Generalize reborrow hints as adjustment hints

crates/hir-ty/src/lib.rs

@@ -53,7 +53,7 @@ pub use builder::{ParamKind, TyBuilder};
 pub use chalk_ext::*;
 pub use infer::{
     could_coerce, could_unify, Adjust, Adjustment, AutoBorrow, BindingMode, InferenceDiagnostic,
-    InferenceResult,
+    InferenceResult, OverloadedDeref, PointerCast,
 };
 pub use interner::Interner;
 pub use lower::{

crates/hir/src/lib.rs

@@ -117,7 +117,7 @@ pub use {
         name::{known, Name},
         ExpandResult, HirFileId, InFile, MacroFile, Origin,
     },
-    hir_ty::display::HirDisplay,
+    hir_ty::{display::HirDisplay, PointerCast, Safety},
 };
 
 // These are negative re-exports: pub using these names is forbidden, they
@@ -3651,6 +3651,28 @@ impl From<ItemInNs> for ScopeDef {
     }
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum Adjust {
+    /// Go from ! to any type.
+    NeverToAny,
+    /// Dereference once, producing a place.
+    Deref(Option<OverloadedDeref>),
+    /// Take the address and produce either a `&` or `*` pointer.
+    Borrow(AutoBorrow),
+    Pointer(PointerCast),
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum AutoBorrow {
+    /// Converts from T to &T.
+    Ref(Mutability),
+    /// Converts from T to *T.
+    RawPtr(Mutability),
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct OverloadedDeref(pub Mutability);
+
 pub trait HasVisibility {
     fn visibility(&self, db: &dyn HirDatabase) -> Visibility;
     fn is_visible_from(&self, db: &dyn HirDatabase, module: Module) -> bool {

crates/hir/src/semantics.rs

@@ -29,9 +29,10 @@ use crate::{
     db::HirDatabase,
     semantics::source_to_def::{ChildContainer, SourceToDefCache, SourceToDefCtx},
     source_analyzer::{resolve_hir_path, SourceAnalyzer},
-    Access, BindingMode, BuiltinAttr, Callable, ConstParam, Crate, DeriveHelper, Field, Function,
+    Access, Adjust, AutoBorrow, BindingMode, BuiltinAttr, Callable, ConstParam, Crate,
-    HasSource, HirFileId, Impl, InFile, Label, LifetimeParam, Local, Macro, Module, ModuleDef,
+    DeriveHelper, Field, Function, HasSource, HirFileId, Impl, InFile, Label, LifetimeParam, Local,
-    Name, Path, ScopeDef, ToolModule, Trait, Type, TypeAlias, TypeParam, VariantDef,
+    Macro, Module, ModuleDef, Name, OverloadedDeref, Path, ScopeDef, ToolModule, Trait, Type,
+    TypeAlias, TypeParam, VariantDef,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -333,9 +334,8 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.resolve_trait(trait_)
     }
 
-    // FIXME: Figure out a nice interface to inspect adjustments
+    pub fn expr_adjustments(&self, expr: &ast::Expr) -> Option<Vec<Adjust>> {
-    pub fn is_implicit_reborrow(&self, expr: &ast::Expr) -> Option<Mutability> {
+        self.imp.expr_adjustments(expr)
-        self.imp.is_implicit_reborrow(expr)
     }
 
     pub fn type_of_expr(&self, expr: &ast::Expr) -> Option<TypeInfo> {
@@ -1067,8 +1067,29 @@ impl<'db> SemanticsImpl<'db> {
         }
     }
 
-    fn is_implicit_reborrow(&self, expr: &ast::Expr) -> Option<Mutability> {
+    fn expr_adjustments(&self, expr: &ast::Expr) -> Option<Vec<Adjust>> {
-        self.analyze(expr.syntax())?.is_implicit_reborrow(self.db, expr)
+        let mutability = |m| match m {
+            hir_ty::Mutability::Not => Mutability::Shared,
+            hir_ty::Mutability::Mut => Mutability::Mut,
+        };
+        self.analyze(expr.syntax())?.expr_adjustments(self.db, expr).map(|it| {
+            it.iter()
+                .map(|adjust| match adjust.kind {
+                    hir_ty::Adjust::NeverToAny => Adjust::NeverToAny,
+                    hir_ty::Adjust::Deref(Some(hir_ty::OverloadedDeref(m))) => {
+                        Adjust::Deref(Some(OverloadedDeref(mutability(m))))
+                    }
+                    hir_ty::Adjust::Deref(None) => Adjust::Deref(None),
+                    hir_ty::Adjust::Borrow(hir_ty::AutoBorrow::RawPtr(m)) => {
+                        Adjust::Borrow(AutoBorrow::RawPtr(mutability(m)))
+                    }
+                    hir_ty::Adjust::Borrow(hir_ty::AutoBorrow::Ref(m)) => {
+                        Adjust::Borrow(AutoBorrow::Ref(mutability(m)))
+                    }
+                    hir_ty::Adjust::Pointer(pc) => Adjust::Pointer(pc),
+                })
+                .collect()
+        })
     }
 
     fn type_of_expr(&self, expr: &ast::Expr) -> Option<TypeInfo> {

crates/hir/src/source_analyzer.rs

@@ -38,8 +38,7 @@ use hir_ty::{
         UnsafeExpr,
     },
     method_resolution::{self, lang_names_for_bin_op},
-    Adjust, Adjustment, AutoBorrow, InferenceResult, Interner, Substitution, Ty, TyExt, TyKind,
+    Adjustment, InferenceResult, Interner, Substitution, Ty, TyExt, TyKind, TyLoweringContext,
-    TyLoweringContext,
 };
 use itertools::Itertools;
 use smallvec::SmallVec;
@@ -156,21 +155,14 @@ impl SourceAnalyzer {
         Some(res)
     }
 
-    pub(crate) fn is_implicit_reborrow(
+    pub(crate) fn expr_adjustments(
         &self,
         db: &dyn HirDatabase,
         expr: &ast::Expr,
-    ) -> Option<Mutability> {
+    ) -> Option<&[Adjustment]> {
         let expr_id = self.expr_id(db, expr)?;
         let infer = self.infer.as_ref()?;
-        let adjustments = infer.expr_adjustments.get(&expr_id)?;
+        infer.expr_adjustments.get(&expr_id).map(|v| &**v)
-        adjustments.windows(2).find_map(|slice| match slice {
-            &[Adjustment {kind: Adjust::Deref(None), ..}, Adjustment {kind: Adjust::Borrow(AutoBorrow::Ref(m)), ..}] => Some(match m {
-                hir_ty::Mutability::Mut => Mutability::Mut,
-                hir_ty::Mutability::Not => Mutability::Shared,
-            }),
-            _ => None,
-        })
     }
 
     pub(crate) fn type_of_expr(

crates/ide/src/inlay_hints.rs

@@ -1,7 +1,10 @@
 use std::fmt;
 
 use either::Either;
-use hir::{known, Callable, HasVisibility, HirDisplay, Mutability, Semantics, TypeInfo};
+use hir::{
+    known, Adjust, AutoBorrow, Callable, HasVisibility, HirDisplay, Mutability, OverloadedDeref,
+    PointerCast, Safety, Semantics, TypeInfo,
+};
 use ide_db::{
     base_db::FileRange, famous_defs::FamousDefs, syntax_helpers::node_ext::walk_ty, FxHashMap,
     RootDatabase,
@@ -22,7 +25,7 @@ pub struct InlayHintsConfig {
     pub type_hints: bool,
     pub parameter_hints: bool,
     pub chaining_hints: bool,
-    pub reborrow_hints: ReborrowHints,
+    pub adjustment_hints: AdjustmentHints,
     pub closure_return_type_hints: ClosureReturnTypeHints,
     pub binding_mode_hints: bool,
     pub lifetime_elision_hints: LifetimeElisionHints,
@@ -48,7 +51,7 @@ pub enum LifetimeElisionHints {
 }
 
 #[derive(Clone, Debug, PartialEq, Eq)]
-pub enum ReborrowHints {
+pub enum AdjustmentHints {
     Always,
     MutableOnly,
     Never,
@@ -61,7 +64,8 @@ pub enum InlayKind {
     ClosingBraceHint,
     ClosureReturnTypeHint,
     GenericParamListHint,
-    ImplicitReborrowHint,
+    AdjustmentHint,
+    AdjustmentHintClosingParenthesis,
     LifetimeHint,
     ParameterHint,
     TypeHint,
@@ -115,6 +119,12 @@ impl From<String> for InlayHintLabel {
     }
 }
 
+impl From<&str> for InlayHintLabel {
+    fn from(s: &str) -> Self {
+        Self { parts: vec![InlayHintLabelPart { text: s.into(), linked_location: None }] }
+    }
+}
+
 impl fmt::Display for InlayHintLabel {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{}", self.parts.iter().map(|part| &part.text).format(""))
@@ -221,6 +231,7 @@ fn hints(
         match node {
             ast::Expr(expr) => {
                 chaining_hints(hints, sema, &famous_defs, config, file_id, &expr);
+                adjustment_hints(hints, sema, config, &expr);
                 match expr {
                     ast::Expr::CallExpr(it) => param_name_hints(hints, sema, config, ast::Expr::from(it)),
                     ast::Expr::MethodCallExpr(it) => {
@@ -229,7 +240,7 @@ fn hints(
                     ast::Expr::ClosureExpr(it) => closure_ret_hints(hints, sema, &famous_defs, config, file_id, it),
                     // We could show reborrows for all expressions, but usually that is just noise to the user
                     // and the main point here is to show why "moving" a mutable reference doesn't necessarily move it
-                    ast::Expr::PathExpr(_) => reborrow_hints(hints, sema, config, &expr),
+                    // ast::Expr::PathExpr(_) => reborrow_hints(hints, sema, config, &expr),
                     _ => None,
                 }
             },
@@ -617,30 +628,83 @@ fn closure_ret_hints(
     Some(())
 }
 
-fn reborrow_hints(
+fn adjustment_hints(
     acc: &mut Vec<InlayHint>,
     sema: &Semantics<'_, RootDatabase>,
     config: &InlayHintsConfig,
     expr: &ast::Expr,
 ) -> Option<()> {
-    if config.reborrow_hints == ReborrowHints::Never {
+    if config.adjustment_hints == AdjustmentHints::Never {
-        return None;
+        // return None;
     }
 
+    let parent = expr.syntax().parent().and_then(ast::Expr::cast);
     let descended = sema.descend_node_into_attributes(expr.clone()).pop();
     let desc_expr = descended.as_ref().unwrap_or(expr);
-    let mutability = sema.is_implicit_reborrow(desc_expr)?;
+    let adjustments = sema.expr_adjustments(desc_expr).filter(|it| !it.is_empty())?;
-    let label = match mutability {
+    let needs_parens = match parent {
-        hir::Mutability::Shared if config.reborrow_hints != ReborrowHints::MutableOnly => "&*",
+        Some(parent) => {
-        hir::Mutability::Mut => "&mut *",
+            match parent {
-        _ => return None,
+                ast::Expr::AwaitExpr(_)
+                | ast::Expr::CallExpr(_)
+                | ast::Expr::CastExpr(_)
+                | ast::Expr::FieldExpr(_)
+                | ast::Expr::MethodCallExpr(_)
+                | ast::Expr::TryExpr(_) => true,
+                // FIXME: shorthands need special casing, though not sure if adjustments are even valid there
+                ast::Expr::RecordExpr(_) => false,
+                ast::Expr::IndexExpr(index) => index.base().as_ref() == Some(expr),
+                _ => false,
+            }
+        }
+        None => false,
     };
-    acc.push(InlayHint {
+    if needs_parens {
-        range: expr.syntax().text_range(),
+        acc.push(InlayHint {
-        kind: InlayKind::ImplicitReborrowHint,
+            range: expr.syntax().text_range(),
-        label: label.to_string().into(),
+            kind: InlayKind::AdjustmentHint,
-        tooltip: Some(InlayTooltip::String("Compiler inserted reborrow".into())),
+            label: "(".into(),
-    });
+            tooltip: None,
+        });
+    }
+    for adjustment in adjustments.into_iter().rev() {
+        // FIXME: Add some nicer tooltips to each of these
+        let text = match adjustment {
+            Adjust::NeverToAny => "<never-to-any>",
+            Adjust::Deref(None) => "*",
+            Adjust::Deref(Some(OverloadedDeref(Mutability::Mut))) => "*",
+            Adjust::Deref(Some(OverloadedDeref(Mutability::Shared))) => "*",
+            Adjust::Borrow(AutoBorrow::Ref(Mutability::Shared)) => "&",
+            Adjust::Borrow(AutoBorrow::Ref(Mutability::Mut)) => "&mut ",
+            Adjust::Borrow(AutoBorrow::RawPtr(Mutability::Shared)) => "&raw const ",
+            Adjust::Borrow(AutoBorrow::RawPtr(Mutability::Mut)) => "&raw mut ",
+            // some of these could be represented via `as` casts, but that's not too nice and
+            // handling everything as a prefix expr makes the `(` and `)` insertion easier
+            Adjust::Pointer(cast) => match cast {
+                PointerCast::ReifyFnPointer => "<fn-item-to-fn-pointer>",
+                PointerCast::UnsafeFnPointer => "<safe-fn-pointer-to-unsafe-fn-pointer>",
+                PointerCast::ClosureFnPointer(Safety::Unsafe) => "<closure-to-unsafe-fn-pointer>",
+                PointerCast::ClosureFnPointer(Safety::Safe) => "<closure-to-fn-pointer>",
+                PointerCast::MutToConstPointer => "<mut-ptr-to-const-ptr>",
+                PointerCast::ArrayToPointer => "<array-ptr-to-element-ptr>",
+                PointerCast::Unsize => "<unsize>",
+            },
+        };
+        acc.push(InlayHint {
+            range: expr.syntax().text_range(),
+            kind: InlayKind::AdjustmentHint,
+            label: text.into(),
+            tooltip: None,
+        });
+    }
+    if needs_parens {
+        acc.push(InlayHint {
+            range: expr.syntax().text_range(),
+            kind: InlayKind::AdjustmentHintClosingParenthesis,
+            label: ")".into(),
+            tooltip: None,
+        });
+    }
     Some(())
 }
 
@@ -785,23 +849,23 @@ fn binding_mode_hints(
             tooltip: Some(InlayTooltip::String("Inferred binding mode".into())),
         });
     });
-    match pat {
+    // match pat {
-        ast::Pat::IdentPat(pat) if pat.ref_token().is_none() && pat.mut_token().is_none() => {
+    //     ast::Pat::IdentPat(pat) if pat.ref_token().is_none() && pat.mut_token().is_none() => {
-            let bm = sema.binding_mode_of_pat(pat)?;
+    //         let bm = sema.binding_mode_of_pat(pat)?;
-            let bm = match bm {
+    //         let bm = match bm {
-                hir::BindingMode::Move => return None,
+    //             hir::BindingMode::Move => return None,
-                hir::BindingMode::Ref(Mutability::Mut) => "ref mut",
+    //             hir::BindingMode::Ref(Mutability::Mut) => "ref mut",
-                hir::BindingMode::Ref(Mutability::Shared) => "ref",
+    //             hir::BindingMode::Ref(Mutability::Shared) => "ref",
-            };
+    //         };
-            acc.push(InlayHint {
+    //         acc.push(InlayHint {
-                range,
+    //             range,
-                kind: InlayKind::BindingModeHint,
+    //             kind: InlayKind::BindingModeHint,
-                label: bm.to_string().into(),
+    //             label: bm.to_string().into(),
-                tooltip: Some(InlayTooltip::String("Inferred binding mode".into())),
+    //             tooltip: Some(InlayTooltip::String("Inferred binding mode".into())),
-            });
+    //         });
-        }
+    //     }
-        _ => (),
+    //     _ => (),
-    }
+    // }
 
     Some(())
 }
@@ -1218,7 +1282,7 @@ mod tests {
     use syntax::{TextRange, TextSize};
     use test_utils::extract_annotations;
 
-    use crate::inlay_hints::ReborrowHints;
+    use crate::inlay_hints::AdjustmentHints;
     use crate::{fixture, inlay_hints::InlayHintsConfig, LifetimeElisionHints};
 
     use super::ClosureReturnTypeHints;
@@ -1230,7 +1294,7 @@ mod tests {
         chaining_hints: false,
         lifetime_elision_hints: LifetimeElisionHints::Never,
         closure_return_type_hints: ClosureReturnTypeHints::Never,
-        reborrow_hints: ReborrowHints::Always,
+        adjustment_hints: AdjustmentHints::Always,
         binding_mode_hints: false,
         hide_named_constructor_hints: false,
         hide_closure_initialization_hints: false,
@@ -1242,7 +1306,7 @@ mod tests {
         type_hints: true,
         parameter_hints: true,
         chaining_hints: true,
-        reborrow_hints: ReborrowHints::Always,
+        adjustment_hints: AdjustmentHints::Always,
         closure_return_type_hints: ClosureReturnTypeHints::WithBlock,
         binding_mode_hints: true,
         lifetime_elision_hints: LifetimeElisionHints::Always,
@@ -2849,7 +2913,7 @@ impl () {
     fn hints_implicit_reborrow() {
         check_with_config(
             InlayHintsConfig {
-                reborrow_hints: ReborrowHints::Always,
+                adjustment_hints: AdjustmentHints::Always,
                 parameter_hints: true,
                 ..DISABLED_CONFIG
             },

crates/ide/src/lib.rs

@@ -81,8 +81,8 @@ pub use crate::{
     highlight_related::{HighlightRelatedConfig, HighlightedRange},
     hover::{HoverAction, HoverConfig, HoverDocFormat, HoverGotoTypeData, HoverResult},
     inlay_hints::{
-        ClosureReturnTypeHints, InlayHint, InlayHintLabel, InlayHintsConfig, InlayKind,
+        AdjustmentHints, ClosureReturnTypeHints, InlayHint, InlayHintLabel, InlayHintsConfig,
-        InlayTooltip, LifetimeElisionHints, ReborrowHints,
+        InlayKind, InlayTooltip, LifetimeElisionHints,
     },
     join_lines::JoinLinesConfig,
     markup::Markup,

crates/ide/src/static_index.rs

@@ -111,7 +111,7 @@ impl StaticIndex<'_> {
                     chaining_hints: true,
                     closure_return_type_hints: crate::ClosureReturnTypeHints::WithBlock,
                     lifetime_elision_hints: crate::LifetimeElisionHints::Never,
-                    reborrow_hints: crate::ReborrowHints::Never,
+                    adjustment_hints: crate::AdjustmentHints::Never,
                     hide_named_constructor_hints: false,
                     hide_closure_initialization_hints: false,
                     param_names_for_lifetime_elision_hints: false,

crates/rust-analyzer/src/config.rs

@@ -261,6 +261,7 @@ config_data! {
         files_excludeDirs: Vec<PathBuf> = "[]",
         /// Controls file watching implementation.
         files_watcher: FilesWatcherDef = "\"client\"",
+
         /// Enables highlighting of related references while the cursor is on `break`, `loop`, `while`, or `for` keywords.
         highlightRelated_breakPoints_enable: bool = "true",
         /// Enables highlighting of all exit points while the cursor is on any `return`, `?`, `fn`, or return type arrow (`->`).
@@ -1200,10 +1201,10 @@ impl Config {
             hide_closure_initialization_hints: self
                 .data
                 .inlayHints_typeHints_hideClosureInitialization,
-            reborrow_hints: match self.data.inlayHints_reborrowHints_enable {
+            adjustment_hints: match self.data.inlayHints_reborrowHints_enable {
-                ReborrowHintsDef::Always => ide::ReborrowHints::Always,
+                ReborrowHintsDef::Always => ide::AdjustmentHints::Always,
-                ReborrowHintsDef::Never => ide::ReborrowHints::Never,
+                ReborrowHintsDef::Never => ide::AdjustmentHints::Never,
-                ReborrowHintsDef::Mutable => ide::ReborrowHints::MutableOnly,
+                ReborrowHintsDef::Mutable => ide::AdjustmentHints::MutableOnly,
             },
             binding_mode_hints: self.data.inlayHints_bindingModeHints_enable,
             param_names_for_lifetime_elision_hints: self

crates/rust-analyzer/src/to_proto.rs

@@ -440,32 +440,35 @@ pub(crate) fn inlay_hint(
     Ok(lsp_types::InlayHint {
         position: match inlay_hint.kind {
             // before annotated thing
-            InlayKind::ParameterHint
+            InlayKind::ParameterHint | InlayKind::AdjustmentHint | InlayKind::BindingModeHint => {
-            | InlayKind::ImplicitReborrowHint
+                position(line_index, inlay_hint.range.start())
-            | InlayKind::BindingModeHint => position(line_index, inlay_hint.range.start()),
+            }
             // after annotated thing
             InlayKind::ClosureReturnTypeHint
             | InlayKind::TypeHint
             | InlayKind::ChainingHint
             | InlayKind::GenericParamListHint
+            | InlayKind::AdjustmentHintClosingParenthesis
             | InlayKind::LifetimeHint
             | InlayKind::ClosingBraceHint => position(line_index, inlay_hint.range.end()),
         },
         padding_left: Some(match inlay_hint.kind {
             InlayKind::TypeHint => !render_colons,
             InlayKind::ChainingHint | InlayKind::ClosingBraceHint => true,
-            InlayKind::BindingModeHint
+            InlayKind::AdjustmentHintClosingParenthesis
+            | InlayKind::BindingModeHint
             | InlayKind::ClosureReturnTypeHint
             | InlayKind::GenericParamListHint
-            | InlayKind::ImplicitReborrowHint
+            | InlayKind::AdjustmentHint
             | InlayKind::LifetimeHint
             | InlayKind::ParameterHint => false,
         }),
         padding_right: Some(match inlay_hint.kind {
-            InlayKind::ChainingHint
+            InlayKind::AdjustmentHintClosingParenthesis
+            | InlayKind::ChainingHint
             | InlayKind::ClosureReturnTypeHint
             | InlayKind::GenericParamListHint
-            | InlayKind::ImplicitReborrowHint
+            | InlayKind::AdjustmentHint
             | InlayKind::TypeHint
             | InlayKind::ClosingBraceHint => false,
             InlayKind::BindingModeHint => inlay_hint.label.as_simple_str() != Some("&"),
@@ -476,10 +479,11 @@ pub(crate) fn inlay_hint(
             InlayKind::ClosureReturnTypeHint | InlayKind::TypeHint | InlayKind::ChainingHint => {
                 Some(lsp_types::InlayHintKind::TYPE)
             }
-            InlayKind::BindingModeHint
+            InlayKind::AdjustmentHintClosingParenthesis
+            | InlayKind::BindingModeHint
             | InlayKind::GenericParamListHint
             | InlayKind::LifetimeHint
-            | InlayKind::ImplicitReborrowHint
+            | InlayKind::AdjustmentHint
             | InlayKind::ClosingBraceHint => None,
         },
         text_edits: None,