Auto merge of #94453 - matthiaskrgr:rollup-xv9y98j, r=matthiaskrgr

Rollup of 6 pull requests

Successful merges:

 - #92399 (fix typo in btree/vec doc: Self -> self)
 - #92823 (Tweak diagnostics)
 - #94248 (Fix ICE when passing block to while-loop condition)
 - #94414 (Fix ICE when using Box<T, A> with large A)
 - #94445 (4 - Make more use of `let_chains`)
 - #94449 (Add long explanation for E0726)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_codegen_ssa/src/mir/place.rs

@@ -453,7 +453,18 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         };
         for elem in place_ref.projection[base..].iter() {
             cg_base = match elem.clone() {
-                mir::ProjectionElem::Deref => bx.load_operand(cg_base).deref(bx.cx()),
+                mir::ProjectionElem::Deref => {
+                    // custom allocators can change box's abi, making it unable to be derefed directly
+                    if cg_base.layout.ty.is_box()
+                        && matches!(cg_base.layout.abi, Abi::Aggregate { .. } | Abi::Uninhabited)
+                    {
+                        let ptr = cg_base.project_field(bx, 0).project_field(bx, 0);
+
+                        bx.load_operand(ptr).deref(bx.cx())
+                    } else {
+                        bx.load_operand(cg_base).deref(bx.cx())
+                    }
+                }
                 mir::ProjectionElem::Field(ref field, _) => {
                     cg_base.project_field(bx, field.index())
                 }

compiler/rustc_error_codes/src/error_codes.rs

@@ -429,6 +429,7 @@ E0720: include_str!("./error_codes/E0720.md"),
 E0722: include_str!("./error_codes/E0722.md"),
 E0724: include_str!("./error_codes/E0724.md"),
 E0725: include_str!("./error_codes/E0725.md"),
+E0726: include_str!("./error_codes/E0726.md"),
 E0727: include_str!("./error_codes/E0727.md"),
 E0728: include_str!("./error_codes/E0728.md"),
 E0729: include_str!("./error_codes/E0729.md"),
@@ -641,6 +642,5 @@ E0787: include_str!("./error_codes/E0787.md"),
     E0717, // rustc_promotable without stability attribute
 //  E0721, // `await` keyword
 //  E0723, // unstable feature in `const` context
-    E0726, // non-explicit (not `'_`) elided lifetime in unsupported position
 //  E0738, // Removed; errored on `#[track_caller] fn`s in `extern "Rust" { ... }`.
 }