Auto merge of #76985 - hbina:clone_check, r=estebank

Prevent stack overflow in deeply nested types.

Related issue #75577 (?)

Unfortunately, I am unable to test whether this actually solves the problem because apparently, 12GB RAM + 2GB swap is not enough to compile the (admittedly toy) source file.

1 files changed, 13 insertions, 1 deletions

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 492d5788fc0..8d9d4123c79 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -27,6 +27,7 @@ use crate::token::{self, CommentKind, DelimToken};
 use crate::tokenstream::{DelimSpan, TokenStream, TokenTree};
 
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::thin_vec::ThinVec;
 use rustc_macros::HashStable_Generic;
@@ -1864,7 +1865,7 @@ pub enum AssocTyConstraintKind {
     Bound { bounds: GenericBounds },
 }
 
-#[derive(Clone, Encodable, Decodable, Debug)]
+#[derive(Encodable, Decodable, Debug)]
 pub struct Ty {
     pub id: NodeId,
     pub kind: TyKind,
@@ -1872,6 +1873,17 @@ pub struct Ty {
     pub tokens: Option<TokenStream>,
 }
 
+impl Clone for Ty {
+    fn clone(&self) -> Self {
+        ensure_sufficient_stack(|| Self {
+            id: self.id,
+            kind: self.kind.clone(),
+            span: self.span,
+            tokens: self.tokens.clone(),
+        })
+    }
+}
+
 #[derive(Clone, Encodable, Decodable, Debug)]
 pub struct BareFnTy {
     pub unsafety: Unsafe,