Result: done
Files: crates/nikaia/src/parser/mod.rs crates/nikaia-std/src/tools/ast.nika crates/nikaia-std/src/tools/check_arguments.nika crates/nikaia-std/src/tools/check_core_args.nika crates/nikaia-std/src/tools/check_core_call.nika crates/nikaia-std/src/tools/check_core_leaves.nika crates/nikaia-std/src/tools/check_decls.nika crates/nikaia-std/src/tools/check_notes.nika crates/nikaia-std/src/tools/check_references.nika crates/nikaia-std/src/tools/declared.nika crates/nikaia-std/src/tools/emit_core_calls.nika crates/nikaia-std/src/tools/emit_core_types.nika crates/nikaia-std/src/tools/ty.nika crates/nikaia-std/src/tools/types.nika crates/nikaia-std/src/tools/views.nika crates/nikaia-std/src/tools/lowered.rs crates/nikaia-std/src/tools/lowered/check_arguments.rs crates/nikaia-std/src/tools/lowered/check_core_args.rs crates/nikaia-std/src/tools/lowered/check_core_call.rs crates/nikaia-std/src/tools/lowered/check_core_leaves.rs crates/nikaia-std/src/tools/lowered/check_decls.rs crates/nikaia-std/src/tools/lowered/check_notes.rs crates/nikaia-std/src/tools/lowered/check_references.rs crates/nikaia-std/src/tools/lowered/declared.rs crates/nikaia-std/src/tools/lowered/emit_core_calls.rs crates/nikaia-std/src/tools/lowered/emit_core_types.rs crates/nikaia-std/src/tools/lowered/ty.rs crates/nikaia-std/src/tools/lowered/types.rs crates/nikaia-std/src/tools/lowered/views.rs tests/compiler/tests/fn_type_mut_param.nika tests/compiler/tests/fn_type_mut_param.stdout tests/compiler/tests/fn_type_mut_param_kept.nika tests/compiler/tests/fn_type_mut_param_kept.stdout tests/compiler/tests/fn_type_mut_param_refused.nika tests/compiler/tests/fn_type_mut_param_refused.stderr
Commit: fn(mut S): a function type keeps a parameter’s mut, lent at each call
Body: The parser reads mut before a parameter type of a function type (code_param, recorded as is_mut without is_view); the checker types it as a mutable pointer (Ty::Pointed { mutable }, printed back fn(mut S), read by Ty::parse), so fn(S) and fn(mut S) are different types. A named function’s mut parameter gives fn(mut S); a lambda handed to it must write mut t (NK1102 names the parameter), a mismatched named function gets a note naming the parameter. The argument at a call through code (run, kept field, kept local) is lent by the same rule as a named function’s mut parameter (lent_to_a_mut_parameter, factored out of check_references), emitted &mut; the code type lowers as impl AsyncFn(&mut S) / Kept<dyn Fn(&mut S)>, the existing shape of code types (the argument changes, not the closure’s state, so no FnMut). The brief’s expected 112 is 113 (1+10+1+100+1).
Fixes: #1134
Tests: fn_type_mut_param, fn_type_mut_param_kept, fn_type_mut_param_refused pass –both-settings and all three FAILED on the unfixed binary; it binary (parser change) 2886 passed, 1 failed: compiler_test_package_passes_at_both_settings on agent_script (settings disagree), the same on the unfixed binary, not this change; parser:: lib tests ok; cargo fmt, clippy clean; lower-std fixpoint clean
Gate: green
Deviation: lowered as impl AsyncFn(&mut S) / Kept<dyn Fn(&mut S)>, the existing code-type lowering, not the brief’s FnMut / Box<dyn FnMut>
Found: none
Needs: none
Changelog: Function types keep a parameter’s mut: fn(mut S) lends the argument as a named function’s mut parameter does (#1134).
Owner: none
Disk freed: target/nikaia-project-tests removed (under 3 GB free), now 5.9G free on /
Rs2nika: none
Attribution:
Co-Authored-By: Claude Opus 5.5 noreply@anthropic.com
Claude-Session: https://claude.ai/code/session_01GFeMqxRbtUMiGVyDMxsvEq
Pushed: local 8a671b67c03a849e468902cced6fe6be2dfb7efc
