language/runtime: enforce strict-mode unresolvable assignment and lexical declaration errors #3571

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1. andrewtdiz commented on Jun 3, 2026

   

   andrewtdiz

   on Jun 3, 2026

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   I am taking a focused strict-mode runtime error slice here.

   Planned scope:

   • propagate real strict directive state into function/global execution paths that currently miss strict-only runtime errors;
   • make strict unresolvable assignments throw Node/Test262-shaped errors instead of creating globals or silently succeeding;
   • cover lexical/global declaration error cases local to the same strict-mode environment path if they are reachable without broad parser changes;
   • add focused parity/regression coverage for strict vs non-prologue directive placement.

   Non-goals for this cut: raw directive escape classification already covered by the separate strict-directive PR, reserved/contextual-word parsing, and broad Test262 harness import work.
2. andrewtdiz commented on Jun 3, 2026

   

   andrewtdiz

   on Jun 3, 2026

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   Opened draft PR #4266 for the strict switch lexical-scope slice: #4266

   Scope covered:

   • adds one shared HIR block scope around lowered switch case blocks in both module and function-body lowering paths
   • prevents strict let and function declarations inside switch cases from leaking after the switch
   • preserves var function-scoping through the existing block-scope pop/hoist behavior
   • adds focused Node parity coverage for strict unresolvable assignment, strict block declarations, strict switch declarations, and switch var hoisting

   Validation:

   • npm exec --yes --package=node@26 -- node --experimental-strip-types test-parity/node-suite/globals/strict-runtime-errors.ts
   • CARGO_TARGET_DIR=/tmp/perry-strict-runtime-errors cargo check -p perry-hir
   • PERRY_NO_AUTO_OPTIMIZE=1 CARGO_TARGET_DIR=/tmp/perry-strict-runtime-errors npm exec --yes --package=node@26 -- ./run_parity_tests.sh --suite node-suite --module globals --filter strict-runtime-errors
     • report: /root/perry-worktrees/perry-node-strict-runtime-errors/test-parity/reports/parity_report_20260603_152435.json
   • existing test-files/test_issue_3585_bindings.ts regression recompiled and passed
   • cargo fmt --all -- --check
   • git diff --check
   • ./scripts/check_file_size.sh
3. andrewtdiz commented on Jun 4, 2026

   

   andrewtdiz

   on Jun 4, 2026

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   Current-main validation update: the checked-in strict runtime fixture is green on 2e0551cb9 (2026-06-04) with Node 26.

   Command:

   CARGO_TARGET_DIR=/root/perry-worktrees/perry-node-probe-20260604/target PERRY_NO_AUTO_OPTIMIZE=1 npm exec --yes --package=node@26 -- bash -lc './run_parity_tests.sh --suite node-suite --module globals --filter strict'\n```\n\nResult: 3 parity pass / 0 parity fail / 0 compile fail / 0 skipped, including `globals/strict-runtime-errors`.\nReport: `test-parity/reports/parity_report_20260604_232300.json`.\n\nThe strict runtime/switch-scope slice is merged, and I do not see a remaining checked-in strict-mode runtime failure on current main, so this looks stale-open unless a new reproduction appears.
4. proggeramlug commented on Jun 13, 2026

   

   proggeramlug

   on Jun 13, 2026

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   Partial progress update via the TC39 test262 differential (corpus @ pinned 4249661388):

   language/directive-prologue  pass=56  diff=0  (none of this issue's func-decl-*/func-expr-*/get-accsr-*/set-accsr-* rows fail)
   language/global-code         pass=27  diff=0  rt-fail=1 (decl-lex.js)
   

   Resolved (no longer in the failure set): all the directive-prologue/func-decl-*-runtime, func-expr-*-runtime, get-accsr-*-runtime, set-accsr-* rows, plus global-code/block-decl-strict, switch-case-decl-strict, and switch-dflt-decl-strict. Direct strict-mode const reassignment also throws correctly (TypeError: Assignment to constant variable).

   Still failing — 1 row: global-code/decl-lex.js. The remaining assertion is top-level lexical-binding semantics at global scope (a top-level class X {} binding's reassignment doesn't take effect — class binding is mutable: Expected SameValue(1, 5)), i.e. a codegen issue in how top-level let/const/class names are bound at module scope, not the unresolvable-assignment path this issue opened on.
5. TheHypnoo

   added

   bugConfirmed defect or regressionConfirmed defect or regression

   parityCompatibility gap with Node.js, ECMAScript, or the supported ecosystemCompatibility gap with Node.js, ECMAScript, or the supported ecosystem

   triagedMaintainer reviewed; type, scope, and next step are clearMaintainer reviewed; type, scope, and next step are clear

   on Jul 26, 2026
6. proggeramlug commented on Jul 30, 2026

   

   proggeramlug

   on Jul 30, 2026

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   This is now fully covered by the merged strict-runtime/switch work and #5853. The last recorded failure, test262 language/global-code/decl-lex.js, is explicitly fixed by the mutable top-level class-binding path in b830bfb, with the restricted-global declaration cases covered in the same regression suite. I reran cargo test -p perry-hir --test issue_5833_global_code_cluster on current main: 6 passed, 0 failed. Closing as fixed.
7. proggeramlug

   closed this as completedon Jul 30, 2026