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Merged
gHashTag merged 1 commit into from
Sep 6, 2026
Merged

fix(rust): box an optional of the struct itself (+3) #3376

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2 changes: 1 addition & 1 deletion .trinity/seals/TriKdTree.json
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@@ -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",
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2 changes: 1 addition & 1 deletion .trinity/seals/TriLinkedList.json
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@@ -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",
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2 changes: 1 addition & 1 deletion .trinity/seals/TriOctree.json
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@@ -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",
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2 changes: 1 addition & 1 deletion .trinity/seals/TriQuadtree.json
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@@ -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",
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4 changes: 2 additions & 2 deletions .trinity/seals/collections_TriLinkedList.json
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@@ -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": "2026-09-06T07:44:28Z",
"sealed_by": "t27c-bootstrap@0.2.0",
"spec_hash": "sha256:5171edf6089a238976e6fad2ba577ed72cff191cf634ee94c28645f3551f9ffc",
"spec_path": "specs/tri/collections/linked_list.t27"
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4 changes: 2 additions & 2 deletions .trinity/seals/trees_TriKdTree.json
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@@ -1,11 +1,11 @@
{
"gen_hash_c": "sha256:7658bd16d1d66d14de50176a27cc78f130863a13853fedc2dacc839a2fe4a68f",
"gen_hash_rust": "sha256:ec452f608b4f52459b4c87a32fcc38622f3b833ff8f0591af58949c5a8530bb9",
"gen_hash_rust": "sha256:5109675652b7451a917c1f6f145b99bef55491f2ac4bbc4d9025d55ca37c5fc6",
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"gen_hash_zig": "sha256:369f3d5632ef02f40c2edea5a3ab0670cce287040188cf7d66ae11fed6ed3dda",
"module": "TriKdTree",
"ring": 12,
"sealed_at": "2026-09-05T01:08:39Z",
"sealed_at": "2026-09-06T07:44:28Z",
"sealed_by": "t27c-bootstrap@0.2.0",
"spec_hash": "sha256:338dda6bd5fe68db61f018bc4216fd6ab671562bcfc3cf92f1692fbdc2440abd",
"spec_path": "specs/tri/trees/kd_tree.t27"
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4 changes: 2 additions & 2 deletions .trinity/seals/trees_TriOctree.json
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@@ -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": "2026-09-06T07:44:28Z",
"sealed_by": "t27c-bootstrap@0.2.0",
"spec_hash": "sha256:63216e4dbe843da95dd62bfc13b7741e6bf343e3bcf3d407e084d6be61e84dfe",
"spec_path": "specs/tri/trees/octree.t27"
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4 changes: 2 additions & 2 deletions .trinity/seals/trees_TriQuadtree.json
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@@ -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": "2026-09-06T07:44:28Z",
"sealed_by": "t27c-bootstrap@0.2.0",
"spec_hash": "sha256:974e62d1cdcc28189ff5fddbf9405c9e02f8bb01325bc2f9860f0578a053b345",
"spec_path": "specs/tri/trees/quadtree.t27"
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18 changes: 18 additions & 0 deletions bootstrap/src/compiler.rs
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Expand Up @@ -23952,6 +23952,24 @@ 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);
// A struct that holds an OPTIONAL of itself is infinitely sized in Rust:
//
// pub left: Option<KDNode> error[E0072]
// pub children: [Option<OctNode>; 8] the same, once per element
//
// Zig writes `?KDNode` and stores it inline because its optional of a
// struct is a tagged union of known size; Rust needs the indirection
// spelled out. rustc says exactly this and names the repair.
//
// Only `Option<ThisStruct>` is rewritten, and only on an exact name match.
// `Vec<ThisStruct>` is already indirect and is left alone; a bare
// `ThisStruct` would still be infinite but does not occur in the corpus,
// and guessing at a shape nothing exhibits is how a rule outgrows its
// evidence.
let field_type = field_type.replace(
&format!("Option<{}>", node.name),
&format!("Option<Box<{}>>", node.name),
);
if field_type.trim() == "bool" {
self.bool_fields.insert(field_name.clone());
}
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2 changes: 1 addition & 1 deletion bootstrap/stage0/FROZEN_HASH
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@@ -1 +1 @@
5b05ef6357a7139dbc16bd60977eda9294eecb01f9d2d3be58c8816796e418cc bootstrap/src/compiler.rs
b1f4644c92c7258c06431fa8a386f1aea6b8e47f6452d0b73ad93a59b9dad9dc bootstrap/src/compiler.rs
16 changes: 16 additions & 0 deletions docs/now/2026-09-06-an-optional-of-itself-is-infinitely-sized.md
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# NOW -- A struct holding an optional of itself is infinitely sized (2026-09-06)

## An optional of itself is infinitely sized (Refs #3375)

- `pub left: Option<KDNode>` inside `KDNode` is E0072. Zig writes `?KDNode` and stores
it inline because its optional of a struct is a tagged union of known size; Rust needs
the indirection spelled out, and rustc names the repair itself.
- Only `Option<ThisStruct>` is rewritten, on an exact name match. `Vec<ThisStruct>` is
already indirect; a bare `ThisStruct` would still be infinite but does not occur, and
guessing at a shape nothing exhibits is how a rule outgrows its evidence.
- Measured: **357 to 360**, zero regressions: `kd_tree`, `octree`, `quadtree`.
- `octree.t27` was recorded as a REGRESSION in #3247, where I wrote that `[8]?OctNode`
is genuinely infinitely sized. That was true of the emitted Rust and not of the spec.
It is no longer a regression.
- Boundary control in one probe: `?Node` inside `Node` boxes; `?Other` does not;
`?NodeExtra` does not, so an exact match does not catch a prefix; `[]Node` does not.
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