gh-39281: fix and activate the ruff check for F811
    
this is about bad imports :

Redefinition of unused something from line xxx

### 📝 Checklist

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
    
URL: #39281
Reported by: Frédéric Chapoton
Reviewer(s): Tobias Diez

Author: Release Manager

src/sage/algebras/weyl_algebra.py

@@ -21,7 +21,6 @@
 from sage.misc.latex import latex, LatexExpr
 from sage.misc.lazy_attribute import lazy_attribute
 from sage.misc.misc_c import prod
-from sage.structure.element import Element
 from sage.structure.parent import Parent
 from sage.structure.unique_representation import UniqueRepresentation
 from sage.categories.action import Action

src/sage/categories/basic.py

@@ -47,7 +47,6 @@
 from sage.categories.principal_ideal_domains import PrincipalIdealDomains
 from sage.categories.euclidean_domains import EuclideanDomains
 from sage.categories.unique_factorization_domains import UniqueFactorizationDomains
-from sage.categories.complete_discrete_valuation import CompleteDiscreteValuationRings
 
 from sage.categories.fields import Fields
 from sage.categories.quotient_fields import QuotientFields

src/sage/coding/guruswami_sudan/gs_decoder.py

@@ -14,18 +14,17 @@
 - David Lucas, ported the original implementation in Sage
 """
 
-#*****************************************************************************
+# ****************************************************************************
 #       Copyright (C) 2015 David Lucas <[email protected]>
 #                     2015 Johan S. R. Nielsen <[email protected]>
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation, either version 2 of the License, or
 # (at your option) any later version.
-#                  http://www.gnu.org/licenses/
-#*****************************************************************************
+#                  https://www.gnu.org/licenses/
+# ****************************************************************************
 
-from sage.arith.misc import integer_floor as floor
 from sage.coding.grs_code import GeneralizedReedSolomonCode
 from sage.rings.integer_ring import ZZ
 from sage.coding.decoder import Decoder

src/sage/modules/with_basis/representation.py

@@ -21,7 +21,6 @@
 from sage.misc.cachefunc import cached_method
 from sage.structure.element import Element
 from sage.combinat.free_module import CombinatorialFreeModule, CombinatorialFreeModule_Tensor
-from sage.modules.with_basis.subquotient import SubmoduleWithBasis
 from sage.categories.modules import Modules
 from sage.matrix.constructor import matrix
 from sage.modules.free_module_element import vector

src/sage/rings/finite_rings/integer_mod_ring.py

@@ -69,7 +69,6 @@
 from sage.arith.misc import CRT_basis
 from sage.rings.ring import Field, CommutativeRing
 from sage.misc.mrange import cartesian_product_iterator
-import sage.rings.ring as ring
 import sage.rings.abc
 from sage.rings.finite_rings import integer_mod
 import sage.rings.integer as integer
@@ -2030,7 +2029,7 @@ def crt(v):
         1027
     """
     if len(v) == 0:
-        return IntegerModRing(1)(1)
+        return IntegerModRing(1).one()
     x = v[0]
     for i in range(1, len(v)):
         x = x.crt(v[i])

src/sage/rings/polynomial/polynomial_ring.py

@@ -230,7 +230,6 @@ def is_PolynomialRing(x):
         sage: type(R)
         <class 'sage.rings.polynomial.multi_polynomial_libsingular.MPolynomialRing_libsingular'>
     """
-    from sage.misc.superseded import deprecation
     deprecation(38266,
                 "The function is_PolynomialRing is deprecated; "
                 "use 'isinstance(..., PolynomialRing_generic)' instead.")

src/sage/schemes/curves/affine_curve.py

@@ -141,7 +141,6 @@
 from sage.rings.polynomial.multi_polynomial_element import degree_lowest_rational_function
 from sage.rings.polynomial.polynomial_ring_constructor import PolynomialRing
 from sage.rings.rational_field import RationalField
-from sage.rings.infinity import infinity
 
 from sage.schemes.affine.affine_space import AffineSpace, AffineSpace_generic
 from sage.schemes.affine.affine_subscheme import (AlgebraicScheme_subscheme_affine,

src/sage/schemes/elliptic_curves/ell_point.py

@@ -140,10 +140,8 @@
 from sage.rings.integer_ring import ZZ
 from sage.rings.padics.precision_error import PrecisionError
 from sage.rings.rational_field import QQ
-from sage.rings.finite_rings.integer_mod import Mod
 from sage.rings.real_mpfr import RealField, RR
 from sage.rings.quotient_ring import QuotientRing_generic
-import sage.groups.generic as generic
 
 from sage.structure.element import AdditiveGroupElement
 from sage.structure.sequence import Sequence

src/sage/symbolic/expression_conversions.py

@@ -23,7 +23,7 @@
 from sage.misc.lazy_import import lazy_import
 from sage.symbolic.ring import SR
 from sage.structure.element import Expression
-from sage.functions.all import exp
+from sage.functions.log import exp
 from sage.symbolic.operators import arithmetic_operators, relation_operators, FDerivativeOperator, add_vararg, mul_vararg
 from sage.rings.number_field.number_field_element_base import NumberFieldElement_base
 from sage.rings.universal_cyclotomic_field import UniversalCyclotomicField
@@ -1651,7 +1651,6 @@ class Exponentialize(ExpressionTreeWalker):
     # the same canned results dictionary at each call.
     from sage.calculus.var import function
     from sage.functions.hyperbolic import sinh, cosh, sech, csch, tanh, coth
-    from sage.functions.log import exp
     from sage.functions.trig import sin, cos, sec, csc, tan, cot
     from sage.rings.integer import Integer
     from sage.symbolic.constants import e, I
@@ -1749,7 +1748,6 @@ def composition(self, ex, op):
             sage: s.composition(q, q.operator())
             (cos(b) + I*sin(b))*e^a
         """
-        from sage.functions.log import exp
         if op is not exp:
             # return super().composition(ex, op)
             return op(*[self(oper) for oper in ex.operands()])

src/tox.ini

@@ -311,7 +311,7 @@ passenv = RUFF_OUTPUT_FORMAT
 #      1        F402    [ ] Import `factor` from line 259 shadowed by loop variable
 #      1        PLC0208 [*] Use a sequence type instead of a `set` when iterating over values
 #
-commands = ruff check --ignore E402,E721,E731,E741,E742,E743,F401,F402,F403,F405,F811,F821,F841,I001,PLC0206,PLC0208,PLC2401,PLC3002,PLE0302,PLR0124,PLR0402,PLR0911,PLR0912,PLR0913,PLR0915,PLR1704,PLR1711,PLR1714,PLR1736,PLR2004,PLR5501,PLW0120,PLW0127,PLW0211,PLW0602,PLW0603,PLW0642,PLW1508,PLW1510,PLW2901,PLW3301 {posargs:{toxinidir}/sage/}
+commands = ruff check --ignore E402,E721,E731,E741,E742,E743,F401,F402,F403,F405,F821,F841,I001,PLC0206,PLC0208,PLC2401,PLC3002,PLE0302,PLR0124,PLR0402,PLR0911,PLR0912,PLR0913,PLR0915,PLR1704,PLR1711,PLR1714,PLR1736,PLR2004,PLR5501,PLW0120,PLW0127,PLW0211,PLW0602,PLW0603,PLW0642,PLW1508,PLW1510,PLW2901,PLW3301 {posargs:{toxinidir}/sage/}
 
 [flake8]
 rst-roles =