Fix for CMakeDeps generator being duplicated when using a conanfile.py

conan_provider.cmake

@@ -477,13 +477,27 @@ macro(conan_provide_dependency method package_name)
         construct_profile_argument(_host_profile_flags CONAN_HOST_PROFILE)
         construct_profile_argument(_build_profile_flags CONAN_BUILD_PROFILE)
         get_property(_MULTICONFIG_GENERATOR GLOBAL PROPERTY GENERATOR_IS_MULTI_CONFIG)
+        if(EXISTS "${CMAKE_SOURCE_DIR}/conanfile.py")
+            file(READ "${CMAKE_SOURCE_DIR}/conanfile.py" outfile)
+            if(NOT "${outfile}" MATCHES ".*CMakeDeps.*")
+                message(WARNING "Cmake-conan: CMakeDeps generator was not defined in the conanfile")
+            endif()
+            set(generator "")
+        else ()
+            file(READ "${CMAKE_SOURCE_DIR}/conanfile.txt" outfile)
+            if(NOT "${outfile}" MATCHES ".*CMakeDeps.*")
+                message(WARNING "Cmake-conan: CMakeDeps generator was not defined in the conanfile. "
+                        "Please define the generator as it will be mandatory in the future")
+            endif()
+            set(generator "-g;CMakeDeps")
+        endif()
         if(NOT _MULTICONFIG_GENERATOR)
             message(STATUS "CMake-Conan: Installing single configuration ${CMAKE_BUILD_TYPE}")
-            conan_install(${_host_profile_flags} ${_build_profile_flags} --build=missing -g CMakeDeps)
+            conan_install(${_host_profile_flags} ${_build_profile_flags} --build=missing ${generator})
         else()
             message(STATUS "CMake-Conan: Installing both Debug and Release")
-            conan_install(${_host_profile_flags} ${_build_profile_flags} -s build_type=Release --build=missing -g CMakeDeps)
-            conan_install(${_host_profile_flags} ${_build_profile_flags} -s build_type=Debug --build=missing -g CMakeDeps)
+            conan_install(${_host_profile_flags} ${_build_profile_flags} -s build_type=Release --build=missing ${generator})
+            conan_install(${_host_profile_flags} ${_build_profile_flags} -s build_type=Debug --build=missing ${generator})
         endif()
         unset(_MULTICONFIG_GENERATOR)
     else()

tests/resources/change_generators/duplicate_generator/conanfile.py

@@ -0,0 +1,15 @@
+from conan import ConanFile
+from conan.tools.cmake import CMakeDeps
+
+class testRecipe(ConanFile):
+    settings = "os", "compiler", "build_type", "arch"
+    generators = "CMakeToolchain", "CMakeDeps"
+
+    def requirements(self):
+        self.requires("hello/0.1")
+        self.requires("bye/0.1")
+
+    def generate(self):
+        deps = CMakeDeps(self)
+        deps.generate()
+

tests/resources/change_generators/no_generator/conanfile.py

@@ -0,0 +1,8 @@
+from conan import ConanFile
+
+class testRecipe(ConanFile):
+    settings = "os", "compiler", "build_type", "arch"
+
+    def requirements(self):
+        self.requires("hello/0.1")
+        self.requires("bye/0.1")

tests/resources/change_generators/single_generator/conanfile.py

@@ -0,0 +1,13 @@
+from conan import ConanFile
+from conan.tools.cmake import CMakeDeps
+
+class testRecipe(ConanFile):
+    settings = "os", "compiler", "build_type", "arch"
+
+    def requirements(self):
+        self.requires("hello/0.1")
+        self.requires("bye/0.1")
+
+    def generate(self):
+        deps = CMakeDeps(self)
+        deps.generate()

tests/test_smoke.py

@@ -40,6 +40,8 @@ def run(cmd, check=True):
 @contextmanager
 def chdir(folder):
     cwd = os.getcwd()
+    if os.path.exists(folder):
+        shutil.rmtree(folder)
     os.makedirs(folder, exist_ok=True)
     os.chdir(folder)
     try:
@@ -609,3 +611,34 @@ def test_msvc_x86(self, capfd, basic_cmake_project):
         run(f'cmake -S {source_dir} -B {binary_dir} -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES={conan_provider} -G "Visual Studio 16 2019" -A Win32')
         out, _ = capfd.readouterr()
         assert "arch=x86" in out
+
+
+class TestCMakeDepsGenerators:
+    # CMakeDeps generator is declared in the generate() function in conanfile.py
+    def test_one_generator(self, capfd, basic_cmake_project):
+        source_dir, binary_dir = change_conanfile(basic_cmake_project, 'single_generator')
+        run(f'cmake -S {source_dir} -B {binary_dir} -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES={conan_provider} -DCMAKE_BUILD_TYPE=Release')
+        out, _ = capfd.readouterr()
+        assert 'Generating done' in out
+
+    # CMakeDeps generator is declared both in generators attribute and generate() function in conanfile.py
+    def test_duplicate_generator(self, capfd, basic_cmake_project):
+        source_dir, binary_dir = change_conanfile(basic_cmake_project, 'duplicate_generator')
+        run(f'cmake -S {source_dir} -B {binary_dir} -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES={conan_provider} -DCMAKE_BUILD_TYPE=Release', check=False)
+        _, err = capfd.readouterr()
+        assert ('ConanException: CMakeDeps is declared in the generators attribute, but was instantiated in the '
+                'generate() method too') in err
+
+    # CMakeDeps generator is not declared in either place
+    def test_no_generator(self, capfd, basic_cmake_project):
+        source_dir, binary_dir = change_conanfile(basic_cmake_project, 'no_generator')
+        run(f'cmake -S {source_dir} -B {binary_dir} -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES={conan_provider} -DCMAKE_BUILD_TYPE=Release', check=False)
+        out, _ = capfd.readouterr()
+        assert 'Could NOT find hello (missing: hello_DIR)' in out
+
+def change_conanfile(basic_cmake_project, gen_resource):
+    source_dir, binary_dir = basic_cmake_project
+    os.chdir(source_dir.as_posix())
+    os.remove("conanfile.txt")
+    shutil.copy2(src_dir / 'tests' / 'resources' / 'change_generators' / gen_resource / 'conanfile.py', source_dir)
+    return source_dir, binary_dir