
+    return false;
    return enc_unicode != 0;
  }
  /* Encodings differ.  However, conversion is not needed when 'enc' is any
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@ -778,44 +778,18 @@ EXTERN int vr_lines_changed INIT(= 0);      /* #Lines changed by "gR" so far */
 # define DBCS_2BYTE     1       /* 2byte- */
 # define DBCS_DEBUG     -1
-EXTERN int enc_dbcs INIT(= 0);                  /* One of DBCS_xxx values if
+// mbyte flags that used to depend on 'encoding'. These are now deprecated, as
-                                                   DBCS encoding */
+// 'encoding' is always "utf-8". Code that use them can be refactored to
-EXTERN int enc_unicode INIT(= 0);       /* 2: UCS-2 or UTF-16, 4: UCS-4 */
+// remove dead code.
-EXTERN bool enc_utf8 INIT(= false);             /* UTF-8 encoded Unicode */
+#define enc_dbcs false
-EXTERN int enc_latin1like INIT(= TRUE);         /* 'encoding' is latin1 comp. */
+#define enc_utf8 true
-EXTERN int has_mbyte INIT(= 0);                 /* any multi-byte encoding */
+#define has_mbyte true
 /// Encoding used when 'fencs' is set to "default"
 EXTERN char_u *fenc_default INIT(= NULL);
-/*
+// To speed up BYTELEN() we keep a table with the byte lengths for utf-8
- * To speed up BYTELEN() we fill a table with the byte lengths whenever
+EXTERN char utf8len_tab[256];
 * enc_utf8 or enc_dbcs changes.
 */
 EXTERN char mb_bytelen_tab[256];
 /*
 * Function pointers, used to quickly get to the right function.  Each has
 * three possible values: latin_ (8-bit), utfc_ or utf_ (utf-8) and dbcs_
 * (DBCS).
 * The value is set in mb_init();
 */
 /* length of char in bytes, including following composing chars */
 EXTERN int (*mb_ptr2len)(const char_u *p) INIT(= latin_ptr2len);
 /* idem, with limit on string length */
 EXTERN int (*mb_ptr2len_len)(const char_u *p, int size) INIT(= latin_ptr2len_len);
 /* byte length of char */
 EXTERN int (*mb_char2len)(int c) INIT(= latin_char2len);
 /* convert char to bytes, return the length */
 EXTERN int (*mb_char2bytes)(int c, char_u *buf) INIT(= latin_char2bytes);
 EXTERN int (*mb_ptr2cells)(const char_u *p) INIT(= latin_ptr2cells);
 EXTERN int (*mb_ptr2cells_len)(const char_u *p, int size) INIT(
      = latin_ptr2cells_len);
 EXTERN int (*mb_char2cells)(int c) INIT(= latin_char2cells);
 EXTERN int (*mb_off2cells)(unsigned off, unsigned max_off) INIT(
      = latin_off2cells);
 EXTERN int (*mb_ptr2char)(const char_u *p) INIT(= latin_ptr2char);
 EXTERN int (*mb_head_off)(const char_u *base, const char_u *p) INIT(= latin_head_off);
 # if defined(USE_ICONV) && defined(DYNAMIC_ICONV)
 /* Pointers to functions and variables to be loaded at runtime */
--- a/src/nvim/macros.h
+++ b/src/nvim/macros.h
@ -122,32 +122,29 @@
 /* Whether to draw the vertical bar on the right side of the cell. */
 # define CURSOR_BAR_RIGHT (curwin->w_p_rl && (!(State & CMDLINE) || cmdmsg_rl))
-/*
+// mb_ptr_adv(): advance a pointer to the next character, taking care of
- * mb_ptr_adv(): advance a pointer to the next character, taking care of
+// multi-byte characters if needed.
- * multi-byte characters if needed.
+// mb_ptr_back(): backup a pointer to the previous character, taking care of
- * mb_ptr_back(): backup a pointer to the previous character, taking care of
+// multi-byte characters if needed.
- * multi-byte characters if needed.
+// MB_COPY_CHAR(f, t): copy one char from "f" to "t" and advance the pointers.
- * MB_COPY_CHAR(f, t): copy one char from "f" to "t" and advance the pointers.
+// PTR2CHAR(): get character from pointer.
 * PTR2CHAR(): get character from pointer.
 */
 /* Get the length of the character p points to */
 # define MB_PTR2LEN(p)          (has_mbyte ? (*mb_ptr2len)(p) : 1)
 /* Advance multi-byte pointer, skip over composing chars. */
 # define mb_ptr_adv(p)      (p += has_mbyte ? (*mb_ptr2len)((char_u *)p) : 1)
 /* Advance multi-byte pointer, do not skip over composing chars. */
 # define mb_cptr_adv(p)     (p += \
  enc_utf8 ? utf_ptr2len(p) : has_mbyte ? (*mb_ptr2len)(p) : 1)
 /* Backup multi-byte pointer. Only use with "p" > "s" ! */
 # define mb_ptr_back(s, p)  (p -= has_mbyte ? ((*mb_head_off)((char_u *)s, (char_u *)p - 1) + 1) : 1)
 /* get length of multi-byte char, not including composing chars */
 # define mb_cptr2len(p)     (enc_utf8 ? utf_ptr2len(p) : (*mb_ptr2len)(p))
-# define MB_COPY_CHAR(f, t) \
+// Get the length of the character p points to
-  if (has_mbyte) mb_copy_char((const char_u **)(&f), &t); \
+# define MB_PTR2LEN(p)          mb_ptr2len(p)
-  else *t++ = *f++
+// Advance multi-byte pointer, skip over composing chars.
-# define MB_CHARLEN(p)      (has_mbyte ? mb_charlen(p) : (int)STRLEN(p))
+# define mb_ptr_adv(p)      (p += mb_ptr2len((char_u *)p))
-# define MB_CHAR2LEN(c)     (has_mbyte ? mb_char2len(c) : 1)
+// Advance multi-byte pointer, do not skip over composing chars.
-# define PTR2CHAR(p)        (has_mbyte ? mb_ptr2char(p) : (int)*(p))
+# define mb_cptr_adv(p)     (p += utf_ptr2len(p))
 // Backup multi-byte pointer. Only use with "p" > "s" !
 # define mb_ptr_back(s, p)  (p -= mb_head_off((char_u *)s, (char_u *)p - 1) + 1)
 // get length of multi-byte char, not including composing chars
 # define mb_cptr2len(p)     utf_ptr2len(p)
 # define MB_COPY_CHAR(f, t) mb_copy_char((const char_u **)(&f), &t);
 # define MB_CHARLEN(p)      mb_charlen(p)
 # define MB_CHAR2LEN(c)     mb_char2len(c)
 # define PTR2CHAR(p)        mb_ptr2char(p)
 # define RESET_BINDING(wp)  (wp)->w_p_scb = FALSE; (wp)->w_p_crb = FALSE
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@ -177,7 +177,6 @@ void early_init(void)
  fs_init();
  handle_init();
  (void)mb_init();      // init mb_bytelen_tab[] to ones
  eval_init();          // init global variables
  // Init the table of Normal mode commands.
--- a/src/nvim/mbyte.c
+++ b/src/nvim/mbyte.c
@ -1,68 +1,27 @@
-/*
+/// mbyte.c: Code specifically for handling multi-byte characters.
- * mbyte.c: Code specifically for handling multi-byte characters.
+/// Multibyte extensions partly by Sung-Hoon Baek
- * Multibyte extensions partly by Sung-Hoon Baek
+///
- *
+/// The encoding used in nvim is always UTF-8. "enc_utf8" and "has_mbyte" is
- * The encoding used in the core is set with 'encoding'.  When 'encoding' is
+/// thus always true. "enc_dbcs" is always zero. The 'encoding' option is
- * changed, the following four variables are set (for speed).
+/// read-only and always reads "utf-8".
- * Currently these types of character encodings are supported:
+///
- *
+/// The cell width on the display needs to be determined from the character
- * "enc_dbcs"	    When non-zero it tells the type of double byte character
+/// value. Recognizing UTF-8 bytes is easy: 0xxx.xxxx is a single-byte char,
- *		    encoding (Chinese, Korean, Japanese, etc.).
+/// 10xx.xxxx is a trailing byte, 11xx.xxxx is a leading byte of a multi-byte
- *		    The cell width on the display is equal to the number of
+/// character. To make things complicated, up to six composing characters
- *		    bytes.  (exception: DBCS_JPNU with first byte 0x8e)
+/// are allowed. These are drawn on top of the first char. For most editing
- *		    Recognizing the first or second byte is difficult, it
+/// the sequence of bytes with composing characters included is considered to
- *		    requires checking a byte sequence from the start.
+/// be one character.
- * "enc_utf8"	    When TRUE use Unicode characters in UTF-8 encoding.
+///
- *		    The cell width on the display needs to be determined from
+/// UTF-8 is used everywhere in the core. This is in registers, text
- *		    the character value.
+/// manipulation, buffers, etc. Nvim core communicates with external plugins
- *		    Recognizing bytes is easy: 0xxx.xxxx is a single-byte
+/// and GUIs in this encoding.
- *		    char, 10xx.xxxx is a trailing byte, 11xx.xxxx is a leading
+///
- *		    byte of a multi-byte character.
+/// The encoding of a file is specified with 'fileencoding'.  Conversion
- *		    To make things complicated, up to six composing characters
+/// is to be done when it's different from "utf-8".
- *		    are allowed.  These are drawn on top of the first char.
+///
- *		    For most editing the sequence of bytes with composing
+/// Vim scripts may contain an ":scriptencoding" command. This has an effect
- *		    characters included is considered to be one character.
+/// for some commands, like ":menutrans".
 * "enc_unicode"    When 2 use 16-bit Unicode characters (or UTF-16).
 *		    When 4 use 32-but Unicode characters.
 *		    Internally characters are stored in UTF-8 encoding to
 *		    avoid NUL bytes.  Conversion happens when doing I/O.
 *		    "enc_utf8" will also be TRUE.
 *
 * "has_mbyte" is set when "enc_dbcs" or "enc_utf8" is non-zero.
 *
 * If none of these is TRUE, 8-bit bytes are used for a character.  The
 * encoding isn't currently specified (TODO).
 *
 * 'encoding' specifies the encoding used in the core.  This is in registers,
 * text manipulation, buffers, etc.  Conversion has to be done when characters
 * in another encoding are received or send:
 *
 *		       clipboard
 *			   ^
 *			   | (2)
 *			   V
 *		   +---------------+
 *	      (1)  |		   | (3)
 *  keyboard ----->|	 core	   |-----> display
 *		   |		   |
 *		   +---------------+
 *			   ^
 *			   | (4)
 *			   V
 *			 file
 *
 * (1) Typed characters arrive in the current locale.
 * (2) Text will be made available with the encoding specified with
 *     'encoding'.  If this is not sufficient, system-specific conversion
 *     might be required.
 * (3) For the GUI the correct font must be selected, no conversion done.
 * (4) The encoding of the file is specified with 'fileencoding'.  Conversion
 *     is to be done when it's different from 'encoding'.
 *
 * The ShaDa file is a special case: Only text is converted, not file names.
 * Vim scripts may contain an ":encoding" command.  This has an effect for
 * some commands, like ":menutrans"
 */
 #include <inttypes.h>
 #include <stdbool.h>
@ -115,7 +74,7 @@ struct interval {
 * Bytes which are illegal when used as the first byte have a 1.
 * The NUL byte has length 1.
 */
-static char utf8len_tab[256] =
+char utf8len_tab[256] =
 {
  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
  1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
@ -384,207 +343,6 @@ int enc_canon_props(const char_u *name)
  return 0;
 }
 /*
 * Set up for using multi-byte characters.
 * Called in three cases:
 * - by main() to initialize (p_enc == NULL)
 * - by set_init_1() after 'encoding' was set to its default.
 * - by do_set() when 'encoding' has been set.
 * p_enc must have been passed through enc_canonize() already.
 * Sets the "enc_unicode", "enc_utf8", "enc_dbcs" and "has_mbyte" flags.
 * Fills mb_bytelen_tab[] and returns NULL when there are no problems.
 * When there is something wrong: Returns an error message and doesn't change
 * anything.
 */
 char_u * mb_init(void)
 {
  int i;
  int idx;
  int n;
  int enc_dbcs_new = 0;
 #if defined(USE_ICONV) && !defined(WIN3264) && !defined(WIN32UNIX) \
  && !defined(MACOS)
 # define LEN_FROM_CONV
  vimconv_T vimconv;
  char_u      *p;
 #endif
  if (p_enc == NULL) {
    /* Just starting up: set the whole table to one's. */
    for (i = 0; i < 256; ++i)
      mb_bytelen_tab[i] = 1;
    return NULL;
  } else if (STRNCMP(p_enc, "8bit-", 5) == 0
      || STRNCMP(p_enc, "iso-8859-", 9) == 0) {
    /* Accept any "8bit-" or "iso-8859-" name. */
    enc_unicode = 0;
    enc_utf8 = false;
  } else if (STRNCMP(p_enc, "2byte-", 6) == 0) {
    /* Unix: accept any "2byte-" name, assume current locale. */
    enc_dbcs_new = DBCS_2BYTE;
  } else if ((idx = enc_canon_search(p_enc)) >= 0) {
    i = enc_canon_table[idx].prop;
    if (i & ENC_UNICODE) {
      /* Unicode */
      enc_utf8 = true;
      if (i & (ENC_2BYTE | ENC_2WORD))
        enc_unicode = 2;
      else if (i & ENC_4BYTE)
        enc_unicode = 4;
      else
        enc_unicode = 0;
    } else if (i & ENC_DBCS) {
      /* 2byte, handle below */
      enc_dbcs_new = enc_canon_table[idx].codepage;
    } else {
      /* Must be 8-bit. */
      enc_unicode = 0;
      enc_utf8 = false;
    }
  } else    /* Don't know what encoding this is, reject it. */
    return e_invarg;
  if (enc_dbcs_new != 0) {
    enc_unicode = 0;
    enc_utf8 = false;
  }
  enc_dbcs = enc_dbcs_new;
  has_mbyte = (enc_dbcs != 0 || enc_utf8);
  /* Detect an encoding that uses latin1 characters. */
  enc_latin1like = (enc_utf8 || STRCMP(p_enc, "latin1") == 0
      || STRCMP(p_enc, "iso-8859-15") == 0);
  /*
   * Set the function pointers.
   */
  if (enc_utf8) {
    mb_ptr2len = utfc_ptr2len;
    mb_ptr2len_len = utfc_ptr2len_len;
    mb_char2len = utf_char2len;
    mb_char2bytes = utf_char2bytes;
    mb_ptr2cells = utf_ptr2cells;
    mb_ptr2cells_len = utf_ptr2cells_len;
    mb_char2cells = utf_char2cells;
    mb_off2cells = utf_off2cells;
    mb_ptr2char = utf_ptr2char;
    mb_head_off = utf_head_off;
  } else if (enc_dbcs != 0) {
    mb_ptr2len = dbcs_ptr2len;
    mb_ptr2len_len = dbcs_ptr2len_len;
    mb_char2len = dbcs_char2len;
    mb_char2bytes = dbcs_char2bytes;
    mb_ptr2cells = dbcs_ptr2cells;
    mb_ptr2cells_len = dbcs_ptr2cells_len;
    mb_char2cells = dbcs_char2cells;
    mb_off2cells = dbcs_off2cells;
    mb_ptr2char = dbcs_ptr2char;
    mb_head_off = dbcs_head_off;
  } else {
    mb_ptr2len = latin_ptr2len;
    mb_ptr2len_len = latin_ptr2len_len;
    mb_char2len = latin_char2len;
    mb_char2bytes = latin_char2bytes;
    mb_ptr2cells = latin_ptr2cells;
    mb_ptr2cells_len = latin_ptr2cells_len;
    mb_char2cells = latin_char2cells;
    mb_off2cells = latin_off2cells;
    mb_ptr2char = latin_ptr2char;
    mb_head_off = latin_head_off;
  }
  /*
   * Fill the mb_bytelen_tab[] for MB_BYTE2LEN().
   */
 #ifdef LEN_FROM_CONV
  /* When 'encoding' is different from the current locale mblen() won't
   * work.  Use conversion to "utf-8" instead. */
  vimconv.vc_type = CONV_NONE;
  if (enc_dbcs) {
    p = enc_locale();
    if (p == NULL || STRCMP(p, p_enc) != 0) {
      convert_setup(&vimconv, p_enc, (char_u *)"utf-8");
      vimconv.vc_fail = true;
    }
    xfree(p);
  }
 #endif
  for (i = 0; i < 256; ++i) {
    /* Our own function to reliably check the length of UTF-8 characters,
     * independent of mblen(). */
    if (enc_utf8)
      n = utf8len_tab[i];
    else if (enc_dbcs == 0)
      n = 1;
    else {
      char buf[MB_MAXBYTES + 1];
      if (i == NUL)             /* just in case mblen() can't handle "" */
        n = 1;
      else {
        buf[0] = i;
        buf[1] = 0;
 #ifdef LEN_FROM_CONV
        if (vimconv.vc_type != CONV_NONE) {
          /*
           * string_convert() should fail when converting the first
           * byte of a double-byte character.
           */
          p = string_convert(&vimconv, (char_u *)buf, NULL);
          if (p != NULL) {
            xfree(p);
            n = 1;
          } else
            n = 2;
        } else
 #endif
        {
          /*
           * mblen() should return -1 for invalid (means the leading
           * multibyte) character.  However there are some platforms
           * where mblen() returns 0 for invalid character.
           * Therefore, following condition includes 0.
           */
          ignored = mblen(NULL, 0);             /* First reset the state. */
          if (mblen(buf, (size_t)1) <= 0)
            n = 2;
          else
            n = 1;
        }
      }
    }
    mb_bytelen_tab[i] = n;
  }
 #ifdef LEN_FROM_CONV
  convert_setup(&vimconv, NULL, NULL);
 #endif
  /* The cell width depends on the type of multi-byte characters. */
  (void)init_chartab();
  /* When enc_utf8 is set or reset, (de)allocate ScreenLinesUC[] */
  screenalloc(false);
 #ifdef HAVE_WORKING_LIBINTL
  /* GNU gettext 0.10.37 supports this feature: set the codeset used for
   * translated messages independently from the current locale. */
  (void)bind_textdomain_codeset(PROJECT_NAME,
                                enc_utf8 ? "utf-8" : (char *)p_enc);
 #endif
  /* Fire an autocommand to let people do custom font setup. This must be
   * after Vim has been setup for the new encoding. */
  apply_autocmds(EVENT_ENCODINGCHANGED, NULL, (char_u *)"", FALSE, curbuf);
  /* Need to reload spell dictionaries */
  spell_reload();
  return NULL;
 }
 /*
 * Return the size of the BOM for the current buffer:
 * 0 - no BOM
@ -597,20 +355,15 @@ int bomb_size(void)
  int n = 0;
  if (curbuf->b_p_bomb && !curbuf->b_p_bin) {
-    if (*curbuf->b_p_fenc == NUL) {
+    if (*curbuf->b_p_fenc == NUL
-      if (enc_utf8) {
+        || STRCMP(curbuf->b_p_fenc, "utf-8") == 0) {
        if (enc_unicode != 0)
          n = enc_unicode;
        else
          n = 3;
      }
    } else if (STRCMP(curbuf->b_p_fenc, "utf-8") == 0)
      n = 3;
-    else if (STRNCMP(curbuf->b_p_fenc, "ucs-2", 5) == 0
+    } else if (STRNCMP(curbuf->b_p_fenc, "ucs-2", 5) == 0
-        || STRNCMP(curbuf->b_p_fenc, "utf-16", 6) == 0)
+               || STRNCMP(curbuf->b_p_fenc, "utf-16", 6) == 0) {
      n = 2;
-    else if (STRNCMP(curbuf->b_p_fenc, "ucs-4", 5) == 0)
+    } else if (STRNCMP(curbuf->b_p_fenc, "ucs-4", 5) == 0) {
      n = 4;
    }
  }
  return n;
 }
@ -803,99 +556,6 @@ int dbcs_class(unsigned lead, unsigned trail)
  return 3;
 }
 /*
 * mb_char2len() function pointer.
 * Return length in bytes of character "c".
 * Returns 1 for a single-byte character.
 */
 int latin_char2len(int c)
 {
  return 1;
 }
 static int dbcs_char2len(int c)
 {
  if (c >= 0x100)
    return 2;
  return 1;
 }
 /*
 * mb_char2bytes() function pointer.
 * Convert a character to its bytes.
 * Returns the length in bytes.
 */
 int latin_char2bytes(int c, char_u *buf)
 {
  buf[0] = c;
  return 1;
 }
 static int dbcs_char2bytes(int c, char_u *buf)
 {
  if (c >= 0x100) {
    buf[0] = (unsigned)c >> 8;
    buf[1] = c;
    /* Never use a NUL byte, it causes lots of trouble.  It's an invalid
     * character anyway. */
    if (buf[1] == NUL)
      buf[1] = '\n';
    return 2;
  }
  buf[0] = c;
  return 1;
 }
 /*
 * mb_ptr2len() function pointer.
 * Get byte length of character at "*p" but stop at a NUL.
 * For UTF-8 this includes following composing characters.
 * Returns 0 when *p is NUL.
 */
 int latin_ptr2len(const char_u *p)
 {
  return MB_BYTE2LEN(*p);
 }
 static int dbcs_ptr2len(const char_u *p)
 {
  int len;
  /* Check if second byte is not missing. */
  len = MB_BYTE2LEN(*p);
  if (len == 2 && p[1] == NUL)
    len = 1;
  return len;
 }
 /*
 * mb_ptr2len_len() function pointer.
 * Like mb_ptr2len(), but limit to read "size" bytes.
 * Returns 0 for an empty string.
 * Returns 1 for an illegal char or an incomplete byte sequence.
 */
 int latin_ptr2len_len(const char_u *p, int size)
 {
  if (size < 1 || *p == NUL)
    return 0;
  return 1;
 }
 static int dbcs_ptr2len_len(const char_u *p, int size)
 {
  int len;
  if (size < 1 || *p == NUL)
    return 0;
  if (size == 1)
    return 1;
  /* Check that second byte is not missing. */
  len = MB_BYTE2LEN(*p);
  if (len == 2 && p[1] == NUL)
    len = 1;
  return len;
 }
 /*
 * Return true if "c" is in "table".
 */
@ -963,16 +623,8 @@ int utf_char2cells(int c)
  return 1;
 }
-/*
+/// Return the number of display cells character at "*p" occupies.
- * mb_ptr2cells() function pointer.
+/// This doesn't take care of unprintable characters, use ptr2cells() for that.
 * Return the number of display cells character at "*p" occupies.
 * This doesn't take care of unprintable characters, use ptr2cells() for that.
 */
 int latin_ptr2cells(const char_u *p)
 {
  return 1;
 }
 int utf_ptr2cells(const char_u *p)
 {
  int c;
@ -991,26 +643,9 @@ int utf_ptr2cells(const char_u *p)
  return 1;
 }
-int dbcs_ptr2cells(const char_u *p)
+/// Like utf_ptr2cells(), but limit string length to "size".
-{
+/// For an empty string or truncated character returns 1.
-  /* Number of cells is equal to number of bytes, except for euc-jp when
+int utf_ptr2cells_len(const char_u *p, int size)
   * the first byte is 0x8e. */
  if (enc_dbcs == DBCS_JPNU && *p == 0x8e)
    return 1;
  return MB_BYTE2LEN(*p);
 }
 /*
 * mb_ptr2cells_len() function pointer.
 * Like mb_ptr2cells(), but limit string length to "size".
 * For an empty string or truncated character returns 1.
 */
 int latin_ptr2cells_len(const char_u *p, int size)
 {
  return 1;
 }
 static int utf_ptr2cells_len(const char_u *p, int size)
 {
  int c;
@ -1030,35 +665,6 @@ static int utf_ptr2cells_len(const char_u *p, int size)
  return 1;
 }
 static int dbcs_ptr2cells_len(const char_u *p, int size)
 {
  /* Number of cells is equal to number of bytes, except for euc-jp when
   * the first byte is 0x8e. */
  if (size <= 1 || (enc_dbcs == DBCS_JPNU && *p == 0x8e))
    return 1;
  return MB_BYTE2LEN(*p);
 }
 /*
 * mb_char2cells() function pointer.
 * Return the number of display cells character "c" occupies.
 * Only takes care of multi-byte chars, not "^C" and such.
 */
 int latin_char2cells(int c)
 {
  return 1;
 }
 static int dbcs_char2cells(int c)
 {
  /* Number of cells is equal to number of bytes, except for euc-jp when
   * the first byte is 0x8e. */
  if (enc_dbcs == DBCS_JPNU && ((unsigned)c >> 8) == 0x8e)
    return 1;
  /* use the first byte */
  return MB_BYTE2LEN((unsigned)c >> 8);
 }
 /// Calculate the number of cells occupied by string `str`.
 ///
 /// @param str The source string, may not be NULL, must be a NUL-terminated
@ -1075,50 +681,13 @@ size_t mb_string2cells(const char_u *str)
  return clen;
 }
-/*
+/// Return number of display cells for char at ScreenLines[off].
- * mb_off2cells() function pointer.
+/// We make sure that the offset used is less than "max_off".
 * Return number of display cells for char at ScreenLines[off].
 * We make sure that the offset used is less than "max_off".
 */
 int latin_off2cells(unsigned off, unsigned max_off)
 {
  return 1;
 }
 int dbcs_off2cells(unsigned off, unsigned max_off)
 {
  /* never check beyond end of the line */
  if (off >= max_off)
    return 1;
  /* Number of cells is equal to number of bytes, except for euc-jp when
   * the first byte is 0x8e. */
  if (enc_dbcs == DBCS_JPNU && ScreenLines[off] == 0x8e)
    return 1;
  return MB_BYTE2LEN(ScreenLines[off]);
 }
 int utf_off2cells(unsigned off, unsigned max_off)
 {
  return (off + 1 < max_off && ScreenLines[off + 1] == 0) ? 2 : 1;
 }
 /*
 * mb_ptr2char() function pointer.
 * Convert a byte sequence into a character.
 */
 int latin_ptr2char(const char_u *p)
 {
  return *p;
 }
 static int dbcs_ptr2char(const char_u *p)
 {
  if (MB_BYTE2LEN(*p) > 1 && p[1] != NUL)
    return (p[0] << 8) + p[1];
  return *p;
 }
 /*
 * Convert a UTF-8 byte sequence to a wide character.
 * If the sequence is illegal or truncated by a NUL the first byte is
@ -2065,68 +1634,9 @@ void show_utf8(void)
  msg(IObuff);
 }
-/*
+/// Return offset from "p" to the first byte of the character it points into.
- * mb_head_off() function pointer.
+/// If "p" points to the NUL at the end of the string return 0.
- * Return offset from "p" to the first byte of the character it points into.
+/// Returns 0 when already at the first byte of a character.
 * If "p" points to the NUL at the end of the string return 0.
 * Returns 0 when already at the first byte of a character.
 */
 int latin_head_off(const char_u *base, const char_u *p)
 {
  return 0;
 }
 int dbcs_head_off(const char_u *base, const char_u *p)
 {
  /* It can't be a trailing byte when not using DBCS, at the start of the
   * string or the previous byte can't start a double-byte. */
  if (p <= base || MB_BYTE2LEN(p[-1]) == 1 || *p == NUL) {
    return 0;
  }
  /* This is slow: need to start at the base and go forward until the
   * byte we are looking for.  Return 1 when we went past it, 0 otherwise. */
  const char_u *q = base;
  while (q < p) {
    q += dbcs_ptr2len(q);
  }
  return (q == p) ? 0 : 1;
 }
 /*
 * Special version of dbcs_head_off() that works for ScreenLines[], where
 * single-width DBCS_JPNU characters are stored separately.
 */
 int dbcs_screen_head_off(const char_u *base, const char_u *p)
 {
  /* It can't be a trailing byte when not using DBCS, at the start of the
   * string or the previous byte can't start a double-byte.
   * For euc-jp an 0x8e byte in the previous cell always means we have a
   * lead byte in the current cell. */
  if (p <= base
      || (enc_dbcs == DBCS_JPNU && p[-1] == 0x8e)
      || MB_BYTE2LEN(p[-1]) == 1
      || *p == NUL)
    return 0;
  /* This is slow: need to start at the base and go forward until the
   * byte we are looking for.  Return 1 when we went past it, 0 otherwise.
   * For DBCS_JPNU look out for 0x8e, which means the second byte is not
   * stored as the next byte. */
  const char_u *q = base;
  while (q < p) {
    if (enc_dbcs == DBCS_JPNU && *q == 0x8e) {
      ++q;
    }
    else {
      q += dbcs_ptr2len(q);
    }
  }
  return (q == p) ? 0 : 1;
 }
 int utf_head_off(const char_u *base, const char_u *p)
 {
  int c;
@ -2232,26 +1742,20 @@ int mb_tail_off(char_u *base, char_u *p)
  if (*p == NUL)
    return 0;
-  if (enc_utf8) {
+  // Find the last character that is 10xx.xxxx
-    /* Find the last character that is 10xx.xxxx */
+  for (i = 0; (p[i + 1] & 0xc0) == 0x80; i++) {}
-    for (i = 0; (p[i + 1] & 0xc0) == 0x80; ++i)
+
-      ;
+  // Check for illegal sequence.
-    /* Check for illegal sequence. */
+  for (j = 0; p - j > base; j++) {
-    for (j = 0; p - j > base; ++j)
+    if ((p[-j] & 0xc0) != 0x80) {
-      if ((p[-j] & 0xc0) != 0x80)
+      break;
-        break;
+    }
    if (utf8len_tab[p[-j]] != i + j + 1)
      return 0;
    return i;
  }
-  /* It can't be the first byte if a double-byte when not using DBCS, at the
+  if (utf8len_tab[p[-j]] != i + j + 1) {
   * end of the string or the byte can't start a double-byte. */
  if (enc_dbcs == 0 || p[1] == NUL || MB_BYTE2LEN(*p) == 1)
    return 0;
-
+  }
-  /* Return 1 when on the lead byte, 0 when on the tail byte. */
+  return i;
  return 1 - dbcs_head_off(base, p);
 }
 /*
@ -2466,13 +1970,10 @@ int mb_fix_col(int col, int row)
 {
  col = check_col(col);
  row = check_row(row);
-  if (has_mbyte && ScreenLines != NULL && col > 0
+  if (ScreenLines != NULL && col > 0
-      && ((enc_dbcs
+      && ScreenLines[LineOffset[row] + col] == 0) {
          && ScreenLines[LineOffset[row] + col] != NUL
          && dbcs_screen_head_off(ScreenLines + LineOffset[row],
            ScreenLines + LineOffset[row] + col))
        || (enc_utf8 && ScreenLines[LineOffset[row] + col] == 0)))
    return col - 1;
  }
  return col;
 }
--- a/src/nvim/mbyte.h
+++ b/src/nvim/mbyte.h
@ -9,8 +9,8 @@
 * MB_BYTE2LEN_CHECK() can be used to count a special key as one byte.
 * Don't call MB_BYTE2LEN(b) with b < 0 or b > 255!
 */
-#define MB_BYTE2LEN(b)         mb_bytelen_tab[b]
+#define MB_BYTE2LEN(b)         utf8len_tab[b]
-#define MB_BYTE2LEN_CHECK(b)   (((b) < 0 || (b) > 255) ? 1 : mb_bytelen_tab[b])
+#define MB_BYTE2LEN_CHECK(b)   (((b) < 0 || (b) > 255) ? 1 : utf8len_tab[b])
 /* properties used in enc_canon_table[] (first three mutually exclusive) */
 #define ENC_8BIT       0x01
@ -28,6 +28,18 @@
 #define ENC_LATIN9     0x400       /* Latin9 */
 #define ENC_MACROMAN   0x800       /* Mac Roman (not Macro Man! :-) */
 // TODO(bfredl): eventually we should keep only one of the namings
 #define mb_ptr2len utfc_ptr2len
 #define mb_ptr2len_len utfc_ptr2len_len
 #define mb_char2len utf_char2len
 #define mb_char2bytes utf_char2bytes
 #define mb_ptr2cells utf_ptr2cells
 #define mb_ptr2cells_len utf_ptr2cells_len
 #define mb_char2cells utf_char2cells
 #define mb_off2cells utf_off2cells
 #define mb_ptr2char utf_ptr2char
 #define mb_head_off utf_head_off
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "mbyte.h.generated.h"
 #endif
--- a/src/nvim/ops.c
+++ b/src/nvim/ops.c
@ -1936,8 +1936,7 @@ int swapchar(int op_type, pos_T *pos)
  if (c >= 0x80 && op_type == OP_ROT13)
    return FALSE;
-  if (op_type == OP_UPPER && c == 0xdf
+  if (op_type == OP_UPPER && c == 0xdf) {
      && (enc_latin1like || STRCMP(p_enc, "iso-8859-2") == 0)) {
    pos_T sp = curwin->w_cursor;
    /* Special handling of German sharp s: change to "SS". */
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@ -780,14 +780,11 @@ void set_init_1(void)
  }
  fenc_default = p;
-  // Initialize multibyte (utf-8) handling
+#ifdef HAVE_WORKING_LIBINTL
-  mb_init();
+  // GNU gettext 0.10.37 supports this feature: set the codeset used for
-
+  // translated messages independently from the current locale.
-  // Don't change &encoding when resetting to defaults with ":set all&".
+  (void)bind_textdomain_codeset(PROJECT_NAME, (char *)p_enc);
-  opt_idx = findoption((char_u *)"encoding");
+#endif
  if (opt_idx >= 0) {
    options[opt_idx].flags |= P_NODEFAULT;
  }
  /* Set the default for 'helplang'. */
  set_helplang_default(get_mess_lang());
@ -2580,19 +2577,17 @@ did_set_string_option (
      errmsg = e_invarg;
  /* 'encoding' and 'fileencoding' */
  } else if (varp == &p_enc || gvarp == &p_fenc) {
-    if (varp == &p_enc && did_source_startup_scripts) {
+    if (gvarp == &p_fenc) {
-       errmsg = e_afterinit;
+      if (!MODIFIABLE(curbuf) && opt_flags != OPT_GLOBAL) {
    } else if (gvarp == &p_fenc) {
      if (!MODIFIABLE(curbuf) && opt_flags != OPT_GLOBAL)
        errmsg = e_modifiable;
-      else if (vim_strchr(*varp, ',') != NULL)
+      } else if (vim_strchr(*varp, ',') != NULL) {
-        /* No comma allowed in 'fileencoding'; catches confusing it
+        // No comma allowed in 'fileencoding'; catches confusing it
-         * with 'fileencodings'. */
+        // with 'fileencodings'.
        errmsg = e_invarg;
-      else {
+      } else {
-        /* May show a "+" in the title now. */
+        // May show a "+" in the title now.
        redraw_titles();
-        /* Add 'fileencoding' to the swap file. */
+        // Add 'fileencoding' to the swap file.
        ml_setflags(curbuf);
      }
    }
@ -2603,17 +2598,12 @@ did_set_string_option (
      xfree(*varp);
      *varp = p;
      if (varp == &p_enc) {
-        errmsg = mb_init();
+        // only encoding=utf-8 allowed
-        redraw_titles();
+        if (STRCMP(p_enc, "utf-8") != 0) {
          errmsg = e_invarg;
        }
      }
    }
    if (errmsg == NULL) {
      /* When 'keymap' is used and 'encoding' changes, reload the keymap
       * (with another encoding). */
      if (varp == &p_enc && *curbuf->b_p_keymap != NUL)
        (void)keymap_init();
    }
  } else if (varp == &p_penc) {
    /* Canonize printencoding if VIM standard one */
    p = enc_canonize(p_penc);
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@ -5292,7 +5292,7 @@ void screen_puts_len(char_u *text, int textlen, int row, int col, int attr)
  int force_redraw_next = FALSE;
  int need_redraw;
-  const int l_has_mbyte = has_mbyte;
+  const bool l_has_mbyte = has_mbyte;
  const bool l_enc_utf8 = enc_utf8;
  const int l_enc_dbcs = enc_dbcs;
@ -5459,9 +5459,6 @@ void screen_puts_len(char_u *text, int textlen, int row, int col, int attr)
  /* If we detected the next character needs to be redrawn, but the text
   * doesn't extend up to there, update the character here. */
  if (force_redraw_next && col < screen_Columns) {
    if (l_enc_dbcs != 0 && dbcs_off2cells(off, max_off) > 1)
      screen_char_2(off, row, col);
    else
      screen_char(off, row, col);
  }
 }
--- a/src/nvim/spell.c
+++ b/src/nvim/spell.c
@ -9266,9 +9266,7 @@ static void allcap_copy(char_u *word, char_u *wcopy)
    else
      c = *s++;
-    // We only change 0xdf to SS when we are certain latin1 is used.  It
+    if (c == 0xdf) {
    // would cause weird errors in other 8-bit encodings.
    if (enc_latin1like && c == 0xdf) {
      c = 'S';
      if (d - wcopy >= MAXWLEN - 1)
        break;
@ -12602,7 +12600,7 @@ static int spell_edit_score(slang_T *slang, char_u *badword, char_u *goodword)
  char_u      *p;
  int wbadword[MAXWLEN];
  int wgoodword[MAXWLEN];
-  const int l_has_mbyte = has_mbyte;
+  const bool l_has_mbyte = has_mbyte;
  if (l_has_mbyte) {
    // Get the characters from the multi-byte strings and put them in an
--- a/src/nvim/tui/input.c
+++ b/src/nvim/tui/input.c
@ -31,8 +31,8 @@ void term_input_init(TermInput *input, Loop *loop)
  if (!term) {
    term = "";  // termkey_new_abstract assumes non-null (#2745)
  }
-  int enc_flag = enc_utf8 ? TERMKEY_FLAG_UTF8 : TERMKEY_FLAG_RAW;
+
-  input->tk = termkey_new_abstract(term, enc_flag);
+  input->tk = termkey_new_abstract(term, TERMKEY_FLAG_UTF8);
  int curflags = termkey_get_canonflags(input->tk);
  termkey_set_canonflags(input->tk, curflags | TERMKEY_CANON_DELBS);
--- a/test/functional/eval/json_functions_spec.lua
+++ b/test/functional/eval/json_functions_spec.lua
@ -489,18 +489,6 @@ describe('json_decode() function', function()
                 '{"b": 3, "a": 1, "c": 4, "d": 2, "\\u0000": 4}')
  end)
  it('converts strings to latin1 when &encoding is latin1', function()
    restart('--cmd', 'set encoding=latin1')
    eq('\171', funcs.json_decode('"\\u00AB"'))
    sp_decode_eq({_TYPE='string', _VAL={'\n\171\n'}}, '"\\u0000\\u00AB\\u0000"')
  end)
  it('fails to convert string to latin1 if it is impossible', function()
    restart('--cmd', 'set encoding=latin1')
    eq('Vim(call):E474: Failed to convert string "ꯍ" from UTF-8',
       exc_exec('call json_decode(\'"\\uABCD"\')'))
  end)
  it('parses U+00C3 correctly', function()
    eq('\195\131', funcs.json_decode('"\195\131"'))
  end)
@ -528,14 +516,6 @@ describe('json_decode() function', function()
    eq({key={'val', 'val2'}, key2=1}, funcs.json_decode(str))
  end)
  it('always treats input as UTF-8', function()
    -- When &encoding is latin1 string "«" is U+00C2 U+00AB U+00C2: Â«Â. So if
    -- '"«"' was parsed as latin1 json_decode would return three characters, and
    -- only one U+00AB when this string is parsed as latin1.
    restart('--cmd', 'set encoding=latin1')
    eq(('%c'):format(0xAB), funcs.json_decode('"«"'))
  end)
  it('does not overflow when writing error message about decoding ["", ""]',
  function()
    eq('\nE474: Attempt to decode a blank string'
@ -762,12 +742,6 @@ describe('json_encode() function', function()
       exc_exec('call json_encode(["", ""], 1)'))
  end)
  it('converts strings from latin1 when &encoding is latin1', function()
    clear('--cmd', 'set encoding=latin1')
    eq('"\\u00AB"', funcs.json_encode('\171'))
    eq('"\\u0000\\u00AB\\u0000"', eval('json_encode({"_TYPE": v:msgpack_types.string, "_VAL": ["\\n\171\\n"]})'))
  end)
  it('ignores improper values in &isprint', function()
    meths.set_option('isprint', '1')
    eq(1, eval('"\1" =~# "\\\\p"'))
--- a/test/functional/ex_cmds/encoding_spec.lua
+++ b/test/functional/ex_cmds/encoding_spec.lua
@ -15,27 +15,26 @@ describe('&encoding', function()
    execute('set encoding=latin1')
    -- error message expected
    feed('<cr>')
-    neq(nil, string.find(eval('v:errmsg'), '^E905:'))
+    neq(nil, string.find(eval('v:errmsg'), '^E474:'))
    eq('utf-8', eval('&encoding'))
    -- check nvim is still in utf-8 mode
    eq(3, eval('strwidth("Bär")'))
  end)
-  it('can be changed before startup', function()
+  it('cannot be changed before startup', function()
    clear('--cmd', 'set enc=latin1')
    execute('set encoding=utf-8')
    -- error message expected
    feed('<cr>')
-    eq('latin1', eval('&encoding'))
+    neq(nil, string.find(eval('v:errmsg'), '^E474:'))
-    eq(4, eval('strwidth("Bär")'))
+    eq('utf-8', eval('&encoding'))
    eq(3, eval('strwidth("Bär")'))
  end)
-  it('is not changed by `set all&`', function()
+  it('can be set to utf-8 without error', function()
-    -- we need to set &encoding to something non-default. Use 'latin1'
+    execute('set encoding=utf-8')
-    clear('--cmd', 'set enc=latin1')
+    eq("", eval('v:errmsg'))
    execute('set all&')
    eq('latin1', eval('&encoding'))
    eq(4, eval('strwidth("Bär")'))
  end)
    clear('--cmd', 'set enc=utf-8')
    eq("", eval('v:errmsg'))
  end)
 end)
--- a/test/functional/shada/history_spec.lua
+++ b/test/functional/shada/history_spec.lua
@ -4,9 +4,7 @@ local nvim_command, funcs, meths, nvim_feed, eq =
  helpers.command, helpers.funcs, helpers.meths, helpers.feed, helpers.eq
 local shada_helpers = require('test.functional.shada.helpers')
-local reset, set_additional_cmd, clear =
+local reset, clear = shada_helpers.reset, shada_helpers.clear
  shada_helpers.reset, shada_helpers.set_additional_cmd,
  shada_helpers.clear
 describe('ShaDa support code', function()
  before_each(reset)
@ -173,120 +171,48 @@ describe('ShaDa support code', function()
    eq('goo', funcs.getline(1))
  end)
-  it('dumps and loads history correctly when &encoding is not UTF-8', function()
+  it('dumps and loads history with UTF-8 characters', function()
    set_additional_cmd('set encoding=latin1')
    reset()
-    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
+    nvim_feed(':echo "«"\n')
    nvim_feed(':echo "\171"\n')
    nvim_command('qall')
    reset()
    eq('echo "\171"', funcs.histget(':', -1))
  end)
  it('dumps and loads history correctly when &encoding /= UTF-8 when dumping',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
    nvim_feed(':echo "\171"\n')
    set_additional_cmd('')
    nvim_command('qall')
    reset()
    eq('echo "«"', funcs.histget(':', -1))
  end)
-  it('dumps and loads history correctly when &encoding /= UTF-8 when loading',
+  it('dumps and loads replacement with UTF-8 characters',
  function()
-    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
+    nvim_command('substitute/./«/ge')
    nvim_feed(':echo "«"\n')
    set_additional_cmd('set encoding=latin1')
    nvim_command('qall')
    reset()
    eq('echo "\171"', funcs.histget(':', -1))
  end)
  it('dumps and loads replacement correctly when &encoding is not UTF-8',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
    nvim_command('substitute/./\171/ge')
    nvim_command('qall!')
    reset()
    funcs.setline('.', {'.'})
    nvim_command('&')
    eq('\171', funcs.getline('.'))
  end)
  it('dumps&loads replacement correctly when &encoding /= UTF-8 when dumping',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
    nvim_command('substitute/./\171/ge')
    set_additional_cmd('')
    nvim_command('qall')
    reset()
    funcs.setline('.', {'.'})
    nvim_command('&')
    eq('«', funcs.getline('.'))
  end)
-  it('dumps&loads replacement correctly when &encoding /= UTF-8 when loading',
+  it('dumps and loads substitute pattern with UTF-8 characters',
  function()
-    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
+    nvim_command('substitute/«/./ge')
    nvim_command('substitute/./«/ge')
    set_additional_cmd('set encoding=latin1')
    nvim_command('qall')
    reset()
    funcs.setline('.', {'.'})
    nvim_command('&')
    eq('\171', funcs.getline('.'))
  end)
  it('dumps and loads substitute pattern correctly when &encoding is not UTF-8',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
    nvim_command('substitute/\171/./ge')
    nvim_command('qall!')
    reset()
    funcs.setline('.', {'\171«'})
    nvim_command('&')
    eq('.«', funcs.getline('.'))
  end)
  it('dumps&loads s/pattern correctly when &encoding /= UTF-8 when dumping',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
    nvim_command('substitute/\171/./ge')
    set_additional_cmd('')
    nvim_command('qall')
    reset()
    funcs.setline('.', {'«\171'})
    nvim_command('&')
    eq('.\171', funcs.getline('.'))
  end)
-  it('dumps&loads s/pattern correctly when &encoding /= UTF-8 when loading',
+  it('dumps and loads search pattern with UTF-8 characters',
  function()
-    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
+    nvim_command('silent! /«/')
-    nvim_command('substitute/«/./ge')
+    nvim_command('set shada+=/0')
-    set_additional_cmd('set encoding=latin1')
+    nvim_command('qall!')
    nvim_command('qall')
    reset()
    funcs.setline('.', {'\171«'})
-    nvim_command('&')
+    nvim_command('~&')
-    eq('.«', funcs.getline('.'))
+    eq('\171', funcs.getline('.'))
    eq('', funcs.histget('/', -1))
  end)
-  it('dumps and loads search pattern correctly when &encoding is not UTF-8',
+  it('dumps and loads search pattern with 8-bit single-byte',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
    nvim_command('silent! /\171/')
    nvim_command('set shada+=/0')
@ -298,33 +224,4 @@ describe('ShaDa support code', function()
    eq('', funcs.histget('/', -1))
  end)
  it('dumps&loads /pattern correctly when &encoding /= UTF-8 when dumping',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
    nvim_command('silent! /\171/')
    nvim_command('set shada+=/0')
    set_additional_cmd('')
    nvim_command('qall')
    reset()
    funcs.setline('.', {'«\171'})
    nvim_command('~&')
    eq('\171', funcs.getline('.'))
    eq('', funcs.histget('/', -1))
  end)
  it('dumps&loads /pattern correctly when &encoding /= UTF-8 when loading',
  function()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
    nvim_command('silent! /«/')
    nvim_command('set shada+=/0')
    set_additional_cmd('set encoding=latin1')
    nvim_command('qall')
    reset()
    funcs.setline('.', {'\171«'})
    nvim_command('~&')
    eq('«', funcs.getline('.'))
    eq('', funcs.histget('/', -1))
  end)
 end)
--- a/test/functional/shada/registers_spec.lua
+++ b/test/functional/shada/registers_spec.lua
@ -128,36 +128,24 @@ describe('ShaDa support code', function()
    eq({{}, ''}, getreg('h'))
  end)
-  it('dumps and loads register correctly when &encoding is not UTF-8',
+  it('dumps and loads register correctly with utf-8 contents',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
-    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
+    setreg('e', {'«'}, 'c')
    setreg('e', {'\171'}, 'c')
    nvim_command('qall')
    reset()
    eq({{'\171'}, 'v'}, getreg('e'))
  end)
  it('dumps and loads history correctly when &encoding /= UTF-8 when dumping',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
    setreg('e', {'\171'}, 'c')
    set_additional_cmd('')
    nvim_command('qall')
    reset()
    eq({{'«'}, 'v'}, getreg('e'))
  end)
-  it('dumps and loads history correctly when &encoding /= UTF-8 when loading',
+  it('dumps and loads history correctly with 8-bit single-byte',
  function()
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
-    setreg('e', {'«'}, 'c')
+    setreg('e', {'\171«'}, 'c')
-    set_additional_cmd('set encoding=latin1')
+    set_additional_cmd('')
    nvim_command('qall')
    reset()
-    eq({{'\171'}, 'v'}, getreg('e'))
+    eq({{'\171«'}, 'v'}, getreg('e'))
  end)
 end)
--- a/test/functional/shada/variables_spec.lua
+++ b/test/functional/shada/variables_spec.lua
@ -91,35 +91,13 @@ describe('ShaDa support code', function()
    eq(0, funcs.exists('g:str_var'))
  end)
-  it('dumps and loads variables correctly when &encoding is not UTF-8',
+  it('dumps and loads variables correctly with utf-8 strings',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
-    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
+    meths.set_var('STRVAR', '«')
-    meths.set_var('STRVAR', '\171')
+    meths.set_var('LSTVAR', {'«'})
-    meths.set_var('LSTVAR', {'\171'})
+    meths.set_var('DCTVAR', {['«']='«'})
-    meths.set_var('DCTVAR', {['\171']='\171'})
+    meths.set_var('NESTEDVAR', {['«']={{'«'}, {['«']='«'}, {a='Test'}}})
    meths.set_var('NESTEDVAR', {['\171']={{'\171'}, {['\171']='\171'},
                                {a='Test'}}})
    nvim_command('qall')
    reset()
    eq('\171', meths.get_var('STRVAR'))
    eq({'\171'}, meths.get_var('LSTVAR'))
    eq({['\171']='\171'}, meths.get_var('DCTVAR'))
    eq({['\171']={{'\171'}, {['\171']='\171'}, {a='Test'}}},
       meths.get_var('NESTEDVAR'))
  end)
  it('dumps and loads variables correctly when &encoding /= UTF-8 when dumping',
  function()
    set_additional_cmd('set encoding=latin1')
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
    meths.set_var('STRVAR', '\171')
    meths.set_var('LSTVAR', {'\171'})
    meths.set_var('DCTVAR', {['\171']='\171'})
    meths.set_var('NESTEDVAR', {['\171']={{'\171'}, {['\171']='\171'},
                                {a='Test'}}})
    set_additional_cmd('')
    nvim_command('qall')
    reset()
@ -129,20 +107,22 @@ describe('ShaDa support code', function()
    eq({['«']={{'«'}, {['«']='«'}, {a='Test'}}}, meths.get_var('NESTEDVAR'))
  end)
-  it('dumps and loads variables correctly when &encoding /= UTF-8 when loading',
+  it('dumps and loads variables correctly with 8-bit strings',
  function()
    reset()
    -- \171 is U+00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK in latin1
-    meths.set_var('STRVAR', '«')
+    -- This is invalid unicode, but we should still dump and restore it.
-    meths.set_var('LSTVAR', {'«'})
+    meths.set_var('STRVAR', '\171')
-    meths.set_var('DCTVAR', {['«']='«'})
+    meths.set_var('LSTVAR', {'\171'})
-    meths.set_var('NESTEDVAR', {['«']={{'«'}, {['«']='«'}, {a='Test'}}})
+    meths.set_var('DCTVAR', {['«\171']='«\171'})
-    set_additional_cmd('set encoding=latin1')
+    meths.set_var('NESTEDVAR', {['\171']={{'\171«'}, {['\171']='\171'},
                                {a='Test'}}})
    nvim_command('qall')
    reset()
    eq('\171', meths.get_var('STRVAR'))
    eq({'\171'}, meths.get_var('LSTVAR'))
-    eq({['\171']='\171'}, meths.get_var('DCTVAR'))
+    eq({['«\171']='«\171'}, meths.get_var('DCTVAR'))
-    eq({['\171']={{'\171'}, {['\171']='\171'}, {a='Test'}}},
+    eq({['\171']={{'\171«'}, {['\171']='\171'}, {a='Test'}}},
       meths.get_var('NESTEDVAR'))
  end)