stop importing cmake when it isn't used

We don't need a CMakeInterpreter until and unless we actually attempt to
use a cmake subproject via the cmake module.

Minus 10 files and 3679 lines of code imported at startup.

mesonbuild/interpreter/interpreter.py

@@ -36,7 +36,6 @@ from ..interpreterbase import Disabler, disablerIfNotFound
 from ..interpreterbase import FeatureNew, FeatureDeprecated, FeatureBroken, FeatureNewKwargs, FeatureDeprecatedKwargs
 from ..interpreterbase import ObjectHolder, ContextManagerObject
 from ..modules import ExtensionModule, ModuleObject, MutableModuleObject, NewExtensionModule, NotFoundExtensionModule
-from ..cmake import CMakeInterpreter
 from ..backend.backends import ExecutableSerialisation
 
 from . import interpreterobjects as OBJ
@@ -1011,6 +1010,7 @@ class Interpreter(InterpreterBase, HoldableObject):
     def _do_subproject_cmake(self, subp_name: str, subdir: str, subdir_abs: str,
                              default_options: T.Dict[OptionKey, str],
                              kwargs: kwtypes.DoSubproject) -> SubprojectHolder:
+        from ..cmake import CMakeInterpreter
         with mlog.nested(subp_name):
             new_build = self.build.copy()
             prefix = self.coredata.options[OptionKey('prefix')].value

test cases/unit/113 empty project/expected_mods.json

@@ -94,14 +94,9 @@
       "http",
       "http.client",
       "importlib",
-      "importlib._abc",
-      "importlib._adapters",
       "importlib._bootstrap",
       "importlib._bootstrap_external",
-      "importlib._common",
-      "importlib.abc",
       "importlib.machinery",
-      "importlib.resources",
       "inspect",
       "io",
       "itertools",
@@ -169,7 +164,7 @@
       "zipimport",
       "zlib"
     ],
-    "count": 167
+    "count": 162
   },
   "meson": {
     "modules": [
@@ -186,15 +181,6 @@
       "mesonbuild.backend.backends",
       "mesonbuild.backend.ninjabackend",
       "mesonbuild.build",
-      "mesonbuild.cmake",
-      "mesonbuild.cmake.common",
-      "mesonbuild.cmake.executor",
-      "mesonbuild.cmake.fileapi",
-      "mesonbuild.cmake.generator",
-      "mesonbuild.cmake.interpreter",
-      "mesonbuild.cmake.toolchain",
-      "mesonbuild.cmake.traceparser",
-      "mesonbuild.cmake.tracetargets",
       "mesonbuild.compilers",
       "mesonbuild.compilers.compilers",
       "mesonbuild.compilers.detect",
@@ -232,7 +218,6 @@
       "mesonbuild.linkers",
       "mesonbuild.linkers.detect",
       "mesonbuild.linkers.linkers",
-      "mesonbuild.mesondata",
       "mesonbuild.mesonlib",
       "mesonbuild.mesonmain",
       "mesonbuild.mintro",
@@ -255,6 +240,6 @@
       "mesonbuild.wrap",
       "mesonbuild.wrap.wrap"
     ],
-    "count": 81
+    "count": 71
   }
 }

unittests/platformagnostictests.py

@@ -253,4 +253,4 @@ class PlatformAgnosticTests(BasePlatformTests):
             expected = json.load(f)['meson']['modules']
 
         self.assertEqual(data['modules'], expected)
-        self.assertEqual(data['count'], 81)
+        self.assertEqual(data['count'], 71)