Diagnostic

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Diagnostic framework
Nvim provides a framework for displaying errors or warnings from external tools, otherwise known as "diagnostics". These diagnostics can come from a variety of sources, such as linters or LSP servers. The diagnostic framework is an extension to existing error handling functionality such as the quickfix list.

QUICKSTART diagnostic-quickstart

Anything that reports diagnostics is referred to below as a "diagnostic producer". Diagnostic producers need only follow a few simple steps to report diagnostics:
1. Create a namespace nvim_create_namespace(). Note that the namespace must have a name. Anonymous namespaces WILL NOT WORK. 2. (Optional) Configure options for the diagnostic namespace vim.diagnostic.config(). 3. Generate diagnostics. 4. Set the diagnostics for the buffer vim.diagnostic.set(). 5. Repeat from step 3.
Generally speaking, the API is split between functions meant to be used by diagnostic producers and those meant for diagnostic consumers (i.e. end users who want to read and view the diagnostics for a buffer). The APIs for producers require a {namespace} as their first argument, while those for consumers generally do not require a namespace (though often one may be optionally supplied). A good rule of thumb is that if a method is meant to modify the diagnostics for a buffer (e.g. vim.diagnostic.set()) then it requires a namespace.
diagnostic-structure A diagnostic is a Lua table with the following keys. Required keys are indicated with (*): bufnr: Buffer number lnum(): The starting line of the diagnostic end_lnum: The final line of the diagnostic col(): The starting column of the diagnostic end_col: The final column of the diagnostic severity: The severity of the diagnostic vim.diagnostic.severity message(): The diagnostic text source: The source of the diagnostic code: The diagnostic code user_data: Arbitrary data plugins or users can add
Diagnostics use the same indexing as the rest of the Nvim API (i.e. 0-based rows and columns). api-indexing
vim.diagnostic.severity diagnostic-severity The "severity" key in a diagnostic is one of the values defined in vim.diagnostic.severity:
vim.diagnostic.severity.ERROR vim.diagnostic.severity.WARN vim.diagnostic.severity.INFO vim.diagnostic.severity.HINT
Functions that take a severity as an optional parameter (e.g. vim.diagnostic.get()) accept one of two forms:
1. A single vim.diagnostic.severity value:
vim.diagnostic.get(0, { severity = vim.diagnostic.severity.WARN })
2. A table with a "min" or "max" key (or both):
vim.diagnostic.get(0, { severity = { min = vim.diagnostic.severity.WARN } })
The latter form allows users to specify a range of severities.

HANDLERS diagnostic-handlers

Diagnostics are shown to the user with vim.diagnostic.show(). The display of diagnostics is managed through handlers. A handler is a table with a "show" and (optionally) a "hide" function. The "show" function has the signature
function(namespace, bufnr, diagnostics, opts)
and is responsible for displaying or otherwise handling the given diagnostics. The "hide" function takes care of "cleaning up" any actions taken by the "show" function and has the signature
function(namespace, bufnr)
Handlers can be configured with vim.diagnostic.config() and added by creating a new key in vim.diagnostic.handlers (see diagnostic-handlers-example).
The {opts} table passed to a handler is the full set of configuration options (that is, it is not limited to just the options for the handler itself). The values in the table are already resolved (i.e. if a user specifies a function for a config option, the function has already been evaluated).
Nvim provides these handlers by default: "virtual_text", "signs", and "underline".
diagnostic-handlers-example The example below creates a new handler that notifies the user of diagnostics with vim.notify():
-- It's good practice to namespace custom handlers to avoid collisions
vim.diagnostic.handlers["my/notify"] = {
  show = function(namespace, bufnr, diagnostics, opts)
    -- In our example, the opts table has a "log_level" option
    local level = opts["my/notify"].log_level
    local name = vim.diagnostic.get_namespace(namespace).name
    local msg = string.format("%d diagnostics in buffer %d from %s",
                              #diagnostics,
                              bufnr,
                              name)
    vim.notify(msg, level)
  end,
}
-- Users can configure the handler
vim.diagnostic.config({
  ["my/notify"] = {
    log_level = vim.log.levels.INFO
  }
})
In this example, there is nothing to do when diagnostics are hidden, so we omit the "hide" function.
Existing handlers can be overridden. For example, use the following to only show a sign for the highest severity diagnostic on a given line:
-- Create a custom namespace. This will aggregate signs from all other
-- namespaces and only show the one with the highest severity on a
-- given line
local ns = vim.api.nvim_create_namespace("my_namespace")
-- Get a reference to the original signs handler
local orig_signs_handler = vim.diagnostic.handlers.signs
-- Override the built-in signs handler
vim.diagnostic.handlers.signs = {
  show = function(_, bufnr, _, opts)
    -- Get all diagnostics from the whole buffer rather than just the
    -- diagnostics passed to the handler
    local diagnostics = vim.diagnostic.get(bufnr)
    -- Find the "worst" diagnostic per line
    local max_severity_per_line = {}
    for _, d in pairs(diagnostics) do
      local m = max_severity_per_line[d.lnum]
      if not m or d.severity < m.severity then
        max_severity_per_line[d.lnum] = d
      end
    end
    -- Pass the filtered diagnostics (with our custom namespace) to
    -- the original handler
    local filtered_diagnostics = vim.tbl_values(max_severity_per_line)
    orig_signs_handler.show(ns, bufnr, filtered_diagnostics, opts)
  end,
  hide = function(_, bufnr)
    orig_signs_handler.hide(ns, bufnr)
  end,
}

HIGHLIGHTS diagnostic-highlights

All highlights defined for diagnostics begin with Diagnostic followed by the type of highlight (e.g., Sign, Underline, etc.) and the severity (e.g. Error, Warn, etc.)
By default, highlights for signs, floating windows, and virtual text are linked to the corresponding default highlight. Underline highlights are not linked and use their own default highlight groups.
For example, the default highlighting for hl-DiagnosticSignError is linked to hl-DiagnosticError. To change the default (and therefore the linked highlights), use the :highlight command:
highlight DiagnosticError guifg="BrightRed"
hl-DiagnosticError DiagnosticError Used as the base highlight group. Other Diagnostic highlights link to this by default (except Underline)
hl-DiagnosticWarn DiagnosticWarn Used as the base highlight group. Other Diagnostic highlights link to this by default (except Underline)
hl-DiagnosticInfo DiagnosticInfo Used as the base highlight group. Other Diagnostic highlights link to this by default (except Underline)
hl-DiagnosticHint DiagnosticHint Used as the base highlight group. Other Diagnostic highlights link to this by default (except Underline)
hl-DiagnosticOk DiagnosticOk Used as the base highlight group. Other Diagnostic highlights link to this by default (except Underline)
hl-DiagnosticVirtualTextError DiagnosticVirtualTextError Used for "Error" diagnostic virtual text.
hl-DiagnosticVirtualTextWarn DiagnosticVirtualTextWarn Used for "Warn" diagnostic virtual text.
hl-DiagnosticVirtualTextInfo DiagnosticVirtualTextInfo Used for "Info" diagnostic virtual text.
hl-DiagnosticVirtualTextHint DiagnosticVirtualTextHint Used for "Hint" diagnostic virtual text.
hl-DiagnosticVirtualTextOk DiagnosticVirtualTextOk Used for "Ok" diagnostic virtual text.
hl-DiagnosticUnderlineError DiagnosticUnderlineError Used to underline "Error" diagnostics.
hl-DiagnosticUnderlineWarn DiagnosticUnderlineWarn Used to underline "Warn" diagnostics.
hl-DiagnosticUnderlineInfo DiagnosticUnderlineInfo Used to underline "Info" diagnostics.
hl-DiagnosticUnderlineHint DiagnosticUnderlineHint Used to underline "Hint" diagnostics.
hl-DiagnosticUnderlineOk DiagnosticUnderlineOk Used to underline "Ok" diagnostics.
hl-DiagnosticFloatingError DiagnosticFloatingError Used to color "Error" diagnostic messages in diagnostics float. See vim.diagnostic.open_float()
hl-DiagnosticFloatingWarn DiagnosticFloatingWarn Used to color "Warn" diagnostic messages in diagnostics float.
hl-DiagnosticFloatingInfo DiagnosticFloatingInfo Used to color "Info" diagnostic messages in diagnostics float.
hl-DiagnosticFloatingHint DiagnosticFloatingHint Used to color "Hint" diagnostic messages in diagnostics float.
hl-DiagnosticFloatingOk DiagnosticFloatingOk Used to color "Ok" diagnostic messages in diagnostics float.
hl-DiagnosticSignError DiagnosticSignError Used for "Error" signs in sign column.
hl-DiagnosticSignWarn DiagnosticSignWarn Used for "Warn" signs in sign column.
hl-DiagnosticSignInfo DiagnosticSignInfo Used for "Info" signs in sign column.
hl-DiagnosticSignHint DiagnosticSignHint Used for "Hint" signs in sign column.
hl-DiagnosticSignOk DiagnosticSignOk Used for "Ok" signs in sign column.

SIGNS diagnostic-signs

Signs are defined for each diagnostic severity. The default text for each sign is the first letter of the severity name (for example, "E" for ERROR). Signs can be customized using the following:
sign define DiagnosticSignError text=E texthl=DiagnosticSignError linehl= numhl=
sign define DiagnosticSignWarn text=W texthl=DiagnosticSignWarn linehl= numhl=
sign define DiagnosticSignInfo text=I texthl=DiagnosticSignInfo linehl= numhl=
sign define DiagnosticSignHint text=H texthl=DiagnosticSignHint linehl= numhl=
When the "severity_sort" option is set (see vim.diagnostic.config()) the priority of each sign depends on the severity of the associated diagnostic. Otherwise, all signs have the same priority (the value of the "priority" option in the "signs" table of vim.diagnostic.config() or 10 if unset).

EVENTS diagnostic-events

DiagnosticChanged DiagnosticChanged After diagnostics have changed. When used from Lua, the new diagnostics are passed to the autocmd callback in the "data" table.
Example:
vim.api.nvim_create_autocmd('DiagnosticChanged', {
  callback = function(args)
    local diagnostics = args.data.diagnostics
    vim.pretty_print(diagnostics)
  end,
})

Lua module: vim.diagnostic diagnostic-api

config({opts}, {namespace}) vim.diagnostic.config() Configure diagnostic options globally or for a specific diagnostic namespace.
Configuration can be specified globally, per-namespace, or ephemerally (i.e. only for a single call to vim.diagnostic.set() or vim.diagnostic.show()). Ephemeral configuration has highest priority, followed by namespace configuration, and finally global configuration.
For example, if a user enables virtual text globally with
vim.diagnostic.config({ virtual_text = true })
and a diagnostic producer sets diagnostics with
vim.diagnostic.set(ns, 0, diagnostics, { virtual_text = false })
then virtual text will not be enabled for those diagnostics.
Note: Each of the configuration options below accepts one of the following:
false: Disable this feature
true: Enable this feature, use default settings.
table: Enable this feature with overrides. Use an empty table to use default values.
function: Function with signature (namespace, bufnr) that returns any of the above.
Parameters:
{opts} (table|nil) When omitted or "nil", retrieve the current configuration. Otherwise, a configuration table with the following keys:
underline: (default true) Use underline for diagnostics. Options:
severity: Only underline diagnostics matching the given severity diagnostic-severity
virtual_text: (default true) Use virtual text for diagnostics. If multiple diagnostics are set for a namespace, one prefix per diagnostic + the last diagnostic message are shown. Options:
severity: Only show virtual text for diagnostics matching the given severity diagnostic-severity
source: (boolean or string) Include the diagnostic source in virtual text. Use "if_many" to only show sources if there is more than one diagnostic source in the buffer. Otherwise, any truthy value means to always show the diagnostic source.
spacing: (number) Amount of empty spaces inserted at the beginning of the virtual text.
prefix: (string) Prepend diagnostic message with prefix.
suffix: (string or function) Append diagnostic message with suffix. If a function, it must have the signature (diagnostic) -> string, where {diagnostic} is of type diagnostic-structure. This can be used to render an LSP diagnostic error code.
format: (function) A function that takes a diagnostic as input and returns a string. The return value is the text used to display the diagnostic. Example:
function(diagnostic)
  if diagnostic.severity == vim.diagnostic.severity.ERROR then
    return string.format("E: %s", diagnostic.message)
  end
  return diagnostic.message
end
signs: (default true) Use signs for diagnostics. Options:
severity: Only show signs for diagnostics matching the given severity diagnostic-severity
priority: (number, default 10) Base priority to use for signs. When {severity_sort} is used, the priority of a sign is adjusted based on its severity. Otherwise, all signs use the same priority.
float: Options for floating windows. See vim.diagnostic.open_float().
update_in_insert: (default false) Update diagnostics in Insert mode (if false, diagnostics are updated on InsertLeave)
severity_sort: (default false) Sort diagnostics by severity. This affects the order in which signs and virtual text are displayed. When true, higher severities are displayed before lower severities (e.g. ERROR is displayed before WARN). Options:
reverse: (boolean) Reverse sort order
{namespace} (number|nil) Update the options for the given namespace. When omitted, update the global diagnostic options.
disable({bufnr}, {namespace}) vim.diagnostic.disable() Disable diagnostics in the given buffer.
Parameters:
{bufnr} (number|nil) Buffer number, or 0 for current buffer. When omitted, disable diagnostics in all buffers.
{namespace} (number|nil) Only disable diagnostics for the given namespace.
enable({bufnr}, {namespace}) vim.diagnostic.enable() Enable diagnostics in the given buffer.
Parameters:
{bufnr} (number|nil) Buffer number, or 0 for current buffer. When omitted, enable diagnostics in all buffers.
{namespace} (number|nil) Only enable diagnostics for the given namespace.
fromqflist({list}) vim.diagnostic.fromqflist() Convert a list of quickfix items to a list of diagnostics.
Parameters:
{list} (table) A list of quickfix items from getqflist() or getloclist().
Return:
Diagnostic [] array of diagnostic-structure
get({bufnr}, {opts}) vim.diagnostic.get() Get current diagnostics.
Parameters:
{bufnr} (number|nil) Buffer number to get diagnostics from. Use 0 for current buffer or nil for all buffers.
{opts} (table|nil) A table with the following keys:
namespace: (number) Limit diagnostics to the given namespace.
lnum: (number) Limit diagnostics to the given line number.
severity: See diagnostic-severity.
Return:
Diagnostic [] table A list of diagnostic items diagnostic-structure.
get_namespace({namespace}) vim.diagnostic.get_namespace() Get namespace metadata.
Parameters:
{namespace} (number) Diagnostic namespace
Return:
(table) Namespace metadata
get_namespaces() vim.diagnostic.get_namespaces() Get current diagnostic namespaces.
Return:
(table) A list of active diagnostic namespaces vim.diagnostic.
get_next({opts}) vim.diagnostic.get_next() Get the next diagnostic closest to the cursor position.
Parameters:
{opts} (table|nil) See vim.diagnostic.goto_next()
Return:
Diagnostic|nil Next diagnostic
get_next_pos({opts}) vim.diagnostic.get_next_pos() Return the position of the next diagnostic in the current buffer.
Parameters:
{opts} (table|nil) See vim.diagnostic.goto_next()
Return:
table|false Next diagnostic position as a (row, col) tuple or false if no next diagnostic.
get_prev({opts}) vim.diagnostic.get_prev() Get the previous diagnostic closest to the cursor position.
Parameters:
{opts} nil|table See vim.diagnostic.goto_next()
Return:
Diagnostic|nil Previous diagnostic
get_prev_pos({opts}) vim.diagnostic.get_prev_pos() Return the position of the previous diagnostic in the current buffer.
Parameters:
{opts} (table|nil) See vim.diagnostic.goto_next()
Return:
table|false Previous diagnostic position as a (row, col) tuple or false if there is no prior diagnostic
goto_next({opts}) vim.diagnostic.goto_next() Move to the next diagnostic.
Parameters:
{opts} (table|nil) Configuration table with the following keys:
namespace: (number) Only consider diagnostics from the given namespace.
cursor_position: (cursor position) Cursor position as a (row, col) tuple. See nvim_win_get_cursor(). Defaults to the current cursor position.
wrap: (boolean, default true) Whether to loop around file or not. Similar to 'wrapscan'.
severity: See diagnostic-severity.
float: (boolean or table, default true) If "true", call vim.diagnostic.open_float() after moving. If a table, pass the table as the {opts} parameter to vim.diagnostic.open_float(). Unless overridden, the float will show diagnostics at the new cursor position (as if "cursor" were passed to the "scope" option).
win_id: (number, default 0) Window ID
goto_prev({opts}) vim.diagnostic.goto_prev() Move to the previous diagnostic in the current buffer.
Parameters:
{opts} (table|nil) See vim.diagnostic.goto_next()
hide({namespace}, {bufnr}) vim.diagnostic.hide() Hide currently displayed diagnostics.
This only clears the decorations displayed in the buffer. Diagnostics can be redisplayed with vim.diagnostic.show(). To completely remove diagnostics, use vim.diagnostic.reset().
To hide diagnostics and prevent them from re-displaying, use vim.diagnostic.disable().
Parameters:
{namespace} (number|nil) Diagnostic namespace. When omitted, hide diagnostics from all namespaces.
{bufnr} (number|nil) Buffer number, or 0 for current buffer. When omitted, hide diagnostics in all buffers.
is_disabled({bufnr}, {namespace}) vim.diagnostic.is_disabled() Check whether diagnostics are disabled in a given buffer.
Parameters:
{bufnr} (number|nil) Buffer number, or 0 for current buffer.
{namespace} (number|nil) Diagnostic namespace. When omitted, checks if all diagnostics are disabled in {bufnr}. Otherwise, only checks if diagnostics from {namespace} are disabled.
Return:
(boolean)
vim.diagnostic.match() match({str}, {pat}, {groups}, {severity_map}, {defaults}) Parse a diagnostic from a string.
For example, consider a line of output from a linter:
WARNING filename:27:3: Variable 'foo' does not exist
This can be parsed into a diagnostic diagnostic-structure with:
local s = "WARNING filename:27:3: Variable 'foo' does not exist"
local pattern = "^(%w+) %w+:(%d+):(%d+): (.+)$"
local groups = { "severity", "lnum", "col", "message" }
vim.diagnostic.match(s, pattern, groups, { WARNING = vim.diagnostic.WARN })
Parameters:
{str} (string) String to parse diagnostics from.
{pat} (string) Lua pattern with capture groups.
{groups} (table) List of fields in a diagnostic-structure to associate with captures from {pat}.
{severity_map} (table) A table mapping the severity field from {groups} with an item from vim.diagnostic.severity.
{defaults} (table|nil) Table of default values for any fields not listed in {groups}. When omitted, numeric values default to 0 and "severity" defaults to ERROR.
Return:
Diagnostic|nil: diagnostic-structure or nil if {pat} fails to match {str}.
open_float({opts}, {...}) vim.diagnostic.open_float() Show diagnostics in a floating window.
Parameters:
{opts} (table|nil) Configuration table with the same keys as vim.lsp.util.open_floating_preview() in addition to the following:
bufnr: (number) Buffer number to show diagnostics from. Defaults to the current buffer.
namespace: (number) Limit diagnostics to the given namespace
scope: (string, default "line") Show diagnostics from the whole buffer ("buffer"), the current cursor line ("line"), or the current cursor position ("cursor"). Shorthand versions are also accepted ("c" for "cursor", "l" for "line", "b" for "buffer").
pos: (number or table) If {scope} is "line" or "cursor", use this position rather than the cursor position. If a number, interpreted as a line number; otherwise, a (row, col) tuple.
severity_sort: (default false) Sort diagnostics by severity. Overrides the setting from vim.diagnostic.config().
severity: See diagnostic-severity. Overrides the setting from vim.diagnostic.config().
header: (string or table) String to use as the header for the floating window. If a table, it is interpreted as a [text, hl_group] tuple. Overrides the setting from vim.diagnostic.config().
source: (boolean or string) Include the diagnostic source in the message. Use "if_many" to only show sources if there is more than one source of diagnostics in the buffer. Otherwise, any truthy value means to always show the diagnostic source. Overrides the setting from vim.diagnostic.config().
format: (function) A function that takes a diagnostic as input and returns a string. The return value is the text used to display the diagnostic. Overrides the setting from vim.diagnostic.config().
prefix: (function, string, or table) Prefix each diagnostic in the floating window. If a function, it must have the signature (diagnostic, i, total) -> (string, string), where {i} is the index of the diagnostic being evaluated and {total} is the total number of diagnostics displayed in the window. The function should return a string which is prepended to each diagnostic in the window as well as an (optional) highlight group which will be used to highlight the prefix. If {prefix} is a table, it is interpreted as a [text, hl_group] tuple as in nvim_echo(); otherwise, if {prefix} is a string, it is prepended to each diagnostic in the window with no highlight. Overrides the setting from vim.diagnostic.config().
suffix: Same as {prefix}, but appends the text to the diagnostic instead of prepending it. Overrides the setting from vim.diagnostic.config().
Return:
number|nil, number|nil: ({float_bufnr}, {win_id})
reset({namespace}, {bufnr}) vim.diagnostic.reset() Remove all diagnostics from the given namespace.
Unlike vim.diagnostic.hide(), this function removes all saved diagnostics. They cannot be redisplayed using vim.diagnostic.show(). To simply remove diagnostic decorations in a way that they can be re-displayed, use vim.diagnostic.hide().
Parameters:
{namespace} (number|nil) Diagnostic namespace. When omitted, remove diagnostics from all namespaces.
{bufnr} (number|nil) Remove diagnostics for the given buffer. When omitted, diagnostics are removed for all buffers.
set({namespace}, {bufnr}, {diagnostics}, {opts}) vim.diagnostic.set() Set diagnostics for the given namespace and buffer.
Parameters:
{namespace} (number) The diagnostic namespace
{bufnr} (number) Buffer number
{diagnostics} (table) A list of diagnostic items diagnostic-structure
{opts} (table|nil) Display options to pass to vim.diagnostic.show()
setloclist({opts}) vim.diagnostic.setloclist() Add buffer diagnostics to the location list.
Parameters:
{opts} (table|nil) Configuration table with the following keys:
namespace: (number) Only add diagnostics from the given namespace.
winnr: (number, default 0) Window number to set location list for.
open: (boolean, default true) Open the location list after setting.
title: (string) Title of the location list. Defaults to "Diagnostics".
severity: See diagnostic-severity.
setqflist({opts}) vim.diagnostic.setqflist() Add all diagnostics to the quickfix list.
Parameters:
{opts} (table|nil) Configuration table with the following keys:
namespace: (number) Only add diagnostics from the given namespace.
open: (boolean, default true) Open quickfix list after setting.
title: (string) Title of quickfix list. Defaults to "Diagnostics".
severity: See diagnostic-severity.
vim.diagnostic.show() show({namespace}, {bufnr}, {diagnostics}, {opts}) Display diagnostics for the given namespace and buffer.
Parameters:
{namespace} (number|nil) Diagnostic namespace. When omitted, show diagnostics from all namespaces.
{bufnr} (number|nil) Buffer number, or 0 for current buffer. When omitted, show diagnostics in all buffers.
{diagnostics} (table|nil) The diagnostics to display. When omitted, use the saved diagnostics for the given namespace and buffer. This can be used to display a list of diagnostics without saving them or to display only a subset of diagnostics. May not be used when {namespace} or {bufnr} is nil.
{opts} (table|nil) Display options. See vim.diagnostic.config().
toqflist({diagnostics}) vim.diagnostic.toqflist() Convert a list of diagnostics to a list of quickfix items that can be passed to setqflist() or setloclist().
Parameters:
{diagnostics} (table) List of diagnostics diagnostic-structure.
Return:
table[] of quickfix list items setqflist-what
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