fixing pacman used for msys2 win_bash (#17103)

conan/tools/system/package_manager.py

@@ -37,7 +37,7 @@ def get_default_tool(self):
         if os_name in ["Linux", "FreeBSD"]:
             import distro
             os_name = distro.id() or os_name
-        elif os_name == "Windows" and self._conanfile.conf.get("tools.microsoft.bash:subsystem") == "msys2":
+        elif os_name == "Windows" and self._conanfile.settings.get_safe("os.subsystem") == "msys2":
             os_name = "msys2"
         manager_mapping = {"apt-get": ["Linux", "ubuntu", "debian", "raspbian", "linuxmint", 'astra', 'elbrus', 'altlinux', 'pop'],
                            "apk": ["alpine"],

test/integration/tools/system/package_manager_test.py

@@ -36,9 +36,14 @@ def test_msys2():
         with mock.patch('conan.ConanFile.context', new_callable=PropertyMock) as context_mock:
             context_mock.return_value = "host"
             conanfile = ConanFileMock()
-            conanfile.settings = Settings()
+            conanfile.settings = Settings({"os": {"Windows": {"subsystem": ["msys2"]}}})
             conanfile.conf.define("tools.microsoft.bash:subsystem", "msys2")
             manager = _SystemPackageManagerTool(conanfile)
+            assert manager.get_default_tool() == "choco"
+
+            conanfile.settings.os = "Windows"
+            conanfile.settings.os.subsystem = "msys2"
+            manager = _SystemPackageManagerTool(conanfile)
             assert manager.get_default_tool() == "pacman"
 
 
@@ -240,6 +245,7 @@ def fake_check(*args, **kwargs):
 
     assert tool._conanfile.command == result
 
+
 @pytest.mark.parametrize("tool_class, arch_host, result", [
     # Install build machine package and not cross-compile -> do not add host architecture
     (Apk, 'x86_64', 'apk add --no-cache package1 package2'),
@@ -281,6 +287,7 @@ def fake_check(*args, **kwargs):
 
     assert tool._conanfile.command == result
 
+
 @pytest.mark.parametrize("tool_class, result", [
     # cross-compile but arch_names=None -> do not add host architecture
     # https://github.com/conan-io/conan/issues/12320 because the package is archless