[dextermos-dev]

Summary & Root Cause (Soundness / Row 13 BUILDABLE)

Fixes #4184.

Under GUARANTEES.md Row 13 (BUILDABLE), any program accepted by hy-check with verdict Accept must compile cleanly under standard Go's toolchain (go build).

Previously, invocations of curated strings package symbols bypassed member call arity verification, and package types (builder, reader, replacer) were accepted as function call targets, leading to downstream go build failures (cannot call non-function strings.<Type>, not enough arguments in call to strings.<Func>, too many arguments in call to strings.<Func>). Furthermore, existing PR #4185 is non-mergeable due to conflicts and omitted type rejection and contained arity discrepancies.

Technical Solution

1. Package Member Validation (buildable.rs):

   • Dispatched pkg == "strings" && self.lookup_kind(pkg).is_none() to check_strings_package_call.
   • Rejects non-callable package types (builder, reader, replacer) fail-closed with HYB-E1002.
   • Enforces exact call arity aligned with standard Go 1.26.9 specification:
     • 1 argument: clone, fields, title, to_lower, to_title, to_upper, trim_space, new_reader.
     • 2 arguments: compare, contains, contains_any, contains_func, contains_rune, count, cut, cut_prefix, cut_suffix, equal_fold, fields_func, has_prefix, has_suffix, index, index_any, index_byte, index_func, index_rune, join, last_index, last_index_any, last_index_byte, last_index_func, map, repeat, split, split_after, to_lower_special, to_title_special, to_upper_special, to_valid_utf8, trim, trim_func, trim_left, trim_left_func, trim_prefix, trim_right, trim_right_func, trim_suffix.
     • 3 arguments: split_n, split_after_n, replace_all.
     • 4 arguments: replace.

2. Complete Unit Test Coverage (tests/strings_call_buildable_soundness.rs):

   • 5 test functions covering all reject paths (types, arity mismatches across unary, binary, ternary, and 4-argument functions) and verifying clean acceptance with 0 diagnostics on valid function calls and symbol references.
   • Clean pass: 5 passed / 0 failed in 0.01s.

3. Tree Integrity:

   • Clean tree directly rebased on Session 171 upstream main (56539008), zero example degradation, zero merge conflicts (Mergeable: True).

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Settlement Wallet

Settlement Wallet: 0x8366bCe3a2D379De7656D7A67015789FaF999f20