Added support for tools.cmake.cmaketoolchain:extra_variables (#16222)

conan/tools/cmake/toolchain/blocks.py

@@ -795,6 +795,9 @@ class GenericSystemBlock(Block):
         message(STATUS "Conan toolchain: CMAKE_GENERATOR_TOOLSET={{ toolset }}")
         set(CMAKE_GENERATOR_TOOLSET "{{ toolset }}" CACHE STRING "" FORCE)
         {% endif %}
+        {% for key, value in extra_variables.items() %}
+        set({{ key }} "{{ value }}")
+        {% endfor %}
         """)
 
     @staticmethod
@@ -955,14 +958,18 @@ def context(self):
         result = self._get_winsdk_version(system_version, generator_platform)
         system_version, winsdk_version, gen_platform_sdk_version = result
 
+        # Reading configuration from "tools.cmake.cmaketoolchain:extra_variables"
+        extra_variables = self._conanfile.conf.get("tools.cmake.cmaketoolchain:extra_variables", default={}, check_type=dict)
+
         return {"toolset": toolset,
                 "generator_platform": generator_platform,
                 "cmake_system_name": system_name,
                 "cmake_system_version": system_version,
                 "cmake_system_processor": system_processor,
                 "cmake_sysroot": cmake_sysroot,
                 "winsdk_version": winsdk_version,
-                "gen_platform_sdk_version": gen_platform_sdk_version}
+                "gen_platform_sdk_version": gen_platform_sdk_version,
+                "extra_variables": extra_variables}
 
 
 class OutputDirsBlock(Block):

conans/model/conf.py

@@ -73,6 +73,7 @@
     "tools.cmake.cmaketoolchain:toolset_arch": "Toolset architecture to be used as part of CMAKE_GENERATOR_TOOLSET in CMakeToolchain",
     "tools.cmake.cmaketoolchain:toolset_cuda": "(Experimental) Path to a CUDA toolset to use, or version if installed at the system level",
     "tools.cmake.cmaketoolchain:presets_environment": "String to define wether to add or not the environment section to the CMake presets. Empty by default, will generate the environment section in CMakePresets. Can take values: 'disabled'.",
+    "tools.cmake.cmaketoolchain:extra_variables": "Dictionary with variables to be injected in CMakeToolchain",
     "tools.cmake.cmake_layout:build_folder_vars": "Settings and Options that will produce a different build folder and different CMake presets names",
     "tools.cmake.cmake_layout:build_folder": "(Experimental) Allow configuring the base folder of the build for local builds",
     "tools.cmake.cmake_layout:test_folder": "(Experimental) Allow configuring the base folder of the build for test_package",

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

@@ -1414,3 +1414,29 @@ def build(self):
     })
     client.run("export tool")
     client.run("create consumer -pr:h host -pr:b build --build=missing")
+
+
+def test_toolchain_extra_variables():
+    windows_profile = textwrap.dedent("""
+        [settings]
+        os=Windows
+        arch=x86_64
+        [conf]
+        tools.cmake.cmaketoolchain:extra_variables={'CMAKE_GENERATOR_INSTANCE': 'C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/', 'FOO': 'bar'}
+        """)
+
+    client = TestClient(path_with_spaces=False)
+    client.save({"conanfile.txt": "[generators]\nCMakeToolchain",
+                 "windows": windows_profile})
+
+    # Test passing extra_variables from profile
+    client.run("install . --profile:build=windows --profile:host=windows")
+    toolchain = client.load("conan_toolchain.cmake")
+    assert 'set(CMAKE_GENERATOR_INSTANCE "C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/")' in toolchain
+    assert 'set(FOO "bar")' in toolchain
+
+    # Test input from command line passing dict between doble quotes
+    client.run("install . -c tools.cmake.cmaketoolchain:extra_variables=\"{'CMAKE_GENERATOR_INSTANCE': 'C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/', 'FOO': 'bar'}\"")
+    toolchain = client.load("conan_toolchain.cmake")
+    assert 'set(CMAKE_GENERATOR_INSTANCE "C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/")' in toolchain
+    assert 'set(FOO "bar")' in toolchain