Add type-hints to spack.bootstrap (#36491)

lib/spack/spack/bootstrap/_common.py

@@ -9,6 +9,7 @@
 import sys
 import sysconfig
 import warnings
+from typing import Dict, Optional, Sequence, Union
 
 import archspec.cpu
 
@@ -21,8 +22,10 @@
 
 from .config import spec_for_current_python
 
+QueryInfo = Dict[str, "spack.spec.Spec"]
 
-def _python_import(module):
+
+def _python_import(module: str) -> bool:
     try:
         __import__(module)
     except ImportError:
@@ -30,7 +33,9 @@ def _python_import(module):
     return True
 
 
-def _try_import_from_store(module, query_spec, query_info=None):
+def _try_import_from_store(
+    module: str, query_spec: Union[str, "spack.spec.Spec"], query_info: Optional[QueryInfo] = None
+) -> bool:
     """Return True if the module can be imported from an already
     installed spec, False otherwise.
 
@@ -52,7 +57,7 @@ def _try_import_from_store(module, query_spec, query_info=None):
         module_paths = [
             os.path.join(candidate_spec.prefix, pkg.purelib),
             os.path.join(candidate_spec.prefix, pkg.platlib),
-        ]  # type: list[str]
+        ]
         path_before = list(sys.path)
 
         # NOTE: try module_paths first and last, last allows an existing version in path
@@ -89,7 +94,7 @@ def _try_import_from_store(module, query_spec, query_info=None):
     return False
 
 
-def _fix_ext_suffix(candidate_spec):
+def _fix_ext_suffix(candidate_spec: "spack.spec.Spec"):
     """Fix the external suffixes of Python extensions on the fly for
     platforms that may need it
 
@@ -157,7 +162,11 @@ def _fix_ext_suffix(candidate_spec):
         os.symlink(abs_path, link_name)
 
 
-def _executables_in_store(executables, query_spec, query_info=None):
+def _executables_in_store(
+    executables: Sequence[str],
+    query_spec: Union["spack.spec.Spec", str],
+    query_info: Optional[QueryInfo] = None,
+) -> bool:
     """Return True if at least one of the executables can be retrieved from
     a spec in store, False otherwise.
 
@@ -193,7 +202,7 @@ def _executables_in_store(executables, query_spec, query_info=None):
     return False
 
 
-def _root_spec(spec_str):
+def _root_spec(spec_str: str) -> str:
     """Add a proper compiler and target to a spec used during bootstrapping.
 
     Args:

lib/spack/spack/bootstrap/config.py

@@ -7,6 +7,7 @@
 import contextlib
 import os.path
 import sys
+from typing import Any, Dict, Generator, MutableSequence, Sequence
 
 from llnl.util import tty
 
@@ -24,12 +25,12 @@
 _REF_COUNT = 0
 
 
-def is_bootstrapping():
+def is_bootstrapping() -> bool:
     """Return True if we are in a bootstrapping context, False otherwise."""
     return _REF_COUNT > 0
 
 
-def spec_for_current_python():
+def spec_for_current_python() -> str:
     """For bootstrapping purposes we are just interested in the Python
     minor version (all patches are ABI compatible with the same minor).
 
@@ -41,14 +42,14 @@ def spec_for_current_python():
     return f"python@{version_str}"
 
 
-def root_path():
+def root_path() -> str:
     """Root of all the bootstrap related folders"""
     return spack.util.path.canonicalize_path(
         spack.config.get("bootstrap:root", spack.paths.default_user_bootstrap_path)
     )
 
 
-def store_path():
+def store_path() -> str:
     """Path to the store used for bootstrapped software"""
     enabled = spack.config.get("bootstrap:enable", True)
     if not enabled:
@@ -59,7 +60,7 @@ def store_path():
 
 
 @contextlib.contextmanager
-def spack_python_interpreter():
+def spack_python_interpreter() -> Generator:
     """Override the current configuration to set the interpreter under
     which Spack is currently running as the only Python external spec
     available.
@@ -76,18 +77,18 @@ def spack_python_interpreter():
         yield
 
 
-def _store_path():
+def _store_path() -> str:
     bootstrap_root_path = root_path()
     return spack.util.path.canonicalize_path(os.path.join(bootstrap_root_path, "store"))
 
 
-def _config_path():
+def _config_path() -> str:
     bootstrap_root_path = root_path()
     return spack.util.path.canonicalize_path(os.path.join(bootstrap_root_path, "config"))
 
 
 @contextlib.contextmanager
-def ensure_bootstrap_configuration():
+def ensure_bootstrap_configuration() -> Generator:
     """Swap the current configuration for the one used to bootstrap Spack.
 
     The context manager is reference counted to ensure we don't swap multiple
@@ -107,7 +108,7 @@ def ensure_bootstrap_configuration():
         _REF_COUNT -= 1
 
 
-def _read_and_sanitize_configuration():
+def _read_and_sanitize_configuration() -> Dict[str, Any]:
     """Read the user configuration that needs to be reused for bootstrapping
     and remove the entries that should not be copied over.
     """
@@ -120,9 +121,11 @@ def _read_and_sanitize_configuration():
     return user_configuration
 
 
-def _bootstrap_config_scopes():
+def _bootstrap_config_scopes() -> Sequence["spack.config.ConfigScope"]:
     tty.debug("[BOOTSTRAP CONFIG SCOPE] name=_builtin")
-    config_scopes = [spack.config.InternalConfigScope("_builtin", spack.config.config_defaults)]
+    config_scopes: MutableSequence["spack.config.ConfigScope"] = [
+        spack.config.InternalConfigScope("_builtin", spack.config.config_defaults)
+    ]
     configuration_paths = (spack.config.configuration_defaults_path, ("bootstrap", _config_path()))
     for name, path in configuration_paths:
         platform = spack.platforms.host().name
@@ -137,7 +140,7 @@ def _bootstrap_config_scopes():
     return config_scopes
 
 
-def _add_compilers_if_missing():
+def _add_compilers_if_missing() -> None:
     arch = spack.spec.ArchSpec.frontend_arch()
     if not spack.compilers.compilers_for_arch(arch):
         new_compilers = spack.compilers.find_new_compilers()
@@ -146,7 +149,7 @@ def _add_compilers_if_missing():
 
 
 @contextlib.contextmanager
-def _ensure_bootstrap_configuration():
+def _ensure_bootstrap_configuration() -> Generator:
     bootstrap_store_path = store_path()
     user_configuration = _read_and_sanitize_configuration()
     with spack.environment.no_active_environment():

lib/spack/spack/bootstrap/core.py

@@ -29,7 +29,7 @@
 import os.path
 import sys
 import uuid
-from typing import Callable, List, Optional
+from typing import Any, Callable, Dict, List, Optional, Tuple
 
 from llnl.util import tty
 from llnl.util.lang import GroupedExceptionHandler
@@ -66,6 +66,9 @@
 _bootstrap_methods = {}
 
 
+ConfigDictionary = Dict[str, Any]
+
+
 def bootstrapper(bootstrapper_type: str):
     """Decorator to register classes implementing bootstrapping
     methods.
@@ -86,7 +89,7 @@ class Bootstrapper:
 
     config_scope_name = ""
 
-    def __init__(self, conf):
+    def __init__(self, conf: ConfigDictionary) -> None:
         self.conf = conf
         self.name = conf["name"]
         self.metadata_dir = spack.util.path.canonicalize_path(conf["metadata"])
@@ -100,7 +103,7 @@ def __init__(self, conf):
         self.url = url
 
     @property
-    def mirror_scope(self):
+    def mirror_scope(self) -> spack.config.InternalConfigScope:
         """Mirror scope to be pushed onto the bootstrapping configuration when using
         this bootstrapper.
         """
@@ -121,7 +124,7 @@ def try_import(self, module: str, abstract_spec_str: str) -> bool:
         """
         return False
 
-    def try_search_path(self, executables: List[str], abstract_spec_str: str) -> bool:
+    def try_search_path(self, executables: Tuple[str], abstract_spec_str: str) -> bool:
         """Try to search some executables in the prefix of specs satisfying the abstract
         spec passed as argument.
 
@@ -139,13 +142,15 @@ def try_search_path(self, executables: List[str], abstract_spec_str: str) -> boo
 class BuildcacheBootstrapper(Bootstrapper):
     """Install the software needed during bootstrapping from a buildcache."""
 
-    def __init__(self, conf):
+    def __init__(self, conf) -> None:
         super().__init__(conf)
-        self.last_search = None
+        self.last_search: Optional[ConfigDictionary] = None
         self.config_scope_name = f"bootstrap_buildcache-{uuid.uuid4()}"
 
     @staticmethod
-    def _spec_and_platform(abstract_spec_str):
+    def _spec_and_platform(
+        abstract_spec_str: str,
+    ) -> Tuple[spack.spec.Spec, spack.platforms.Platform]:
         """Return the spec object and platform we need to use when
         querying the buildcache.
 
@@ -158,7 +163,7 @@ def _spec_and_platform(abstract_spec_str):
         bincache_platform = spack.platforms.real_host()
         return abstract_spec, bincache_platform
 
-    def _read_metadata(self, package_name):
+    def _read_metadata(self, package_name: str) -> Any:
         """Return metadata about the given package."""
         json_filename = f"{package_name}.json"
         json_dir = self.metadata_dir
@@ -167,7 +172,13 @@ def _read_metadata(self, package_name):
             data = json.load(stream)
         return data
 
-    def _install_by_hash(self, pkg_hash, pkg_sha256, index, bincache_platform):
+    def _install_by_hash(
+        self,
+        pkg_hash: str,
+        pkg_sha256: str,
+        index: List[spack.spec.Spec],
+        bincache_platform: spack.platforms.Platform,
+    ) -> None:
         index_spec = next(x for x in index if x.dag_hash() == pkg_hash)
         # Reconstruct the compiler that we need to use for bootstrapping
         compiler_entry = {
@@ -192,7 +203,13 @@ def _install_by_hash(self, pkg_hash, pkg_sha256, index, bincache_platform):
                         match, allow_root=True, unsigned=True, force=True, sha256=pkg_sha256
                     )
 
-    def _install_and_test(self, abstract_spec, bincache_platform, bincache_data, test_fn):
+    def _install_and_test(
+        self,
+        abstract_spec: spack.spec.Spec,
+        bincache_platform: spack.platforms.Platform,
+        bincache_data,
+        test_fn,
+    ) -> bool:
         # Ensure we see only the buildcache being used to bootstrap
         with spack.config.override(self.mirror_scope):
             # This index is currently needed to get the compiler used to build some
@@ -217,13 +234,14 @@ def _install_and_test(self, abstract_spec, bincache_platform, bincache_data, tes
                 for _, pkg_hash, pkg_sha256 in item["binaries"]:
                     self._install_by_hash(pkg_hash, pkg_sha256, index, bincache_platform)
 
-                info = {}
+                info: ConfigDictionary = {}
                 if test_fn(query_spec=abstract_spec, query_info=info):
                     self.last_search = info
                     return True
         return False
 
-    def try_import(self, module, abstract_spec_str):
+    def try_import(self, module: str, abstract_spec_str: str) -> bool:
+        info: ConfigDictionary
         test_fn, info = functools.partial(_try_import_from_store, module), {}
         if test_fn(query_spec=abstract_spec_str, query_info=info):
             return True
@@ -235,7 +253,8 @@ def try_import(self, module, abstract_spec_str):
         data = self._read_metadata(module)
         return self._install_and_test(abstract_spec, bincache_platform, data, test_fn)
 
-    def try_search_path(self, executables, abstract_spec_str):
+    def try_search_path(self, executables: Tuple[str], abstract_spec_str: str) -> bool:
+        info: ConfigDictionary
         test_fn, info = functools.partial(_executables_in_store, executables), {}
         if test_fn(query_spec=abstract_spec_str, query_info=info):
             self.last_search = info
@@ -251,13 +270,13 @@ def try_search_path(self, executables, abstract_spec_str):
 class SourceBootstrapper(Bootstrapper):
     """Install the software needed during bootstrapping from sources."""
 
-    def __init__(self, conf):
+    def __init__(self, conf) -> None:
         super().__init__(conf)
-        self.last_search = None
+        self.last_search: Optional[ConfigDictionary] = None
         self.config_scope_name = f"bootstrap_source-{uuid.uuid4()}"
 
-    def try_import(self, module, abstract_spec_str):
+    def try_import(self, module: str, abstract_spec_str: str) -> bool:
-        info = {}
+        info: ConfigDictionary = {}
         if _try_import_from_store(module, abstract_spec_str, query_info=info):
             self.last_search = info
             return True
@@ -293,8 +312,8 @@ def try_import(self, module, abstract_spec_str):
             return True
         return False
 
-    def try_search_path(self, executables, abstract_spec_str):
+    def try_search_path(self, executables: Tuple[str], abstract_spec_str: str) -> bool:
-        info = {}
+        info: ConfigDictionary = {}
         if _executables_in_store(executables, abstract_spec_str, query_info=info):
             self.last_search = info
             return True
@@ -323,13 +342,13 @@ def try_search_path(self, executables, abstract_spec_str):
         return False
 
 
-def create_bootstrapper(conf):
+def create_bootstrapper(conf: ConfigDictionary):
     """Return a bootstrap object built according to the configuration argument"""
     btype = conf["type"]
     return _bootstrap_methods[btype](conf)
 
 
-def source_is_enabled_or_raise(conf):
+def source_is_enabled_or_raise(conf: ConfigDictionary):
     """Raise ValueError if the source is not enabled for bootstrapping"""
     trusted, name = spack.config.get("bootstrap:trusted"), conf["name"]
     if not trusted.get(name, False):
@@ -454,7 +473,7 @@ def ensure_executables_in_path_or_raise(
     raise RuntimeError(msg)
 
 
-def _add_externals_if_missing():
+def _add_externals_if_missing() -> None:
     search_list = [
         # clingo
         spack.repo.path.get_pkg_class("cmake"),
@@ -468,41 +487,41 @@ def _add_externals_if_missing():
     spack.detection.update_configuration(detected_packages, scope="bootstrap")
 
 
-def clingo_root_spec():
+def clingo_root_spec() -> str:
     """Return the root spec used to bootstrap clingo"""
     return _root_spec("clingo-bootstrap@spack+python")
 
 
-def ensure_clingo_importable_or_raise():
+def ensure_clingo_importable_or_raise() -> None:
     """Ensure that the clingo module is available for import."""
     ensure_module_importable_or_raise(module="clingo", abstract_spec=clingo_root_spec())
 
 
-def gnupg_root_spec():
+def gnupg_root_spec() -> str:
     """Return the root spec used to bootstrap GnuPG"""
     return _root_spec("gnupg@2.3:")
 
 
-def ensure_gpg_in_path_or_raise():
+def ensure_gpg_in_path_or_raise() -> None:
     """Ensure gpg or gpg2 are in the PATH or raise."""
     return ensure_executables_in_path_or_raise(
         executables=["gpg2", "gpg"], abstract_spec=gnupg_root_spec()
     )
 
 
-def patchelf_root_spec():
+def patchelf_root_spec() -> str:
     """Return the root spec used to bootstrap patchelf"""
     # 0.13.1 is the last version not to require C++17.
     return _root_spec("patchelf@0.13.1:")
 
 
-def verify_patchelf(patchelf):
+def verify_patchelf(patchelf: "spack.util.executable.Executable") -> bool:
     """Older patchelf versions can produce broken binaries, so we
     verify the version here.
 
     Arguments:
 
-        patchelf (spack.util.executable.Executable): patchelf executable
+        patchelf: patchelf executable
     """
     out = patchelf("--version", output=str, error=os.devnull, fail_on_error=False).strip()
     if patchelf.returncode != 0:
@@ -517,7 +536,7 @@ def verify_patchelf(patchelf):
     return version >= spack.version.Version("0.13.1")
 
 
-def ensure_patchelf_in_path_or_raise():
+def ensure_patchelf_in_path_or_raise() -> None:
     """Ensure patchelf is in the PATH or raise."""
     # The old concretizer is not smart and we're doing its job: if the latest patchelf
     # does not concretize because the compiler doesn't support C++17, we try to
@@ -534,7 +553,7 @@ def ensure_patchelf_in_path_or_raise():
         )
 
 
-def ensure_core_dependencies():
+def ensure_core_dependencies() -> None:
     """Ensure the presence of all the core dependencies."""
     if sys.platform.lower() == "linux":
         ensure_patchelf_in_path_or_raise()
@@ -543,7 +562,7 @@ def ensure_core_dependencies():
     ensure_clingo_importable_or_raise()
 
 
-def all_core_root_specs():
+def all_core_root_specs() -> List[str]:
     """Return a list of all the core root specs that may be used to bootstrap Spack"""
     return [clingo_root_spec(), gnupg_root_spec(), patchelf_root_spec()]
 

lib/spack/spack/bootstrap/environment.py

@@ -9,6 +9,7 @@
 import pathlib
 import sys
 import warnings
+from typing import List
 
 import archspec.cpu
 
@@ -27,7 +28,7 @@ class BootstrapEnvironment(spack.environment.Environment):
     """Environment to install dependencies of Spack for a given interpreter and architecture"""
 
     @classmethod
-    def spack_dev_requirements(cls):
+    def spack_dev_requirements(cls) -> List[str]:
         """Spack development requirements"""
         return [
             isort_root_spec(),
@@ -38,7 +39,7 @@ def spack_dev_requirements(cls):
         ]
 
     @classmethod
-    def environment_root(cls):
+    def environment_root(cls) -> pathlib.Path:
         """Environment root directory"""
         bootstrap_root_path = root_path()
         python_part = spec_for_current_python().replace("@", "")
@@ -52,12 +53,12 @@ def environment_root(cls):
         )
 
     @classmethod
-    def view_root(cls):
+    def view_root(cls) -> pathlib.Path:
         """Location of the view"""
         return cls.environment_root().joinpath("view")
 
     @classmethod
-    def pythonpaths(cls):
+    def pythonpaths(cls) -> List[str]:
         """Paths to be added to sys.path or PYTHONPATH"""
         python_dir_part = f"python{'.'.join(str(x) for x in sys.version_info[:2])}"
         glob_expr = str(cls.view_root().joinpath("**", python_dir_part, "**"))
@@ -68,21 +69,21 @@ def pythonpaths(cls):
         return result
 
     @classmethod
-    def bin_dirs(cls):
+    def bin_dirs(cls) -> List[pathlib.Path]:
         """Paths to be added to PATH"""
         return [cls.view_root().joinpath("bin")]
 
     @classmethod
-    def spack_yaml(cls):
+    def spack_yaml(cls) -> pathlib.Path:
         """Environment spack.yaml file"""
         return cls.environment_root().joinpath("spack.yaml")
 
-    def __init__(self):
+    def __init__(self) -> None:
         if not self.spack_yaml().exists():
             self._write_spack_yaml_file()
         super().__init__(self.environment_root())
 
-    def update_installations(self):
+    def update_installations(self) -> None:
         """Update the installations of this environment.
 
         The update is done using a depfile on Linux and macOS, and using the ``install_all``
@@ -103,7 +104,7 @@ def update_installations(self):
                 self._install_with_depfile()
             self.write(regenerate=True)
 
-    def update_syspath_and_environ(self):
+    def update_syspath_and_environ(self) -> None:
         """Update ``sys.path`` and the PATH, PYTHONPATH environment variables to point to
         the environment view.
         """
@@ -119,7 +120,7 @@ def update_syspath_and_environ(self):
             + [str(x) for x in self.pythonpaths()]
         )
 
-    def _install_with_depfile(self):
+    def _install_with_depfile(self) -> None:
         spackcmd = spack.util.executable.which("spack")
         spackcmd(
             "-e",
@@ -141,7 +142,7 @@ def _install_with_depfile(self):
             **kwargs,
         )
 
-    def _write_spack_yaml_file(self):
+    def _write_spack_yaml_file(self) -> None:
         tty.msg(
             "[BOOTSTRAPPING] Spack has missing dependencies, creating a bootstrapping environment"
         )
@@ -159,32 +160,32 @@ def _write_spack_yaml_file(self):
         self.spack_yaml().write_text(template.render(context), encoding="utf-8")
 
 
-def isort_root_spec():
+def isort_root_spec() -> str:
     """Return the root spec used to bootstrap isort"""
     return _root_spec("py-isort@4.3.5:")
 
 
-def mypy_root_spec():
+def mypy_root_spec() -> str:
     """Return the root spec used to bootstrap mypy"""
     return _root_spec("py-mypy@0.900:")
 
 
-def black_root_spec():
+def black_root_spec() -> str:
     """Return the root spec used to bootstrap black"""
     return _root_spec("py-black@:23.1.0")
 
 
-def flake8_root_spec():
+def flake8_root_spec() -> str:
     """Return the root spec used to bootstrap flake8"""
     return _root_spec("py-flake8")
 
 
-def pytest_root_spec():
+def pytest_root_spec() -> str:
     """Return the root spec used to bootstrap flake8"""
     return _root_spec("py-pytest")
 
 
-def ensure_environment_dependencies():
+def ensure_environment_dependencies() -> None:
     """Ensure Spack dependencies from the bootstrap environment are installed and ready to use"""
     with BootstrapEnvironment() as env:
         env.update_installations()

lib/spack/spack/bootstrap/status.py

@@ -4,6 +4,7 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 """Query the status of bootstrapping on this machine"""
 import platform
+from typing import List, Optional, Sequence, Tuple, Union
 
 import spack.util.executable
 
@@ -19,8 +20,12 @@
     pytest_root_spec,
 )
 
+ExecutablesType = Union[str, Sequence[str]]
+RequiredResponseType = Tuple[bool, Optional[str]]
+SpecLike = Union["spack.spec.Spec", str]
 
-def _required_system_executable(exes, msg):
+
+def _required_system_executable(exes: ExecutablesType, msg: str) -> RequiredResponseType:
     """Search for an executable is the system path only."""
     if isinstance(exes, str):
         exes = (exes,)
@@ -29,7 +34,9 @@ def _required_system_executable(exes, msg):
     return False, msg
 
 
-def _required_executable(exes, query_spec, msg):
+def _required_executable(
+    exes: ExecutablesType, query_spec: SpecLike, msg: str
+) -> RequiredResponseType:
     """Search for an executable in the system path or in the bootstrap store."""
     if isinstance(exes, str):
         exes = (exes,)
@@ -38,7 +45,7 @@ def _required_executable(exes, query_spec, msg):
     return False, msg
 
 
-def _required_python_module(module, query_spec, msg):
+def _required_python_module(module: str, query_spec: SpecLike, msg: str) -> RequiredResponseType:
     """Check if a Python module is available in the current interpreter or
     if it can be loaded from the bootstrap store
     """
@@ -47,7 +54,7 @@ def _required_python_module(module, query_spec, msg):
     return False, msg
 
 
-def _missing(name, purpose, system_only=True):
+def _missing(name: str, purpose: str, system_only: bool = True) -> str:
     """Message to be printed if an executable is not found"""
     msg = '[{2}] MISSING "{0}": {1}'
     if not system_only:
@@ -55,7 +62,7 @@ def _missing(name, purpose, system_only=True):
     return msg.format(name, purpose, "@*y{{-}}")
 
 
-def _core_requirements():
+def _core_requirements() -> List[RequiredResponseType]:
     _core_system_exes = {
         "make": _missing("make", "required to build software from sources"),
         "patch": _missing("patch", "required to patch source code before building"),
@@ -80,7 +87,7 @@ def _core_requirements():
     return result
 
 
-def _buildcache_requirements():
+def _buildcache_requirements() -> List[RequiredResponseType]:
     _buildcache_exes = {
         "file": _missing("file", "required to analyze files for buildcaches"),
         ("gpg2", "gpg"): _missing("gpg2", "required to sign/verify buildcaches", False),
@@ -103,7 +110,7 @@ def _buildcache_requirements():
     return result
 
 
-def _optional_requirements():
+def _optional_requirements() -> List[RequiredResponseType]:
     _optional_exes = {
         "zstd": _missing("zstd", "required to compress/decompress code archives"),
         "svn": _missing("svn", "required to manage subversion repositories"),
@@ -114,7 +121,7 @@ def _optional_requirements():
     return result
 
 
-def _development_requirements():
+def _development_requirements() -> List[RequiredResponseType]:
     # Ensure we trigger environment modifications if we have an environment
     if BootstrapEnvironment.spack_yaml().exists():
         with BootstrapEnvironment() as env:
@@ -139,7 +146,7 @@ def _development_requirements():
     ]
 
 
-def status_message(section):
+def status_message(section) -> Tuple[str, bool]:
     """Return a status message to be printed to screen that refers to the
     section passed as argument and a bool which is True if there are missing
     dependencies.
@@ -161,7 +168,7 @@ def status_message(section):
     with ensure_bootstrap_configuration():
         missing_software = False
         for found, err_msg in required_software():
-            if not found:
+            if not found and err_msg:
                 missing_software = True
                 msg += "\n  " + err_msg
         msg += "\n"