[SYCL][COMPAT] Fix error on headers, add helloworld test

[Ruyk]

This PR fixes an error on the SYCL compat headers that caused build to fail.
The error manifests when building the basic hello world from the documentation.
To prevent the basic hello world from failing again, this PR adds an e2e for the basic hello world
and updates the documentation to match the updated hello world source code.

[Copilot]

Pull Request Overview

This PR fixes a build error in the SYCL compat headers and adds an end-to-end test for the basic hello world example while updating the corresponding documentation.

• Fixes header issues causing build failures in SYCLcompat.
• Adds an e2e test (helloworld.cpp) to verify the hello world example.
• Updates the documentation to reflect the changes in header includes and error checking.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
sycl/test-e2e/Compat/helloworld.cpp	Adds an e2e test for the hello world example
sycl/include/syclcompat/traits.hpp	Updates type alias to use correct item instantiation
sycl/doc/syclcompat/README.md	Updates header include path and error checking logic

[ProGTX]

EXIT_FAILURE and EXIT_SUCCESS need the cstdlib header

[ProGTX]

Missing trailing newline

Suggested change

	}
	}

[ProGTX]

Suggested change

	.get_info<sycl::info::device::max_work_group_size>())
	block_size = 16;
	.get_info<sycl::info::device::max_work_group_size>()) {
	block_size = 16;
	}

I suppose we allow single line bodies without braces, but this particular line is a bit difficult to read.

[ProGTX]

This file should be moved into the syclcompat folder instead of Compat

[ProGTX]

sycl/sycl.hpp is included twice, should only be once.

Also the current guidelines are to include as little as needed in E2E tests, so not the full sycl.hpp and syclcompat.hpp, in order to reduce testing times. Though I guess this particular test could be an exception if it's supposed to be used as learning material.

[ldrumm]

I don't like this direction. It's just going to diverge very shortly. If you want tests to test examples in documentation, then the correct way to do this is with a tool that parses the documentation and then builds that code, or conversely preprocesses a documentation template to include an external source file.
As it stands this doesn't test the documentation. It tests another piece of code somewhere else in the repository.

Worse: There's no note in the actual test file to say that it needs to be kept in sync with the README so we're pretty much guaranteed divergence unless someone's very careful with the git log...
Which brings up the second point: this PR does not do what the description says. It's described as fixing a header error, but it's actually about testing example code in documentation

Please reconsider this patch.

[ldrumm]

std::endl on stderr does a double flush. I know this is example code, but I think it's best to lead by example, so \n would be better.

Also, why the de-morgan change? What does that buy us?

Also, if you're getting rid of the assert, then remove the header.

[ldrumm]

The correct way to do this is with a tool that parses the documentation and then builds that code

#!/usr/bin/env python

import sys
import tempfile
import re
import subprocess

ASCIIDOC_HEADER_PATTERN = re.compile(
    r'^==+ example (?P<example_name>[0-9]+)\s*$',
    re.IGNORECASE | re.UNICODE
)


def parse_example_sections(lines):
    sections = {}

    i = -1
    while i < len(lines) - 1:
        i += 1
        if not (match := ASCIIDOC_HEADER_PATTERN.match(lines[i])):
            continue
        if lines[i + 1].strip() != '[source,c++]':
            continue
        if lines[i + 2].strip() != '----':
            continue
        start = i + 3
        i = start
        while i < len(lines) and lines[i].strip() != '----':
            i += 1
        end = i
        sections[match.groupdict()['example_name']] = lines[start:end]
    return sections


if __name__ == '__main__':
    import argparse
    parser = argparse.ArgumentParser()
    parser.add_argument(
        'infile', nargs='?',
        type=argparse.FileType('r'),
        default=sys.stdin

    )
    known_args, extra_args = parser.parse_known_args()
    examples = parse_example_sections(known_args.infile.readlines())

    for example, source in examples.items():
        source = ''.join(source)
        print(f"compiling example {example}:")
        print(source)
        print("-------------------------------------------")
        with tempfile.NamedTemporaryFile(suffix='.cpp', delete=False) as f:
            f.write(source.encode('utf-8'))
            f.flush()
            subprocess.check_call(['clang++', '-fsycl',
            '-fsycl-targets=amdgcn-amd-amdhsa',
            '-Xsycl-target-backend=amdgcn-amd-amdhsa', '--offload-arch=gfx1032',
            '--rocm-path=/home/luke/h/hip/install'] + extra_args + [f.name])
        subprocess.check_call(['./a.out'])
        print(f"{example} passed")

Here's one I wrote for local testing of example code in a sycl extension doc I worked on. Should be simple to adapt the idea to markdown