parser: reattach trailing .N to multi-token call results#572
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The greedy call-args loop in parse_call_or_atom and the nested-call expansion in parse_call_arg stopped at the leading `.` because Dot doesn't start an operand. The trailing `.N` was left dangling for the infix parser to choke on (ILO-P001 'expected declaration, got `.`'). Route every Call return site through parse_field_chain so the postfix chain reattaches to the call result the same way it does for (expr).N and xs.N. This means `spl "a.b" "." .0` and `num spl "1.2.3" ".".1` now parse without parens, matching the bare-ident and parenthesised shapes.
Pins the new shape across every public engine (VM and Cranelift JIT when the feature is on): - top-level multi-token call with trailing .N (glued and spaced) - nested call inside outer arity-1 caller (the originating repro) - safe .?N shorthand on the call result - arity-known call (`at xs 0 .1`) inside list-element context - equivalence with the parenthesised workaround - existing bare-ident and paren shapes unchanged examples/call-result-dot-index.ilo demonstrates the canonical shape with -- run / -- out assertions so the examples_engines harness picks it up as a regression test too. Notes the bare-ident-last-arg caveat inline so agents reading the example don't get surprised when `at rows i .1` glues .1 to i instead of the call result.
SPEC.md records section and ai.txt RECORDS section both now describe the new multi-token-call shape alongside the existing parenthesised and bare-ident shapes, with the bare-ident-last-arg caveat called out so agents know when to fall back to parens or bind-first.
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CI checks failing are pre-existing on origin/main at my base commit (
I verified my parser change doesn't introduce the panic — Recommend either rebasing once the upstream fix lands, or merging as-is given the failures are unrelated. Happy to defer either way. |
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Summary
Pending P2 #12.
num spl "1.2.3" ".".1and the spaced variantspl "a.b.c" "." .0both failed ILO-P001 because the greedy call-args loop stopped at the leading.and the trailing.Nwas left dangling for the infix parser to choke on. Workaround wasnum (spl "1.2.3" ".").1. After this PR the parens become optional - the trailing.Nreattaches to the call result the same way it does for(expr).Nandxs.N.Manifesto framing: 2-3 tokens saved per call-result pick-off, and the surface becomes consistent across the three head shapes (bare ident / parens / multi-token call). Agents stop hitting the "wrap the inner call" trap.
Repro before/after
Before:
After:
What's in the diff
Expr::Callreturn site inparse_call_or_atomandparse_call_argthroughparse_field_chain. Touches the 5 sites that build a call out of greedy args (name!/name!!form, zero-arg paren-call, no-whitespace-call arity-capped list element, variadic-fmt expansion, nested arity-known call, top-level greedy call).tests/regression_call_result_dot_index.rspins the new shape on VM + Cranelift JIT, plusexamples/call-result-dot-index.iloso theexamples_enginesharness exercises it too. Both the glued (.".1) and spaced (. .1) forms are covered, along with safe.?Nand equivalence with the paren workaround. Existing bare-ident and paren shapes pinned unchanged..Nglues to the variable, not the call) so agents know when to fall back to(at rows i).1or bind-first.Test plan
cargo test --release --features cranelift --test regression_call_result_dot_index— 8 tests pass across VM + JITexamples_enginesruns the newcall-result-dot-index.iloacross all enginescargo test --release --features cranelift— only pre-existing flakes (spec_reserved_short_names_match_builtin_registryfor upstreamb64/hexdoc drift,zgunzip.iloexample missing builtin on this branch base,wr_csv_field_with_newline_is_quotedflake from shared/tmppaths) — none touched by this changecargo clippy --release --features cranelift -- -D warningscleancargo fmtcleanFollow-ups
at rows i .1glues.1toiinstead of theatresult) is documented but not fixed - lifting it requires a wider lookahead inparse_atom's Ident branch and would risk regressingxs.Nshapes. Filed as a smaller follow-up if it shows up in persona reports.