fix: Bring back the hex in const hover

crates/hir-ty/src/display.rs

@@ -5,7 +5,7 @@
 use std::fmt::{self, Debug};
 
 use base_db::CrateId;
-use chalk_ir::BoundVar;
+use chalk_ir::{BoundVar, TyKind};
 use hir_def::{
     adt::VariantData,
     body,
@@ -36,7 +36,7 @@ use crate::{
     AdtId, AliasEq, AliasTy, Binders, CallableDefId, CallableSig, Const, ConstScalar, ConstValue,
     DomainGoal, GenericArg, ImplTraitId, Interner, Lifetime, LifetimeData, LifetimeOutlives,
     MemoryMap, Mutability, OpaqueTy, ProjectionTy, ProjectionTyExt, QuantifiedWhereClause, Scalar,
-    Substitution, TraitRef, TraitRefExt, Ty, TyExt, TyKind, WhereClause,
+    Substitution, TraitRef, TraitRefExt, Ty, TyExt, WhereClause,
 };
 
 pub trait HirWrite: fmt::Write {
@@ -383,6 +383,28 @@ impl HirDisplay for Const {
     }
 }
 
+pub struct HexifiedConst(pub Const);
+
+impl HirDisplay for HexifiedConst {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        let data = &self.0.data(Interner);
+        if let TyKind::Scalar(s) = data.ty.kind(Interner) {
+            if matches!(s, Scalar::Int(_) | Scalar::Uint(_)) {
+                if let ConstValue::Concrete(c) = &data.value {
+                    if let ConstScalar::Bytes(b, m) = &c.interned {
+                        let value = u128::from_le_bytes(pad16(b, false));
+                        if value >= 10 {
+                            render_const_scalar(f, &b, m, &data.ty)?;
+                            return write!(f, " ({:#X})", value);
+                        }
+                    }
+                }
+            }
+        }
+        self.0.hir_fmt(f)
+    }
+}
+
 fn render_const_scalar(
     f: &mut HirFormatter<'_>,
     b: &[u8],

crates/hir/src/lib.rs

@@ -60,6 +60,7 @@ use hir_ty::{
     all_super_traits, autoderef,
     consteval::{try_const_usize, unknown_const_as_generic, ConstEvalError, ConstExt},
     diagnostics::BodyValidationDiagnostic,
+    display::HexifiedConst,
     layout::layout_of_ty,
     method_resolution::{self, TyFingerprint},
     mir::interpret_mir,
@@ -1883,8 +1884,18 @@ impl Const {
         Type::new_with_resolver_inner(db, &resolver, ty)
     }
 
-    pub fn eval(self, db: &dyn HirDatabase) -> Result<hir_ty::Const, ConstEvalError> {
-        db.const_eval(self.id)
+    pub fn render_eval(self, db: &dyn HirDatabase) -> Result<String, ConstEvalError> {
+        let c = db.const_eval(self.id)?;
+        let r = format!("{}", HexifiedConst(c).display(db));
+        // We want to see things like `<utf8-error>` and `<layout-error>` as they are probably bug in our
+        // implementation, but there is no need to show things like `<enum-not-supported>` or `<ref-not-supported>` to
+        // the user.
+        if r.contains("not-supported>") {
+            return Err(ConstEvalError::MirEvalError(MirEvalError::NotSupported(
+                "rendering complex constants".to_string(),
+            )));
+        }
+        return Ok(r);
     }
 }
 

crates/ide/src/hover/render.rs

@@ -432,9 +432,9 @@ pub(super) fn definition(
             }
         }),
         Definition::Const(it) => label_value_and_docs(db, it, |it| {
-            let body = it.eval(db);
+            let body = it.render_eval(db);
             match body {
-                Ok(x) => Some(format!("{}", x.display(db))),
+                Ok(x) => Some(x),
                 Err(_) => {
                     let source = it.source(db)?;
                     let mut body = source.value.body()?.syntax().clone();

crates/ide/src/hover/tests.rs

@@ -531,7 +531,7 @@ fn hover_const_static() {
             ```
 
             ```rust
-            const foo: u32 = 123
+            const foo: u32 = 123 (0x7B)
             ```
         "#]],
     );
@@ -3770,7 +3770,6 @@ const FOO$0: usize = 1 << 3;
             This is a doc
         "#]],
     );
-    // FIXME: show hex for >10
     check(
         r#"
 /// This is a doc
@@ -3784,7 +3783,7 @@ const FOO$0: usize = (1 << 3) + (1 << 2);
             ```
 
             ```rust
-            const FOO: usize = 12
+            const FOO: usize = 12 (0xC)
             ```
 
             ---
@@ -3828,7 +3827,7 @@ const FOO$0: i32 = 2 - 3;
             ```
 
             ```rust
-            const FOO: i32 = -1
+            const FOO: i32 = -1 (0xFFFFFFFF)
             ```
 
             ---
@@ -3915,7 +3914,7 @@ const FOO$0: u8 = b'a';
             ```
 
             ```rust
-            const FOO: u8 = 97
+            const FOO: u8 = 97 (0x61)
             ```
 
             ---
@@ -3937,7 +3936,7 @@ const FOO$0: u8 = b'\x61';
             ```
 
             ```rust
-            const FOO: u8 = 97
+            const FOO: u8 = 97 (0x61)
             ```
 
             ---
@@ -3989,6 +3988,28 @@ const FOO$0: f32 = 1f32;
             This is a doc
         "#]],
     );
+    // Don't show `<ref-not-supported>` in const hover
+    check(
+        r#"
+/// This is a doc
+const FOO$0: &i32 = &2;
+"#,
+        expect![[r#"
+            *FOO*
+
+            ```rust
+            test
+            ```
+
+            ```rust
+            const FOO: &i32 = &2
+            ```
+
+            ---
+
+            This is a doc
+        "#]],
+    );
     //show f64 typecasted from float
     check(
         r#"