baremetal clang toolchain does not define _GNU_SOURCE [254916723]

Fixed

Bug

Status Update

No update yet.

Description

to...@google.com

created issue #1

Oct 21, 2022 10:09PM

When building [libcxx], I noticed that _GNU_SOURCE is not defined automatically by armv7m-cros-eabi-clang++.

Some comparisons (where empty.cc is an empty file):

_GNU_SOURCE is defined:

clang++ -E -dD -o empty empty.cc
armv7a-cros-linux-gnueabihf-clang++ -E -dD -o empty empty.cc

_GNU_SOURCE is not defined:

armv7m-cros-eabi-clang++ -E -dD -o empty empty.cc
/opt/coreboot-sdk/bin/arm-eabi-g++ -E -dD -o empty empty.cc
arm-none-eabi-clang++ -E -dD -o empty empty.cc

It looks the baremetal variants don't define it. I guess the assumption is that baremetal targets won't use libc?

Comments

bl...@google.com <bl...@google.com> #2Oct 21, 2022 10:23PM

Assigned to in...@google.com.

To be clear, when you say jump pages, do you mean recyclerview is scrolling down, or is viewpager scrolling across multiple fragments?

A repro / sample project demonstrating the issue would definitely be helpful here.

in...@google.com <in...@google.com> #3Oct 21, 2022 10:39PM

You also mentioned alph09 in the title, but alpha07 in the comment - could you specify which version of viewpager and paging you are using?

to...@google.com <to...@google.com> #4Oct 21, 2022 11:15PM

Ah sorry I see that you have used both here, still could you specify which version of viewpager you are using as well?

ma...@google.com <ma...@google.com> #5Oct 22, 2022 02:33AM

Hi,
View Pager 2 : - implementation "androidx.viewpager2:viewpager2:1.0.0"
Paging 3 : - implementation "androidx.paging:paging-runtime-ktx:3.0.0-alpha09"

Example

https://github.com/vivek-modi/ViewPagerExample

Attached Video Explanation

When i click slowly on previous button it swipe single page, but if i click quickly multiple times on previous button it start scrolling more than we click and it's not stopping until we click on viewpager.

to...@google.com <to...@google.com> #6Oct 28, 2022 06:40PM

Hi, Did you get something, what is the cause?

ap...@google.com <ap...@google.com> #7Nov 2, 2022 04:54PM

Haven't forgotten this - this is on my queue, just that my queue is quite long :)

ap...@google.com <ap...@google.com> #8Nov 19, 2022 06:07PM

okkk, no problem. Thanks

ma...@google.com <ma...@google.com> Nov 19, 2022 06:08PM

Marked as fixed.

ap...@google.com <ap...@google.com> #9Dec 2, 2022 09:59PM

This looks like a weird race scenario where the smooth scroll behavior in RV / ViewPager is attempting to do an animated scroll to an absolute position, but Paging is able to PREPEND items to the front of the list faster than the animation can scroll there.

I noticed that you're attempting to enablePlaceholders to mitigate this by telling Paging the total item count, but you never pass a value for placeholdersBefore / After in the initial result on REFRESH. This will prevent Paging understanding how many placeholder items there are in the list. This is probably something Paging should check for, but the proper solution to this ticket should probably be some kind of relative scrolling behavior on RecyclerView or ViewPager, however I expect boundary cases to be quite annoying to deal with there.