[Support] Remove LLVM_ATTRIBUTE_NORETURN

[gAlfonso-bit]

Summary

Code should use C++11 [[noreturn]] or C11 _Noreturn instead.

[gAlfonso-bit]

I had to format my changes using clang format, which is why the file has formatting changes.

[mclow.lists]

I would like to see you undo all the formatting changes.
They are not germane for this patch, and (IMHO) reduce the readability of the code.

[gAlfonso-bit]

Removed unneeded formatting changes

[gAlfonso-bit]

In D106899#2908301, @mclow.lists wrote:

I would like to see you undo all the formatting changes.
They are not germane for this patch, and (IMHO) reduce the readability of the code.

Done!

[gAlfonso-bit]

Fixed typo

[mclow.lists]

In D106899#2908395, @gAlfonso-bit wrote:

Done!

Thank you. That's *much* easier to review.

[mclow.lists]

I am not an approver for LLVM, but this LGTM.

[gAlfonso-bit]

In D106899#2908480, @mclow.lists wrote:

I am not an approver for LLVM, but this LGTM.

Who is though?

[gAlfonso-bit]

Had to fix an attribute list compile error due to the expanded macro

[gAlfonso-bit]

@MaskRay could you please look at this when you get the chance?

[gAlfonso-bit]

Fix more compilation errors

[gAlfonso-bit]

Every touched file that isn't Compiler.h had to be slightly tweaked (just word order change in function declarations) in order for the compilation to go through without any errors

[MaskRay]

[[noreturn]] is C++11.
In Oct 2016, the minimum compiler requirement was raised to GCC 4.8/MSVC 2015.
We can use [[noreturn]] since then.

I migrated lld/. I will watch the build bots and migrate llvm/

[gAlfonso-bit]

I did that for you. Did a search and replace. Now we don't need the keyword anymore!

[gAlfonso-bit]

Removed LLVM_ATTRIBUTE_NORETURN entirely since the project's minimum requirements now allow us to use [[noreturn]] directly.

[gAlfonso-bit]

Formatted ONLY the code I changed

[gAlfonso-bit]

@MaskRay I finished the migration to noreturn

[gAlfonso-bit]

Also, I rebased my fork to LLVM 13 Release Branch so they don't clash with your changes

[gAlfonso-bit]

This comment was removed by gAlfonso-bit.

[MaskRay]

I migrated all llvm/ files. You need to remove them from the patch.

It is a good idea to drop the macro definition in llvm/include/llvm/Support/Compiler.h separately.

It makes it easy to bring back the definition if some important downstream users want extended time for migration.
(Note: the policy is that downstream is on their own. Our thinking of this is kindness, not an obligation of llvm-project.)
For example, swift is using LLVM_ATTRIBUTE_NORETURN.
(I researched a bit: LLVM_ATTRIBUTE_NORETURN is not common in downstream projects.)

[gAlfonso-bit]

Rebased

[gAlfonso-bit]

In D106899#2910655, @MaskRay wrote:

I migrated all llvm/ files. You need to remove them from the patch.

It is a good idea to drop the macro definition in llvm/include/llvm/Support/Compiler.h separately.

It makes it easy to bring back the definition if some important downstream users want extended time for migration.
(Note: the policy is that downstream is on their own. Our thinking of this is kindness, not an obligation of llvm-project.)
For example, swift is using LLVM_ATTRIBUTE_NORETURN.
(I researched a bit: LLVM_ATTRIBUTE_NORETURN is not common in downstream projects.)

Alright, but can we cherry pick this to release when this is all said and done?

[gAlfonso-bit]

Fixed clang format

[MaskRay]

Drop llvm/include/llvm/Support/Compiler.h change.

[gAlfonso-bit]

Removed Compiler.h changes

[gAlfonso-bit]

This comment was removed by gAlfonso-bit.

[gAlfonso-bit]

Had to fix a clang-tidy issue for this to even compile, because buildbot was throwing a fit about it

[gAlfonso-bit]

Still not passing (what is going on?)

[MaskRay]

In D106899#2913925, @gAlfonso-bit wrote:

Still not passing (what is going on?)

If you click a harbomaster URI, sometimes the builds are good

x64 debian passed
x64 windows passed

and sometimes there may be failures apparently unrelated to your patch.
Some discretion is needed.

I ended up making the refactoring by myself. Your change included some whole-file clang-format formatting which wasn't suitable.
I usually run git diff -U0 --no-color 'HEAD^' | clang/tools/clang-format/clang-format-diff.py -i -p1 to only format related lines.

[gAlfonso-bit]

Ok thanks