Print rendered miri values in rustdoc

Author: oli-obk

src/librustc/mir/mod.rs

@@ -1778,7 +1778,7 @@ fn fmt_const_val<W: Write>(fmt: &mut W, const_val: &ty::Const) -> fmt::Result {
     }
 }
 
-fn print_miri_value<W: Write>(value: Value, ty: Ty, f: &mut W) -> fmt::Result {
+pub fn print_miri_value<W: Write>(value: Value, ty: Ty, f: &mut W) -> fmt::Result {
     use ty::TypeVariants::*;
     use rustc_const_math::ConstFloat;
     match (value, &ty.sty) {

src/librustdoc/clean/mod.rs

@@ -2066,14 +2066,24 @@ impl Clean<Type> for hir::Ty {
                     promoted: None
                 };
                 let n = cx.tcx.const_eval(param_env.and(cid)).unwrap();
-                let n = if let ConstVal::Unevaluated(def_id, _) = n.val {
-                    if let Some(node_id) = cx.tcx.hir.as_local_node_id(def_id) {
-                        print_const_expr(cx, cx.tcx.hir.body_owned_by(node_id))
-                    } else {
-                        inline::print_inlined_const(cx, def_id)
-                    }
-                } else {
-                    format!("{:?}", n)
+                let n = match n.val {
+                    ConstVal::Unevaluated(def_id, _) => {
+                        if let Some(node_id) = cx.tcx.hir.as_local_node_id(def_id) {
+                            print_const_expr(cx, cx.tcx.hir.body_owned_by(node_id))
+                        } else {
+                            inline::print_inlined_const(cx, def_id)
+                        }
+                    },
+                    ConstVal::Value(val) => {
+                        let mut s = String::new();
+                        ::rustc::mir::print_miri_value(val, n.ty, &mut s).unwrap();
+                        // array lengths are obviously usize
+                        if s.ends_with("usize") {
+                            let n = s.len() - "usize".len();
+                            s.truncate(n);
+                        }
+                        s
+                    },
                 };
                 Array(box ty.clean(cx), n)
             },
@@ -2199,14 +2209,24 @@ impl<'tcx> Clean<Type> for Ty<'tcx> {
                     };
                     n = cx.tcx.const_eval(param_env.and(cid)).unwrap()
                 };
-                let n = if let ConstVal::Unevaluated(def_id, _) = n.val {
-                    if let Some(node_id) = cx.tcx.hir.as_local_node_id(def_id) {
-                        print_const_expr(cx, cx.tcx.hir.body_owned_by(node_id))
-                    } else {
-                        inline::print_inlined_const(cx, def_id)
-                    }
-                } else {
-                    format!("{:?}", n)
+                let n = match n.val {
+                    ConstVal::Unevaluated(def_id, _) => {
+                        if let Some(node_id) = cx.tcx.hir.as_local_node_id(def_id) {
+                            print_const_expr(cx, cx.tcx.hir.body_owned_by(node_id))
+                        } else {
+                            inline::print_inlined_const(cx, def_id)
+                        }
+                    },
+                    ConstVal::Value(val) => {
+                        let mut s = String::new();
+                        ::rustc::mir::print_miri_value(val, n.ty, &mut s).unwrap();
+                        // array lengths are obviously usize
+                        if s.ends_with("usize") {
+                            let n = s.len() - "usize".len();
+                            s.truncate(n);
+                        }
+                        s
+                    },
                 };
                 Array(box ty.clean(cx), n)
             }