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UI & Output Tests

When updating UI test files (tests/ui-* or zerocopy-derive/tests/ui-*) or functionality which could affect compiler error output or derive output, run: ./tools/update-expected-test-output.sh.

Note: We maintain separate UI tests for different toolchains (ui-msrv, ui-stable, ui-nightly) because compiler output varies. The script handles this automatically.

Symlink Pattern

To share test code across toolchains while allowing for different error output, we use a symlink pattern:

1. Canonical Source: The ui-nightly directory holds the actual source files (.rs).
2. Symlinks: The ui-stable and ui-msrv directories contain symlinks to the .rs files in ui-nightly.
   • Example: tests/ui-stable/foo.rs -> ../ui-nightly/foo.rs
3. Unique Output: Each directory contains its own .stderr files.

Workflow Rules

• Adding a Test:
  1. Create the .rs file in ui-nightly.
  2. Create relative symlinks in ui-stable and ui-msrv pointing to the new file in ui-nightly.
  3. Run ./tools/update-expected-test-output.sh to generate the .stderr files.
• Modifying a Test:
  1. Edit the .rs file in ui-nightly.
  2. Run ./tools/update-expected-test-output.sh to update the .stderr files.
• Removing a Test:
  1. Delete the .rs file from ui-nightly.
  2. Delete the symlinks from ui-stable and ui-msrv.
  3. Delete the corresponding .stderr files from all three directories.

NEVER edit .stderr files directly. Only update them via the script or the commands it runs. If a .stderr file is causing a test failure and updating it via tooling does not fix the failure, that indicates a bug.