Rollup merge of rust-lang#115749 - oli-obk:smir_consts, r=compiler-errors

Allow loading the SMIR for constants and statics

cc rust-lang/project-stable-mir#34

before this PR we were ICEing when trying to access the SMIR of anything other than functions

Author: matthiaskrgr

compiler/rustc_smir/src/rustc_smir/mod.rs

@@ -84,7 +84,7 @@ impl<'tcx> Context for Tables<'tcx> {
 
     fn mir_body(&mut self, item: stable_mir::DefId) -> stable_mir::mir::Body {
         let def_id = self[item];
-        let mir = self.tcx.optimized_mir(def_id);
+        let mir = self.tcx.instance_mir(ty::InstanceDef::Item(def_id));
         stable_mir::mir::Body {
             blocks: mir
                 .basic_blocks

tests/ui-fulldeps/stable-mir/crate-info.rs

@@ -154,6 +154,10 @@ fn test_stable_mir(tcx: TyCtxt<'_>) -> ControlFlow<()> {
         }
     }
 
+    let foo_const = get_item(tcx, &items, (DefKind::Const, "FOO")).unwrap();
+    // Ensure we don't panic trying to get the body of a constant.
+    foo_const.body();
+
     ControlFlow::Continue(())
 }
 
@@ -191,6 +195,8 @@ fn generate_input(path: &str) -> std::io::Result<()> {
     write!(
         file,
         r#"
+    pub const FOO: u32 = 1 + 2;
+
     fn generic<T, const U: usize>(t: T) -> [(); U] {{
         _ = t;
         [(); U]