Implement location link for type inlay hints

Author: HKalbasi

crates/hir-ty/src/display.rs

@@ -16,7 +16,7 @@ use hir_def::{
     path::{Path, PathKind},
     type_ref::{ConstScalar, TraitBoundModifier, TypeBound, TypeRef},
     visibility::Visibility,
-    HasModule, ItemContainerId, Lookup, ModuleId, TraitId,
+    HasModule, ItemContainerId, Lookup, ModuleDefId, ModuleId, TraitId,
 };
 use hir_expand::{hygiene::Hygiene, name::Name};
 use itertools::Itertools;
@@ -35,16 +35,44 @@ use crate::{
     TraitRefExt, Ty, TyExt, TyKind, WhereClause,
 };
 
+pub trait HirWrite: fmt::Write {
+    fn start_location_link(&mut self, location: ModuleDefId);
+    fn end_location_link(&mut self);
+}
+
+// String will ignore link metadata
+impl HirWrite for String {
+    fn start_location_link(&mut self, _: ModuleDefId) {}
+
+    fn end_location_link(&mut self) {}
+}
+
+// `core::Formatter` will ignore metadata
+impl HirWrite for fmt::Formatter<'_> {
+    fn start_location_link(&mut self, _: ModuleDefId) {}
+    fn end_location_link(&mut self) {}
+}
+
 pub struct HirFormatter<'a> {
     pub db: &'a dyn HirDatabase,
-    fmt: &'a mut dyn fmt::Write,
+    fmt: &'a mut dyn HirWrite,
     buf: String,
     curr_size: usize,
     pub(crate) max_size: Option<usize>,
     omit_verbose_types: bool,
     display_target: DisplayTarget,
 }
 
+impl HirFormatter<'_> {
+    fn start_location_link(&mut self, location: ModuleDefId) {
+        self.fmt.start_location_link(location);
+    }
+
+    fn end_location_link(&mut self) {
+        self.fmt.end_location_link();
+    }
+}
+
 pub trait HirDisplay {
     fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError>;
 
@@ -245,20 +273,26 @@ pub struct HirDisplayWrapper<'a, T> {
     display_target: DisplayTarget,
 }
 
-impl<'a, T> fmt::Display for HirDisplayWrapper<'a, T>
-where
-    T: HirDisplay,
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self.t.hir_fmt(&mut HirFormatter {
+impl<T: HirDisplay> HirDisplayWrapper<'_, T> {
+    pub fn write_to<F: HirWrite>(&self, f: &mut F) -> Result<(), HirDisplayError> {
+        self.t.hir_fmt(&mut HirFormatter {
             db: self.db,
             fmt: f,
             buf: String::with_capacity(20),
             curr_size: 0,
             max_size: self.max_size,
             omit_verbose_types: self.omit_verbose_types,
             display_target: self.display_target,
-        }) {
+        })
+    }
+}
+
+impl<'a, T> fmt::Display for HirDisplayWrapper<'a, T>
+where
+    T: HirDisplay,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.write_to(f) {
             Ok(()) => Ok(()),
             Err(HirDisplayError::FmtError) => Err(fmt::Error),
             Err(HirDisplayError::DisplaySourceCodeError(_)) => {
@@ -530,6 +564,7 @@ impl HirDisplay for Ty {
                 }
             }
             TyKind::Adt(AdtId(def_id), parameters) => {
+                f.start_location_link((*def_id).into());
                 match f.display_target {
                     DisplayTarget::Diagnostics | DisplayTarget::Test => {
                         let name = match *def_id {
@@ -554,6 +589,7 @@ impl HirDisplay for Ty {
                         }
                     }
                 }
+                f.end_location_link();
 
                 if parameters.len(Interner) > 0 {
                     let parameters_to_write = if f.display_target.is_source_code()

crates/hir/src/lib.rs

@@ -114,12 +114,20 @@ pub use {
         path::{ModPath, PathKind},
         type_ref::{Mutability, TypeRef},
         visibility::Visibility,
+        // FIXME: This is here since it is input of a method in `HirWrite`
+        // and things outside of hir need to implement that trait. We probably
+        // should move whole `hir_ty::display` to this crate so we will become
+        // able to use `ModuleDef` or `Definition` instead of `ModuleDefId`.
+        ModuleDefId,
     },
     hir_expand::{
         name::{known, Name},
         ExpandResult, HirFileId, InFile, MacroFile, Origin,
     },
-    hir_ty::{display::HirDisplay, PointerCast, Safety},
+    hir_ty::{
+        display::{HirDisplay, HirWrite},
+        PointerCast, Safety,
+    },
 };
 
 // These are negative re-exports: pub using these names is forbidden, they

crates/ide/src/inlay_hints.rs

@@ -1,15 +1,19 @@
-use std::fmt;
+use std::{
+    fmt::{self, Write},
+    mem::take,
+};
 
 use either::Either;
-use hir::{known, HasVisibility, HirDisplay, Semantics};
+use hir::{known, HasVisibility, HirDisplay, HirWrite, ModuleDef, ModuleDefId, Semantics};
 use ide_db::{base_db::FileRange, famous_defs::FamousDefs, RootDatabase};
 use itertools::Itertools;
+use stdx::never;
 use syntax::{
     ast::{self, AstNode},
     match_ast, NodeOrToken, SyntaxNode, TextRange, TextSize,
 };
 
-use crate::FileId;
+use crate::{navigation_target::TryToNav, FileId};
 
 mod closing_brace;
 mod implicit_static;
@@ -89,6 +93,7 @@ pub enum InlayTooltip {
     HoverOffset(FileId, TextSize),
 }
 
+#[derive(Default)]
 pub struct InlayHintLabel {
     pub parts: Vec<InlayHintLabelPart>,
 }
@@ -172,6 +177,96 @@ impl fmt::Debug for InlayHintLabelPart {
     }
 }
 
+#[derive(Debug)]
+struct InlayHintLabelBuilder<'a> {
+    db: &'a RootDatabase,
+    result: InlayHintLabel,
+    last_part: String,
+    location: Option<FileRange>,
+}
+
+impl fmt::Write for InlayHintLabelBuilder<'_> {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.last_part.write_str(s)
+    }
+}
+
+impl HirWrite for InlayHintLabelBuilder<'_> {
+    fn start_location_link(&mut self, def: ModuleDefId) {
+        if self.location.is_some() {
+            never!("location link is already started");
+        }
+        self.make_new_part();
+        let Some(location) = ModuleDef::from(def).try_to_nav(self.db) else { return };
+        let location =
+            FileRange { file_id: location.file_id, range: location.focus_or_full_range() };
+        self.location = Some(location);
+    }
+
+    fn end_location_link(&mut self) {
+        self.make_new_part();
+    }
+}
+
+impl InlayHintLabelBuilder<'_> {
+    fn make_new_part(&mut self) {
+        self.result.parts.push(InlayHintLabelPart {
+            text: take(&mut self.last_part),
+            linked_location: self.location.take(),
+        });
+    }
+
+    fn finish(mut self) -> InlayHintLabel {
+        self.make_new_part();
+        self.result
+    }
+}
+
+fn label_of_ty(
+    sema: &Semantics<'_, RootDatabase>,
+    desc_pat: &impl AstNode,
+    config: &InlayHintsConfig,
+    ty: hir::Type,
+) -> Option<InlayHintLabel> {
+    fn rec(
+        sema: &Semantics<'_, RootDatabase>,
+        famous_defs: &FamousDefs<'_, '_>,
+        mut max_length: Option<usize>,
+        ty: hir::Type,
+        label_builder: &mut InlayHintLabelBuilder<'_>,
+    ) {
+        let iter_item_type = hint_iterator(sema, &famous_defs, &ty);
+        match iter_item_type {
+            Some(ty) => {
+                const LABEL_START: &str = "impl Iterator<Item = ";
+                const LABEL_END: &str = ">";
+
+                max_length =
+                    max_length.map(|len| len.saturating_sub(LABEL_START.len() + LABEL_END.len()));
+
+                label_builder.write_str(LABEL_START).unwrap();
+                rec(sema, famous_defs, max_length, ty, label_builder);
+                label_builder.write_str(LABEL_END).unwrap();
+            }
+            None => {
+                let _ = ty.display_truncated(sema.db, max_length).write_to(label_builder);
+            }
+        };
+    }
+
+    let krate = sema.scope(desc_pat.syntax())?.krate();
+    let famous_defs = FamousDefs(sema, krate);
+    let mut label_builder = InlayHintLabelBuilder {
+        db: sema.db,
+        last_part: String::new(),
+        location: None,
+        result: InlayHintLabel::default(),
+    };
+    rec(sema, &famous_defs, config.max_length, ty, &mut label_builder);
+    let r = label_builder.finish();
+    Some(r)
+}
+
 // Feature: Inlay Hints
 //
 // rust-analyzer shows additional information inline with the source code.
@@ -224,7 +319,7 @@ pub(crate) fn inlay_hints(
 
 fn hints(
     hints: &mut Vec<InlayHint>,
-    famous_defs @ FamousDefs(sema, _): &FamousDefs<'_, '_>,
+    FamousDefs(sema, _): &FamousDefs<'_, '_>,
     config: &InlayHintsConfig,
     file_id: FileId,
     node: SyntaxNode,
@@ -233,14 +328,14 @@ fn hints(
     match_ast! {
         match node {
             ast::Expr(expr) => {
-                chaining::hints(hints, sema, &famous_defs, config, file_id, &expr);
+                chaining::hints(hints, sema, 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) => {
                         param_name::hints(hints, sema, config, ast::Expr::from(it))
                     }
-                    ast::Expr::ClosureExpr(it) => closure_ret::hints(hints, sema, &famous_defs, config, file_id, it),
+                    ast::Expr::ClosureExpr(it) => closure_ret::hints(hints, sema, 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),
@@ -270,13 +365,12 @@ fn hints(
     };
 }
 
-/// Checks if the type is an Iterator from std::iter and replaces its hint with an `impl Iterator<Item = Ty>`.
+/// Checks if the type is an Iterator from std::iter and returns its item type.
 fn hint_iterator(
     sema: &Semantics<'_, RootDatabase>,
     famous_defs: &FamousDefs<'_, '_>,
-    config: &InlayHintsConfig,
     ty: &hir::Type,
-) -> Option<String> {
+) -> Option<hir::Type> {
     let db = sema.db;
     let strukt = ty.strip_references().as_adt()?;
     let krate = strukt.module(db).krate();
@@ -299,21 +393,7 @@ fn hint_iterator(
             _ => None,
         })?;
         if let Some(ty) = ty.normalize_trait_assoc_type(db, &[], assoc_type_item) {
-            const LABEL_START: &str = "impl Iterator<Item = ";
-            const LABEL_END: &str = ">";
-
-            let ty_display = hint_iterator(sema, famous_defs, config, &ty)
-                .map(|assoc_type_impl| assoc_type_impl.to_string())
-                .unwrap_or_else(|| {
-                    ty.display_truncated(
-                        db,
-                        config
-                            .max_length
-                            .map(|len| len.saturating_sub(LABEL_START.len() + LABEL_END.len())),
-                    )
-                    .to_string()
-                });
-            return Some(format!("{}{}{}", LABEL_START, ty_display, LABEL_END));
+            return Some(ty);
         }
     }