| name | stage2-olean-test |
| description | Diagnose a spurious stage1 test failure caused by olean-persisted compiler changes. Use when a stage1 test fails unexpectedly and the change adds or modifies an environment extension or other information persisted into .olean files. |
| allowed-tools | Bash, Read |
Stage2 Is Required for Changes to Olean-Persisted Compiler Information
When a change alters information that is persisted into .olean files (e.g. a new or changed
environment extension that the compiler reads back), a stage1 test run can fail spuriously: stage1's
src/ (including Init) is compiled by the stage0 compiler, which lacks the change, so the
stage1 lean binary imports oleans that predate the change. In that situation the relevant tests
must be run against stage2 instead, where the new compiler compiles everything consistently.
So: on a test failure, if the change depends on changed olean information, test stage2 instead.
Procedure
Building stage2 is expensive, so confirm with the user before switching to a stage2 build.
For the actual build/test commands (make stage2, clean-stdlib, per-module Lake builds, and
running tests against stage2), use the stage2-build skill.
