Broken conversion from ZZ['x'] to Qp['y']

[EnderWannabe]

Currently, the following code fails:

sage: R.<x> = PolynomialRing(ZZ)
sage: f = x^4 - x - 1
sage: S.<y> = PolynomialRing(Qp(5))
sage: g2 = S(f)
sage: g2.factor()

TypeError: 'sage.rings.fraction_field_element.FractionFieldElement_1poly_field' object is not iterable

However, the following code works

sage: g = y^4 - y - 1
sage: g.factor()

and moreover

sage: g == g2
True

The cause seems to be the following:

sage: g2._poly
x^4 - x - 1

To fix this, we change the line where ._poly is initialized when converting from ZZ[] to Qp[].

CC: @bhutz @pfili

Component: padics

Keywords: gsoc20

Author: Alexander Galarraga

Branch/Commit: 726c83b

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/29828

[EnderWannabe]

Branch: u/gh-EnderWannabe/broken_conversion_from_zz__x___to_qp__y__

[EnderWannabe]

Commit: d2fd21f

[EnderWannabe]

New commits:

d2fd21f

Fix for conversion from ZZ[] to Qp[]

[sagetrac-git]

Changed commit from d2fd21f to 12a0454

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

12a0454

Better fix

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:5

The fix is good. Just add a doctest showing the issue is fixed and prevent a regression.

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

d7975d5

Added doctest

[sagetrac-git]

Changed commit from 12a0454 to d7975d5

[EnderWannabe]

comment:7

Replying to @tscrim:

The fix is good. Just add a doctest showing the issue is fixed and prevent a regression.

Doctest added. Tests multiplication since this also breaks without the fix

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

726c83b

Better test

[sagetrac-git]

Changed commit from d7975d5 to 726c83b

[tscrim]

comment:9

Thank you. LGTM.

[vbraun]

Changed branch from u/gh-EnderWannabe/broken_conversion_from_zz__x___to_qp__y__ to 726c83b