Assert projection call bases are evaluated once

[aaronvg]

Summary

• make the nested projection assignment regression track calls to Store.require()
• assert the assignment still mutates the expected nested field
• assert the projection base is evaluated exactly once

Why

This is a test-only follow-up to the unresolved review on #4140. The original regression used a pure require() method, so it could not detect duplicate evaluation of the projection base.

Impact

No production behavior changes. The strengthened regression now guards both correct nested assignment and exactly-once evaluation.

Validation

• cargo nextest run -p bex_vm --test projection_dest_calls method_call_result_can_be_the_base_of_nested_field_assignment
• cargo nextest run -p bex_vm --test projection_dest_calls
• cargo fmt --all --check
• git diff --check

---

Note

Low Risk
Only updates an integration test; no compiler, MIR, or runtime behavior changes.

Overview
Test-only change to method_call_result_can_be_the_base_of_nested_field_assignment in projection_dest_calls.rs.

The nested assignment store.require().info.title = "triage" still must mutate the right field; the test now also proves the projection base is evaluated exactly once. Store gains a calls counter incremented inside require(), and main asserts store.calls == 1 in addition to the title check. A pure require() that only returned self.record could pass even if MIR evaluated the call twice.

^{Reviewed by Cursor Bugbot for commit 7f02714. Bugbot is set up for automated code reviews on this repo. Configure here.}

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Review details

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: f9416893-4fe9-473f-9e74-09cac6485235

📥 Commits

Reviewing files that changed from the base of the PR and between 65ebcc0 and 7f02714.

📒 Files selected for processing (1)

• baml_language/crates/bex_vm/tests/projection_dest_calls.rs

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/upstream-projection-once-regression

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[github-actions]

Binary size checks passed

✅ 7 passed

	Artifact	Platform	File	Gzip	Gated on	Baseline	Delta	Status
✅	baml-cli	Linux	🔒 25.6 MB	10.9 MB	file	25.3 MB	+353.7 KB (+1.4%)	OK
✅	packed-program	Linux	🔒 17.2 MB	7.1 MB	file	17.0 MB	+164.3 KB (+1.0%)	OK
✅	baml-cli	macOS	🔒 19.9 MB	9.5 MB	file	19.6 MB	+281.3 KB (+1.4%)	OK
✅	packed-program	macOS	🔒 13.4 MB	6.2 MB	file	13.2 MB	+198.4 KB (+1.5%)	OK
✅	baml-cli	Windows	🔒 21.4 MB	9.7 MB	file	21.1 MB	+303.6 KB (+1.4%)	OK
✅	packed-program	Windows	🔒 14.3 MB	6.3 MB	file	14.2 MB	+159.7 KB (+1.1%)	OK
✅	bridge_wasm	WASM	16.2 MB	🔒 4.4 MB	gzip	4.4 MB	+13.0 KB (+0.3%)	OK

🔒 = the size this artifact is GATED on (ceiling + delta). Binaries gate on file size (installed binary); WASM gates on gzip (download size). The other size is shown for information only.

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Generated by cargo size-gate · workflow run