Fix build with cmake_find_package generator

The issue was that the CMake variables `CONAN_EMBEDDED_PYTHON_ROOT` and
`CONAN_USER_EMBEDDED_PYTHON_pyversion` are only set when using the `cmake`
generator but not with `cmake_find_package`.

The solution is to avoid using these variables and instead rely on the
fact that `Python_ROOT_DIR` is in the same directory as the `embedded_python.cmake`
file. And for the version number, we do a string replacement in `conanfile.py`.
It's fine to hardcode this since the version is always unique to the
Conan package.

Author: dean0x7d

changelog.md

@@ -3,6 +3,7 @@
 ## v1.4.4 | In development
 
 - Fixed build with Python >= 3.9.11 and >= 3.10.3 on Windows (the installer changed)
+- Fixed configuration with the Conan `cmake_find_package` generator
 
 ## v1.4.3 | 2022-01-28
 

conanfile.py

@@ -124,6 +124,8 @@ def _gather_licenses(self, bootstrap):
                  f" --with-license-file --no-license-path --output-file=package_licenses.txt")
 
     def build(self):
+        tools.replace_in_file("embedded_python.cmake", "${self.pyversion}", str(self.pyversion))
+
         prefix = pathlib.Path(self.build_folder) / "embedded_python"
         if self.settings.os == "Windows":
             build_helper = WindowsBuildHelper(self, prefix)

embedded_python.cmake

@@ -1,9 +1,8 @@
 # A hint for `find_package(Python)`
-set(Python_ROOT_DIR "${CONAN_EMBEDDED_PYTHON_ROOT}/embedded_python")
+set(Python_ROOT_DIR "${CMAKE_CURRENT_LIST_DIR}/embedded_python")
 
 if(WIN32) # Extra hint to speed up the find (not needed for correctness)
     set(Python_EXECUTABLE "${Python_ROOT_DIR}/python.exe")
 endif()
 
-find_package(Python ${CONAN_USER_EMBEDDED_PYTHON_pyversion} EXACT REQUIRED
-             COMPONENTS Interpreter Development)
+find_package(Python ${self.pyversion} EXACT REQUIRED COMPONENTS Interpreter Development)

test_package/CMakeLists.txt

@@ -1,9 +1,19 @@
 cmake_minimum_required(VERSION 3.18)
 project(test_package)
 
+# `cmake` generator
 include(${CMAKE_BINARY_DIR}/conanbuildinfo.cmake)
 conan_basic_setup(KEEP_RPATHS)
 
 if(NOT Python_VERSION VERSION_EQUAL CONAN_USER_EMBEDDED_PYTHON_pyversion)
-    message(FATAL_ERROR "Failed to find the correct Python version")
+    message(FATAL_ERROR "`cmake` failed to find the correct Python version")
+endif()
+
+# `cmake_find_package` generator
+unset(Python_ROOT_DIR)
+unset(Python_VERSION)
+find_package(embedded_python)
+
+if(NOT Python_VERSION VERSION_EQUAL CONAN_USER_EMBEDDED_PYTHON_pyversion)
+    message(FATAL_ERROR "`cmake_find_package` failed to find the correct Python version")
 endif()

test_package/conanfile.py

@@ -14,7 +14,7 @@ def _read_env(name):
 class TestEmbeddedPython(ConanFile):
     name = "test_embedded_python"
     settings = "os"
-    generators = "cmake"
+    generators = "cmake", "cmake_find_package"
     options = {"env": "ANY"}
     default_options = {
         "env": None,