path: root/mesonbuild/dependencies/cmake.py

# Copyright 2013-2021 The Meson development team

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import annotations

from .base import ExternalDependency, DependencyException, DependencyTypeName
from ..mesonlib import is_windows, MesonException, PerMachine, stringlistify, extract_as_list
from ..cmake import CMakeExecutor, CMakeTraceParser, CMakeException, CMakeToolchain, CMakeExecScope, check_cmake_args, resolve_cmake_trace_targets, cmake_is_debug
from .. import mlog
import importlib.resources
from pathlib import Path
import functools
import re
import os
import shutil
import textwrap
import typing as T

if T.TYPE_CHECKING:
    from ..cmake import CMakeTarget
    from ..environment import Environment
    from ..envconfig import MachineInfo

class CMakeInfo(T.NamedTuple):
    module_paths: T.List[str]
    cmake_root: str
    archs: T.List[str]
    common_paths: T.List[str]

class CMakeDependency(ExternalDependency):
    # The class's copy of the CMake path. Avoids having to search for it
    # multiple times in the same Meson invocation.
    class_cmakeinfo: PerMachine[T.Optional[CMakeInfo]] = PerMachine(None, None)
    # Version string for the minimum CMake version
    class_cmake_version = '>=3.4'
    # CMake generators to try (empty for no generator)
    class_cmake_generators = ['', 'Ninja', 'Unix Makefiles', 'Visual Studio 10 2010']
    class_working_generator: T.Optional[str] = None

    def _gen_exception(self, msg: str) -> DependencyException:
        return DependencyException(f'Dependency {self.name} not found: {msg}')

    def _main_cmake_file(self) -> str:
        return 'CMakeLists.txt'

    def _extra_cmake_opts(self) -> T.List[str]:
        return []

    def _map_module_list(self, modules: T.List[T.Tuple[str, bool]], components: T.List[T.Tuple[str, bool]]) -> T.List[T.Tuple[str, bool]]:
        # Map the input module list to something else
        # This function will only be executed AFTER the initial CMake
        # interpreter pass has completed. Thus variables defined in the
        # CMakeLists.txt can be accessed here.
        #
        # Both the modules and components inputs contain the original lists.
        return modules

    def _map_component_list(self, modules: T.List[T.Tuple[str, bool]], components: T.List[T.Tuple[str, bool]]) -> T.List[T.Tuple[str, bool]]:
        # Map the input components list to something else. This
        # function will be executed BEFORE the initial CMake interpreter
        # pass. Thus variables from the CMakeLists.txt can NOT be accessed.
        #
        # Both the modules and components inputs contain the original lists.
        return components

    def _original_module_name(self, module: str) -> str:
        # Reverse the module mapping done by _map_module_list for
        # one module
        return module

    def __init__(self, name: str, environment: 'Environment', kwargs: T.Dict[str, T.Any], language: T.Optional[str] = None, force_use_global_compilers: bool = False) -> None:
        # Gather a list of all languages to support
        self.language_list = []  # type: T.List[str]
        if language is None or force_use_global_compilers:
            compilers = None
            if kwargs.get('native', False):
                compilers = environment.coredata.compilers.build
            else:
                compilers = environment.coredata.compilers.host

            candidates = ['c', 'cpp', 'fortran', 'objc', 'objcxx']
            self.language_list += [x for x in candidates if x in compilers]
        else:
            self.language_list += [language]

        # Add additional languages if required
        if 'fortran' in self.language_list:
            self.language_list += ['c']

        # Ensure that the list is unique
        self.language_list = list(set(self.language_list))

        super().__init__(DependencyTypeName('cmake'), environment, kwargs, language=language)
        self.name = name
        self.is_libtool = False
        # Store a copy of the CMake path on the object itself so it is
        # stored in the pickled coredata and recovered.
        self.cmakebin:  T.Optional[CMakeExecutor] = None
        self.cmakeinfo: T.Optional[CMakeInfo] = None

        # Where all CMake "build dirs" are located
        self.cmake_root_dir = environment.scratch_dir

        # T.List of successfully found modules
        self.found_modules: T.List[str] = []

        # Initialize with None before the first return to avoid
        # AttributeError exceptions in derived classes
        self.traceparser: T.Optional[CMakeTraceParser] = None

        # TODO further evaluate always using MachineChoice.BUILD
        self.cmakebin = CMakeExecutor(environment, CMakeDependency.class_cmake_version, self.for_machine, silent=self.silent)
        if not self.cmakebin.found():
            self.cmakebin = None
            msg = f'CMake binary for machine {self.for_machine} not found. Giving up.'
            if self.required:
                raise DependencyException(msg)
            mlog.debug(msg)
            return

        # Setup the trace parser
        self.traceparser = CMakeTraceParser(self.cmakebin.version(), self._get_build_dir(), self.env)

        cm_args = stringlistify(extract_as_list(kwargs, 'cmake_args'))
        cm_args = check_cmake_args(cm_args)
        if CMakeDependency.class_cmakeinfo[self.for_machine] is None:
            CMakeDependency.class_cmakeinfo[self.for_machine] = self._get_cmake_info(cm_args)
        self.cmakeinfo = CMakeDependency.class_cmakeinfo[self.for_machine]
        if self.cmakeinfo is None:
            raise self._gen_exception('Unable to obtain CMake system information')

        package_version = kwargs.get('cmake_package_version', '')
        if not isinstance(package_version, str):
            raise DependencyException('Keyword "cmake_package_version" must be a string.')
        components = [(x, True) for x in stringlistify(extract_as_list(kwargs, 'components'))]
        modules = [(x, True) for x in stringlistify(extract_as_list(kwargs, 'modules'))]
        modules += [(x, False) for x in stringlistify(extract_as_list(kwargs, 'optional_modules'))]
        cm_path = stringlistify(extract_as_list(kwargs, 'cmake_module_path'))
        cm_path = [x if os.path.isabs(x) else os.path.join(environment.get_source_dir(), x) for x in cm_path]
        if cm_path:
            cm_args.append('-DCMAKE_MODULE_PATH=' + ';'.join(cm_path))
        if not self._preliminary_find_check(name, cm_path, self.cmakebin.get_cmake_prefix_paths(), environment.machines[self.for_machine]):
            mlog.debug('Preliminary CMake check failed. Aborting.')
            return
        self._detect_dep(name, package_version, modules, components, cm_args)

    def __repr__(self) -> str:
        return f'<{self.__class__.__name__} {self.name}: {self.is_found} {self.version_reqs}>'

    def _get_cmake_info(self, cm_args: T.List[str]) -> T.Optional[CMakeInfo]:
        mlog.debug("Extracting basic cmake information")

        # Try different CMake generators since specifying no generator may fail
        # in cygwin for some reason
        gen_list = []
        # First try the last working generator
        if CMakeDependency.class_working_generator is not None:
            gen_list += [CMakeDependency.class_working_generator]
        gen_list += CMakeDependency.class_cmake_generators

        temp_parser = CMakeTraceParser(self.cmakebin.version(), self._get_build_dir(), self.env)
        toolchain = CMakeToolchain(self.cmakebin, self.env, self.for_machine, CMakeExecScope.DEPENDENCY, self._get_build_dir())
        toolchain.write()

        for i in gen_list:
            mlog.debug('Try CMake generator: {}'.format(i if len(i) > 0 else 'auto'))

            # Prepare options
            cmake_opts = temp_parser.trace_args() + toolchain.get_cmake_args() + ['.']
            cmake_opts += cm_args
            if len(i) > 0:
                cmake_opts = ['-G', i] + cmake_opts

            # Run CMake
            ret1, out1, err1 = self._call_cmake(cmake_opts, 'CMakePathInfo.txt')

            # Current generator was successful
            if ret1 == 0:
                CMakeDependency.class_working_generator = i
                break

            mlog.debug(f'CMake failed to gather system information for generator {i} with error code {ret1}')
            mlog.debug(f'OUT:\n{out1}\n\n\nERR:\n{err1}\n\n')

        # Check if any generator succeeded
        if ret1 != 0:
            return None

        try:
            temp_parser.parse(err1)
        except MesonException:
            return None

        def process_paths(l: T.List[str]) -> T.Set[str]:
            if is_windows():
                # Cannot split on ':' on Windows because its in the drive letter
                tmp = [x.split(os.pathsep) for x in l]
            else:
                # https://github.com/mesonbuild/meson/issues/7294
                tmp = [re.split(r':|;', x) for x in l]
            flattened = [x for sublist in tmp for x in sublist]
            return set(flattened)

        # Extract the variables and sanity check them
        root_paths_set = process_paths(temp_parser.get_cmake_var('MESON_FIND_ROOT_PATH'))
        root_paths_set.update(process_paths(temp_parser.get_cmake_var('MESON_CMAKE_SYSROOT')))
        root_paths = sorted(root_paths_set)
        root_paths = [x for x in root_paths if os.path.isdir(x)]
        module_paths_set = process_paths(temp_parser.get_cmake_var('MESON_PATHS_LIST'))
        rooted_paths: T.List[str] = []
        for j in [Path(x) for x in root_paths]:
            for p in [Path(x) for x in module_paths_set]:
                rooted_paths.append(str(j / p.relative_to(p.anchor)))
        module_paths = sorted(module_paths_set.union(rooted_paths))
        module_paths = [x for x in module_paths if os.path.isdir(x)]
        archs = temp_parser.get_cmake_var('MESON_ARCH_LIST')

        common_paths = ['lib', 'lib32', 'lib64', 'libx32', 'share']
        for i in archs:
            common_paths += [os.path.join('lib', i)]

        res = CMakeInfo(
            module_paths=module_paths,
            cmake_root=temp_parser.get_cmake_var('MESON_CMAKE_ROOT')[0],
            archs=archs,
            common_paths=common_paths,
        )

        mlog.debug(f'  -- Module search paths:    {res.module_paths}')
        mlog.debug(f'  -- CMake root:             {res.cmake_root}')
        mlog.debug(f'  -- CMake architectures:    {res.archs}')
        mlog.debug(f'  -- CMake lib search paths: {res.common_paths}')

        return res

    @staticmethod
    @functools.lru_cache(maxsize=None)
    def _cached_listdir(path: str) -> T.Tuple[T.Tuple[str, str], ...]:
        try:
            return tuple((x, str(x).lower()) for x in os.listdir(path))
        except OSError:
            return tuple()

    @staticmethod
    @functools.lru_cache(maxsize=None)
    def _cached_isdir(path: str) -> bool:
        try:
            return os.path.isdir(path)
        except OSError:
            return False

    def _preliminary_find_check(self, name: str, module_path: T.List[str], prefix_path: T.List[str], machine: 'MachineInfo') -> bool:
        lname = str(name).lower()

        # Checks <path>, <path>/cmake, <path>/CMake
        def find_module(path: str) -> bool:
            for i in [path, os.path.join(path, 'cmake'), os.path.join(path, 'CMake')]:
                if not self._cached_isdir(i):
                    continue

                # Check the directory case insensitive
                content = self._cached_listdir(i)
                candidates = ['Find{}.cmake', '{}Config.cmake', '{}-config.cmake']
                candidates = [x.format(name).lower() for x in candidates]
                if any(x[1] in candidates for x in content):
                    return True
            return False

        # Search in <path>/(lib/<arch>|lib*|share) for cmake files
        def search_lib_dirs(path: str) -> bool:
            for i in [os.path.join(path, x) for x in self.cmakeinfo.common_paths]:
                if not self._cached_isdir(i):
                    continue

                # Check <path>/(lib/<arch>|lib*|share)/cmake/<name>*/
                cm_dir = os.path.join(i, 'cmake')
                if self._cached_isdir(cm_dir):
                    content = self._cached_listdir(cm_dir)
                    content = tuple(x for x in content if x[1].startswith(lname))
                    for k in content:
                        if find_module(os.path.join(cm_dir, k[0])):
                            return True

                # <path>/(lib/<arch>|lib*|share)/<name>*/
                # <path>/(lib/<arch>|lib*|share)/<name>*/(cmake|CMake)/
                content = self._cached_listdir(i)
                content = tuple(x for x in content if x[1].startswith(lname))
                for k in content:
                    if find_module(os.path.join(i, k[0])):
                        return True

            return False

        # Check the user provided and system module paths
        for i in module_path + [os.path.join(self.cmakeinfo.cmake_root, 'Modules')]:
            if find_module(i):
                return True

        # Check the user provided prefix paths
        for i in prefix_path:
            if search_lib_dirs(i):
                return True

        # Check PATH
        system_env = []  # type: T.List[str]
        for i in os.environ.get('PATH', '').split(os.pathsep):
            if i.endswith('/bin') or i.endswith('\\bin'):
                i = i[:-4]
            if i.endswith('/sbin') or i.endswith('\\sbin'):
                i = i[:-5]
            system_env += [i]

        # Check the system paths
        for i in self.cmakeinfo.module_paths + system_env:
            if find_module(i):
                return True

            if search_lib_dirs(i):
                return True

            content = self._cached_listdir(i)
            content = tuple(x for x in content if x[1].startswith(lname))
            for k in content:
                if search_lib_dirs(os.path.join(i, k[0])):
                    return True

            # Mac framework support
            if machine.is_darwin():
                for j in [f'{lname}.framework', f'{lname}.app']:
                    for k in content:
                        if k[1] != j:
                            continue
                        if find_module(os.path.join(i, k[0], 'Resources')) or find_module(os.path.join(i, k[0], 'Version')):
                            return True

        # Check the environment path
        env_path = os.environ.get(f'{name}_DIR')
        if env_path and find_module(env_path):
            return True

        # Check the Linux CMake registry
        linux_reg = Path.home() / '.cmake' / 'packages'
        for p in [linux_reg / name, linux_reg / lname]:
            if p.exists():
                return True

        return False

    def _detect_dep(self, name: str, package_version: str, modules: T.List[T.Tuple[str, bool]], components: T.List[T.Tuple[str, bool]], args: T.List[str]) -> None:
        # Detect a dependency with CMake using the '--find-package' mode
        # and the trace output (stderr)
        #
        # When the trace output is enabled CMake prints all functions with
        # parameters to stderr as they are executed. Since CMake 3.4.0
        # variables ("${VAR}") are also replaced in the trace output.
        mlog.debug('\nDetermining dependency {!r} with CMake executable '
                   '{!r}'.format(name, self.cmakebin.executable_path()))

        # Try different CMake generators since specifying no generator may fail
        # in cygwin for some reason
        gen_list = []
        # First try the last working generator
        if CMakeDependency.class_working_generator is not None:
            gen_list += [CMakeDependency.class_working_generator]
        gen_list += CMakeDependency.class_cmake_generators

        # Map the components
        comp_mapped = self._map_component_list(modules, components)
        toolchain = CMakeToolchain(self.cmakebin, self.env, self.for_machine, CMakeExecScope.DEPENDENCY, self._get_build_dir())
        toolchain.write()

        for i in gen_list:
            mlog.debug('Try CMake generator: {}'.format(i if len(i) > 0 else 'auto'))

            # Prepare options
            cmake_opts = []
            cmake_opts += [f'-DNAME={name}']
            cmake_opts += ['-DARCHS={}'.format(';'.join(self.cmakeinfo.archs))]
            cmake_opts += [f'-DVERSION={package_version}']
            cmake_opts += ['-DCOMPS={}'.format(';'.join([x[0] for x in comp_mapped]))]
            cmake_opts += args
            cmake_opts += self.traceparser.trace_args()
            cmake_opts += toolchain.get_cmake_args()
            cmake_opts += self._extra_cmake_opts()
            cmake_opts += ['.']
            if len(i) > 0:
                cmake_opts = ['-G', i] + cmake_opts

            # Run CMake
            ret1, out1, err1 = self._call_cmake(cmake_opts, self._main_cmake_file())

            # Current generator was successful
            if ret1 == 0:
                CMakeDependency.class_working_generator = i
                break

            mlog.debug(f'CMake failed for generator {i} and package {name} with error code {ret1}')
            mlog.debug(f'OUT:\n{out1}\n\n\nERR:\n{err1}\n\n')

        # Check if any generator succeeded
        if ret1 != 0:
            return

        try:
            self.traceparser.parse(err1)
        except CMakeException as e:
            e2 = self._gen_exception(str(e))
            if self.required:
                raise
            else:
                self.compile_args = []
                self.link_args = []
                self.is_found = False
                self.reason = e2
                return

        # Whether the package is found or not is always stored in PACKAGE_FOUND
        self.is_found = self.traceparser.var_to_bool('PACKAGE_FOUND')
        if not self.is_found:
            return

        # Try to detect the version
        vers_raw = self.traceparser.get_cmake_var('PACKAGE_VERSION')

        if len(vers_raw) > 0:
            self.version = vers_raw[0]
            self.version.strip('"\' ')

        # Post-process module list. Used in derived classes to modify the
        # module list (append prepend a string, etc.).
        modules = self._map_module_list(modules, components)
        autodetected_module_list = False

        # Try guessing a CMake target if none is provided
        if len(modules) == 0:
            for i in self.traceparser.targets:
                tg = i.lower()
                lname = name.lower()
                if f'{lname}::{lname}' == tg or lname == tg.replace('::', ''):
                    mlog.debug(f'Guessed CMake target \'{i}\'')
                    modules = [(i, True)]
                    autodetected_module_list = True
                    break

        # Failed to guess a target --> try the old-style method
        if len(modules) == 0:
            # Warn when there might be matching imported targets but no automatic match was used
            partial_modules: T.List[CMakeTarget] = []
            for k, v in self.traceparser.targets.items():
                tg = k.lower()
                lname = name.lower()
                if tg.startswith(f'{lname}::'):
                    partial_modules += [v]
            if partial_modules:
                mlog.warning(textwrap.dedent(f'''\
                    Could not find and exact match for the CMake dependency {name}.

                    However, Meson found the following partial matches:

                        {[x.name for x in partial_modules]}

                    Using imported is recommended, since this approach is less error prone
                    and better supported by Meson. Consider explicitly specifying one of
                    these in the dependency call with:

                        dependency('{name}', modules: ['{name}::<name>', ...])

                    Meson will now continue to use the old-style {name}_LIBRARIES CMake
                    variables to extract the dependency information since no explicit
                    target is currently specified.

                '''))
                mlog.debug('More info for the partial match targets:')
                for tgt in partial_modules:
                    mlog.debug(tgt)

            incDirs = [x for x in self.traceparser.get_cmake_var('PACKAGE_INCLUDE_DIRS') if x]
            defs = [x for x in self.traceparser.get_cmake_var('PACKAGE_DEFINITIONS') if x]
            libs_raw = [x for x in self.traceparser.get_cmake_var('PACKAGE_LIBRARIES') if x]

            # CMake has a "fun" API, where certain keywords describing
            # configurations can be in the *_LIBRARIES vraiables. See:
            # - https://github.com/mesonbuild/meson/issues/9197
            # - https://gitlab.freedesktop.org/libnice/libnice/-/issues/140
            # - https://cmake.org/cmake/help/latest/command/target_link_libraries.html#overview  (the last point in the section)
            libs: T.List[str] = []
            cfg_matches = True
            is_debug = cmake_is_debug(self.env)
            cm_tag_map = {'debug': is_debug, 'optimized': not is_debug, 'general': True}
            for i in libs_raw:
                if i.lower() in cm_tag_map:
                    cfg_matches = cm_tag_map[i.lower()]
                    continue
                if cfg_matches:
                    libs += [i]
                # According to the CMake docs, a keyword only works for the
                # directly the following item and all items without a keyword
                # are implizitly `general`
                cfg_matches = True

            # Try to use old style variables if no module is specified
            if len(libs) > 0:
                self.compile_args = list(map(lambda x: f'-I{x}', incDirs)) + defs
                self.link_args = []
                for j in libs:
                    rtgt = resolve_cmake_trace_targets(j, self.traceparser, self.env, clib_compiler=self.clib_compiler)
                    self.link_args += rtgt.libraries
                    self.compile_args += [f'-I{x}' for x in rtgt.include_directories]
                    self.compile_args += rtgt.public_compile_opts
                mlog.debug(f'using old-style CMake variables for dependency {name}')
                mlog.debug(f'Include Dirs:         {incDirs}')
                mlog.debug(f'Compiler Definitions: {defs}')
                mlog.debug(f'Libraries:            {libs}')
                return

            # Even the old-style approach failed. Nothing else we can do here
            self.is_found = False
            raise self._gen_exception('CMake: failed to guess a CMake target for {}.\n'
                                      'Try to explicitly specify one or more targets with the "modules" property.\n'
                                      'Valid targets are:\n{}'.format(name, list(self.traceparser.targets.keys())))

        # Set dependencies with CMake targets
        # recognise arguments we should pass directly to the linker
        incDirs = []
        compileOptions = []
        libraries = []

        for i, required in modules:
            if i not in self.traceparser.targets:
                if not required:
                    mlog.warning('CMake: T.Optional module', mlog.bold(self._original_module_name(i)), 'for', mlog.bold(name), 'was not found')
                    continue
                raise self._gen_exception('CMake: invalid module {} for {}.\n'
                                          'Try to explicitly specify one or more targets with the "modules" property.\n'
                                          'Valid targets are:\n{}'.format(self._original_module_name(i), name, list(self.traceparser.targets.keys())))

            if not autodetected_module_list:
                self.found_modules += [i]

            rtgt = resolve_cmake_trace_targets(i, self.traceparser, self.env,
                                               clib_compiler=self.clib_compiler,
                                               not_found_warning=lambda x:
                                                   mlog.warning('CMake: Dependency', mlog.bold(x), 'for', mlog.bold(name), 'was not found')
                                               )
            incDirs += rtgt.include_directories
            compileOptions += rtgt.public_compile_opts
            libraries += rtgt.libraries + rtgt.link_flags

        # Make sure all elements in the lists are unique and sorted
        incDirs = sorted(set(incDirs))
        compileOptions = sorted(set(compileOptions))
        libraries = sorted(set(libraries))

        mlog.debug(f'Include Dirs:         {incDirs}')
        mlog.debug(f'Compiler Options:     {compileOptions}')
        mlog.debug(f'Libraries:            {libraries}')

        self.compile_args = compileOptions + [f'-I{x}' for x in incDirs]
        self.link_args = libraries

    def _get_build_dir(self) -> Path:
        build_dir = Path(self.cmake_root_dir) / f'cmake_{self.name}'
        build_dir.mkdir(parents=True, exist_ok=True)
        return build_dir

    def _setup_cmake_dir(self, cmake_file: str) -> Path:
        # Setup the CMake build environment and return the "build" directory
        build_dir = self._get_build_dir()

        # Remove old CMake cache so we can try out multiple generators
        cmake_cache = build_dir / 'CMakeCache.txt'
        cmake_files = build_dir / 'CMakeFiles'
        if cmake_cache.exists():
            cmake_cache.unlink()
        shutil.rmtree(cmake_files.as_posix(), ignore_errors=True)

        # Insert language parameters into the CMakeLists.txt and write new CMakeLists.txt
        cmake_txt = importlib.resources.read_text('mesonbuild.dependencies.data', cmake_file, encoding = 'utf-8')

        # In general, some Fortran CMake find_package() also require C language enabled,
        # even if nothing from C is directly used. An easy Fortran example that fails
        # without C language is
        #   find_package(Threads)
        # To make this general to
        # any other language that might need this, we use a list for all
        # languages and expand in the cmake Project(... LANGUAGES ...) statement.
        from ..cmake import language_map
        cmake_language = [language_map[x] for x in self.language_list if x in language_map]
        if not cmake_language:
            cmake_language += ['NONE']

        cmake_txt = textwrap.dedent("""
            cmake_minimum_required(VERSION ${{CMAKE_VERSION}})
            project(MesonTemp LANGUAGES {})
        """).format(' '.join(cmake_language)) + cmake_txt

        cm_file = build_dir / 'CMakeLists.txt'
        cm_file.write_text(cmake_txt, encoding='utf-8')
        mlog.cmd_ci_include(cm_file.absolute().as_posix())

        return build_dir

    def _call_cmake(self,
                    args: T.List[str],
                    cmake_file: str,
                    env: T.Optional[T.Dict[str, str]] = None) -> T.Tuple[int, T.Optional[str], T.Optional[str]]:
        build_dir = self._setup_cmake_dir(cmake_file)
        return self.cmakebin.call(args, build_dir, env=env)

    @staticmethod
    def log_tried() -> str:
        return 'cmake'

    def log_details(self) -> str:
        modules = [self._original_module_name(x) for x in self.found_modules]
        modules = sorted(set(modules))
        if modules:
            return 'modules: ' + ', '.join(modules)
        return ''

    def get_variable(self, *, cmake: T.Optional[str] = None, pkgconfig: T.Optional[str] = None,
                     configtool: T.Optional[str] = None, internal: T.Optional[str] = None,
                     default_value: T.Optional[str] = None,
                     pkgconfig_define: T.Optional[T.List[str]] = None) -> str:
        if cmake and self.traceparser is not None:
            try:
                v = self.traceparser.vars[cmake]
            except KeyError:
                pass
            else:
                # CMake does NOT have a list datatype. We have no idea whether
                # anything is a string or a string-separated-by-; Internally,
                # we treat them as the latter and represent everything as a
                # list, because it is convenient when we are mostly handling
                # imported targets, which have various properties that are
                # actually lists.
                #
                # As a result we need to convert them back to strings when grabbing
                # raw variables the user requested.
                return ';'.join(v)
        if default_value is not None:
            return default_value
        raise DependencyException(f'Could not get cmake variable and no default provided for {self!r}')