Do not pass compiler executable for AppleClang if it is the default

conan_provider.cmake

@@ -265,18 +265,31 @@ function(detect_build_type BUILD_TYPE)
     endif()
 endfunction()
 
+macro(set_conan_compiler_if_appleclang lang command output_variable)
+    if(CMAKE_${lang}_COMPILER_ID STREQUAL "AppleClang")
+        execute_process(COMMAND xcrun --find ${command}
+            OUTPUT_VARIABLE _xcrun_out OUTPUT_STRIP_TRAILING_WHITESPACE)
+        if (_xcrun_out STREQUAL "${CMAKE_${lang}_COMPILER}")
+            set(${output_variable} "")
+        endif()
+        unset(_xcrun_out)      
+    endif()
+endmacro()
+
 
 macro(append_compiler_executables_configuration)
     set(_conan_c_compiler "")
     set(_conan_cpp_compiler "")
     if(CMAKE_C_COMPILER)
         set(_conan_c_compiler "\"c\":\"${CMAKE_C_COMPILER}\",")
+        set_conan_compiler_if_appleclang(C cc _conan_c_compiler)
     else()
         message(WARNING "CMake-Conan: The C compiler is not defined. "
                         "Please define CMAKE_C_COMPILER or enable the C language.")
     endif()
     if(CMAKE_CXX_COMPILER)
         set(_conan_cpp_compiler "\"cpp\":\"${CMAKE_CXX_COMPILER}\"")
+        set_conan_compiler_if_appleclang(CXX c++ _conan_cpp_compiler)
     else()
         message(WARNING "CMake-Conan: The C++ compiler is not defined. "
                         "Please define CMAKE_CXX_COMPILER or enable the C++ language.")

tests/resources/autotools_dependency/CMakeLists.txt

@@ -0,0 +1,8 @@
+cmake_minimum_required(VERSION 3.24)
+project(MyApp CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+
+find_package(helloautotools REQUIRED)
+add_executable(app main.cpp)
+target_link_libraries(app helloautotools::helloautotools)

tests/resources/autotools_dependency/conanfile.txt

@@ -0,0 +1,2 @@
+[requires]
+helloautotools/0.1

tests/test_smoke.py

@@ -62,11 +62,17 @@ def setup_conan_home(conan_home_dir, tmp_path_factory):
     # Detect default profile
     run("conan profile detect -vquiet")
 
-    # Create hello lib from built-in template
+    # Create hello lib from built-in CMake template
     os.chdir(workdir.as_posix())
     run("conan new cmake_lib -d name=hello -d version=0.1 -vquiet")
     run("conan export . -vquiet")
 
+    # Create hello-autootols from built-in autotools template
+    recipe_dir = tmp_path_factory.mktemp(f"temp_autotools")
+    os.chdir(recipe_dir.as_posix())
+    run("conan new autotools_lib -d name=helloautotools -d version=0.1 -vquiet")
+    run("conan export . -vquiet")
+
     # additional recipes to export from resources, overlay on top of `hello` and export
     additional_recipes = ['boost', 'bye', 'cmake-module-only', 'cmake-module-with-dependency']
 
@@ -324,6 +330,18 @@ def test_propagate_non_default_compiler(self, capfd, basic_cmake_project):
         assert "The C compiler is not defined." not in err
         assert 'tools.build:compiler_executables={"c":"/usr/bin/clang","cpp":"/usr/bin/clang++"}' in out
 
+    @darwin
+    def test_propagate_compiler_mac_autotools(self, capfd, basic_cmake_project):
+        """Test that if the compiler is inside an XCode installation, we don't
+        propagate the path if that's the compiler that would be found by default"""
+        source_dir, binary_dir = basic_cmake_project
+        shutil.copytree(src_dir / 'tests' / 'resources' / 'autotools_dependency', source_dir, dirs_exist_ok=True)
+        run(f"cmake -S {source_dir} -B {binary_dir} -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES={conan_provider} -DCMAKE_BUILD_TYPE=Release", check=False)
+        out, err = capfd.readouterr()
+        assert "configure: error: C++ compiler cannot create executables" not in err
+        assert "-- Generating done" in out
+        pass
+
 class TestProfileCustomization:
     def test_profile_defaults(self, capfd, basic_cmake_project):
         """Test the defaults passed for host and build profiles"""