Rebase

Make changes requested by @ldionne and rebase.

Ping

Ping

In D154246#4647568, @ldionne wrote:

Is this ready for review?

Rebase

Rebase

Hi Sam, I won't be able to take this forward but you have my encouragement. To facilitate this change I got as far as changing Git [1], and GitHub has been updated accordingly [2], but I ran out of steam before getting to the change itself.
I'd be happy to let someone else (you?) take the lead and commandeer the change.

LGTM

some nasty and repetitive regexes

OK if I get any more review comments I'll do that. The new "Armv7-M picolibc" configuration is passing in BuildKite now and the failures in other configurations look unrelated so I have no changes planned at this point.

Rebase after -Wcast-qual error was fixed

Rebase after -Wcast-qual error was fixed

LGTM and fixes the issue for me. I agree there doesn't seem to be a good reason to have the const there in the first place.

Handle command line arguments

atomics -> has-64-bit-atomics

LGTM but please allow a day for others to comment.

In D155521#4510398, @DavidSpickett wrote:

QEMU has been installed.

buildkite-linaro-aarch64-libcxx-02:/# qemu-system-arm --version
QEMU emulator version 4.2.1 (Debian 1:4.2-3ubuntu6.27)
Copyright (c) 2003-2019 Fabrice Bellard and the QEMU Project developers

And it's on PATH, no /usr/local... stuff needed this time.

Use 16MB area of RAM to enable running bigger tests

Use 16MB area of RAM to enable running bigger tests

In D155521#4509345, @DavidSpickett wrote:

Surprised to not see bootcode here, but it is qemu and one can get away without it a lot of the time. Is that the case?

I will add qemu-system-arm to our containers. Focal's apt version is 4.2.1 and I checked it has the board and cpu options needed, so I expect it'll work fine.

Move code to find qemu-system-arm program

Change how atomics feature is detected and change atomic REQUIRES back to negated XFAIL

XFAIL: !atomics -> REQUIRES: atomics

Add "atomics" feature, run git-clang-format, and other minor tweaks

@lhames ping

Hi Joe, it's nice to see multilib.yaml getting some adoption :)

Compile and link tests

Hi @MaskRay, thanks for the add. Yes, we've been deleting a lot of eabi recently, but that's specific to AArch64. I have no particular insight into PowerPC but from @jroelofs' link, I agree eabi seems correct here.

Add summary comment to build-picolibc.sh

LGTM

Default to compiling picolibc with cc

clang -> $CC

Thanks for this, LGTM.

Fix duplicate implicit group warning

In D154390#4471948, @ldionne wrote:

Ok, thanks a lot. But just to be sure, this wasn't working previously with picolibc, was it? Or did it start failing only when I split up the source files?

The fixes building with picolibc, thanks!

With these changes, copied from chrono.cpp, this patch fixes building with picolibc.

Does that mean the platform doesn't provide a way to check the time, or is it that the API it provides is just different? How is e.g. std::system_clock implemented on that platform?

Apply @ldionne's suggestions

In D152382#4469614, @ldionne wrote:

Anyway, I'm trying something out in D154390

send error messages to stderr

In D154246#4467715, @DavidSpickett wrote:

Let me know when it makes sense for me to try this locally and I'll get that done. Once the containers are updated you'll be able to get a green build here before landing.

Apply review suggestions

In D153430#4453908, @MaskRay wrote:

Thank you for implementing this warning. Side note: it would be better to (a) fix the tests separately from (b) implementing the warning and (c) adding tests to demonstrate the warning.
This way the patch is more focused.

Rename variable

LGTM

The change seems OK to me in principle, but I'd appreciate the code being more self-descriptive. Thanks.

Tweak warning message

<input triple> selects the fallback GCC toolchain driver; did you mean <proposed triple>

This is a correct description of the current behaviour, but I want to keep the freedom to change the behaviour in future. Therefore I'd like to avoid defining what behaviour an invalid target triple will cause.