[0-size Retest] Fix var、std、selu api to support 0-size Tensor

[DanielSun11]

PR Category

Operator Mechanism

PR Types

Bug fixes

Description

修复复测发现的0-size问题

• var相关的api（var、std）grad为none

def _replace_nan(out): out_nan = paddle.full_like(out, paddle.nan) out_nan.stop_gradient = out.stop_gradient return out_nan 

full_like没有反向，导致梯度回传时回传不到输入x

• selu反向过程报cuda error 9

修复完paddleapitest回测
var

selu

pcard-67164

[paddle-bot]

你的PR提交成功，感谢你对开源项目的贡献!
请关注后续CI自动化测试结果，详情请参考Paddle-CI手册。
Your PR has been submitted. Thanks for your contribution!
Please wait for the result of CI firstly. See Paddle CI Manual for details.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (develop@89ad47c). Learn more about missing BASE report.

Additional details and impacted files

@@ Coverage Diff @@ ## develop #74153 +/- ## =========================================== Coverage ? 100.00% =========================================== Files ? 1 Lines ? 2 Branches ? 0 =========================================== Hits ? 2 Misses ? 0 Partials ? 0 

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.