Encode MIR for const ctors in metadata and allow eval for them

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

@@ -2,7 +2,7 @@ use std::sync::atomic::Ordering::Relaxed;
 
 use either::{Left, Right};
 use rustc_abi::{self as abi, BackendRepr};
-use rustc_hir::def::DefKind;
+use rustc_hir::def::{CtorKind, DefKind};
 use rustc_middle::mir::interpret::{AllocId, ErrorHandled, InterpErrorInfo, ReportedErrorInfo};
 use rustc_middle::mir::{self, ConstAlloc, ConstValue};
 use rustc_middle::query::TyCtxtAt;
@@ -41,6 +41,7 @@ fn eval_body_using_ecx<'tcx, R: InterpretationResult<'tcx>>(
                     | DefKind::AnonConst
                     | DefKind::InlineConst
                     | DefKind::AssocConst
+                    | DefKind::Ctor(_, CtorKind::Const)
             ),
         "Unexpected DefKind: {:?}",
         ecx.tcx.def_kind(cid.instance.def_id())

compiler/rustc_mir_transform/src/lib.rs

@@ -21,7 +21,7 @@ use rustc_const_eval::util;
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_data_structures::steal::Steal;
 use rustc_hir as hir;
-use rustc_hir::def::{CtorKind, DefKind};
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalDefId;
 use rustc_index::IndexVec;
 use rustc_middle::mir::{
@@ -324,7 +324,7 @@ fn mir_keys(tcx: TyCtxt<'_>, (): ()) -> FxIndexSet<LocalDefId> {
     for item in tcx.hir_crate_items(()).free_items() {
         if let DefKind::Struct | DefKind::Enum = tcx.def_kind(item.owner_id) {
             for variant in tcx.adt_def(item.owner_id).variants() {
-                if let Some((CtorKind::Fn, ctor_def_id)) = variant.ctor {
+                if let Some((_, ctor_def_id)) = variant.ctor {
                     set.insert(ctor_def_id.expect_local());
                 }
             }

tests/ui-fulldeps/stable-mir/check_item_kind.rs

@@ -27,7 +27,7 @@ const CRATE_NAME: &str = "input";
 /// This function uses the Stable MIR APIs to get information about the test crate.
 fn test_item_kind() -> ControlFlow<()> {
     let items = stable_mir::all_local_items();
-    assert_eq!(items.len(), 4);
+    assert_eq!(items.len(), 5);
     // Constructor item.
     for item in items {
         let expected_kind = match item.name().as_str() {

tests/ui/const-generics/auxiliary/xcrate-const-ctor-a.rs

@@ -1,4 +1,7 @@
+// NOTE: This aux file inherits revisions from its parent tests.
+
 #![feature(adt_const_params)]
+#![cfg_attr(mgca, feature(min_generic_const_args), allow(incomplete_features))]
 
 use std::marker::ConstParamTy;
 

tests/ui/const-generics/xcrate-const-ctor-b.rs

@@ -1,7 +1,9 @@
 //@ check-pass
+//@ revisions: normal mgca
 //@ aux-build:xcrate-const-ctor-a.rs
 
 #![feature(adt_const_params)]
+#![cfg_attr(mgca, feature(min_generic_const_args), allow(incomplete_features))]
 
 extern crate xcrate_const_ctor_a;
 use xcrate_const_ctor_a::Foo;

tests/ui/stable-mir-print/operands.stdout

@@ -250,6 +250,13 @@ fn closures::{closure#0}(_1: {closure@$DIR/operands.rs:47:5: 47:19}, _2: bool) -
         return;
     }
 }
+fn Ctors::Unit() -> Ctors {
+    let mut _0: Ctors;
+    bb0: {
+        _0 = Ctors::Unit;
+        return;
+    }
+}
 fn Ctors::TupLike(_1: bool) -> Ctors {
     let mut _0: Ctors;
     bb0: {