cmake: Do not pass install prefix explicitly to the CMake interpreter

There is no point in doing so as it can be readily obtained from the
environment. This in preparation of extracting more installation
location from the environment.

Author: dnicolodi

mesonbuild/cmake/interpreter.py

@@ -786,12 +786,12 @@ def log(self) -> None:
         mlog.log('  -- depends:      ', mlog.bold(str(self.depends)))
 
 class CMakeInterpreter:
-    def __init__(self, subdir: Path, install_prefix: Path, env: 'Environment', backend: 'Backend'):
+    def __init__(self, subdir: Path, env: 'Environment', backend: 'Backend'):
         self.subdir = subdir
         self.src_dir = Path(env.get_source_dir(), subdir)
         self.build_dir_rel = subdir / '__CMake_build'
         self.build_dir = Path(env.get_build_dir()) / self.build_dir_rel
-        self.install_prefix = install_prefix
+        self.install_prefix = Path(T.cast('str', env.coredata.optstore.get_value_for(OptionKey('prefix'))))
         self.env = env
         self.for_machine = MachineChoice.HOST # TODO make parameter
         self.backend_name = backend.name

mesonbuild/interpreter/interpreter.py

@@ -1049,12 +1049,10 @@ def _do_subproject_cmake(self, subp_name: str, subdir: str,
                              kwargs: kwtypes.DoSubproject) -> SubprojectHolder:
         from ..cmake import CMakeInterpreter
         with mlog.nested(subp_name):
-            prefix = self.coredata.optstore.get_value_for('prefix')
-
             from ..modules.cmake import CMakeSubprojectOptions
             kw_opts = kwargs.get('options') or CMakeSubprojectOptions()
             cmake_options = kwargs.get('cmake_options', []) + kw_opts.cmake_options
-            cm_int = CMakeInterpreter(Path(subdir), Path(prefix), self.build.environment, self.backend)
+            cm_int = CMakeInterpreter(Path(subdir), self.build.environment, self.backend)
             cm_int.initialise(cmake_options)
             cm_int.analyse()