Brummel
7a42989b34
Resolves Gitea #12 — the design fork from the 2026-05-20 /boss session, surfaced independently by two prior fieldtests (mut-local F3 + loop-recur `run_forever`). Mechanics, layer by layer: Parser — `crates/ailang-surface/src/parse.rs:1322-1331` drops the 4-line `expected at least one argument` guard in `parse_app_body`. Grammar comments at file top change `term+` to `term*` on both `app-term` and `tail-app-term`; doc comment on `parse_app_body` changes `1+ args` to `0+ args`. Inline comment cites #12 and notes which layers below already accept empty args. Serde — `crates/ailang-core/src/ast.rs:419-425` annotates `Term::App.args` with `#[serde(default)]`, mirroring `Term::Ctor.args`'s *actual* attrs verbatim (no `skip_serializing_if`). Write behaviour unchanged — canonical JSON still emits `"args":[]` for nullary calls; only read behaviour gains tolerance for the `args` key being absent. Verified hash-impact-free at plan time: `grep -rn '"args":\[\]' examples/*.ail.json` returns zero matches, so no existing fixture's canonical bytes shift. Doc-honesty — `design/contracts/data-model.md`: (a) the `app` jsonc shape gains an explicit "args may be empty / read-tolerant" note; (b) the existing `ctor` comment claiming "args omitted when empty" was factually false (Ctor.args has no `skip_serializing_if`; a serde probe at plan time confirmed writes always emit `"args":[]`). Rewritten to describe the actual write/read asymmetry, with a cross-reference to the new `app` note. E2E pin — `crates/ail/tests/nullary_app_e2e.rs` + `examples/nullary_app_smoke.ail`. Defines `greet : fn() -> Unit !IO` and calls it as `(app greet)`; asserts stdout `"hello\n"`. RED→GREEN pin for the parser change AND the milestone-protecting E2E for nullary call surface going forward. Fixture literal is `"hello"` (no `\n`) because `io/print_str` lowers via `puts` which appends a newline — the plan body had a `"hello\n"` literal which would have yielded `"hello\n\n"`; the implementer caught and aligned to the canonical pattern in `examples/hello.ail` while writing the fixture, fix scoped to that single file. Layers below parser untouched: typechecker's arity check at `crates/ailang-check/src/lib.rs:3300` is `args.len() != params.len()` which is `0 != 0 → false` for nullary; codegen's `args.iter().zip(sig.params.iter())` at `crates/ailang-codegen/src/lib.rs:2410` is an empty loop; LLVM `call @ail_<mod>_<name>()` with empty arglist is valid; surface printer's arg-emit loop at `crates/ailang-surface/src/print.rs:430-434` writes nothing for empty args, producing exactly `(app f)`. Verification: full workspace `cargo test --workspace --quiet` green (0 failed across all crates); drift pins `design_index_pin 5/5` + `design_schema_drift 8/8`; round-trip `2/2`; new `nullary_app_e2e 1/1`. Stats file: `bench/orchestrator-stats/2026-05-20-iter-nullary-app.1.json`. closes #12
63 lines
2.3 KiB
Rust
63 lines
2.3 KiB
Rust
//! Gitea #12 RED→GREEN pin — nullary `(app f)` surface acceptance.
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//!
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//! Pre-fix, `ail build` rejects `examples/nullary_app_smoke.ail`
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//! at parse with `parse_app_body`'s "expected at least one
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//! argument" error. Post-fix (parse guard dropped), the file
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//! builds, runs, and prints `"hello\n"` from the nullary `greet`
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//! invoked as `(app greet)`.
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//!
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//! Two independent fieldtest specs flagged the same gap:
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//! `docs/specs/2026-05-15-fieldtest-mut-local.md` F3 and
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//! `docs/specs/2026-05-18-fieldtest-loop-recur.md` spec_gap. The
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//! Form-A surface refusing nullary calls had no schema backing —
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//! `Term::App.args` is `[Term...]` (zero-or-more), so the parser
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//! guard was an unbacked rule.
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use std::path::Path;
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use std::process::Command;
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fn ail_bin() -> &'static str {
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env!("CARGO_BIN_EXE_ail")
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}
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fn build_and_run(example: &str) -> String {
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let manifest_dir = env!("CARGO_MANIFEST_DIR");
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let workspace = Path::new(manifest_dir).parent().unwrap().parent().unwrap();
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let src = workspace.join("examples").join(example);
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let tmp = std::env::temp_dir().join(format!(
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"ailang_e2e_{}_{}",
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example.replace('.', "_"),
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std::process::id()
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));
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std::fs::create_dir_all(&tmp).unwrap();
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let out = tmp.join("bin");
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let status = Command::new(ail_bin())
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.args(["build", src.to_str().unwrap(), "-o"])
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.arg(&out)
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.status()
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.expect("ail build failed to run");
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assert!(status.success(), "ail build failed for {example}");
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let output = Command::new(&out).output().expect("execute binary");
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assert!(
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output.status.success(),
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"binary {} exited non-zero",
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out.display()
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);
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String::from_utf8(output.stdout).expect("stdout utf8")
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}
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/// A nullary user fn called as `(app greet)` builds and runs; the
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/// nullary application surface form is the canonical zero-arg
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/// shape under the resolution of Gitea #12.
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#[test]
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fn nullary_app_builds_and_runs() {
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let out = build_and_run("nullary_app_smoke.ail");
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assert_eq!(
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out, "hello\n",
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"nullary `(app greet)` must build, run, and emit `hello\\n`; \
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got `{out}` — pre-fix surface parser rejects empty-args at \
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`parse_app_body` with `expected at least one argument` (see \
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Gitea #12).",
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);
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}
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