be more specific when raising "not a constant polynomial"

src/doc/en/thematic_tutorials/coercion_and_categories.rst

@@ -837,7 +837,7 @@ The four axioms requested for coercions
           sage: ZZ(P2.gen(1))
           Traceback (most recent call last):
           ...
-          TypeError: not a constant polynomial
+          TypeError: not a constant polynomial: v
 
       Hence, we only have a *partial* map. This is fine for a *conversion*,
       but a partial map does not qualify as a *coercion*.

src/sage/categories/action.pyx

@@ -148,7 +148,7 @@ cdef class Action(Functor):
             sage: A(x, 5)
             Traceback (most recent call last):
             ...
-            TypeError: not a constant polynomial
+            TypeError: not a constant polynomial: x
             sage: A = IntegerMulAction(ZZ, R, False)  # Right action
             sage: A(x, 5)
             5*x
@@ -157,7 +157,7 @@ cdef class Action(Functor):
             sage: A(5, x)
             Traceback (most recent call last):
             ...
-            TypeError: not a constant polynomial
+            TypeError: not a constant polynomial: x
         """
         if len(args) == 2:
             # Normal case, called with (g, x) or (x, g) as arguments

src/sage/categories/map.pyx

@@ -2087,7 +2087,7 @@ cdef class FormalCompositeMap(Map):
             sage: ZZ(3*x + 45)              # indirect doctest
             Traceback (most recent call last):
             ...
-            TypeError: not a constant polynomial
+            TypeError: not a constant polynomial: 3*x + 45
         """
         sections = []
         for m in reversed(list(self)):

src/sage/categories/modules_with_basis.py

@@ -1332,7 +1332,7 @@ def _from_dict(self, d, coerce=True, remove_zeros=True):
                 sage: A._from_dict(d, coerce=True)                                      # needs sage.modules
                 Traceback (most recent call last):
                 ...
-                TypeError: not a constant polynomial
+                TypeError: not a constant polynomial: y
             """
             R = self.base_ring()
             B = self.basis()

src/sage/dynamics/arithmetic_dynamics/dynamical_semigroup.py

@@ -697,7 +697,7 @@ def orbit(self, p, n):
             sage: d.orbit(2, x)
             Traceback (most recent call last):
             ...
-            TypeError: not a constant polynomial
+            TypeError: not a constant polynomial: x
 
         ::
 

src/sage/matrix/matrix1.pyx

@@ -726,7 +726,7 @@
             sage: b.dtype
             dtype('int32')  # 32-bit
             dtype('int64')  # 64-bit
             sage: b.shape
             (3, 4)
         """
         import numpy
@@ -1925,7 +1925,7 @@
             sage: D = A.augment(B)
             Traceback (most recent call last):
             ...
-            TypeError: not a constant polynomial
+            TypeError: not a constant polynomial: y
 
             sage: E = A.change_ring(R)
             sage: F = E.augment(B); F

src/sage/rings/polynomial/ore_polynomial_element.pyx

@@ -3010,15 +3010,15 @@ cdef class ConstantOrePolynomialSection(Map):
             sage: m(S([0,1])-S([0,t]))
             Traceback (most recent call last):
             ...
-            TypeError: not a constant polynomial
+            TypeError: not a constant polynomial: (-t + 1)*x
         """
         if x.degree() <= 0:
             try:
                 return <Element>(x.constant_coefficient())
             except AttributeError:
                 return <Element>((<OrePolynomial>x).constant_coefficient())
         else:
-            raise TypeError("not a constant polynomial")
+            raise TypeError(f"not a constant polynomial: {x}")
 
 
 cdef class OrePolynomialBaseringInjection(Morphism):

src/sage/rings/polynomial/polynomial_element.pyx

@@ -1476,7 +1476,7 @@ cdef class Polynomial(CommutativePolynomial):
             sage: QQ(3*x + 45)
             Traceback (most recent call last):
             ...
-            TypeError: not a constant polynomial
+            TypeError: not a constant polynomial: 3*x + 45
         """
         return self._scalar_conversion(sage.rings.rational.Rational)
 
@@ -12894,7 +12894,7 @@ cdef class ConstantPolynomialSection(Map):
         sage: phi(y_1)
         Traceback (most recent call last):
         ...
-        TypeError: not a constant polynomial
+        TypeError: not a constant polynomial: y_1
     """
     cpdef Element _call_(self, x) noexcept:
         """
@@ -12913,15 +12913,15 @@ cdef class ConstantPolynomialSection(Map):
             sage: m(x)
             Traceback (most recent call last):
             ...
-            TypeError: not a constant polynomial
+            TypeError: not a constant polynomial: x
         """
         if x.degree() <= 0:
             try:
                 return <Element>(x.constant_coefficient())
             except AttributeError:
                 return <Element>((<Polynomial>x).constant_coefficient())
         else:
-            raise TypeError("not a constant polynomial")
+            raise TypeError(f"not a constant polynomial: {x}")
 
 cdef class PolynomialBaseringInjection(Morphism):
     """

src/sage/rings/polynomial/polynomial_zz_pex.pyx

@@ -99,7 +99,7 @@ cdef class Polynomial_ZZ_pEX(Polynomial_template):
             sage: R([3,x])
             Traceback (most recent call last):
             ...
-            TypeError: not a constant polynomial
+            TypeError: not a constant polynomial: x
 
         Check that NTL contexts are correctly restored and that
         :issue:`9524` has been fixed::