5 files changed, 25 insertions, 0 deletions
diff --git a/compiler/rustc_middle/messages.ftl b/compiler/rustc_middle/messages.ftl
index 8dc529b4d7a..cfb495df9d5 100644
--- a/compiler/rustc_middle/messages.ftl
+++ b/compiler/rustc_middle/messages.ftl
@@ -32,6 +32,8 @@ middle_assert_shl_overflow =
 middle_assert_shr_overflow =
     attempt to shift right by `{$val}`, which would overflow
 
+middle_autodiff_unsafe_inner_const_ref = reading from a `Duplicated` const {$ty} is unsafe
+
 middle_bounds_check =
     index out of bounds: the length is {$len} but the index is {$index}
 
@@ -107,6 +109,8 @@ middle_type_length_limit = reached the type-length limit while instantiating `{$
 middle_unknown_layout =
     the type `{$ty}` has an unknown layout
 
+middle_unsupported_union = we don't support unions yet: '{$ty_name}'
+
 middle_values_too_big =
     values of the type `{$ty}` are too big for the target architecture
 
diff --git a/compiler/rustc_middle/src/arena.rs b/compiler/rustc_middle/src/arena.rs
index 750531b638e..eaccd8c360e 100644
--- a/compiler/rustc_middle/src/arena.rs
+++ b/compiler/rustc_middle/src/arena.rs
@@ -87,6 +87,7 @@ macro_rules! arena_types {
             [] codegen_unit: rustc_middle::mir::mono::CodegenUnit<'tcx>,
             [decode] attribute: rustc_hir::Attribute,
             [] name_set: rustc_data_structures::unord::UnordSet<rustc_span::Symbol>,
+            [] autodiff_item: rustc_ast::expand::autodiff_attrs::AutoDiffItem,
             [] ordered_name_set: rustc_data_structures::fx::FxIndexSet<rustc_span::Symbol>,
             [] pats: rustc_middle::ty::PatternKind<'tcx>,
 
diff --git a/compiler/rustc_middle/src/error.rs b/compiler/rustc_middle/src/error.rs
index b0187a1848c..b30d3a950c6 100644
--- a/compiler/rustc_middle/src/error.rs
+++ b/compiler/rustc_middle/src/error.rs
@@ -37,6 +37,20 @@ pub struct OpaqueHiddenTypeMismatch<'tcx> {
     pub sub: TypeMismatchReason,
 }
 
+#[derive(Diagnostic)]
+#[diag(middle_unsupported_union)]
+pub struct UnsupportedUnion {
+    pub ty_name: String,
+}
+
+#[derive(Diagnostic)]
+#[diag(middle_autodiff_unsafe_inner_const_ref)]
+pub struct AutodiffUnsafeInnerConstRef {
+    #[primary_span]
+    pub span: Span,
+    pub ty: String,
+}
+
 #[derive(Subdiagnostic)]
 pub enum TypeMismatchReason {
     #[label(middle_conflict_types)]
diff --git a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
index cc980f6e62a..1784665bcae 100644
--- a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
+++ b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
@@ -1,4 +1,5 @@
 use rustc_abi::Align;
+use rustc_ast::expand::autodiff_attrs::AutoDiffAttrs;
 use rustc_attr_parsing::{InlineAttr, InstructionSetAttr, OptimizeAttr};
 use rustc_macros::{HashStable, TyDecodable, TyEncodable};
 use rustc_span::Symbol;
@@ -52,6 +53,8 @@ pub struct CodegenFnAttrs {
     /// The `#[patchable_function_entry(...)]` attribute. Indicates how many nops should be around
     /// the function entry.
     pub patchable_function_entry: Option<PatchableFunctionEntry>,
+    /// For the `#[autodiff]` macros.
+    pub autodiff_item: Option<AutoDiffAttrs>,
 }
 
 #[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
@@ -160,6 +163,7 @@ impl CodegenFnAttrs {
             instruction_set: None,
             alignment: None,
             patchable_function_entry: None,
+            autodiff_item: None,
         }
     }
 
diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs
index 3eccf56d8c4..b93046ca8e2 100644
--- a/compiler/rustc_middle/src/mir/mono.rs
+++ b/compiler/rustc_middle/src/mir/mono.rs
@@ -1,6 +1,7 @@
 use std::fmt;
 use std::hash::Hash;
 
+use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_attr_parsing::InlineAttr;
 use rustc_data_structures::base_n::{BaseNString, CASE_INSENSITIVE, ToBaseN};
 use rustc_data_structures::fingerprint::Fingerprint;
@@ -251,6 +252,7 @@ impl ToStableHashKey<StableHashingContext<'_>> for MonoItem<'_> {
 pub struct MonoItemPartitions<'tcx> {
     pub codegen_units: &'tcx [CodegenUnit<'tcx>],
     pub all_mono_items: &'tcx DefIdSet,
+    pub autodiff_items: &'tcx [AutoDiffItem],
 }
 
 #[derive(Debug, HashStable)]