The different tools utilize a common parsing core and so share a common configuration system and in fact can share the same configuration file(s).

The tools accept configuration files in yaml, json, or python format.


In order to read your configuration files in YAML format, the tools require the pyyaml python package to be installed. This dependency is not enforced by default during installation since this is an optional feature. It can be enabled by installing with a command like pip install cmake_format[YAML]. Or you can install pyyaml manually.

You may specify a path to one or more configuration files with the --config-file (--config-files) command line option. Otherwise, the tools will search the ancestry of each source file looking for a configuration file to use. If no configuration file is found it will use sensible defaults.

Automatically detected configuration files may have any name that matches \.?cmake-format(.yaml|.json|.py).

If you’d like to create a new configuration file, cmake-format can help by dumping out the default configuration in your preferred format. You can run cmake-format --dump-config [python|json|yaml] to print the default configuration to stdout and use that as a starting point.


cmake-format will detect and load an automatic configuration file, even when executing --dump-config. This is so that you can debug the active configuration from a certain location in your tree. If you have a corrupt / un-parsable configuration file in an automatic location --dump-config may fail. You can always cd to a clean location (/ or /tmp) and execute --dump-config to get a default configuration.

Here is an example python-style configuration file with the default options and help-text. Some detailed explanation and examples can be found at Various configuration options and parameters.

# ----------------------------------
# Options affecting listfile parsing
# ----------------------------------
with section("parse"):

  # Specify structure for custom cmake functions
  additional_commands = { 'format_and_lint': { 'kwargs': { 'CC': '*',
                                     'CCDEPENDS': '*',
                                     'CMAKE': '*',
                                     'EXCLUDE': '*',
                                     'JS': '*',
                                     'PY': '*'}},
    'pkg_find': {'kwargs': {'PKG': '*'}}}

  # Specify variable tags.
  vartags = []

  # Specify property tags.
  proptags = []

# -----------------------------
# Options affecting formatting.
# -----------------------------
with section("format"):

  # How wide to allow formatted cmake files
  line_width = 80

  # How many spaces to tab for indent
  tab_size = 2

  # If an argument group contains more than this many sub-groups (parg or kwarg
  # groups) then force it to a vertical layout.
  max_subgroups_hwrap = 2

  # If a positional argument group contains more than this many arguments, then
  # force it to a vertical layout.
  max_pargs_hwrap = 6

  # If a cmdline positional group consumes more than this many lines without
  # nesting, then invalidate the layout (and nest)
  max_rows_cmdline = 2

  # If true, separate flow control names from their parentheses with a space
  separate_ctrl_name_with_space = False

  # If true, separate function names from parentheses with a space
  separate_fn_name_with_space = False

  # If a statement is wrapped to more than one line, than dangle the closing
  # parenthesis on its own line.
  dangle_parens = False

  # If the trailing parenthesis must be 'dangled' on its on line, then align it
  # to this reference: `prefix`: the start of the statement,  `prefix-indent`:
  # the start of the statement, plus one indentation  level, `child`: align to
  # the column of the arguments
  dangle_align = 'prefix'

  # If the statement spelling length (including space and parenthesis) is
  # smaller than this amount, then force reject nested layouts.
  min_prefix_chars = 4

  # If the statement spelling length (including space and parenthesis) is larger
  # than the tab width by more than this amount, then force reject un-nested
  # layouts.
  max_prefix_chars = 10

  # If a candidate layout is wrapped horizontally but it exceeds this many
  # lines, then reject the layout.
  max_lines_hwrap = 2

  # What style line endings to use in the output.
  line_ending = 'unix'

  # Format command names consistently as 'lower' or 'upper' case
  command_case = 'canonical'

  # Format keywords consistently as 'lower' or 'upper' case
  keyword_case = 'unchanged'

  # A list of command names which should always be wrapped
  always_wrap = []

  # If true, the argument lists which are known to be sortable will be sorted
  # lexicographicall
  enable_sort = True

  # If true, the parsers may infer whether or not an argument list is sortable
  # (without annotation).
  autosort = False

  # By default, if cmake-format cannot successfully fit everything into the
  # desired linewidth it will apply the last, most agressive attempt that it
  # made. If this flag is True, however, cmake-format will print error, exit
  # with non-zero status code, and write-out nothing
  require_valid_layout = False

  # A dictionary mapping layout nodes to a list of wrap decisions. See the
  # documentation for more information.
  layout_passes = {}

# ------------------------------------------------
# Options affecting comment reflow and formatting.
# ------------------------------------------------
with section("markup"):

  # What character to use for bulleted lists
  bullet_char = '*'

  # What character to use as punctuation after numerals in an enumerated list
  enum_char = '.'

  # If comment markup is enabled, don't reflow the first comment block in each
  # listfile. Use this to preserve formatting of your copyright/license
  # statements.
  first_comment_is_literal = False

  # If comment markup is enabled, don't reflow any comment block which matches
  # this (regex) pattern. Default is `None` (disabled).
  literal_comment_pattern = None

  # Regular expression to match preformat fences in comments default=
  # ``r'^\s*([`~]{3}[`~]*)(.*)$'``
  fence_pattern = '^\\s*([`~]{3}[`~]*)(.*)$'

  # Regular expression to match rulers in comments default=
  # ``r'^\s*[^\w\s]{3}.*[^\w\s]{3}$'``
  ruler_pattern = '^\\s*[^\\w\\s]{3}.*[^\\w\\s]{3}$'

  # If a comment line matches starts with this pattern then it is explicitly a
  # trailing comment for the preceeding argument. Default is '#<'
  explicit_trailing_pattern = '#<'

  # If a comment line starts with at least this many consecutive hash
  # characters, then don't lstrip() them off. This allows for lazy hash rulers
  # where the first hash char is not separated by space
  hashruler_min_length = 10

  # If true, then insert a space between the first hash char and remaining hash
  # chars in a hash ruler, and normalize its length to fill the column
  canonicalize_hashrulers = True

  # enable comment markup parsing and reflow
  enable_markup = True

# ----------------------------
# Options affecting the linter
# ----------------------------
with section("lint"):

  # a list of lint codes to disable
  disabled_codes = []

  # regular expression pattern describing valid function names
  function_pattern = '[0-9a-z_]+'

  # regular expression pattern describing valid macro names
  macro_pattern = '[0-9A-Z_]+'

  # regular expression pattern describing valid names for variables with global
  # scope
  global_var_pattern = '[0-9A-Z][0-9A-Z_]+'

  # regular expression pattern describing valid names for variables with global
  # scope (but internal semantic)
  internal_var_pattern = '_[0-9A-Z][0-9A-Z_]+'

  # regular expression pattern describing valid names for variables with local
  # scope
  local_var_pattern = '[0-9a-z_]+'

  # regular expression pattern describing valid names for privatedirectory
  # variables
  private_var_pattern = '_[0-9a-z_]+'

  # regular expression pattern describing valid names for publicdirectory
  # variables
  public_var_pattern = '[0-9A-Z][0-9A-Z_]+'

  # regular expression pattern describing valid names for keywords used in
  # functions or macros
  keyword_pattern = '[0-9A-Z_]+'

  # In the heuristic for C0201, how many conditionals to match within a loop in
  # before considering the loop a parser.
  max_conditionals_custom_parser = 2

  # Require at least this many newlines between statements
  min_statement_spacing = 1

  # Require no more than this many newlines between statements
  max_statement_spacing = 1
  max_returns = 6
  max_branches = 12
  max_arguments = 5
  max_localvars = 15
  max_statements = 50

# -------------------------------
# Options affecting file encoding
# -------------------------------
with section("encode"):

  # If true, emit the unicode byte-order mark (BOM) at the start of the file
  emit_byteorder_mark = False

  # Specify the encoding of the input file. Defaults to utf-8
  input_encoding = 'utf-8'

  # Specify the encoding of the output file. Defaults to utf-8. Note that cmake
  # only claims to support utf-8 so be careful when using anything else
  output_encoding = 'utf-8'

# -------------------------------------
# Miscellaneous configurations options.
# -------------------------------------
with section("misc"):

  # A dictionary containing any per-command configuration overrides. Currently
  # only `command_case` is supported.
  per_command = {}