Follow-up to #17805

[jbrockmendel]

This replaces uses of pandas_datetime_to_datetimestruct and pandas_datetimestruct_to_datetime with dt64_to_dtstruct and dtstruct_to_dt64 respectively, but leaves some un-replaced to avoid creating conflicts with other open PRs.

• closes #xxxx
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

[jreback]

looks fine. ping when green.

[codecov]

Codecov Report

Merging #18023 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #18023      +/-   ##
==========================================
- Coverage   91.26%   91.24%   -0.02%     
==========================================
  Files         163      163              
  Lines       50099    50099              
==========================================
- Hits        45724    45715       -9     
- Misses       4375     4384       +9

Flag	Coverage Δ
#multiple	89.05% <ø> (ø)	⬆️
#single	40.24% <ø> (-0.06%)	⬇️

Impacted Files	Coverage Δ
pandas/io/gbq.py	25% <0%> (-58.34%)	⬇️
pandas/core/frame.py	97.75% <0%> (-0.1%)	⬇️

---

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[codecov]

Codecov Report

Merging #18023 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #18023      +/-   ##
==========================================
- Coverage   91.26%   91.24%   -0.02%     
==========================================
  Files         163      163              
  Lines       50099    50099              
==========================================
- Hits        45724    45715       -9     
- Misses       4375     4384       +9

Flag	Coverage Δ
#multiple	89.05% <ø> (ø)	⬆️
#single	40.24% <ø> (-0.06%)	⬇️

Impacted Files	Coverage Δ
pandas/io/gbq.py	25% <0%> (-58.34%)	⬇️
pandas/core/frame.py	97.75% <0%> (-0.1%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update a355ed2...04dd69d. Read the comment docs.

[jbrockmendel]

ping

[jreback]

thanks

i assume u have a note to change the remaining on tslib at some point