std: regression test for Windows junction_point stack buffer overflow

[devnexen]

Temporary CI-verification test for #158147. Without the fix, a >16 KiB junction target passes the old > u16::MAX length check yet overflows the inline reparse stack buffer. This test must fail on master and pass once the fix lands.

[rustbot]

r? @joboet

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The reviewer was selected based on:

• Owners of files modified in this PR: @ChrisDenton, libs
• @ChrisDenton, libs expanded to 12 candidates
• Random selection from Darksonn, Mark-Simulacrum, clarfonthey, jhpratt, joboet

[rustbot]

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  • 7930d02

[Darksonn]

r? @Darksonn

[Darksonn]

@bors try

[ChrisDenton]

By default @bors try only tests linux. To test windows you need to select the jobs to run. See the dev guide's section on try builds.

@bors try jobs=x86_64-msvc-1,x86_64-msvc-2

[Darksonn]

Ah, thanks.

[rust-log-analyzer]

The job x86_64-msvc-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

test fs::tests::invalid_path_raises ... ok
error: test failed, to rerun pass `-p std --lib`

Caused by:
  process didn't exit successfully: `D:\a\rust\rust\build\x86_64-pc-windows-msvc\stage2-std\x86_64-pc-windows-msvc\dist\deps\std-409e131965b35c7e.exe -Z unstable-options --format json` (exit code: 0xc0000005, STATUS_ACCESS_VIOLATION)
note: test exited abnormally; to see the full output pass --no-capture to the harness.
Bootstrap failed while executing `test --stage 2 --skip=compiler --skip=src`
Build completed unsuccessfully in 1:59:34
make: *** [Makefile:115: ci-msvc-py] Error 1
  local time: Sun Jun 21 11:16:25 CUT 2026
  network time: Sun, 21 Jun 2026 11:16:25 GMT
##[error]Process completed with exit code 2.
##[group]Run echo "disk usage:"
echo "disk usage:"

[devnexen]

Can I close it ?

[rust-bors]

💔 Test for 4b1b77e failed: CI. Failed job:

• try - x86_64-msvc-1 (web logs, enhanced plaintext logs)

[Darksonn]

Thanks!