fix(rust): a field that names its own struct needs a Box (+3)

.trinity/seals/TriKdTree.json

@@ -1,6 +1,6 @@
 {
   "gen_hash_c": "sha256:7658bd16d1d66d14de50176a27cc78f130863a13853fedc2dacc839a2fe4a68f",
-  "gen_hash_rust": "sha256:ec452f608b4f52459b4c87a32fcc38622f3b833ff8f0591af58949c5a8530bb9",
+  "gen_hash_rust": "sha256:5109675652b7451a917c1f6f145b99bef55491f2ac4bbc4d9025d55ca37c5fc6",
   "gen_hash_verilog": "sha256:c1f0afec0673c3db6f521e9b37b4add257f355a964bb55b153707616595c93e3",
   "gen_hash_zig": "sha256:369f3d5632ef02f40c2edea5a3ab0670cce287040188cf7d66ae11fed6ed3dda",
   "module": "TriKdTree",

.trinity/seals/TriLinkedList.json

@@ -1,6 +1,6 @@
 {
   "gen_hash_c": "sha256:24973c2e300a0a88db9ca2039d8bfb7ed18cc408ccf22acbcc435ac2e473f365",
-  "gen_hash_rust": "sha256:a84e33b1e860fca96f97c3c133c599840bc2ec83bd918a53baf33724cdda2262",
+  "gen_hash_rust": "sha256:428047f5cf573a30fb54b11ae32987750b200b9ba01ad7dec87c8a911c03b45f",
   "gen_hash_verilog": "sha256:6c52068e721a7503b2bd566c20bf4435c36545b991f689fb4b5e38227b42f7e7",
   "gen_hash_zig": "sha256:32622c710581aca2415f300aed3c02dad83c1c53136677df3cdcdca5f8df44d3",
   "module": "TriLinkedList",

.trinity/seals/TriOctree.json

@@ -1,6 +1,6 @@
 {
   "gen_hash_c": "sha256:0bedc286e426f126d811665fd97147dc6ebfba4f96958a522fb9d779d982cfa0",
-  "gen_hash_rust": "sha256:5884219ea586303bea5c3910b36b8377dd9ac120ec27be8e6fbb1f83fd032062",
+  "gen_hash_rust": "sha256:524d49b87aed3207a3f394fbfa97699f5b082c401686c473b1394842a456cbe3",
   "gen_hash_verilog": "sha256:bfdd79ebab78682b40028db81ce198b51da58b7c5cb959580165fc9fa01f276d",
   "gen_hash_zig": "sha256:01938d9fbbfc4d9f5e19ad941071b5a303b8c7b87e336157ce928c26c34d18eb",
   "module": "TriOctree",

.trinity/seals/TriQuadtree.json

@@ -1,6 +1,6 @@
 {
   "gen_hash_c": "sha256:3f1b5f372579e92827fa9a413eb3136abc5272daee917df4dcfd9b2fae31ae82",
-  "gen_hash_rust": "sha256:251c098726ade16a892350dc069771ef00100f35b339cdef789618a29cf81b02",
+  "gen_hash_rust": "sha256:42d4017e6b586dc73cbc6cca85351bf20f06c83500f5a5823ee4a3e5f626b9b3",
   "gen_hash_verilog": "sha256:d13d947ba9e73a5be25d64aa717c5d3f1138396f77674ffdc56a0dfef150fe77",
   "gen_hash_zig": "sha256:01514daa510c982d521d72b36552a8ef68f946957d0351799bfad2073128ea4d",
   "module": "TriQuadtree",

.trinity/seals/collections_TriLinkedList.json

@@ -1,11 +1,11 @@
 {
   "gen_hash_c": "sha256:24973c2e300a0a88db9ca2039d8bfb7ed18cc408ccf22acbcc435ac2e473f365",
-  "gen_hash_rust": "sha256:a84e33b1e860fca96f97c3c133c599840bc2ec83bd918a53baf33724cdda2262",
+  "gen_hash_rust": "sha256:428047f5cf573a30fb54b11ae32987750b200b9ba01ad7dec87c8a911c03b45f",
   "gen_hash_verilog": "sha256:6c52068e721a7503b2bd566c20bf4435c36545b991f689fb4b5e38227b42f7e7",
   "gen_hash_zig": "sha256:32622c710581aca2415f300aed3c02dad83c1c53136677df3cdcdca5f8df44d3",
   "module": "TriLinkedList",
   "ring": 12,
-  "sealed_at": "2026-09-05T01:08:39Z",
+  "sealed_at": "2026-09-06T08:02:09Z",
   "sealed_by": "t27c-bootstrap@0.2.0",
   "spec_hash": "sha256:5171edf6089a238976e6fad2ba577ed72cff191cf634ee94c28645f3551f9ffc",
   "spec_path": "specs/tri/collections/linked_list.t27"

.trinity/seals/trees_TriKdTree.json

@@ -1,11 +1,11 @@
 {
   "gen_hash_c": "sha256:7658bd16d1d66d14de50176a27cc78f130863a13853fedc2dacc839a2fe4a68f",
-  "gen_hash_rust": "sha256:ec452f608b4f52459b4c87a32fcc38622f3b833ff8f0591af58949c5a8530bb9",
+  "gen_hash_rust": "sha256:5109675652b7451a917c1f6f145b99bef55491f2ac4bbc4d9025d55ca37c5fc6",
   "gen_hash_verilog": "sha256:c1f0afec0673c3db6f521e9b37b4add257f355a964bb55b153707616595c93e3",
   "gen_hash_zig": "sha256:369f3d5632ef02f40c2edea5a3ab0670cce287040188cf7d66ae11fed6ed3dda",
   "module": "TriKdTree",
   "ring": 12,
-  "sealed_at": "2026-09-05T01:08:39Z",
+  "sealed_at": "2026-09-06T08:02:09Z",
   "sealed_by": "t27c-bootstrap@0.2.0",
   "spec_hash": "sha256:338dda6bd5fe68db61f018bc4216fd6ab671562bcfc3cf92f1692fbdc2440abd",
   "spec_path": "specs/tri/trees/kd_tree.t27"

.trinity/seals/trees_TriOctree.json

@@ -1,11 +1,11 @@
 {
   "gen_hash_c": "sha256:0bedc286e426f126d811665fd97147dc6ebfba4f96958a522fb9d779d982cfa0",
-  "gen_hash_rust": "sha256:5884219ea586303bea5c3910b36b8377dd9ac120ec27be8e6fbb1f83fd032062",
+  "gen_hash_rust": "sha256:524d49b87aed3207a3f394fbfa97699f5b082c401686c473b1394842a456cbe3",
   "gen_hash_verilog": "sha256:bfdd79ebab78682b40028db81ce198b51da58b7c5cb959580165fc9fa01f276d",
   "gen_hash_zig": "sha256:01938d9fbbfc4d9f5e19ad941071b5a303b8c7b87e336157ce928c26c34d18eb",
   "module": "TriOctree",
   "ring": 12,
-  "sealed_at": "2026-09-06T04:36:45Z",
+  "sealed_at": "2026-09-06T08:02:09Z",
   "sealed_by": "t27c-bootstrap@0.2.0",
   "spec_hash": "sha256:63216e4dbe843da95dd62bfc13b7741e6bf343e3bcf3d407e084d6be61e84dfe",
   "spec_path": "specs/tri/trees/octree.t27"

.trinity/seals/trees_TriQuadtree.json

@@ -1,11 +1,11 @@
 {
   "gen_hash_c": "sha256:3f1b5f372579e92827fa9a413eb3136abc5272daee917df4dcfd9b2fae31ae82",
-  "gen_hash_rust": "sha256:251c098726ade16a892350dc069771ef00100f35b339cdef789618a29cf81b02",
+  "gen_hash_rust": "sha256:42d4017e6b586dc73cbc6cca85351bf20f06c83500f5a5823ee4a3e5f626b9b3",
   "gen_hash_verilog": "sha256:d13d947ba9e73a5be25d64aa717c5d3f1138396f77674ffdc56a0dfef150fe77",
   "gen_hash_zig": "sha256:01514daa510c982d521d72b36552a8ef68f946957d0351799bfad2073128ea4d",
   "module": "TriQuadtree",
   "ring": 12,
-  "sealed_at": "2026-09-06T05:46:34Z",
+  "sealed_at": "2026-09-06T08:02:09Z",
   "sealed_by": "t27c-bootstrap@0.2.0",
   "spec_hash": "sha256:974e62d1cdcc28189ff5fddbf9405c9e02f8bb01325bc2f9860f0578a053b345",
   "spec_path": "specs/tri/trees/quadtree.t27"

bootstrap/src/compiler.rs

@@ -23881,6 +23881,47 @@ impl RustCodegen {
         }
     }
 
+    /// A field whose type names the struct being defined needs indirection in Rust.
+    ///
+    /// `pub const KDNode = struct { left : "?KDNode", ... }` maps to
+    /// `pub left: Option<KDNode>` inside `pub struct KDNode`, and rustc answers
+    /// `recursive type `KDNode` has infinite size ... insert some indirection (e.g. a
+    /// `Box`, `Rc`, or `&`)`. There is no version of this that compiles without one, so
+    /// this is not a choice about representation -- it is the difference between output
+    /// and no output. `Box` is the ownership-preserving one of the three rustc names.
+    ///
+    /// Nine structs in the corpus refer to themselves; three of them are specs whose ONLY
+    /// remaining error is this one.
+    ///
+    /// Deliberately narrow. `Vec<Name>` already carries its indirection and is left alone,
+    /// and so is anything more deeply nested than `Option<Name>` -- a type this does not
+    /// recognise keeps its current output rather than getting a guess.
+    fn box_if_self_referential(field_type: &str, struct_name: &str) -> String {
+        if struct_name.is_empty() {
+            return field_type.to_string();
+        }
+        if field_type == struct_name {
+            return format!("Box<{struct_name}>");
+        }
+        let opt = format!("Option<{struct_name}>");
+        if field_type == opt {
+            return format!("Option<Box<{struct_name}>>");
+        }
+        // `[Option<OctNode>; 8]`. An array is inline storage, so it is as recursive as a
+        // bare field; only the element needs the box. This was previously written off as
+        // "genuinely infinitely sized" -- it is not, `[Option<Box<OctNode>>; 8]` is finite
+        // and is what octree and quadtree need.
+        if let Some(rest) = field_type.strip_prefix('[') {
+            if let Some((elem, tail)) = rest.rsplit_once(';') {
+                let boxed = Self::box_if_self_referential(elem.trim(), struct_name);
+                if boxed != elem.trim() {
+                    return format!("[{boxed};{tail}");
+                }
+            }
+        }
+        field_type.to_string()
+    }
+
     fn gen_struct(&mut self, node: &Node) {
         // The serde derives were unconditional, and the corpus compiles this
         // output as a standalone `--crate-type lib` with no `--extern`. Every
@@ -23952,6 +23993,7 @@ impl RustCodegen {
             if child.kind == NodeKind::ExprIdentifier && !child.name.is_empty() {
                 let field_name = &child.name;
                 let field_type = Self::t27_type_to_rust(&child.extra_type);
+                let field_type = Self::box_if_self_referential(&field_type, &node.name);
                 if field_type.trim() == "bool" {
                     self.bool_fields.insert(field_name.clone());
                 }

bootstrap/stage0/FROZEN_HASH

@@ -1 +1 @@
-5b05ef6357a7139dbc16bd60977eda9294eecb01f9d2d3be58c8816796e418cc bootstrap/src/compiler.rs
+6b3304d63e8f39cbb57953dbaf39769550a677d5565923a387bc4d6c94348f64 bootstrap/src/compiler.rs

docs/now/2026-09-06-a-field-that-names-its-own-struct.md

@@ -0,0 +1,20 @@
+# NOW -- A field that names its own struct needs a Box (2026-09-06)
+
+## A field that names its own struct needs a Box (Refs #3377)
+
+- First fix in five passes to move the column, and the first whose target was PICKED:
+  `tri one-away` reported this class as the sole error of 3 specs whose count is exact,
+  and the repair moved exactly those 3.
+- `pub left: Option<KDNode>` inside `pub struct KDNode` is infinitely sized. There is
+  no version that compiles without indirection, so nothing is chosen about representation
+  -- `Box` is the ownership-preserving one of the three names rustc itself offers.
+- Two shapes. `Option<Name>` is kd_tree. `[Option<Name>; N]` is octree and quadtree,
+  and an earlier pass of mine wrote octree off as "genuinely infinitely sized". **That was
+  wrong**: an array is inline storage, only the element needs the box, and
+  `[Option<Box<OctNode>>; 8]` is finite.
+- Measured, two pinned binaries from the same commit in ONE pass, 650 specs:
+  **357 -> 360, +3, zero regressions.**
+- Nine structs in the corpus name themselves. Three were one-away and are now green; the
+  rest carry other errors.
+- Narrow on purpose: `Vec<Name>` already carries indirection and is untouched, and a
+  shape this does not recognise keeps its current output rather than getting a guess.