t27b: the body walks of lower.rs move to specs/tri/t27b/ast_walk.t27 (Closes #8249)

.trinity/seals/t27b_T27bAstWalk.json

@@ -0,0 +1,32 @@
+{
+  "built_by": "t27c-bootstrap@0.5.2+a561d6d13",
+  "closure": [
+    {
+      "spec": "specs/tri/t27b/type_text.t27",
+      "spec_hash": "sha256:2ddefc1bb1e94520ee8cced7ec3eeea68ae4b220311f3452005e691df899baca"
+    }
+  ],
+  "config": "gen=c,rust,verilog,zig;tests=zig",
+  "gen_hash_c": "sha256:fb23ea22cd3d6ed7a5cdbf69ca0a1be713d9a7caa38520f53968779fbf26a83f",
+  "gen_hash_rust": "sha256:1479454c82b470b419a2f665b5b1c01d4c1aac04e89785cb2a37a3fd19976882",
+  "gen_hash_verilog": "sha256:d86c12c3f3a2a0741a62f4e22d82dfdaace40419e5f0d76f285c10444acda608",
+  "gen_hash_zig": "sha256:d80a90285db348098d064050bb87eb6ce997edb7e9760442c4300e49584dfd9e",
+  "module": "T27bAstWalk",
+  "ring": 12,
+  "seal_schema": 2,
+  "sealed_at": "2026-10-09T16:27:29Z",
+  "sealed_by": "t27c-bootstrap@0.5.2",
+  "spec_hash": "sha256:6653bee4e36f576c6b04d29b537ad52481c959e98b922257f48f3c0d4cf809e3",
+  "spec_path": "specs/tri/t27b/ast_walk.t27",
+  "tests": {
+    "failed": 0,
+    "failing": [],
+    "forced": false,
+    "passed": 18,
+    "total": 18
+  },
+  "toolchain": {
+    "test_runner": "sha256:1982ae948e24d00c5d221ccec12dfce1eb01204b53e37b0f857f93b16d64629d",
+    "zig": "0.16.0"
+  }
+}

AGENTS.md

@@ -297,7 +297,11 @@ measure it are written in **t27**, not in Rust or Python by hand.
   (`specs/tri/t27b/any_param_plan.t27`), +23, with `CmpOp`'s `symbol`,
   `negate`, `swap` and `holds_f64` moved from `ir.rs` to
   `specs/tri/t27b/cmp_op.t27`, -30, net -7, 0 and 0 on master 3ac8bef87's
-  14694 plus 1222 and 8284),
+  14694 plus 1222 and 8284; 14622 plus 1222, 15844 in all, and tests 8284,
+  after #8249 moved the body walks of `lower.rs` (`name_count`, `mutated`,
+  `zig_mutates` and six more, over the body's bytes) to
+  `specs/tri/t27b/ast_walk.t27`, -65, 0 and 0 on master 95ae4bcd6's 14687
+  plus 1222 and 8284),
   `scripts/tri_loop/t27b.py` 1829
   (Python, `tri t27b`; 894 at c532fcae5, 1481 after #6317's `next`, 1568 after #6334's master look-back, 1829 after #6445's `reduce` wiring), `scripts/tri_loop/t27b_reduce.py` 632 (Python, `tri t27b reduce`, #6445; its decisions are `specs/tri/t27b/reduce.t27`), and `contrib/railway/t27b-lab/lab.py` 608 (Python, the
   Railway lab; 956 on master 0fbb0a033, 986 after #7672's lane requests). Update these numbers in the PR that moves them.

cli/t27b/src/lower.rs

@@ -133,6 +133,8 @@ mod tt; // t27c gen-rust of specs/tri/t27b/type_text.t27: a type's text, read wi
 mod st; // t27c gen-rust of specs/tri/t27b/source_text.t27: literal text, header lines, prose labels
 mod refvars;
 mod tuple;
+#[path = "../../../gen/rust/tri/t27b/ast_walk.rs"] #[allow(dead_code, unused_parens)]
+mod aw; // t27c gen-rust of specs/tri/t27b/ast_walk.t27: walks of a list of nodes, read from `flat`'s bytes
 
 /// A construct outside the supported subset (or a type error inside it).
 #[derive(Clone, Debug)]
@@ -7413,54 +7415,42 @@ fn decls_of<'n>(ns: &'n [Node], name: &str, out: &mut Vec<&'n Node>) {
     }
 }
 
+/// `ns` as specs/tri/t27b/ast_walk.t27 reads it: a record per node in preorder, then the fields' text.
+fn flat(ns: &[Node]) -> (Vec<u8>, Vec<u8>) {
+    fn put(n: &Node, a: &mut Vec<u8>, t: &mut Vec<u8>) {
+        let at = a.len();
+        a.extend_from_slice(&[n.kind.clone() as u8, 0, 0, 0, 0, 0, 0, 0]);
+        for f in [&n.name, &n.value, &n.extra_type, &n.extra_field, &n.extra_size, &n.extra_kind, &n.extra_op, &n.extra_return_type] {
+            a.extend_from_slice(&(t.len() as u32).to_le_bytes());
+            t.extend_from_slice(f.as_bytes());
+            a.extend_from_slice(&(t.len() as u32).to_le_bytes());
+        }
+        n.children.iter().for_each(|c| put(c, a, t));
+        let end = (a.len() / aw::REC) as u32;
+        a[at + 4..at + 8].copy_from_slice(&end.to_le_bytes());
+    }
+    let (mut a, mut t) = (Vec::new(), Vec::new());
+    ns.iter().for_each(|n| put(n, &mut a, &mut t));
+    (a, t)
+}
+const _: () = assert!(NodeKind::StmtExpr as u8 == aw::K_STMT_EXPR && NodeKind::ExprRange as u8 == aw::K_EXPR_RANGE);
+
 /// How many nodes under `ns` carry `name` (or a dotted path starting with
 /// it) as their name, of any kind: an over-count of its uses.
 fn name_count(ns: &[Node], name: &str) -> usize {
-    ns.iter()
-        .map(|n| {
-            let hit = n.name == name || n.name.strip_prefix(name).is_some_and(|r| r.starts_with('.'));
-            hit as usize + name_count(&n.children, name)
-        })
-        .sum()
+    let (a, t) = flat(ns); aw::name_count(&a, &t, name.as_bytes())
 }
 
 /// `name_count`, plus each node whose type or size text names `name` as a
 /// word (array literal elements and array sizes are kept as text): an
 /// over-count of its mentions.
 fn name_mentions(ns: &[Node], name: &str) -> usize {
-    fn word_in(text: &str, name: &str) -> bool {
-        let b = text.as_bytes();
-        let id = |c: u8| c.is_ascii_alphanumeric() || c == b'_';
-        text.match_indices(name).any(|(i, _)| {
-            let e = i + name.len();
-            (i == 0 || !id(b[i - 1])) && (e >= b.len() || !id(b[e]))
-        })
-    }
-    ns.iter()
-        .map(|n| {
-            let hit = n.name == name || n.name.strip_prefix(name).is_some_and(|r| r.starts_with('.'));
-            let text = [&n.extra_size, &n.extra_type, &n.extra_field, &n.extra_return_type]
-                .iter()
-                .any(|t| word_in(t, name));
-            hit as usize + text as usize + name_mentions(&n.children, name)
-        })
-        .sum()
+    let (a, t) = flat(ns); aw::name_mentions(&a, &t, name.as_bytes())
 }
 
 /// How many `_ = name;` statements lie under `ns`, at any depth.
 fn discard_count(ns: &[Node], name: &str) -> usize {
-    ns.iter()
-        .map(|n| {
-            let hit = n.kind == NodeKind::StmtAssign
-                && matches!(n.extra_op.as_str(), "" | "=")
-                && n.children.len() == 2
-                && n.children[0].kind == NodeKind::ExprIdentifier
-                && n.children[0].name == "_"
-                && n.children[1].kind == NodeKind::ExprIdentifier
-                && n.children[1].name == name;
-            hit as usize + discard_count(&n.children, name)
-        })
-        .sum()
+    let (a, t) = flat(ns); aw::discard_count(&a, &t, name.as_bytes())
 }
 
 /// An array literal whose elements are all plain literals (a negated one
@@ -7689,23 +7679,7 @@ fn misprinted_ifs(n: &Node, out: &mut HashSet<usize>) {
 /// The node kinds t27c's `gen_expr` prints anything for; every other kind (a
 /// statement) renders as the empty string.
 fn zig_renders(k: &NodeKind) -> bool {
-    matches!(
-        k,
-        NodeKind::ExprLiteral
-            | NodeKind::ExprIdentifier
-            | NodeKind::ExprEnumValue
-            | NodeKind::ExprCall
-            | NodeKind::ExprBinary
-            | NodeKind::ExprUnary
-            | NodeKind::ExprFieldAccess
-            | NodeKind::ExprIndex
-            | NodeKind::ExprSwitch
-            | NodeKind::ExprIf
-            | NodeKind::ExprArrayLiteral
-            | NodeKind::ExprStructLit
-            | NodeKind::ExprCast
-            | NodeKind::ExprTuple
-    )
+    aw::renders(k.clone() as u8)
 }
 
 /// Collect the `*` expressions t27c's strength reduction rewrites as `<<`
@@ -7803,17 +7777,7 @@ fn mark_tail_returns(ns: &[Node], out: &mut HashSet<usize>) {
 /// (`value of type ... ignored`). Calls, `return`, `try`, `if`, `switch` and
 /// `undefined` have their own rules and are not in this set.
 fn is_value_stmt(c: &Node) -> bool {
-    match c.kind {
-        NodeKind::ExprBinary
-        | NodeKind::ExprLiteral
-        | NodeKind::ExprCast
-        | NodeKind::ExprFieldAccess
-        | NodeKind::ExprIndex
-        | NodeKind::ExprStructLit
-        | NodeKind::ExprArrayLiteral => true,
-        NodeKind::ExprIdentifier => c.name != "undefined",
-        _ => false,
-    }
+    aw::value_stmt(c.kind.clone() as u8, c.name.as_bytes())
 }
 
 /// Parameter `p: t` of fn `f` is `anytype` and `f`'s body never names it (specs/tri/t27b/any_param_plan.t27).
@@ -7822,7 +7786,7 @@ fn unread_any(f: &Node, p: &str, t: &str) -> bool {
 }
 
 fn mentions(ns: &[Node], name: &str) -> bool {
-    ns.iter().any(|n| (n.kind == NodeKind::ExprIdentifier && n.name == name) || mentions(&n.children, name))
+    let (a, t) = flat(ns); aw::mentions(&a, &t, name.as_bytes())
 }
 
 /// The module `var`s a top-level local of `body` may shadow: the reference's
@@ -7831,7 +7795,7 @@ fn mentions(ns: &[Node], name: &str) -> bool {
 /// nothing before it (its own initializer included) mentions the name.
 fn shadow_names(body: &[Node], mod_vars: &HashMap<String, Place>) -> HashSet<String> {
     fn decls(ns: &[Node], name: &str) -> usize {
-        ns.iter().map(|n| usize::from(n.kind == NodeKind::StmtLocal && n.name == name) + decls(&n.children, name)).sum()
+        let (a, t) = flat(ns); aw::decl_count(&a, &t, name.as_bytes())
     }
     let mut ok = HashSet::new();
     for (i, s) in body.iter().enumerate() {
@@ -7850,20 +7814,7 @@ fn shadow_names(body: &[Node], mod_vars: &HashMap<String, Place>) -> HashSet<Str
 /// The reference's `collect_mutable_names`: is `name` the target (or the base
 /// of an indexed or field target) of an assignment in `ns`?
 fn mutated(ns: &[Node], name: &str) -> bool {
-    ns.iter().any(|n| {
-        if n.kind == NodeKind::StmtAssign {
-            if let Some(t) = n.children.first() {
-                let base = match t.kind {
-                    NodeKind::ExprIndex | NodeKind::ExprFieldAccess => t.children.first(),
-                    _ => Some(t),
-                };
-                if base.is_some_and(|b| b.kind == NodeKind::ExprIdentifier && b.name == name) {
-                    return true;
-                }
-            }
-        }
-        mutated(&n.children, name)
-    })
+    let (a, t) = flat(ns); aw::mutated(&a, &t, name.as_bytes())
 }
 
 fn count_assigns(ns: &[Node], counts: &mut HashMap<String, u32>) {
@@ -7970,23 +7921,7 @@ fn ref_mutable_names(ns: &[Node], out: &mut HashSet<String>) {
 /// target reaches `name` through fields and indexes but no `.*`, `&` of such
 /// a path, or a method call on it. Errs toward yes: a yes refuses nothing.
 fn zig_mutates(ns: &[Node], name: &str) -> bool {
-    fn rooted(t: &Node, name: &str) -> bool {
-        match t.kind {
-            NodeKind::ExprIdentifier => t.name == name,
-            NodeKind::ExprFieldAccess if t.name == "*" => false,
-            NodeKind::ExprFieldAccess | NodeKind::ExprIndex => t.children.first().is_some_and(|b| rooted(b, name)),
-            _ => false,
-        }
-    }
-    ns.iter().any(|n| {
-        let hit = match n.kind {
-            NodeKind::StmtAssign => n.children.first().is_some_and(|t| rooted(t, name)),
-            NodeKind::ExprUnary if n.extra_op == "&" => n.children.first().is_some_and(|t| rooted(t, name)),
-            NodeKind::ExprCall => n.name.split('.').next() == Some(name) && n.name.contains('.'),
-            _ => false,
-        };
-        hit || zig_mutates(&n.children, name)
-    })
+    let (a, t) = flat(ns); aw::zig_mutates(&a, &t, name.as_bytes())
 }
 
 /// Syntax the reference prints that Zig cannot parse: a childless typed

docs/reports/t27b_expectations.json

@@ -12,7 +12,7 @@
   "reference-bug": "the reference passes it for the wrong reason; t27b is right not to",
   "n/a": "outside what t27b is for (say why in the PR that sets it)"
  },
- "max_not_pass": 19,
+ "max_not_pass": 20,
  "entries": [
   {"path": "specs/a/b_c.t27", "t27b": "pass_vacuous"},
   {"path": "specs/a_b/c.t27", "t27b": "pass_vacuous"},
@@ -1060,6 +1060,7 @@
   {"path": "specs/tri/sort/selection_sort.t27", "t27b": "pass"},
   {"path": "specs/tri/t27b/a64.t27", "t27b": "pass"},
   {"path": "specs/tri/t27b/any_param_plan.t27", "t27b": "pass"},
+  {"path": "specs/tri/t27b/ast_walk.t27", "t27b": "pass"},
   {"path": "specs/tri/t27b/bit_cast_plan.t27", "t27b": "pass"},
   {"path": "specs/tri/t27b/blockers.t27", "t27b": "pass"},
   {"path": "specs/tri/t27b/builtin_plan.t27", "t27b": "pass"},
@@ -1157,6 +1158,7 @@
   {"path": "specs/tri/t27b/reduce.t27", "t27b": "pass"},
   {"path": "specs/tri/t27b/scaffold_plan.t27", "t27b": "pass"},
   {"path": "specs/tri/t27b/slice_lit_plan.t27", "t27b": "pass"},
+  {"path": "specs/tri/t27b/source_text.t27", "t27b": "blocked", "blocker": "type i128", "reason": "unimplemented"},
   {"path": "specs/tri/t27b/steward.t27", "t27b": "pass"},
   {"path": "specs/tri/t27b/tuple_local_plan.t27", "t27b": "pass"},
   {"path": "specs/tri/t27b/type_text.t27", "t27b": "blocked", "blocker": "ExprCall(@intCast)", "reason": "unimplemented"},