cc_common

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Utilities for C++ compilation, linking, and command line generation.

Members

action_is_enabled

bool cc_common.action_is_enabled(feature_configuration, action_name)

Returns True if given action_config is enabled in the feature configuration.

Parameters

Parameter Description
feature_configuration required
Feature configuration to be queried.
action_name required
Name of the action_config.

CcToolchainInfo

Provider cc_common.CcToolchainInfo

The key used to retrieve the provider that contains information about the C++ toolchain being used

configure_features

FeatureConfiguration cc_common.configure_features(ctx=None, cc_toolchain, language=None, requested_features=[], unsupported_features=[])

Creates a feature_configuration instance. Requires the cpp configuration fragment.

Parameters

Parameter Description
ctx ctx; or None; default is None
The rule context.
cc_toolchain required
cc_toolchain for which we configure features.
language string; or None; default is None
The language to configure for: either c++ or objc (default c++)
requested_features default is []
List of features to be enabled.
unsupported_features default is []
List of features that are unsupported by the current rule.

create_cc_toolchain_config_info

CcToolchainConfigInfo cc_common.create_cc_toolchain_config_info(ctx, features=[], action_configs=[], artifact_name_patterns=[], cxx_builtin_include_directories=[], toolchain_identifier, host_system_name=None, target_system_name, target_cpu, target_libc, compiler, abi_version=None, abi_libc_version=None, tool_paths=[], make_variables=[], builtin_sysroot=None, cc_target_os=None)

Creates a CcToolchainConfigInfo provider

Parameters

Parameter Description
ctx required
The rule context.
features default is []
Contains all flag specifications for one feature.

Arguments:

name: The feature's name. It is possible to introduce a feature without a change to Bazel by adding a 'feature' section to the toolchain and adding the corresponding string as feature in the BUILD file.

enabled: If 'True', this feature is enabled unless a rule type explicitly marks it as unsupported.

flag_sets: A FlagSet list. If the given feature is enabled, the flag sets will be applied for the actions are specified for.

env_sets: an EnvSet list. If the given feature is enabled, the env sets will be applied for the actions they are specified for.

requires: A list of feature sets defining when this feature is supported by the toolchain. The feature is supported if any of the feature sets fully apply, that is, when all features of a feature set are enabled. If requires is omitted, the feature is supported independently of which other features are enabled. Use this for example to filter flags depending on the build mode enabled (opt / fastbuild / dbg).

implies: A string list of features or action configs that are automatically enabled when this feature is enabled. If any of the implied features or action configs cannot be enabled, this feature will (silently) not be enabled either.

provides: A list of names this feature conflicts with.

A feature cannot be enabled if:
- provides contains the name of a different feature or action config that we want to enable.
- provides contains the same value as a 'provides' in a different feature or action config that we want to enable. Use this in order to ensure that incompatible features cannot be accidentally activated at the same time, leading to hard to diagnose compiler errors.
action_configs default is []
An action config corresponds to a Bazel action, and allows selection of a tool based on activated features. Action config activation occurs by the same semantics as features: a feature can 'require' or 'imply' an action config in the same way that it would another feature.

Arguments:

action_name: The name of the Bazel action that this config applies to, e.g. 'c-compile' or 'c-module-compile'.

enabled: If 'True', this action is enabled unless a rule type explicitly marks it as unsupported.

tools: The tool applied to the action will be the first tool with a feature set that matches the feature configuration. An error will be thrown if no tool matches a provided feature configuration - for that reason, it's a good idea to provide a default tool with an empty feature set.

flag_sets: If the given action config is enabled, the flag sets will be applied to the corresponding action.

implies: A list of features or action configs that are automatically enabled when this action config is enabled. If any of the implied features or action configs cannot be enabled, this action config will (silently) not be enabled either.
artifact_name_patterns default is []
The name for an artifact of a given category of input or output artifacts to an action.

Arguments:

category_name: The category of artifacts that this selection applies to. This field is compared against a list of categories defined in Bazel. Example categories include "linked_output" or the artifact for this selection. Together with the extension it is used to create an artifact name based on the target name.

extension: The extension for creating the artifact for this selection. Together with the prefix it is used to create an artifact name based on the target name.
cxx_builtin_include_directories default is []

Built-in include directories for C++ compilation. These should be the exact paths used by the compiler, and are generally relative to the exec root.

The paths used by the compiler can be determined by 'gcc -E -xc++ - -v'.

We currently use the C++ paths also for C compilation, which is safe as long as there are no name clashes between C++ and C header files.

Relative paths are resolved relative to the configuration file directory.

If the compiler has --sysroot support, then these paths should use %sysroot% rather than the include path, and specify the sysroot attribute in order to give blaze the information necessary to make the correct replacements.
toolchain_identifier required

The unique identifier of the toolchain within the crosstool release. It must be possible to use this as a directory name in a path.

It has to match the following regex: [a-zA-Z_][\.\- \w]*
host_system_name string; or None; default is None
Ignored.
target_system_name required
The GNU System Name.
target_cpu required
The target architecture string.
target_libc required
The libc version string (e.g. "glibc-2.2.2").
compiler required
The compiler version string (e.g. "gcc-4.1.1").
abi_version string; or None; default is None
The abi in use, which is a gcc version. E.g.: "gcc-3.4"
abi_libc_version string; or None; default is None
The glibc version used by the abi we're using.
tool_paths default is []
Tool locations.

Arguments:

name: Name of the tool.

path: Location of the tool; Can be absolute path (in case of non hermetic toolchain), or path relative to the cc_toolchain's package.
make_variables default is []
A make variable that is made accessible to rules.
builtin_sysroot string; or None; default is None
The built-in sysroot. If this attribute is not present, Bazel does not allow using a different sysroot, i.e. through the --grte_top option.
cc_target_os string; or None; default is None
Internal purpose only, do not use.

create_compilation_context

CompilationContext cc_common.create_compilation_context(headers=unbound, system_includes=unbound, includes=unbound, quote_includes=unbound, framework_includes=unbound, defines=unbound, local_defines=unbound)

Creates a CompilationContext.

Parameters

Parameter Description
headers default is unbound
Set of headers needed to compile this target
system_includes default is unbound
Set of search paths for header files referenced by angle brackets, i.e. #include <foo/bar/header.h>. They can be either relative to the exec root or absolute. Usually passed with -isystem
includes default is unbound
Set of search paths for header files referenced both by angle bracket and quotes.Usually passed with -I
quote_includes default is unbound
Set of search paths for header files referenced by quotes, i.e. #include "foo/bar/header.h". They can be either relative to the exec root or absolute. Usually passed with -iquote
framework_includes default is unbound
Set of framework search paths for header files (Apple platform only)
defines default is unbound
Set of defines needed to compile this target. Each define is a string. Propagated transitively to dependents.
local_defines default is unbound
Set of defines needed to compile this target. Each define is a string. Not propagated transitively to dependents.

create_compilation_outputs

CcCompilationOutputs cc_common.create_compilation_outputs(objects=None, pic_objects=None)

Create compilation outputs object.

Parameters

Parameter Description
objects depset; or None; default is None
List of object files.
pic_objects depset; or None; default is None
List of pic object files.

create_compile_variables

Variables cc_common.create_compile_variables(cc_toolchain, feature_configuration, source_file=None, output_file=None, user_compile_flags=None, include_directories=None, quote_include_directories=None, system_include_directories=None, framework_include_directories=None, preprocessor_defines=None, thinlto_index=None, thinlto_input_bitcode_file=None, thinlto_output_object_file=None, use_pic=False, add_legacy_cxx_options=False, variables_extension=unbound)

Returns variables used for compilation actions.

Parameters

Parameter Description
cc_toolchain required
cc_toolchain for which we are creating build variables.
feature_configuration required
Feature configuration to be queried.
source_file default is None
Optional source file for the compilation. Please prefer passing source_file here over appending it to the end of the command line generated from cc_common.get_memory_inefficient_command_line, as then it's in the power of the toolchain author to properly specify and position compiler flags.
output_file default is None
Optional output file of the compilation. Please prefer passing output_file here over appending it to the end of the command line generated from cc_common.get_memory_inefficient_command_line, as then it's in the power of the toolchain author to properly specify and position compiler flags.
user_compile_flags sequence of strings; or None; default is None
List of additional compilation flags (copts).
include_directories depset; or None; default is None
Depset of include directories.
quote_include_directories depset; or None; default is None
Depset of quote include directories.
system_include_directories depset; or None; default is None
Depset of system include directories.
framework_include_directories depset; or None; default is None
Depset of framework include directories.
preprocessor_defines depset; or None; default is None
Depset of preprocessor defines.
thinlto_index string; or None; default is None
LTO index file path.
thinlto_input_bitcode_file string; or None; default is None
Bitcode file that is input to LTO backend.
thinlto_output_object_file string; or None; default is None
Object file that is output by LTO backend.
use_pic default is False
When true the compilation will generate position independent code.
add_legacy_cxx_options default is False
Unused.
variables_extension dict; default is unbound
A dictionary of additional variables used by compile actions. 

LibraryToLink cc_common.create_library_to_link(actions, feature_configuration=None, cc_toolchain=None, static_library=None, pic_static_library=None, dynamic_library=None, interface_library=None, pic_objects=unbound, objects=unbound, alwayslink=False, dynamic_library_symlink_path='', interface_library_symlink_path='')

Creates LibraryToLink

Parameters

Parameter Description
actions required
actions object.
feature_configuration default is None
feature_configuration to be queried.
cc_toolchain default is None
CcToolchainInfo provider to be used.
static_library File; or None; default is None
File of static library to be linked.
pic_static_library File; or None; default is None
File of pic static library to be linked.
dynamic_library File; or None; default is None
File of dynamic library to be linked. Always used for runtime and used for linking if interface_library is not passed.
interface_library File; or None; default is None
File of interface library to be linked.
pic_objects sequence of Files; default is unbound
Experimental, do not use
objects sequence of Files; default is unbound
Experimental, do not use
default is False
Whether to link the static library/objects in the --whole_archive block.
string; default is ''
Override the default path of the dynamic library link in the solib directory. Empty string to use the default.
default is ''
Override the default path of the interface library link in the solib directory. Empty string to use the default. 

Variables cc_common.create_link_variables(cc_toolchain, feature_configuration, library_search_directories=None, runtime_library_search_directories=None, user_link_flags=None, output_file=None, param_file=None, def_file=None, is_using_linker=True, is_linking_dynamic_library=False, must_keep_debug=True, use_test_only_flags=False, is_static_linking_mode=True)

Returns link variables used for linking actions.

Parameters

Parameter Description
required
cc_toolchain for which we are creating build variables.
required
Feature configuration to be queried.
None; or depset; default is None
Depset of directories where linker will look for libraries at link time.
None; or depset; default is None
Depset of directories where loader will look for libraries at runtime.
None; or sequence; default is None
List of additional link flags (linkopts).
default is None
Optional output file path.
default is None
Optional param file path.
default is None
Optional .def file path.
default is True
True when using linker, False when archiver. Caller is responsible for keeping this in sync with action name used (is_using_linker = True for linking executable or dynamic library, is_using_linker = False for archiving static library).
default is False
True when creating dynamic library, False when executable or static library. Caller is responsible for keeping this in sync with action name used. This field will be removed once b/65151735 is fixed.
default is True
When set to False, bazel will expose 'strip_debug_symbols' variable, which is usually used to use the linker to strip debug symbols from the output file.
default is False
When set to true, 'is_cc_test' variable will be set.
default is True
Unused.

create_linker_input

LinkerInput cc_common.create_linker_input(owner, libraries=None, user_link_flags=None, additional_inputs=None)

Creates a LinkerInput.

Parameters

Parameter Description
owner required
The label of the target that produced all files used in this input.
libraries None; or depset; default is None
List of LibraryToLink.
None; or depset of strings; or sequence of strings; default is None
User link flags passed as strings. Accepts either [String], [[String]] or depset(String). The latter is discouraged as it's only kept for compatibility purposes, the depset is flattened. If you want to propagate user_link_flags via unflattened depsets() wrap them in a LinkerInput so that they are not flattened till the end.
additional_inputs None; or depset; default is None
For additional inputs to the linking action, e.g.: linking scripts.

create_linking_context

LinkingContext cc_common.create_linking_context(linker_inputs=None, libraries_to_link=None, user_link_flags=None, additional_inputs=None)

Creates a LinkingContext.

Parameters

Parameter Description
linker_inputs None; or depset; default is None
Depset of LinkerInput.
None; or sequence; default is None
Deprecated. This parameter is deprecated and will be removed soon. Please do not depend on it. It is disabled with --+incompatible_require_linker_input_cc_api. Use this flag to verify your code is compatible with its imminent removal.
List of LibraryToLink.
None; or sequence; default is None
Deprecated. This parameter is deprecated and will be removed soon. Please do not depend on it. It is disabled with --+incompatible_require_linker_input_cc_api. Use this flag to verify your code is compatible with its imminent removal.
List of user link flags passed as strings.
additional_inputs None; or sequence; default is None
Deprecated. This parameter is deprecated and will be removed soon. Please do not depend on it. It is disabled with --+incompatible_require_linker_input_cc_api. Use this flag to verify your code is compatible with its imminent removal.
For additional inputs to the linking action, e.g.: linking scripts.

create_linking_context_from_compilation_outputs

tuple cc_common.create_linking_context_from_compilation_outputs(actions, feature_configuration, cc_toolchain, compilation_outputs, user_link_flags=[], linking_contexts=[], name, language='c++', alwayslink=False, additional_inputs=[], disallow_static_libraries=False, disallow_dynamic_library=False)

Should be used for creating library rules that can propagate information downstream in order to be linked later by a top level rule that does transitive linking to create an executable or dynamic library. Returns tuple of (CcLinkingContext, CcLinkingOutputs).

Parameters

Parameter Description
actions required
actions object.
feature_configuration required
feature_configuration to be queried.
cc_toolchain required
CcToolchainInfo provider to be used.
compilation_outputs required
Compilation outputs containing object files to link.
default is []
Additional list of linking options.
linking_contexts default is []
Libraries from dependencies. These libraries will be linked into the output artifact of the link() call, be it a binary or a library.
name required
This is used for naming the output artifacts of actions created by this method.
language default is 'c++'
Only C++ supported for now. Do not use this parameter.
default is False
Whether this library should always be linked.
additional_inputs default is []
For additional inputs to the linking action, e.g.: linking scripts.
disallow_static_libraries default is False
Whether static libraries should be created.
disallow_dynamic_library default is False
Whether a dynamic library should be created.

do_not_use_tools_cpp_compiler_present

None cc_common.do_not_use_tools_cpp_compiler_present

Do not use this field, its only purpose is to help with migration from config_setting.values{'compiler') to config_settings.flag_values{'@bazel_tools//tools/cpp:compiler'}

get_environment_variables

dict cc_common.get_environment_variables(feature_configuration, action_name, variables)

Returns environment variables to be set for given action.

Parameters

Parameter Description
feature_configuration required
Feature configuration to be queried.
action_name required
Name of the action. Has to be one of the names in @bazel_tools//tools/build_defs/cc:action_names.bzl (https://github.com/bazelbuild/bazel/blob/master/tools/build_defs/cc/action_names.bzl)
variables required
Build variables to be used for template expansion.

get_execution_requirements

sequence cc_common.get_execution_requirements(feature_configuration, action_name)

Returns execution requirements for given action.

Parameters

Parameter Description
feature_configuration required
Feature configuration to be queried.
action_name required
Name of the action. Has to be one of the names in @bazel_tools//tools/build_defs/cc:action_names.bzl (https://github.com/bazelbuild/bazel/blob/master/tools/build_defs/cc/action_names.bzl)

get_memory_inefficient_command_line

sequence cc_common.get_memory_inefficient_command_line(feature_configuration, action_name, variables)

Returns flattened command line flags for given action, using given variables for expansion. Flattens nested sets and ideally should not be used, or at least should not outlive analysis. Work on memory efficient function returning Args is ongoing.

Parameters

Parameter Description
feature_configuration required
Feature configuration to be queried.
action_name required
Name of the action. Has to be one of the names in @bazel_tools//tools/build_defs/cc:action_names.bzl (https://github.com/bazelbuild/bazel/blob/master/tools/build_defs/cc/action_names.bzl)
variables required
Build variables to be used for template expansions.

get_tool_for_action

string cc_common.get_tool_for_action(feature_configuration, action_name)

Returns tool path for given action.

Parameters

Parameter Description
feature_configuration required
Feature configuration to be queried.
action_name required
Name of the action. Has to be one of the names in @bazel_tools//tools/build_defs/cc:action_names.bzl (https://github.com/bazelbuild/bazel/blob/master/tools/build_defs/cc/action_names.bzl)

is_enabled

bool cc_common.is_enabled(feature_configuration, feature_name)

Returns True if given feature is enabled in the feature configuration.

Parameters

Parameter Description
feature_configuration required
Feature configuration to be queried.
feature_name required
Name of the feature. 

CcLinkingOutputs cc_common.link(actions, feature_configuration, cc_toolchain, compilation_outputs=None, user_link_flags=[], linking_contexts=[], name, language='c++', output_type='executable', link_deps_statically=True, stamp=0, additional_inputs=[], additional_outputs=unbound)

Should be used for C++ transitive linking.

Parameters

Parameter Description
actions required
actions object.
feature_configuration required
feature_configuration to be queried.
cc_toolchain required
CcToolchainInfo provider to be used.
compilation_outputs CcCompilationOutputs; or None; default is None
Compilation outputs containing object files to link.
default is []
Additional list of linker options.
linking_contexts default is []
Linking contexts from dependencies to be linked into the linking context generated by this rule.
name required
This is used for naming the output artifacts of actions created by this method.
language default is 'c++'
Only C++ supported for now. Do not use this parameter.
output_type default is 'executable'
Can be either 'executable' or 'dynamic_library'.
default is True
True to link dependencies statically, False dynamically.
stamp default is 0
Whether to include build information in the linked executable, if output_type is 'executable'. If 1, build information is always included. If 0 (the default build information is always excluded. If -1, uses the default behavior, which may be overridden by the --[no]stamp flag. This should be unset (or set to 0) when generating the executable output for test rules.
additional_inputs sequence; or depset; default is []
For additional inputs to the linking action, e.g.: linking scripts.
additional_outputs sequence; default is unbound
For additional outputs to the linking action, e.g.: map files.

merge_compilation_contexts

CompilationContext cc_common.merge_compilation_contexts(compilation_contexts=[])

Merges multiple CompilationContextss into one.

Parameters

Parameter Description
compilation_contexts default is []
List of CompilationContextss to be merged. The headers of each context will be exported by the direct fields in the returned provider.

merge_compilation_outputs

CcCompilationOutputs cc_common.merge_compilation_outputs(compilation_outputs=[])

Merge compilation outputs.

Parameters

Parameter Description
compilation_outputs default is []