[Diagnostics] Hooking up remarks emitted from Clang.

[vguerra]

Now that Swift support remarks ClangImporter we pass them
to the Clang diagnostic producer instead of ignoring them.

Fixes SR-10915

[jrose-apple]

Looks great! Thanks, @vguerra.

[jrose-apple]

@swift-ci Please smoke test

[vguerra]

Thank you for the quick review @jrose-apple.

Just a small follow up on this: #25603

[compnerd]

This breaks on windows! https://compnerd.visualstudio.com/windows-swift/_build/results?buildId=3363&view=logs&j=2d2b3007-3c5c-5840-9bb0-2b1ea49925f3

[vguerra]

hello @compnerd .. will have a look at it, sorry for that :/

should I revert in the mean-time?

[jrose-apple]

Looking at the failure:

D:\a\1\s\swift\test\ClangImporter\remarks.swift:6:16: error: CHECK-NEXT: is not on the line after the previous match
// CHECK-NEXT: remark: importing module 'Requires'
               ^
<stdin>:9:14: note: 'next' match was here
<unknown>:0: remark: importing module 'Requires' from 'BUILD_DIR/swift-test-results/x86_64-unknown-windows-msvc/clang-module-cache/3HA27GCPD6Q8U/Requires-1XF48MFV80W6X.pcm'
             ^
<stdin>:1:51: note: previous match ended here
<unknown>:0: remark: importing module 'SwiftShims' from 'BUILD_DIR/swift-test-results/x86_64-unknown-windows-msvc/clang-module-cache/3HA27GCPD6Q8U/SwiftShims-2VP0I72R3U78H.pcm'

<stdin>:2:1: note: non-matching line after previous match is here
<unknown>:0: remark: importing module 'visualc' into 'SwiftShims' from 'BUILD_DIR/swift-test-results/x86_64-unknown-windows-msvc/clang-module-cache/3HA27GCPD6Q8U/visualc-12GK0U120S9VQ.pcm'
^

I think it'd be okay to make the test a little looser by dropping the "NEXT". We just want to make sure remarks are printed; the precise remarks aren't so important.

(@compnerd, is it really okay to import visualc into SwiftShims, though? The point of SwiftShims is usually to avoid a cycle with the platform overlay.)

[compnerd]

@vguerra - I think I would rather fix forward, dropping the -NEXT suffix.
@jrose-apple - that gets pulled in since visualc provides io.h. If there is a way to avoid that, I would be happy to see that cycle broken.

[jrose-apple]

SwiftShims deliberately "redeclares" a bunch of things normally in the C standard library to avoid these.

[vguerra]

thanks for pushing the fix @compnerd ... indeed dropping the -NEXT was the easiest.

[compnerd]

Right, but, it does still include headers and that seems to be pulling in the visualc module. I think that it may be due to the io.h inclusion?

[jrose-apple]

I mean, we didn't write the Windows includes. Feel free to change them to do the same sort of redeclaring rather than including headers.

[compnerd]

Will do; at the very least, I will create a SR to track this item.
Edit: https://bugs.swift.org/browse/SR-10971