Issue #15767: Use ModuleNotFoundError.

3 files changed, 24 insertions, 10 deletions

diff --git a/Doc/c-api/exceptions.rst b/Doc/c-api/exceptions.rst
index 5644410..25fb29c 100644
--- a/Doc/c-api/exceptions.rst
+++ b/Doc/c-api/exceptions.rst
@@ -306,6 +306,13 @@ an error value).
    :mod:`warnings` module and the :option:`-W` option in the command line
    documentation.  There is no C API for warning control.
 
+.. c:function:: PyObject* PyErr_SetImportErrorSubclass(PyObject *msg, PyObject *name, PyObject *path)
+
+   Much like :c:func:`PyErr_SetImportError` but this function allows for
+   specifying a subclass of :exc:`ImportError` to raise.
+
+   .. versionadded:: 3.4
+
 
 .. c:function:: int PyErr_WarnExplicitObject(PyObject *category, PyObject *message, PyObject *filename, int lineno, PyObject *module, PyObject *registry)
 
diff --git a/Doc/reference/import.rst b/Doc/reference/import.rst
index fcc707b..5e2c1c8 100644
--- a/Doc/reference/import.rst
+++ b/Doc/reference/import.rst
@@ -36,7 +36,7 @@ implement import semantics.
 
 When a module is first imported, Python searches for the module and if found,
 it creates a module object [#fnmo]_, initializing it.  If the named module
-cannot be found, an :exc:`ImportError` is raised.  Python implements various
+cannot be found, an :exc:`ModuleNotFoundError` is raised.  Python implements various
 strategies to search for the named module when the import machinery is
 invoked.  These strategies can be modified and extended by using various hooks
 described in the sections below.
@@ -167,7 +167,7 @@ arguments to the :keyword:`import` statement, or from the parameters to the
 This name will be used in various phases of the import search, and it may be
 the dotted path to a submodule, e.g. ``foo.bar.baz``.  In this case, Python
 first tries to import ``foo``, then ``foo.bar``, and finally ``foo.bar.baz``.
-If any of the intermediate imports fail, an :exc:`ImportError` is raised.
+If any of the intermediate imports fail, an :exc:`ModuleNotFoundError` is raised.
 
 
 The module cache
@@ -186,7 +186,7 @@ object.
 During import, the module name is looked up in :data:`sys.modules` and if
 present, the associated value is the module satisfying the import, and the
 process completes.  However, if the value is ``None``, then an
-:exc:`ImportError` is raised.  If the module name is missing, Python will
+:exc:`ModuleNotFoundError` is raised.  If the module name is missing, Python will
 continue searching for the module.
 
 :data:`sys.modules` is writable.  Deleting a key may not destroy the
@@ -194,7 +194,7 @@ associated module (as other modules may hold references to it),
 but it will invalidate the cache entry for the named module, causing
 Python to search anew for the named module upon its next
 import. The key can also be assigned to ``None``, forcing the next import
-of the module to result in an :exc:`ImportError`.
+of the module to result in an :exc:`ModuleNotFoundError`.
 
 Beware though, as if you keep a reference to the module object,
 invalidate its cache entry in :data:`sys.modules`, and then re-import the
@@ -288,8 +288,8 @@ the named module or not.
 If the meta path finder knows how to handle the named module, it returns a
 spec object.  If it cannot handle the named module, it returns ``None``.  If
 :data:`sys.meta_path` processing reaches the end of its list without returning
-a spec, then an :exc:`ImportError` is raised.  Any other exceptions raised
-are simply propagated up, aborting the import process.
+a spec, then a :exc:`ModuleNotFoundError` is raised.  Any other exceptions
+raised are simply propagated up, aborting the import process.
 
 The :meth:`~importlib.abc.MetaPathFinder.find_spec()` method of meta path
 finders is called with two or three arguments.  The first is the fully
@@ -298,9 +298,9 @@ The second argument is the path entries to use for the module search.  For
 top-level modules, the second argument is ``None``, but for submodules or
 subpackages, the second argument is the value of the parent package's
 ``__path__`` attribute. If the appropriate ``__path__`` attribute cannot
-be accessed, an :exc:`ImportError` is raised.  The third argument is an
-existing module object that will be the target of loading later.  The
-import system passes in a target module only during reload.
+be accessed, an :exc:`ModuleNotFoundError` is raised.  The third argument
+is an existing module object that will be the target of loading later.
+The import system passes in a target module only during reload.
 
 The meta path may be traversed multiple times for a single import request.
 For example, assuming none of the modules involved has already been cached,
@@ -887,7 +887,7 @@ import statements within that module.
 
 To selectively prevent import of some modules from a hook early on the
 meta path (rather than disabling the standard import system entirely),
-it is sufficient to raise :exc:`ImportError` directly from
+it is sufficient to raise :exc:`ModuleNoFoundError` directly from
 :meth:`~importlib.abc.MetaPathFinder.find_spec` instead of returning
 ``None``. The latter indicates that the meta path search should continue,
 while raising an exception terminates it immediately.
diff --git a/Doc/whatsnew/3.6.rst b/Doc/whatsnew/3.6.rst
index ebb142c..e48ed01 100644
--- a/Doc/whatsnew/3.6.rst
+++ b/Doc/whatsnew/3.6.rst
@@ -350,6 +350,10 @@ Some smaller changes made to the core Python language are:
   :ref:`py36-traceback` for an example).
   (Contributed by Emanuel Barry in :issue:`26823`.)
 
+* Import now raises the new exception :exc:`ModuleNotFoundError`
+  (subclass of :exc:`ImportError`) when it cannot find a module.  Code
+  that current checks for ImportError (in try-except) will still work.
+
 
 New Modules
 ===========
@@ -959,6 +963,9 @@ Changes in the Python API
 * When :meth:`importlib.abc.Loader.exec_module` is defined,
   :meth:`importlib.abc.Loader.create_module` must also be defined.
 
+* :c:func:`PyErr_SetImportError` now sets :exc:`TypeError` when its **msg**
+  argument is not set. Previously only ``NULL`` was returned.
+
 * The format of the ``co_lnotab`` attribute of code objects changed to support
   negative line number delta. By default, Python does not emit bytecode with
   negative line number delta. Functions using ``frame.f_lineno``,