refactor(highlight)!: rename attributes to match Vim (#19159)

Ref: https://github.com/vim/vim/commit/84f546363068e4ddfe14a8a2a2322bb8d3a25417
Rename:
- `underlineline` to `underdouble`
- `underdot` to `underdotted`
- `underdash` to `underdashed`

`underdouble` also now takes higher precedence than `undercurl`.

5 files changed, 21 insertions, 22 deletions

diff --git a/runtime/doc/api.txt b/runtime/doc/api.txt
index 46f4bc63c9..9b7f1f1632 100644
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@@ -1477,10 +1477,10 @@ nvim_set_hl({ns_id}, {name}, {*val})                           *nvim_set_hl()*
                              • bold: boolean
                              • standout: boolean
                              • underline: boolean
-                             • underlineline: boolean
                              • undercurl: boolean
-                             • underdot: boolean
-                             • underdash: boolean
+                             • underdouble: boolean
+                             • underdotted: boolean
+                             • underdashed: boolean
                              • strikethrough: boolean
                              • italic: boolean
                              • reverse: boolean
diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index ac42b315a4..a8f75066e8 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -8026,10 +8026,10 @@ synIDattr({synID}, {what} [, {mode}])			*synIDattr()*
 		"inverse"	"1" if inverse (= reverse)
 		"standout"	"1" if standout
 		"underline"	"1" if underlined
-		"underlineline"	"1" if double underlined
 		"undercurl"	"1" if undercurled
-		"underdot"	"1" if dotted underlined
-		"underdash"	"1" if dashed underlined
+		"underdouble"	"1" if double underlined
+		"underdotted"	"1" if dotted underlined
+		"underdashed"	"1" if dashed underlined
 		"strikethrough" "1" if struckthrough
 
 		Example (echoes the color of the syntax item under the
diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index 4122f4ad9c..3c3792ad0b 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -4895,19 +4895,19 @@ the same syntax file on all UIs.
 
 1. TUI highlight arguments
 
-					*bold* *underline* *underlineline*
-					*undercurl* *underdot* *underdash*
-					*inverse* *italic* *standout*
-					*nocombine* *strikethrough*
+					*bold* *underline* *undercurl*
+					*underdouble* *underdotted*
+					*underdashed* *inverse* *italic*
+					*standout* *nocombine* *strikethrough*
 cterm={attr-list}			*attr-list* *highlight-cterm* *E418*
 	attr-list is a comma-separated list (without spaces) of the
 	following items (in any order):
 		bold
 		underline
-		underlineline	double underline
 		undercurl	curly underline
-		underdot	dotted underline
-		underdash	dashed underline
+		underdouble	double underline
+		underdotted	dotted underline
+		underdashed	dashed underline
 		strikethrough
 		reverse
 		inverse		same as reverse
@@ -4918,7 +4918,7 @@ cterm={attr-list}			*attr-list* *highlight-cterm* *E418*
 
 	Note that "bold" can be used here and by using a bold font.  They
 	have the same effect.
-	"underlineline", "undercurl", "underdot", and "underdash" fall back
+	"undercurl", "underdouble", "underdotted", and "underdashed" fall back
 	to "underline" in a terminal that does not support them. The color is
 	set using |highlight-guisp|.
 
diff --git a/runtime/doc/ui.txt b/runtime/doc/ui.txt
index eb12fd38a0..3fb9ed1125 100644
--- a/runtime/doc/ui.txt
+++ b/runtime/doc/ui.txt
@@ -314,11 +314,10 @@ numerical highlight ids to the actual attributes.
 	`bold`:			bold text.
 	`strikethrough`:	struckthrough text.
 	`underline`:		underlined text. The line has `special` color.
-	`underlineline`:	double underlined text. The lines have `special`
-				color.
 	`undercurl`:		undercurled text. The curl has `special` color.
-	`underdot`:		underdotted text. The dots have `special` color.
-	`underdash`:		underdashed text. The dashes have `special` color.
+	`underdouble`:		double underlined text. The lines have `special` color.
+	`underdotted`:		underdotted text. The dots have `special` color.
+	`underdashed`:		underdashed text. The dashes have `special` color.
 	`blend`:		Blend level (0-100). Could be used by UIs to
 				support blending floating windows to the
 				background or to signal a transparent cursor.
@@ -477,10 +476,10 @@ is not active. New UIs should implement |ui-linegrid| instead.
 	`bold`:		bold text.
 	`strikethrough`:  struckthrough text.
 	`underline`:	underlined text. The line has `special` color.
-	`underlineline`:  double underlined text. The lines have `special` color.
 	`undercurl`:	undercurled text. The curl has `special` color.
-	`underdot`:	underdotted text. The dots have `special` color.
-	`underdash`:	underdashed text. The dashes have `special` color.
+	`underdouble`:	double underlined text. The lines have `special` color.
+	`underdotted`:	underdotted text. The dots have `special` color.
+	`underdashed`:	underdashed text. The dashes have `special` color.
 
 ["put", text]
 	The (utf-8 encoded) string `text` is put at the cursor position
diff --git a/runtime/syntax/vim.vim b/runtime/syntax/vim.vim
index 76ad1d523d..3a5b6b6418 100644
--- a/runtime/syntax/vim.vim
+++ b/runtime/syntax/vim.vim
@@ -572,7 +572,7 @@ syn match	vimHiBang	contained	"!"	skipwhite nextgroup=@vimHighlightCluster
 
 syn match	vimHiGroup	contained	"\i\+"
 syn case ignore
-syn keyword	vimHiAttrib	contained	none bold inverse italic nocombine reverse standout strikethrough underline underlineline undercurl underdot underdash
+syn keyword	vimHiAttrib	contained	none bold inverse italic nocombine reverse standout strikethrough underline undercurl underdouble underdotted underdashed
 syn keyword	vimFgBgAttrib	contained	none bg background fg foreground
 syn case match
 syn match	vimHiAttribList	contained	"\i\+"	contains=vimHiAttrib