[5.0.0] Issues with host system temp directory for transient lcov.info file

[aram-yesildeniz]

We run lcov-result-merger on a remote system, after updating to 5.0.0 we get the following error:

[Error: EXDEV: cross-device link not permitted, rename '/tmp/lcov-result-merger-abc/lcov.info' -> './coverage/lcov.info'] {
	errno: -18,
	code: 'EXDEV',
	syscall: 'rename',
	path: '/tmp/lcov-result-merger-abc/lcov.info',
	dest: './coverage/lcov.info'
}

Im posting this here as I guess that others will come across this too.
The problem is easy solvable by adding the flag legacy-temp-file, e.g.:

./node_modules/.bin/lcov-result-merger './coverage/**/lcov.info' './coverage/lcov.info' --legacy-temp-file

[mfittko]

also had to downgrade to 4.1.0, as it happened just out of the blue today on CircleCI

[mfittko]

downgrade also didn't work, trying the legacy-temp-file patch

[KADacey4]

Encountered the same issue. This bit of code:
if (args.outFile) { await rename(tempFilePath, args.outFile); } else { process.stdout.write(await readFile(tempFilePath, 'utf-8')); }

should be changed to something like:
if (args.outFile) { await copyFile(tempFilePath, args.outFile); } else { process.stdout.write(await readFile(tempFilePath, 'utf-8')); }

That should avoid the error when rename() is attempted on paths that are not on the same mounted filesystem. Linux permits a filesystem to be mounted at multiple points, but rename() does not work across different mount points, even if the same filesystem is mounted on both.

[mdeanjones]

Thanks for the insight @KADacey4.

I have a suspicion that things can be simplified further by removing the temp file behavior altogether. So far as I can reason, due to the way that we're trying to stitch various files together, everything needs to be held in memory for the duration of the process. At this point, I think the behavior might just be a historical holdover that it is time to retire.

Happy holidays all!

[ringo-anva]

It's merging but lines/function/branches are all 0/0 tried all versions.