NAME

       gn - Meta-build system that generates build files for Ninja

DESCRIPTION

   Commands (type  gn help <command>" for more help):"
              analyze:  Analyze  which targets are affected by a list of files.  args: Display or
              configure arguments declared by  the  build.   check:  Check  header  dependencies.
              clean:  Cleans  the  output  directory.  clean_stale: Cleans the stale output files
              from the output directory.  desc: Show  lots  of  insightful  information  about  a
              target  or  config.   format:  Format .gn files.  gen: Generate ninja files.  help:
              Does what you think.  ls:  List  matching  targets.   meta:  List  target  metadata
              collection  results.   outputs: Which files a source/target make.  path: Find paths
              between two targets.  refs: Find stuff referencing a target or file.

   Target declarations (type  gn help <function>" for more help):"
              action: Declare a target that runs a script a single time.  action_foreach: Declare
              a  target that runs a script over a set of files.  bundle_data: [iOS/macOS] Declare
              a target without output.  copy: Declare a target that copies files.  create_bundle:
              [iOS/macOS]  Build  an  iOS  or  macOS  bundle.   executable: Declare an executable
              target.  generated_file: Declare a generated_file target.  group: Declare  a  named
              group   of   targets.    loadable_module:   Declare   a   loadable  module  target.
              rust_library: Declare a Rust  library  target.   rust_proc_macro:  Declare  a  Rust
              procedural   macro  target.   shared_library:  Declare  a  shared  library  target.
              source_set: Declare a source set target.  static_library: Declare a static  library
              target.  target: Declare an target with the given programmatic type.

   Buildfile functions (type  gn help <function>" for more help):"
              assert:  Assert  an  expression  is  true  at  generation  time.  config: Defines a
              configuration object.  declare_args: Declare  build  arguments.   defined:  Returns
              whether  an  identifier  is  defined.   exec_script: Synchronously run a script and
              return the output.  filter_exclude: Remove values that match  a  set  of  patterns.
              filter_include:  Remove  values  that  do  not  match  a set of patterns.  foreach:
              Iterate over a list.  forward_variables_from: Copies  variables  from  a  different
              scope.   get_label_info:  Get  an  attribute from a target's label.  get_path_info:
              Extract parts of a file or directory name.  get_target_outputs: [file list] Get the
              list  of  outputs  from  a  target.   getenv: Get an environment variable.  import:
              Import a file into the current scope.  not_needed: Mark variables from scope as not
              needed.    pool:   Defines   a   pool   object.   print:  Prints  to  the  console.
              process_file_template: Do template expansion over a list of files.  read_file: Read
              a  file  into  a  variable.   rebase_path:  Rebase  a  file or directory to another
              location.  set_default_toolchain: Sets the default toolchain  name.   set_defaults:
              Set  default  values for a target type.  split_list: Splits a list into N different
              sub-lists.   string_join:  Concatenates  a  list  of  strings  with  a   separator.
              string_replace: Replaces substring in the given string.  string_split: Split string
              into a list of strings.  template: Define a template rule.  tool: Specify arguments
              to  a toolchain tool.  toolchain: Defines a toolchain.  write_file: Write a file to
              disk.

   Built-in predefined variables (type  gn help <variable>" for more help):"
              current_cpu:  [string]  The  processor  architecture  of  the  current   toolchain.
              current_os:   [string]   The   operating   system   of   the   current   toolchain.
              current_toolchain: [string] Label of  the  current  toolchain.   default_toolchain:
              [string]  Label  of the default toolchain.  gn_version: [number] The version of gn.
              host_cpu: [string] The processor architecture that  GN  is  running  on.   host_os:
              [string]  The  operating  system  that  GN  is  running  on.  invoker: [string] The
              invoking scope inside a template.  python_path: [string] Absolute path  of  Python.
              root_build_dir:  [string]  Directory  where  build commands are run.  root_gen_dir:
              [string] Directory for the toolchain's  generated  files.   root_out_dir:  [string]
              Root  directory  for  toolchain output files.  target_cpu: [string] The desired cpu
              architecture for the build.  target_gen_dir:  [string]  Directory  for  a  target's
              generated files.  target_name: [string] The name of the current target.  target_os:
              [string] The desired operating system  for  the  build.   target_out_dir:  [string]
              Directory for target output files.

   Variables you set in targets (type  gn help <variable>" for more help):"
              aliased_deps: [scope] Set of crate-dependency pairs.  all_dependent_configs: [label
              list] Configs to be forced  on  dependents.   allow_circular_includes_from:  [label
              list]  Permit  includes  from  deps.   arflags:  [string  list] Arguments passed to
              static_library archiver.  args:  [string  list]  Arguments  passed  to  an  action.
              asmflags:  [string  list]  Flags  passed to the assembler.  assert_no_deps:??[label
              pattern list] Ensure no deps on these targets.   bridge_header:  [string]  Path  to
              C/Objective-C    compatibility    header.     bundle_contents_dir:   Expansion   of
              {{bundle_contents_dir}} in create_bundle.  bundle_deps_filter: [label list] A  list
              of   labels   that   are   filtered   out.    bundle_executable_dir:  Expansion  of
              {{bundle_executable_dir}}  in  create_bundle  bundle_resources_dir:  Expansion   of
              {{bundle_resources_dir}}   in   create_bundle.    bundle_root_dir:   Expansion   of
              {{bundle_root_dir}} in create_bundle.  cflags: [string list] Flags passed to all  C
              compiler  variants.   cflags_c:  [string  list]  Flags  passed  to  the C compiler.
              cflags_cc: [string list] Flags passed to the C++  compiler.   cflags_objc:  [string
              list]  Flags passed to the Objective C compiler.  cflags_objcc: [string list] Flags
              passed to the Objective C++ compiler.  check_includes: [boolean] Controls whether a
              target's  files  are checked.  code_signing_args: [string list] Arguments passed to
              code signing script.  code_signing_outputs:  [file  list]  Output  files  for  code
              signing   step.    code_signing_script:   [file  name]  Script  for  code  signing.
              code_signing_sources:   [file   list]    Sources    for    code    signing    step.
              complete_static_lib:  [boolean]  Links  all  deps  into a static library.  configs:
              [label list] Configs applying to this target  or  config.   contents:  Contents  to
              write  to file.  crate_name: [string] The name for the compiled crate.  crate_root:
              [string] The root source file for a binary or library.   crate_type:  [string]  The
              type  of  linkage  to use on a shared_library.  data: [file list] Runtime data file
              dependencies.  data_deps: [label list] Non-linked dependencies.  data_keys: [string
              list]  Keys  from which to collect metadata.  defines: [string list] C preprocessor
              defines.  depfile: [string] File name for input dependencies  for  actions.   deps:
              [label   list]   Private   linked  dependencies.   externs:  [scope]  Set  of  Rust
              crate-dependency pairs.   framework_dirs:  [directory  list]  Additional  framework
              search  directories.   frameworks:  [name  list]  Name  of  frameworks that must be
              linked.  friend: [label pattern list] Allow targets  to  include  private  headers.
              gen_deps:  [label  list]  Declares targets that should generate when this one does.
              include_dirs: [directory list] Additional include directories.  inputs: [file list]
              Additional  compile-time  dependencies.  ldflags: [string list] Flags passed to the
              linker.  lib_dirs: [directory list] Additional library directories.  libs:  [string
              list]  Additional  libraries  to  link.  metadata: [scope] Metadata of this target.
              module_name: [string] The name for the compiled  module.   output_conversion:  Data
              format for generated_file targets.  output_dir: [directory] Directory to put output
              file in.  output_extension: [string] Value to use for the output's file  extension.
              output_name:   [string]   Name   for  the  output  file  other  than  the  default.
              output_prefix_override: [boolean] Don't use prefix for output name.  outputs: [file
              list]  Output  files  for actions and copy targets.  partial_info_plist: [filename]
              Path plist from asset catalog compiler.  pool: [string] Label of the pool  used  by
              the    action.    precompiled_header:   [string]   Header   file   to   precompile.
              precompiled_header_type: [string] "gcc" or "msvc".  precompiled_source: [file name]
              Source file to precompile.  product_type: [string] Product type for Xcode projects.
              public: [file list] Declare public header  files  for  a  target.   public_configs:
              [label  list]  Configs  applied  to  dependents.  public_deps: [label list] Declare
              public  dependencies.   rebase:  [boolean]  Rebase  collected  metadata  as  files.
              response_file_contents:  [string  list] Contents of .rsp file for actions.  script:
              [file name] Script file for actions.  sources:  [file  list]  Source  files  for  a
              target.   swiftflags:  [string list] Flags passed to the swift compiler.  testonly:
              [boolean] Declares a target must only be  used  for  testing.   visibility:  [label
              list]  A  list  of  labels  that  can depend on a target.  walk_keys: [string list]
              Key(s) for managing the metadata collection  walk.   weak_frameworks:  [name  list]
              Name  of  frameworks  that  must  be  weak  linked.  write_runtime_deps: Writes the
              target's runtime_deps to the given  path.   xcasset_compiler_flags:  [string  list]
              Flags  passed to xcassets compiler xcode_extra_attributes: [scope] Extra attributes
              for Xcode projects.  xcode_test_application_name:  [string]  Name  for  Xcode  test
              target.

   Other help topics:
              all: Print all the help at once buildargs: How build arguments work.  dotfile: Info
              about the toplevel .gn  file.   execution:  Build  graph  and  execution  overview.
              grammar:  Language  and  grammar  for GN build files.  input_conversion: Processing
              input from exec_script and read_file.  file_pattern: Matching more than  one  file.
              label_pattern:   Matching   more   than   one   label.    labels:   About   labels.
              metadata_collection: About metadata and its  collection.   ninja_rules:  How  Ninja
              build   rules   are   named.    nogncheck:   Annotating   includes   for  checking.
              output_conversion: Specifies how to transform a value to output.  runtime_deps: How
              runtime dependency computation works.  source_expansion: Map sources to outputs for
              scripts.  switches: Show available command-line switches.