Cache variables declaration in CMakeToolchain

conan/tools/cmake/presets.py

@@ -42,7 +42,6 @@ def _configure_preset_name(conanfile, multiconfig):
         return str(build_type).lower()
 
 
-
 def _add_configure_preset(conanfile, generator, cache_variables, toolchain_file, multiconfig):
     build_type = conanfile.settings.get_safe("build_type")
     name = _configure_preset_name(conanfile, multiconfig)
@@ -78,15 +77,19 @@ def _contents(conanfile, toolchain_file, cache_variables, generator):
     return ret
 
 
-def write_cmake_presets(conanfile, toolchain_file, generator):
-    cache_variables = {}
+def write_cmake_presets(conanfile, toolchain_file, generator, cache_variables):
+    cache_variables = cache_variables or {}
     if platform.system() == "Windows" and generator == "MinGW Makefiles":
-        cache_variables["CMAKE_SH"] = "CMAKE_SH-NOTFOUND"
-        cmake_make_program = conanfile.conf.get("tools.gnu:make_program", default=None)
+        if "CMAKE_SH" not in cache_variables:
+            cache_variables["CMAKE_SH"] = "CMAKE_SH-NOTFOUND"
+
+        cmake_make_program = conanfile.conf.get("tools.gnu:make_program", default=cache_variables.get("CMAKE_MAKE_PROGRAM"))
         if cmake_make_program:
             cmake_make_program = cmake_make_program.replace("\\", "/")
             cache_variables["CMAKE_MAKE_PROGRAM"] = cmake_make_program
-    cache_variables["CMAKE_POLICY_DEFAULT_CMP0091"] = "NEW"
+
+    if "CMAKE_POLICY_DEFAULT_CMP0091" not in cache_variables:
+        cache_variables["CMAKE_POLICY_DEFAULT_CMP0091"] = "NEW"
 
     preset_path = os.path.join(conanfile.generators_folder, "CMakePresets.json")
     multiconfig = is_multi_configuration(generator)

conan/tools/cmake/toolchain/toolchain.py

@@ -119,6 +119,8 @@ def __init__(self, conanfile, generator=None):
         self._conanfile = conanfile
         self.generator = self._get_generator(generator)
         self.variables = Variables()
+        # This doesn't support multi-config, they go to the same configPreset common in multi-config
+        self.cache_variables = {}
         self.preprocessor_definitions = Variables()
 
         self.blocks = ToolchainBlocks(self._conanfile, self,
@@ -175,7 +177,14 @@ def generate(self):
         elif self.generator is not None and "Visual" not in self.generator:
             VCVars(self._conanfile).generate()
         toolchain = os.path.join(self._conanfile.generators_folder, toolchain_file or self.filename)
-        write_cmake_presets(self._conanfile, toolchain, self.generator)
+        cache_variables = {}
+        for name, value in self.cache_variables.items():
+            if isinstance(value, bool):
+                cache_variables[name] = "ON" if value else "OFF"
+            else:
+                cache_variables[name] = value
+
+        write_cmake_presets(self._conanfile, toolchain, self.generator, cache_variables)
 
     def _get_generator(self, recipe_generator):
         # Returns the name of the generator to be used by CMake

conans/test/integration/toolchains/cmake/test_cmaketoolchain.py

@@ -4,6 +4,7 @@
 import textwrap
 
 import pytest
+from mock import mock
 
 from conan.tools.cmake.presets import load_cmake_presets
 from conans.test.assets.genconanfile import GenConanfile
@@ -439,3 +440,36 @@ def test_cmake_presets_singleconfig():
     client.run("install mylib/1.0@ -g CMakeToolchain -s build_type=Debug --profile:h=profile")
     presets = json.loads(client.load("CMakePresets.json"))
     assert len(presets["configurePresets"]) == 2
+
+
+def test_toolchain_cache_variables():
+    client = TestClient()
+    conanfile = textwrap.dedent("""
+        from conans import ConanFile
+        from conan.tools.cmake import CMakeToolchain, CMake
+
+        class Conan(ConanFile):
+            settings = "os", "arch", "compiler", "build_type"
+
+            def generate(self):
+                toolchain = CMakeToolchain(self)
+                toolchain.cache_variables["foo"] = True
+                toolchain.cache_variables["foo2"] = False
+                toolchain.cache_variables["var"] = "23"
+                toolchain.cache_variables["CMAKE_SH"] = "THIS VALUE HAS PRIORITY"
+                toolchain.cache_variables["CMAKE_POLICY_DEFAULT_CMP0091"] = "THIS VALUE HAS PRIORITY"
+                toolchain.cache_variables["CMAKE_MAKE_PROGRAM"] = "THIS VALUE HAS NO PRIORITY"
+                toolchain.generate()
+        """)
+    client.save({"conanfile.py": conanfile})
+    with mock.patch("platform.system", mock.MagicMock(return_value="Windows")):
+        client.run("install . mylib/1.0@ -c tools.cmake.cmaketoolchain:generator='MinGW Makefiles' "
+                   "-c tools.gnu:make_program='MyMake'")
+    presets = json.loads(client.load("CMakePresets.json"))
+    cache_variables = presets["configurePresets"][0]["cacheVariables"]
+    assert cache_variables["foo"] == 'ON'
+    assert cache_variables["foo2"] == 'OFF'
+    assert cache_variables["var"] == '23'
+    assert cache_variables["CMAKE_SH"] == "THIS VALUE HAS PRIORITY"
+    assert cache_variables["CMAKE_POLICY_DEFAULT_CMP0091"] == "THIS VALUE HAS PRIORITY"
+    assert cache_variables["CMAKE_MAKE_PROGRAM"] == "MyMake"

conans/test/unittests/tools/cmake/test_cmake_presets_definitions.py

@@ -40,7 +40,7 @@ def run(command):
     conanfile.conf.define("tools.gnu:make_program", "C:\\mymake.exe")
 
     with mock.patch("platform.system", mock.MagicMock(return_value='Windows')):
-        write_cmake_presets(conanfile, "the_toolchain.cmake", "MinGW Makefiles")
+        write_cmake_presets(conanfile, "the_toolchain.cmake", "MinGW Makefiles", {})
 
     cmake = CMake(conanfile)
     cmake.configure()