From 142a3703d8b60804a5ff1179a0dbc6bcbf37ce64 Mon Sep 17 00:00:00 2001
From: Sebastian Berg <sebastianb@nvidia.com>
Date: Tue, 3 Jan 2023 14:44:04 +0100
Subject: [PATCH] MAINT: Add additional information to missing scalar
 AttributeError

This is a followup on gh-22607 which removed them.  Since it appears some
users missed the DeprecationWarning entirely, it may help them to
include the old information as an attribute error.

An example is:
```
In [1]: np.int

AttributeError: module 'numpy' has no attribute 'int'.
`np.int` was a deprecated alias for the builtin `int`. To avoid this error in existing code, use `int` by itself.
Doing this will not modify any behavior and is safe. When replacing `np.int`, you may wish to use e.g. `np.int64`
or `np.int32` to specify the precision. If you wish to review your current use, check the release note link for
additional information.
The aliases was originally deprecated in NumPy 1.20; for more details and guidance see the original release note
at:
    https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations
```

Yes, that is very verbose...

your changes. Lines starting
---
 numpy/__init__.py                     | 40 +++++++++++++++++++++++++--
 numpy/core/tests/test_deprecations.py | 15 ++++++++++
 2 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/numpy/__init__.py b/numpy/__init__.py
index bdea595ed3f5..e20a83ab1e7b 100644
--- a/numpy/__init__.py
+++ b/numpy/__init__.py
@@ -155,6 +155,40 @@
     from . import matrixlib as _mat
     from .matrixlib import *
 
+    # Deprecations introduced in NumPy 1.20.0, 2020-06-06
+    import builtins as _builtins
+
+    _msg = (
+        "module 'numpy' has no attribute '{n}'.\n"
+        "`np.{n}` was a deprecated alias for the builtin `{n}`. "
+        "To avoid this error in existing code, use `{n}` by itself. "
+        "Doing this will not modify any behavior and is safe. {extended_msg}\n"
+        "The aliases was originally deprecated in NumPy 1.20; for more "
+        "details and guidance see the original release note at:\n"
+        "    https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations")
+
+    _specific_msg = (
+        "If you specifically wanted the numpy scalar type, use `np.{}` here.")
+
+    _int_extended_msg = (
+        "When replacing `np.{}`, you may wish to use e.g. `np.int64` "
+        "or `np.int32` to specify the precision. If you wish to review "
+        "your current use, check the release note link for "
+        "additional information.")
+
+    _type_info = [
+        ("object", ""),  # The NumPy scalar only exists by name.
+        ("bool", _specific_msg.format("bool_")),
+        ("float", _specific_msg.format("float64")),
+        ("complex", _specific_msg.format("complex128")),
+        ("str", _specific_msg.format("str_")),
+        ("int", _int_extended_msg.format("int"))]
+
+    __former_attrs__ = {
+         n: _msg.format(n=n, extended_msg=extended_msg)
+         for n, extended_msg in _type_info
+     }
+
     # Future warning introduced in NumPy 1.24.0, 2022-11-17
     _msg = (
         "`np.{n}` is a deprecated alias for `{an}`.  (Deprecated NumPy 1.24)")
@@ -265,8 +299,10 @@ def _expired(*args, **kwds):
             # the AttributeError
             warnings.warn(
                 f"In the future `np.{attr}` will be defined as the "
-                "corresponding NumPy scalar.  (This may have returned Python "
-                "scalars in past versions.", FutureWarning, stacklevel=2)
+                "corresponding NumPy scalar.", FutureWarning, stacklevel=2)
+
+        if attr in __former_attrs__:
+            raise AttributeError(__former_attrs__[attr])
 
         # Importing Tester requires importing all of UnitTest which is not a
         # cheap import Since it is mainly used in test suits, we lazy import it
diff --git a/numpy/core/tests/test_deprecations.py b/numpy/core/tests/test_deprecations.py
index dba301418612..033815150b0e 100644
--- a/numpy/core/tests/test_deprecations.py
+++ b/numpy/core/tests/test_deprecations.py
@@ -1176,3 +1176,18 @@ def test_future_scalar_attributes(name):
     # Unfortunately, they are currently still valid via `np.dtype()`
     np.dtype(name)
     name in np.sctypeDict
+
+
+# Ignore the above future attribute warning for this test.
+@pytest.mark.filterwarnings("ignore:In the future:FutureWarning")
+class TestRemovedGlobals:
+    # Removed 2023-01-12, NumPy 1.24.0
+    # Not a deprecation, but the large error was added to aid those who missed
+    # the previous deprecation, and should be removed similarly to one
+    # (or faster).
+    @pytest.mark.parametrize("name",
+            ["object", "bool", "float", "complex", "str", "int"])
+    def test_attributeerror_includes_info(self, name):
+        msg = f".*\n`np.{name}` was a deprecated alias for the builtin"
+        with pytest.raises(AttributeError, match=msg):
+            getattr(np, name)