cmake: Always use all compilers for LLVM (fixes mesonbuild#10249)

mesonbuild/dependencies/cmake.py

@@ -76,10 +76,10 @@ def _original_module_name(self, module: str) -> str:
         # one module
         return module
 
-    def __init__(self, name: str, environment: 'Environment', kwargs: T.Dict[str, T.Any], language: T.Optional[str] = None) -> None:
+    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:
+        if language is None or force_use_global_compilers:
             compilers = None
             if kwargs.get('native', False):
                 compilers = environment.coredata.compilers.build

mesonbuild/dependencies/data/CMakeListsLLVM.txt

@@ -1,4 +1,3 @@
-cmake_minimum_required(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}.${CMAKE_PATCH_VERSION} )
 
 set(PACKAGE_FOUND FALSE)
 

mesonbuild/dependencies/dev.py

@@ -404,7 +404,18 @@ class LLVMDependencyCMake(CMakeDependency):
     def __init__(self, name: str, env: 'Environment', kwargs: T.Dict[str, T.Any]) -> None:
         self.llvm_modules = stringlistify(extract_as_list(kwargs, 'modules'))
         self.llvm_opt_modules = stringlistify(extract_as_list(kwargs, 'optional_modules'))
-        super().__init__(name, env, kwargs, language='cpp')
+
+        compilers = None
+        if kwargs.get('native', False):
+            compilers = env.coredata.compilers.build
+        else:
+            compilers = env.coredata.compilers.host
+        if not compilers or not all(x in compilers for x in ('c', 'cpp')):
+            self.is_found = False
+            mlog.warning('The LLVM dependency was not found via CMake since both a C and C++ compiler are required.')
+            return
+
+        super().__init__(name, env, kwargs, language='cpp', force_use_global_compilers=True)
 
         # Cmake will always create a statically linked binary, so don't use
         # cmake if dynamic is required