fix: array params no longer get auto-const per ADR-006

[jlaustill]

Summary

Fixes #986: Array parameters were incorrectly getting const applied when passed to C APIs expecting mutable pointers.

Problem:

• ADR-006 specifies all params are pass-by-reference as mutable
• Scalar params correctly transpiled as mutable pointers (uint8_t*)
• Array params incorrectly got const when not directly modified in the function body
• This broke C API compatibility:

void handle(u8[8] data) {
  global.process_data(data);  // C API expects mutable uint8_t*
}

Generated: void handle(const uint8_t data[8]) - compile error
Expected: void handle(uint8_t data[8]) - correct

Fix:
Arrays now never get auto-const. Only explicit const from source code (const u8[8] data) adds the qualifier.

Changes

• ParameterInputAdapter: Set isAutoConst=false for all array params
• Transpiler: Remove arrays from auto-const logic in header generation
• Add unit test for new array auto-const behavior
• Add regression test in bugs/issue-986-const-array-param/
• Update affected test snapshots (arrays that were read-only now don't have const)

Test plan

• New regression test compiles and executes successfully
• All 952 integration tests pass
• All 5579 unit tests pass
• Build passes with no type errors

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[jlaustill]

Review Summary

PR: #987 — fix: array params no longer get auto-const per ADR-006
Reviewed by: Claude (automated review)

Overview

Clean, well-scoped bug fix that correctly removes auto-const inference from array parameters. The change aligns with ADR-006's principle that all params are pass-by-reference and mutable. The fix addresses both code paths (CodeGenerator via ParameterInputAdapter and header generation via Transpiler.convertToHeaderSymbols), preventing const from being applied to array params that are only read — which broke compatibility with C APIs expecting mutable pointers.

Findings

Severity	Count
Critical	0
Important	1
Moderate	0
Nit	0

Key Issues

1. [important] The tests/const-params/auto-const-pointer.expected.h file was NOT updated in this PR, but it contains arrayReadOnly(const uint8_t arr[4]) which should now be arrayReadOnly(uint8_t arr[4]) per the behavioral change. See inline comment.

What Looks Good

• Both code paths fixed: The ParameterInputAdapter._buildArrayInputFromAST() and Transpiler.convertToHeaderSymbols() changes together eliminate all paths where arrays could get auto-const. The cross-reference agent confirmed no other paths exist.
• Excellent regression test: The fake_lib.c/.h approach directly exercises the real-world scenario (passing an array to a C API that mutates it), with execution validation via return codes.
• Minimal, focused change: The actual logic changes are ~6 lines across 2 files, with the rest being consistent snapshot updates. No scope creep.
• Good comment hygiene: Updated the auto-const-pointer.test.cnx comments to explain the new behavior, and the ParameterSignatureBuilder.test.ts comments clarify why existing builder tests still pass.

---

🤖 Automated review by Claude Code

[jlaustill]

[important] design: The .expected.c and .expected.cpp snapshots were correctly updated here to remove const from arrayReadOnly, but the corresponding auto-const-pointer.expected.h file was not updated in this PR.

On main, that file still contains:

uint8_t arrayReadOnly(const uint8_t arr[4]);

Since Transpiler.convertToHeaderSymbols() no longer sets isAutoConst: true for array params, the generated header should now be:

uint8_t arrayReadOnly(uint8_t arr[4]);

This is the only .expected.h file in the repo affected (I checked all others — none have const on array params in header prototypes). If the test framework compares .expected.h files, this would cause a test failure. If it doesn't, the file is still stale and misleading.

Fix: Update tests/const-params/auto-const-pointer.expected.h line 21:

Suggested change

	// (arrays are mutable by default; use explicit const if needed)
	uint8_t arrayReadOnly(uint8_t arr[4]);