feat(treesitter/extmark): support removing a conceal highlight #35087

Problem:
Cannot remove a `@conceal` highlight when defined in highlights.scm.

Solution:
Support a `@noconceal` highlight that works similarly to `@nospell` where it
overrides the conceal set on the range to remove it. Additionally, can
set the conceal metadata field to false for the same behavior.

runtime/lua/vim/_meta/api.gen.lua

@@ -702,11 +702,14 @@ function vim.api.nvim_buf_line_count(buf) end
 --- - cursorline_hl_group: highlight group used for the sign
 ---     column text when the cursor is on the same line as the
 ---     mark and 'cursorline' is enabled.
---- - conceal: string which should be either empty or a single
----     character. Enable concealing similar to `:syn-conceal`.
----     When a character is supplied it is used as `:syn-cchar`.
----     "hl_group" is used as highlight for the cchar if provided,
----     otherwise it defaults to `hl-Conceal`.
+--- - conceal: either a boolean or a string.
+---     - when a string is given, it should be either empty or a single
+---       character. Enable concealing similar to `:syn-conceal`.
+---       When a character is supplied it is used as `:syn-cchar`.
+---       "hl_group" is used as highlight for the cchar if provided,
+---       otherwise it defaults to `hl-Conceal`.
+---     - when a boolean is given, true is equivalent to "" and false
+---       overrides any existing conceal to remove it.
 --- - conceal_lines: string which should be empty. When
 ---     provided, lines in the range are not drawn at all
 ---     (according to 'conceallevel'); the next unconcealed line

runtime/lua/vim/_meta/api_keysets.gen.lua

@@ -437,7 +437,7 @@ error('Cannot require a meta file')
 --- @field number_hl_group? integer|string
 --- @field line_hl_group? integer|string
 --- @field cursorline_hl_group? integer|string
---- @field conceal? string
+--- @field conceal? string|boolean
 --- @field conceal_lines? string
 --- @field spell? boolean
 --- @field ui_watched? boolean

runtime/lua/vim/_meta/api_keysets_extra.lua

@@ -22,7 +22,7 @@ error('Cannot require a meta file')
 --- @field hl_group? string
 --- @field hl_eol? boolean
 ---
---- @field conceal? string
+--- @field conceal? string|false
 --- @field spell? boolean
 --- @field ui_watched? boolean
 --- @field url? string

runtime/lua/vim/treesitter/highlighter.lua

@@ -427,14 +427,29 @@ local function on_range_impl(
 
           local spell, spell_pri_offset = get_spell(capture_name)
 
+          local is_noconceal = capture_name == 'noconceal'
+          -- The "conceal" attribute can be set at the pattern level or on a particular capture
+          local conceal_attr = (metadata.conceal ~= nil and metadata.conceal)
+            or (metadata[capture] and metadata[capture].conceal)
+          local conceal ---@type boolean|string?
+          if is_noconceal then
+            conceal = false
+          else
+            conceal = conceal_attr
+            if conceal_attr == false then
+              is_noconceal = true
+            end
+          end
+          is_noconceal = is_noconceal or conceal_attr == false
+          local conceal_pri_offset = is_noconceal and 1 or 0
+
           -- The "priority" attribute can be set at the pattern level or on a particular capture
           local priority = (
             vim._tointeger(metadata.priority or metadata[capture] and metadata[capture].priority)
             or vim.hl.priorities.treesitter
-          ) + spell_pri_offset
-
-          -- The "conceal" attribute can be set at the pattern level or on a particular capture
-          local conceal = metadata.conceal or metadata[capture] and metadata[capture].conceal
+          )
+            + spell_pri_offset
+            + conceal_pri_offset
 
           local url = get_url(match, buf, capture, metadata)
 

runtime/lua/vim/treesitter/query.lua

@@ -609,7 +609,7 @@ predicate_handlers['any-vim-match?'] = predicate_handlers['any-match?']
 ---@class vim.treesitter.query.TSMetadata
 ---@field range? Range
 ---@field offset? Range4
----@field conceal? string
+---@field conceal? string|boolean
 ---@field bo.commentstring? string
 ---@field [integer]? vim.treesitter.query.TSMetadata
 ---@field [string]? integer|string