Type checker: wire up @expect directive suppression for type/dnu warnings

[jamesc]

Summary

• Wire up @expect dnu and @expect type suppression in the type checker so @expect directives properly suppress type-checker diagnostics
• Tag 5 previously-uncategorised type checker diagnostics with DiagnosticCategory::Type so @expect type can match them
• Add infer_stmts helper that skips ExpectDirective AST nodes during body iteration (prevents them from clobbering return-type inference)
• Add @expect dnu annotations to Collection.bt collect: and select: methods to suppress false "Object does not understand 'withAll:'" warnings from the species pattern

Context

self species withAll: result returns the receiver's metaclass at runtime — inherently dynamic, cannot be type-checked statically. The species method returns -> Object, but the actual class at runtime will understand withAll:. The @expect dnu directive suppresses this known-safe warning.

Test plan

• just test — all Rust tests pass (including 3 new @expect integration tests)
• just build — stdlib builds cleanly, no more withAll: warnings
• just test-stdlib — all tests pass
• just clippy — clean

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • More consistent and accurate type-checking diagnostics and severity for parameter/return/field warnings.
  • @expect suppression correctly applies only to the immediate following expression.

• Refactor

  • Centralized statement inference to simplify and standardize body and block type-checking.

• Documentation

  • Clarifying annotations added to collection operations about species/return-type behavior (no runtime changes).

• Tests

  • Added tests covering @expect behavior, type warnings, and selector compatibility.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between e54fc44 and ed9a80f.

📒 Files selected for processing (1)

• stdlib/src/Collection.bt

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📝 Walkthrough

Walkthrough

Centralizes statement-sequence type inference into a new infer_stmts helper that skips @expect directives and returns the last expression type (or Dynamic for empty lists); replaces per-body loops with calls to this helper, standardizes several type diagnostics to DiagnosticCategory::Type, and adds tests/helpers for @expect behavior.

Changes

Cohort / File(s)	Summary
Type checker core crates/beamtalk-core/src/semantic_analysis/type_checker.rs	Add infer_stmts to infer types for sequences of ExpressionStatement, skip @expect directives, and use its return value for body/return-type checks; replace multiple inline loops (module top-level, method bodies, blocks) with calls to the helper; adjust related control flow.
Diagnostics & tests crates/beamtalk-core/src/..., crates/beamtalk-core/tests/...	Replace several warning constructions to attach DiagnosticCategory::Type; add helpers to lex/parse and run diagnostics with apply_expect_directives; add tests verifying @expect suppression semantics and scoping.
Stdlib annotations stdlib/src/Collection.bt	Add @expect dnu directives and explanatory comments to collect: and select: implementations (non-functional annotation/comment changes only).

Sequence Diagram(s)

mermaid
sequenceDiagram
participant AST as AST (statements)
participant TypeChk as TypeChecker::infer_stmts
participant Expect as ExpectDirectiveHandler
participant Diag as Diagnostics

AST->>TypeChk: provide sequence of ExpressionStatement
TypeChk->>Expect: detect & skip `@expect` directives
Note right of TypeChk: infer types for non-directive expressions
TypeChk->>Diag: emit warnings/errors with Type category
TypeChk-->>AST: return last expression type (or Dynamic)

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• Type check arguments and return types (BT-671) #657 — Refactors body-type inference and return-type determination in the same type_checker.rs.
• Implement type inference engine (BT-583) #556 — Modifies the semantic analysis inference engine and related type-checking structures; closely related to these changes.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title accurately describes the main changes: adding @expect directive suppression for type and DNU warnings in the type checker. The changes include wiring up suppression logic and extending diagnostic construction with DiagnosticCategory::Type across multiple warning types.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch worktree-chore/type-warns-in-compile

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[coderabbitai]

🧹 Nitpick comments (1)

stdlib/src/Collection.bt (1)

140-141: Consider adding a brief comment for consistency.

The @expect dnu in collect: (line 124) has an explanatory comment while this one doesn't. A one-line comment like // species withAll: — see collect: for rationale would help future readers.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@stdlib/src/Collection.bt` around lines 140 - 141, Add a one-line explanatory
comment above the "@expect dnu" in the species-withAll code path to match
collect:'s style; for example, add "// species withAll: — see collect: for
rationale" immediately before the "@expect dnu" that precedes "self species
withAll: result" so future readers know the rationale and can find the related
explanation in collect:.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@stdlib/src/Collection.bt`:
- Around line 140-141: Add a one-line explanatory comment above the "@expect
dnu" in the species-withAll code path to match collect:'s style; for example,
add "// species withAll: — see collect: for rationale" immediately before the
"@expect dnu" that precedes "self species withAll: result" so future readers
know the rationale and can find the related explanation in collect:.

---

ℹ️ Review info

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Disabled knowledge base sources:

• Linear integration is disabled

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📥 Commits

Reviewing files that changed from the base of the PR and between 8a75539 and e54fc44.

📒 Files selected for processing (2)

• crates/beamtalk-core/src/semantic_analysis/type_checker.rs
• stdlib/src/Collection.bt