Merge pull request #8812 from mensinda/cmakeToolchain

CMake toolchain file improvements (fixes #8293)

8 files changed, 203 insertions, 96 deletions

diff --git a/mesonbuild/cmake/__init__.py b/mesonbuild/cmake/__init__.py
index b13b5a8..d39bf24 100644
--- a/mesonbuild/cmake/__init__.py
+++ b/mesonbuild/cmake/__init__.py
@@ -30,11 +30,13 @@ __all__ = [
     'TargetOptions',
     'parse_generator_expressions',
     'language_map',
+    'backend_generator_map',
+    'cmake_get_generator_args',
     'cmake_defines_to_args',
     'check_cmake_args',
 ]
 
-from .common import CMakeException, SingleTargetOptions, TargetOptions, cmake_defines_to_args, language_map, check_cmake_args
+from .common import CMakeException, SingleTargetOptions, TargetOptions, cmake_defines_to_args, language_map, backend_generator_map, cmake_get_generator_args, check_cmake_args
 from .client import CMakeClient
 from .executor import CMakeExecutor
 from .fileapi import CMakeFileAPI
diff --git a/mesonbuild/cmake/common.py b/mesonbuild/cmake/common.py
index f0a54b5..d1f86f0 100644
--- a/mesonbuild/cmake/common.py
+++ b/mesonbuild/cmake/common.py
@@ -15,11 +15,14 @@
 # This class contains the basic functionality needed to run any interpreter
 # or an interpreter-based tool.
 
-from ..mesonlib import MesonException
+from ..mesonlib import MesonException, OptionKey
 from .. import mlog
 from pathlib import Path
 import typing as T
 
+if T.TYPE_CHECKING:
+    from ..environment import Environment
+
 language_map = {
     'c': 'C',
     'cpp': 'CXX',
@@ -32,6 +35,15 @@ language_map = {
     'swift': 'Swift',
 }
 
+backend_generator_map = {
+    'ninja': 'Ninja',
+    'xcode': 'Xcode',
+    'vs2010': 'Visual Studio 10 2010',
+    'vs2015': 'Visual Studio 15 2017',
+    'vs2017': 'Visual Studio 15 2017',
+    'vs2019': 'Visual Studio 16 2019',
+}
+
 blacklist_cmake_defs = [
     'CMAKE_TOOLCHAIN_FILE',
     'CMAKE_PROJECT_INCLUDE',
@@ -87,6 +99,12 @@ def _flags_to_list(raw: str) -> T.List[str]:
     res = list(filter(lambda x: len(x) > 0, res))
     return res
 
+def cmake_get_generator_args(env: 'Environment') -> T.List[str]:
+    backend_name = env.coredata.get_option(OptionKey('backend'))
+    assert isinstance(backend_name, str)
+    assert backend_name in backend_generator_map
+    return ['-G', backend_generator_map[backend_name]]
+
 def cmake_defines_to_args(raw: T.Any, permissive: bool = False) -> T.List[str]:
     res = []  # type: T.List[str]
     if not isinstance(raw, list):
diff --git a/mesonbuild/cmake/generator.py b/mesonbuild/cmake/generator.py
index 02d56cc..848fdf9 100644
--- a/mesonbuild/cmake/generator.py
+++ b/mesonbuild/cmake/generator.py
@@ -23,6 +23,10 @@ def parse_generator_expressions(raw: str) -> str:
     use cases.
     '''
 
+    # Early abort if no generator expression present
+    if '$<' not in raw:
+        return raw
+
     out = ''  # type: str
     i = 0     # type: int
 
diff --git a/mesonbuild/cmake/interpreter.py b/mesonbuild/cmake/interpreter.py
index 130723f..cc6adf1 100644
--- a/mesonbuild/cmake/interpreter.py
+++ b/mesonbuild/cmake/interpreter.py
@@ -15,7 +15,7 @@
 # This class contains the basic functionality needed to run any interpreter
 # or an interpreter-based tool.
 
-from .common import CMakeException, CMakeTarget, TargetOptions, CMakeConfiguration, language_map, check_cmake_args
+from .common import CMakeException, CMakeTarget, TargetOptions, CMakeConfiguration, language_map, backend_generator_map, cmake_get_generator_args, check_cmake_args
 from .client import CMakeClient, RequestCMakeInputs, RequestConfigure, RequestCompute, RequestCodeModel, ReplyCMakeInputs, ReplyCodeModel
 from .fileapi import CMakeFileAPI
 from .executor import CMakeExecutor
@@ -74,15 +74,6 @@ disable_policy_warnings = [
     'CMP0102',
 ]
 
-backend_generator_map = {
-    'ninja': 'Ninja',
-    'xcode': 'Xcode',
-    'vs2010': 'Visual Studio 10 2010',
-    'vs2015': 'Visual Studio 15 2017',
-    'vs2017': 'Visual Studio 15 2017',
-    'vs2019': 'Visual Studio 16 2019',
-}
-
 target_type_map = {
     'STATIC_LIBRARY': 'static_library',
     'MODULE_LIBRARY': 'shared_module',
@@ -892,15 +883,14 @@ class CMakeInterpreter:
         self.trace = CMakeTraceParser(cmake_exe.version(), self.build_dir, permissive=True)
 
         preload_file = mesondata['cmake/data/preload.cmake'].write_to_private(self.env)
-        toolchain = CMakeToolchain(self.env, self.for_machine, CMakeExecScope.SUBPROJECT, self.build_dir.parent, preload_file)
+        toolchain = CMakeToolchain(cmake_exe, self.env, self.for_machine, CMakeExecScope.SUBPROJECT, self.build_dir, preload_file)
         toolchain_file = toolchain.write()
 
         # TODO: drop this check once the deprecated `cmake_args` kwarg is removed
         extra_cmake_options = check_cmake_args(extra_cmake_options)
 
-        generator = backend_generator_map[self.backend_name]
         cmake_args = []
-        cmake_args += ['-G', generator]
+        cmake_args += cmake_get_generator_args(self.env)
         cmake_args += [f'-DCMAKE_INSTALL_PREFIX={self.install_prefix}']
         cmake_args += extra_cmake_options
         trace_args = self.trace.trace_args()
@@ -953,6 +943,7 @@ class CMakeInterpreter:
             cmake_files = self.fileapi.get_cmake_sources()
             self.bs_files = [x.file for x in cmake_files if not x.is_cmake and not x.is_temp]
             self.bs_files = [relative_to_if_possible(x, Path(self.env.get_source_dir())) for x in self.bs_files]
+            self.bs_files = [x for x in self.bs_files if not path_is_in_root(x, Path(self.env.get_build_dir()), resolve=True)]
             self.bs_files = list(OrderedSet(self.bs_files))
 
             # Load the codemodel configurations
@@ -980,6 +971,7 @@ class CMakeInterpreter:
         src_dir = bs_reply.src_dir
         self.bs_files = [x.file for x in bs_reply.build_files if not x.is_cmake and not x.is_temp]
         self.bs_files = [relative_to_if_possible(src_dir / x, Path(self.env.get_source_dir()), resolve=True) for x in self.bs_files]
+        self.bs_files = [x for x in self.bs_files if not path_is_in_root(x, Path(self.env.get_build_dir()), resolve=True)]
         self.bs_files = list(OrderedSet(self.bs_files))
         self.codemodel_configs = cm_reply.configs
 
diff --git a/mesonbuild/cmake/toolchain.py b/mesonbuild/cmake/toolchain.py
index c9f821a..f3e487d 100644
--- a/mesonbuild/cmake/toolchain.py
+++ b/mesonbuild/cmake/toolchain.py
@@ -13,9 +13,10 @@
 # limitations under the License.
 
 from pathlib import Path
+from .traceparser import CMakeTraceParser
 from ..envconfig import CMakeSkipCompilerTest
 from ..mesonlib import MachineChoice
-from .common import language_map
+from .common import language_map, cmake_get_generator_args
 from .. import mlog
 
 import shutil
@@ -24,53 +25,49 @@ from enum import Enum
 from textwrap import dedent
 
 if T.TYPE_CHECKING:
+    from .executor import CMakeExecutor
     from ..envconfig import MachineInfo, Properties, CMakeVariables
     from ..environment import Environment
-    from ..compilers import Compiler
-
-
-_MESON_TO_CMAKE_MAPPING = {
-    'arm':          'ARMCC',
-    'armclang':     'ARMClang',
-    'clang':        'Clang',
-    'clang-cl':     'MSVC',
-    'flang':        'Flang',
-    'g95':          'G95',
-    'gcc':          'GNU',
-    'intel':        'Intel',
-    'intel-cl':     'MSVC',
-    'msvc':         'MSVC',
-    'pathscale':    'PathScale',
-    'pgi':          'PGI',
-    'sun':          'SunPro',
-}
 
 class CMakeExecScope(Enum):
     SUBPROJECT = 'subproject'
     DEPENDENCY = 'dependency'
 
 class CMakeToolchain:
-    def __init__(self, env: 'Environment', for_machine: MachineChoice, exec_scope: CMakeExecScope, out_dir: Path, preload_file: T.Optional[Path] = None) -> None:
+    def __init__(self, cmakebin: 'CMakeExecutor', env: 'Environment', for_machine: MachineChoice, exec_scope: CMakeExecScope, build_dir: Path, preload_file: T.Optional[Path] = None) -> None:
         self.env            = env
+        self.cmakebin       = cmakebin
         self.for_machine    = for_machine
         self.exec_scope     = exec_scope
         self.preload_file   = preload_file
-        self.toolchain_file = out_dir / 'CMakeMesonToolchainFile.cmake'
-        self.toolchain_file = self.toolchain_file.resolve()
+        self.build_dir      = build_dir
+        self.build_dir      = self.build_dir.resolve()
+        self.toolchain_file = build_dir / 'CMakeMesonToolchainFile.cmake'
+        self.cmcache_file   = build_dir / 'CMakeCache.txt'
         self.minfo          = self.env.machines[self.for_machine]
         self.properties     = self.env.properties[self.for_machine]
         self.compilers      = self.env.coredata.compilers[self.for_machine]
         self.cmakevars      = self.env.cmakevars[self.for_machine]
+        self.cmakestate     = self.env.coredata.cmake_cache[self.for_machine]
 
         self.variables = self.get_defaults()
         self.variables.update(self.cmakevars.get_variables())
 
+        # Determine whether CMake the compiler test should be skipped
+        skip_status = self.properties.get_cmake_skip_compiler_test()
+        self.skip_check = skip_status == CMakeSkipCompilerTest.ALWAYS
+        if skip_status == CMakeSkipCompilerTest.DEP_ONLY and self.exec_scope == CMakeExecScope.DEPENDENCY:
+            self.skip_check = True
+        if not self.properties.get_cmake_defaults():
+            self.skip_check = False
+
         assert self.toolchain_file.is_absolute()
 
     def write(self) -> Path:
         if not self.toolchain_file.parent.exists():
             self.toolchain_file.parent.mkdir(parents=True)
         self.toolchain_file.write_text(self.generate())
+        self.cmcache_file.write_text(self.generate_cache())
         mlog.cmd_ci_include(self.toolchain_file.as_posix())
         return self.toolchain_file
 
@@ -80,6 +77,16 @@ class CMakeToolchain:
             args += ['-DMESON_PRELOAD_FILE=' + self.preload_file.as_posix()]
         return args
 
+    @staticmethod
+    def _print_vars(vars: T.Dict[str, T.List[str]]) -> str:
+        res = ''
+        for key, value in vars.items():
+            res += 'set(' + key
+            for i in value:
+                res += f' "{i}"'
+            res += ')\n'
+        return res
+
     def generate(self) -> str:
         res = dedent('''\
             ######################################
@@ -100,14 +107,19 @@ class CMakeToolchain:
         for key, value in self.variables.items():
             self.variables[key] = [x.replace('\\', '/') for x in value]
 
+        # Set compiler
+        if self.skip_check:
+            self.update_cmake_compiler_state()
+            res += '# CMake compiler state variables\n'
+            for lang, vars in self.cmakestate:
+                res += f'# -- Variables for language {lang}\n'
+                res += self._print_vars(vars)
+                res += '\n'
+            res += '\n'
+
         # Set variables from the current machine config
         res += '# Variables from meson\n'
-        for key, value in self.variables.items():
-            res += 'set(' + key
-            for i in value:
-                res += f' "{i}"'
-
-            res += ')\n'
+        res += self._print_vars(self.variables)
         res += '\n'
 
         # Add the user provided toolchain file
@@ -121,6 +133,15 @@ class CMakeToolchain:
 
         return res
 
+    def generate_cache(self) -> str:
+        if not self.skip_check:
+            return ''
+
+        res = ''
+        for name, v in self.cmakestate.cmake_cache.items():
+            res += f'{name}:{v.type}={";".join(v.value)}\n'
+        return res
+
     def get_defaults(self) -> T.Dict[str, T.List[str]]:
         defaults = {}  # type: T.Dict[str, T.List[str]]
 
@@ -151,11 +172,6 @@ class CMakeToolchain:
         if sys_root:
             defaults['CMAKE_SYSROOT'] = [sys_root]
 
-        # Determine whether CMake the compiler test should be skipped
-        skip_check = self.properties.get_cmake_skip_compiler_test() == CMakeSkipCompilerTest.ALWAYS
-        if self.properties.get_cmake_skip_compiler_test() == CMakeSkipCompilerTest.DEP_ONLY and self.exec_scope == CMakeExecScope.DEPENDENCY:
-            skip_check = True
-
         def make_abs(exe: str) -> str:
             if Path(exe).is_absolute():
                 return exe
@@ -168,9 +184,6 @@ class CMakeToolchain:
         # Set the compiler variables
         for lang, comp_obj in self.compilers.items():
             exe_list = [make_abs(x) for x in comp_obj.get_exelist()]
-            comp_id = CMakeToolchain.meson_compiler_to_cmake_id(comp_obj)
-            comp_version = comp_obj.version.upper()
-
             prefix = 'CMAKE_{}_'.format(language_map.get(lang, lang.upper()))
 
             if not exe_list:
@@ -183,35 +196,53 @@ class CMakeToolchain:
             if comp_obj.get_id() == 'clang-cl':
                 defaults['CMAKE_LINKER'] = comp_obj.get_linker_exelist()
 
-            # Setting the variables after this check cause CMake to skip
-            # validating the compiler
-            if not skip_check:
-                continue
-
-            defaults[prefix + 'COMPILER_ID']      = [comp_id]
-            defaults[prefix + 'COMPILER_VERSION'] = [comp_version]
-            #defaults[prefix + 'COMPILER_LOADED']  = ['1']
-            defaults[prefix + 'COMPILER_FORCED']  = ['1']
-            defaults[prefix + 'COMPILER_WORKS']   = ['TRUE']
-            #defaults[prefix + 'ABI_COMPILED']     = ['TRUE']
-
         return defaults
 
-    @staticmethod
-    def meson_compiler_to_cmake_id(cobj: 'Compiler') -> str:
-        """Translate meson compiler's into CMAKE compiler ID's.
-
-        Most of these can be handled by a simple table lookup, with a few
-        exceptions.
-
-        Clang and Apple's Clang are both identified as "clang" by meson. To make
-        things more complicated gcc and vanilla clang both use Apple's ld64 on
-        macOS. The only way to know for sure is to do an isinstance() check.
-        """
-        from ..compilers import (AppleClangCCompiler, AppleClangCPPCompiler,
-                                AppleClangObjCCompiler, AppleClangObjCPPCompiler)
-        if isinstance(cobj, (AppleClangCCompiler, AppleClangCPPCompiler,
-                            AppleClangObjCCompiler, AppleClangObjCPPCompiler)):
-            return 'AppleClang'
-        # If no mapping, try GNU and hope that the build files don't care
-        return _MESON_TO_CMAKE_MAPPING.get(cobj.get_id(), 'GNU')
+    def update_cmake_compiler_state(self) -> None:
+        # Check if all variables are already cached
+        if self.cmakestate.languages.issuperset(self.compilers.keys()):
+            return
+
+        # Generate the CMakeLists.txt
+        mlog.debug('CMake Toolchain: Calling CMake once to generate the compiler state')
+        languages     = list(self.compilers.keys())
+        lang_ids      = [language_map.get(x, x.upper()) for x in languages]
+        cmake_content = dedent(f'''
+            cmake_minimum_required(VERSION 3.7)
+            project(CompInfo {' '.join(lang_ids)})
+        ''')
+
+        build_dir = Path(self.env.scratch_dir) / '__CMake_compiler_info__'
+        build_dir.mkdir(parents=True, exist_ok=True)
+        cmake_file = build_dir / 'CMakeLists.txt'
+        cmake_file.write_text(cmake_content)
+
+        # Generate the temporary toolchain file
+        temp_toolchain_file = build_dir / 'CMakeMesonTempToolchainFile.cmake'
+        temp_toolchain_file.write_text(CMakeToolchain._print_vars(self.variables))
+
+        # Configure
+        trace = CMakeTraceParser(self.cmakebin.version(), build_dir)
+        self.cmakebin.set_exec_mode(print_cmout=False, always_capture_stderr=trace.requires_stderr())
+        cmake_args = []
+        cmake_args += trace.trace_args()
+        cmake_args += cmake_get_generator_args(self.env)
+        cmake_args += [f'-DCMAKE_TOOLCHAIN_FILE={temp_toolchain_file.as_posix()}', '.']
+        rc, _, raw_trace = self.cmakebin.call(cmake_args, build_dir=build_dir, disable_cache=True)
+
+        if rc != 0:
+            mlog.warning('CMake Toolchain: Failed to determine CMake compilers state')
+            return
+
+        # Parse output
+        trace.parse(raw_trace)
+        self.cmakestate.cmake_cache = {**trace.cache}
+
+        vars_by_file = {k.name: v for (k, v) in trace.vars_by_file.items()}
+
+        for lang in languages:
+            lang_cmake = language_map.get(lang, lang.upper())
+            file_name  = f'CMake{lang_cmake}Compiler.cmake'
+            vars = vars_by_file.setdefault(file_name, {})
+            vars[f'CMAKE_{lang_cmake}_COMPILER_FORCED'] = ['1']
+            self.cmakestate.update(lang, vars)
diff --git a/mesonbuild/cmake/traceparser.py b/mesonbuild/cmake/traceparser.py
index 6294fa1..23a1852 100644
--- a/mesonbuild/cmake/traceparser.py
+++ b/mesonbuild/cmake/traceparser.py
@@ -22,21 +22,31 @@ from ..mesonlib import version_compare
 
 import typing as T
 from pathlib import Path
+from functools import lru_cache
 import re
 import json
 import textwrap
 
 class CMakeTraceLine:
-    def __init__(self, file: Path, line: int, func: str, args: T.List[str]) -> None:
-        self.file = file
+    def __init__(self, file_str: str, line: int, func: str, args: T.List[str]) -> None:
+        self.file = CMakeTraceLine._to_path(file_str)
         self.line = line
         self.func = func.lower()
         self.args = args
 
+    @staticmethod
+    @lru_cache(maxsize=None)
+    def _to_path(file_str: str) -> Path:
+        return Path(file_str)
+
     def __repr__(self) -> str:
         s = 'CMake TRACE: {0}:{1} {2}({3})'
         return s.format(self.file, self.line, self.func, self.args)
 
+class CMakeCacheEntry(T.NamedTuple):
+    value: T.List[str]
+    type: str
+
 class CMakeTarget:
     def __init__(
                 self,
@@ -81,8 +91,10 @@ class CMakeGeneratorTarget(CMakeTarget):
 
 class CMakeTraceParser:
     def __init__(self, cmake_version: str, build_dir: Path, permissive: bool = True) -> None:
-        self.vars = {}     # type: T.Dict[str, T.List[str]]
-        self.targets = {}  # type: T.Dict[str, CMakeTarget]
+        self.vars:                      T.Dict[str, T.List[str]]     = {}
+        self.vars_by_file: T.Dict[Path, T.Dict[str, T.List[str]]]    = {}
+        self.targets:                   T.Dict[str, CMakeTarget]     = {}
+        self.cache:                     T.Dict[str, CMakeCacheEntry] = {}
 
         self.explicit_headers = set()  # type: T.Set[Path]
 
@@ -234,6 +246,14 @@ class CMakeTraceParser:
         """
         # DOC: https://cmake.org/cmake/help/latest/command/set.html
 
+        cache_type  = None
+        cache_force = 'FORCE' in tline.args
+        try:
+            cache_idx  = tline.args.index('CACHE')
+            cache_type = tline.args[cache_idx + 1]
+        except (ValueError, IndexError):
+            pass
+
         # 1st remove PARENT_SCOPE and CACHE from args
         args = []
         for i in tline.args:
@@ -256,12 +276,19 @@ class CMakeTraceParser:
         identifier = args.pop(0)
         value = ' '.join(args)
 
+        # Write to the CMake cache instead
+        if cache_type:
+            # Honor how the CMake FORCE parameter works
+            if identifier not in self.cache or cache_force:
+                self.cache[identifier] = CMakeCacheEntry(value.split(';'), cache_type)
+
         if not value:
             # Same as unset
             if identifier in self.vars:
                 del self.vars[identifier]
         else:
             self.vars[identifier] = value.split(';')
+            self.vars_by_file.setdefault(tline.file, {})[identifier] = value.split(';')
 
     def _cmake_unset(self, tline: CMakeTraceLine) -> None:
         # DOC: https://cmake.org/cmake/help/latest/command/unset.html
@@ -437,17 +464,18 @@ class CMakeTraceParser:
         if not value:
             return
 
-        def do_target(tgt: str) -> None:
-            if i not in self.targets:
-                return self._gen_exception('set_property', f'TARGET {i} not found', tline)
+        def do_target(t: str) -> None:
+            if t not in self.targets:
+                return self._gen_exception('set_property', f'TARGET {t} not found', tline)
 
-            if identifier not in self.targets[i].properties:
-                self.targets[i].properties[identifier] = []
+            tgt = self.targets[t]
+            if identifier not in tgt.properties:
+                tgt.properties[identifier] = []
 
             if append:
-                self.targets[i].properties[identifier] += value
+                tgt.properties[identifier] += value
             else:
-                self.targets[i].properties[identifier] = value
+                tgt.properties[identifier] = value
 
         def do_source(src: str) -> None:
             if identifier != 'HEADER_FILE_ONLY' or not self._str_to_bool(value):
@@ -652,7 +680,7 @@ class CMakeTraceParser:
             argl = args.split(' ')
             argl = list(map(lambda x: x.strip(), argl))
 
-            yield CMakeTraceLine(Path(file), int(line), func, argl)
+            yield CMakeTraceLine(file, int(line), func, argl)
 
     def _lex_trace_json(self, trace: str) -> T.Generator[CMakeTraceLine, None, None]:
         lines = trace.splitlines(keepends=False)
@@ -667,7 +695,7 @@ class CMakeTraceParser:
             for j in args:
                 assert isinstance(j, str)
             args = [parse_generator_expressions(x) for x in args]
-            yield CMakeTraceLine(Path(data['file']), data['line'], data['cmd'], args)
+            yield CMakeTraceLine(data['file'], data['line'], data['cmd'], args)
 
     def _flatten_args(self, args: T.List[str]) -> T.List[str]:
         # Split lists in arguments
diff --git a/mesonbuild/coredata.py b/mesonbuild/coredata.py
index 5e726a4..2fbab52 100644
--- a/mesonbuild/coredata.py
+++ b/mesonbuild/coredata.py
@@ -36,6 +36,7 @@ if T.TYPE_CHECKING:
     from .compilers.compilers import Compiler, CompileResult  # noqa: F401
     from .environment import Environment
     from .mesonlib import OptionOverrideProxy
+    from .cmake.traceparser import CMakeCacheEntry
 
     OptionDictType = T.Union[T.Dict[str, 'UserOption[T.Any]'], OptionOverrideProxy]
     KeyedOptionDictType = T.Union[T.Dict['OptionKey', 'UserOption[T.Any]'], OptionOverrideProxy]
@@ -374,6 +375,34 @@ class DependencyCache:
     def clear(self) -> None:
         self.__cache.clear()
 
+
+class CMakeStateCache:
+    """Class that stores internal CMake compiler states.
+
+    This cache is used to reduce the startup overhead of CMake by caching
+    all internal CMake compiler variables.
+    """
+
+    def __init__(self) -> None:
+        self.__cache: T.Dict[str, T.Dict[str, T.List[str]]] = {}
+        self.cmake_cache: T.Dict[str, 'CMakeCacheEntry'] = {}
+
+    def __iter__(self) -> T.Iterator[T.Tuple[str, T.Dict[str, T.List[str]]]]:
+        return iter(self.__cache.items())
+
+    def items(self) -> T.Iterator[T.Tuple[str, T.Dict[str, T.List[str]]]]:
+        return iter(self.__cache.items())
+
+    def update(self, language: str, variables: T.Dict[str, T.List[str]]):
+        if language not in self.__cache:
+            self.__cache[language] = {}
+        self.__cache[language].update(variables)
+
+    @property
+    def languages(self) -> T.Set[str]:
+        return set(self.__cache.keys())
+
+
 # Can't bind this near the class method it seems, sadly.
 _V = T.TypeVar('_V')
 
@@ -414,6 +443,9 @@ class CoreData:
 
         self.compiler_check_cache = OrderedDict()  # type: T.Dict[CompilerCheckCacheKey, compiler.CompileResult]
 
+        # CMake cache
+        self.cmake_cache: PerMachine[CMakeStateCache] = PerMachine(CMakeStateCache(), CMakeStateCache())
+
         # Only to print a warning if it changes between Meson invocations.
         self.config_files = self.__load_config_files(options, scratch_dir, 'native')
         self.builtin_options_libdir_cross_fixup()
diff --git a/mesonbuild/dependencies/base.py b/mesonbuild/dependencies/base.py
index 2252800..d4b45fa 100644
--- a/mesonbuild/dependencies/base.py
+++ b/mesonbuild/dependencies/base.py
@@ -1146,7 +1146,7 @@ class CMakeDependency(ExternalDependency):
         gen_list += CMakeDependency.class_cmake_generators
 
         temp_parser = CMakeTraceParser(self.cmakebin.version(), self._get_build_dir())
-        toolchain = CMakeToolchain(self.env, self.for_machine, CMakeExecScope.DEPENDENCY, self._get_build_dir())
+        toolchain = CMakeToolchain(self.cmakebin, self.env, self.for_machine, CMakeExecScope.DEPENDENCY, self._get_build_dir())
         toolchain.write()
 
         for i in gen_list:
@@ -1346,7 +1346,7 @@ class CMakeDependency(ExternalDependency):
 
         # Map the components
         comp_mapped = self._map_component_list(modules, components)
-        toolchain = CMakeToolchain(self.env, self.for_machine, CMakeExecScope.DEPENDENCY, self._get_build_dir())
+        toolchain = CMakeToolchain(self.cmakebin, self.env, self.for_machine, CMakeExecScope.DEPENDENCY, self._get_build_dir())
         toolchain.write()
 
         for i in gen_list: