Take into account the limitation of the microbenchmark

Author: Pierre-Sassoulas

doc/user_guide/checkers/extensions.rst

@@ -88,6 +88,9 @@ Code Style checker Messages
   'typing.NamedTuple' uses the well-known 'class' keyword with type-hints for
   readability (it's also faster as it avoids an internal exec call). Disabled
   by default!
+:use-math-not-float (R6106): *%smath.%s is preferable to %s*
+  Using math.inf or math.nan permits to benefit from typing and it is 4 time
+  faster than a float call (notwithstanding the initial import of math).
 
 
 .. _pylint.extensions.comparison_placement:

doc/user_guide/checkers/features.rst

@@ -689,11 +689,11 @@ Match Statements checker Messages
 :invalid-match-args-definition (E1902): *`__match_args__` must be a tuple of strings.*
   Emitted if `__match_args__` isn't a tuple of strings required for match.
 :too-many-positional-sub-patterns (E1903): *%s expects %d positional sub-patterns (given %d)*
-  Emitted when the number of allowed positional sub-patterns exceeds the
-  number of allowed sub-patterns specified in `__match_args__`.
+  Emitted when the number of allowed positional sub-patterns exceeds the number
+  of allowed sub-patterns specified in `__match_args__`.
 :multiple-class-sub-patterns (E1904): *Multiple sub-patterns for attribute %s*
-  Emitted when there is more than one sub-pattern for a specific attribute in
-  a class pattern.
+  Emitted when there is more than one sub-pattern for a specific attribute in a
+  class pattern.
 :match-class-bind-self (R1905): *Use '%s() as %s' instead*
   Match class patterns are faster if the name binding happens for the whole
   pattern and any lookup for `__match_args__` can be avoided.

doc/user_guide/messages/messages_overview.rst

@@ -559,6 +559,7 @@ All messages in the refactor category:
    refactor/use-a-generator
    refactor/use-dict-literal
    refactor/use-list-literal
+   refactor/use-math-not-float
    refactor/use-set-for-membership
    refactor/use-yield-from
    refactor/useless-object-inheritance

doc/whatsnew/fragments/10621.new_check

@@ -1,6 +1,6 @@
-Add a ``use-math-not-float`` message. float("nan") and float("inf") are slower
-than their counterpart ``math.inf`` and ``math.nan`` by a factor of 4 and they
-are also not well typed when using mypy.
+Add a ``use-math-not-float`` message. ``float("nan")`` and ``float("inf")`` are slower
+than their counterpart ``math.inf`` and ``math.nan`` by a factor of 4 (notwithstanding
+the initial import of math) and they are also not well typed when using mypy.
 
 The :ref:`pylint.extensions.code_style` need to be activated for this check to work.
 

pylint/extensions/code_style.py

@@ -78,8 +78,8 @@ class CodeStyleChecker(BaseChecker):
             "%smath.%s is preferable to %s",
             "use-math-not-float",
             "Using math.inf or math.nan permits to benefit from typing "
-            "and it is 4 time faster than a float call.\n"
-            "Requires 'import math' in the file.",
+            "and it is 4 time faster than a float call (notwithstanding"
+            " the initial import of math).",
         ),
     }
     options = (