feat: Add dereferencing autocomplete

6 files changed, 110 insertions, 37 deletions

diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/item.rs b/src/tools/rust-analyzer/crates/ide-completion/src/item.rs
index b91f915619d..dc2f9a76802 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/item.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/item.rs
@@ -79,7 +79,7 @@ pub struct CompletionItem {
     // FIXME: We shouldn't expose Mutability here (that is HIR types at all), its fine for now though
     // until we have more splitting completions in which case we should think about
     // generalizing this. See https://github.com/rust-lang/rust-analyzer/issues/12571
-    pub ref_match: Option<(Mutability, TextSize)>,
+    pub ref_match: Option<(CompletionItemRefMode, TextSize)>,
 
     /// The import data to add to completion's edits.
     /// (ImportPath, LastSegment)
@@ -128,8 +128,15 @@ impl fmt::Debug for CompletionItem {
             s.field("relevance", &self.relevance);
         }
 
-        if let Some((mutability, offset)) = &self.ref_match {
-            s.field("ref_match", &format!("&{}@{offset:?}", mutability.as_keyword_for_ref()));
+        if let Some((ref_mode, offset)) = self.ref_match {
+            let prefix = match ref_mode {
+                CompletionItemRefMode::Reference(mutability) => match mutability {
+                    Mutability::Shared => "&",
+                    Mutability::Mut => "&mut ",
+                },
+                CompletionItemRefMode::Dereference => "*",
+            };
+            s.field("ref_match", &format!("{}@{offset:?}", prefix));
         }
         if self.trigger_call_info {
             s.field("trigger_call_info", &true);
@@ -400,6 +407,12 @@ impl CompletionItemKind {
     }
 }
 
+#[derive(Copy, Clone, Debug)]
+pub enum CompletionItemRefMode {
+    Reference(Mutability),
+    Dereference,
+}
+
 impl CompletionItem {
     pub(crate) fn new(
         kind: impl Into<CompletionItemKind>,
@@ -441,15 +454,14 @@ impl CompletionItem {
         let mut relevance = self.relevance;
         relevance.type_match = Some(CompletionRelevanceTypeMatch::Exact);
 
-        self.ref_match.map(|(mutability, offset)| {
-            (
-                format!("&{}{}", mutability.as_keyword_for_ref(), self.label.primary),
-                ide_db::text_edit::Indel::insert(
-                    offset,
-                    format!("&{}", mutability.as_keyword_for_ref()),
-                ),
-                relevance,
-            )
+        self.ref_match.map(|(mode, offset)| {
+            let prefix = match mode {
+                CompletionItemRefMode::Reference(Mutability::Shared) => "&",
+                CompletionItemRefMode::Reference(Mutability::Mut) => "&mut ",
+                CompletionItemRefMode::Dereference => "*",
+            };
+            let label = format!("{prefix}{}", self.label.primary);
+            (label, ide_db::text_edit::Indel::insert(offset, String::from(prefix)), relevance)
         })
     }
 }
@@ -473,7 +485,7 @@ pub(crate) struct Builder {
     deprecated: bool,
     trigger_call_info: bool,
     relevance: CompletionRelevance,
-    ref_match: Option<(Mutability, TextSize)>,
+    ref_match: Option<(CompletionItemRefMode, TextSize)>,
     edition: Edition,
 }
 
@@ -657,8 +669,12 @@ impl Builder {
         self.imports_to_add.push(import_to_add);
         self
     }
-    pub(crate) fn ref_match(&mut self, mutability: Mutability, offset: TextSize) -> &mut Builder {
-        self.ref_match = Some((mutability, offset));
+    pub(crate) fn ref_match(
+        &mut self,
+        ref_mode: CompletionItemRefMode,
+        offset: TextSize,
+    ) -> &mut Builder {
+        self.ref_match = Some((ref_mode, offset));
         self
     }
 }
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/lib.rs b/src/tools/rust-analyzer/crates/ide-completion/src/lib.rs
index ca6c9ad9f08..56d7eeaf8ea 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/lib.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/lib.rs
@@ -33,8 +33,9 @@ use crate::{
 pub use crate::{
     config::{AutoImportExclusionType, CallableSnippets, CompletionConfig},
     item::{
-        CompletionItem, CompletionItemKind, CompletionRelevance, CompletionRelevancePostfixMatch,
-        CompletionRelevanceReturnType, CompletionRelevanceTypeMatch,
+        CompletionItem, CompletionItemKind, CompletionItemRefMode, CompletionRelevance,
+        CompletionRelevancePostfixMatch, CompletionRelevanceReturnType,
+        CompletionRelevanceTypeMatch,
     },
     snippet::{Snippet, SnippetScope},
 };
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/render.rs b/src/tools/rust-analyzer/crates/ide-completion/src/render.rs
index eb5d136b8b3..0bfb8900229 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/render.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/render.rs
@@ -28,7 +28,8 @@ use crate::{
         literal::render_variant_lit,
         macro_::{render_macro, render_macro_pat},
     },
-    CompletionContext, CompletionItem, CompletionItemKind, CompletionRelevance,
+    CompletionContext, CompletionItem, CompletionItemKind, CompletionItemRefMode,
+    CompletionRelevance,
 };
 /// Interface for data and methods required for items rendering.
 #[derive(Debug, Clone)]
@@ -192,8 +193,8 @@ pub(crate) fn render_field(
     }
     if let Some(receiver) = &dot_access.receiver {
         if let Some(original) = ctx.completion.sema.original_ast_node(receiver.clone()) {
-            if let Some(ref_match) = compute_ref_match(ctx.completion, ty) {
-                item.ref_match(ref_match, original.syntax().text_range().start());
+            if let Some(ref_mode) = compute_ref_match(ctx.completion, ty) {
+                item.ref_match(ref_mode, original.syntax().text_range().start());
             }
         }
     }
@@ -638,20 +639,34 @@ fn compute_exact_name_match(ctx: &CompletionContext<'_>, completion_name: &str)
 fn compute_ref_match(
     ctx: &CompletionContext<'_>,
     completion_ty: &hir::Type,
-) -> Option<hir::Mutability> {
+) -> Option<CompletionItemRefMode> {
     let expected_type = ctx.expected_type.as_ref()?;
-    if completion_ty != expected_type {
-        let expected_type_without_ref = expected_type.remove_ref()?;
-        if completion_ty.autoderef(ctx.db).any(|deref_ty| deref_ty == expected_type_without_ref) {
+    let expected_without_ref = expected_type.remove_ref();
+    let completion_without_ref = completion_ty.remove_ref();
+
+    if completion_ty == expected_type {
+        return None;
+    }
+
+    if let Some(expected_without_ref) = &expected_without_ref {
+        if completion_ty.autoderef(ctx.db).any(|ty| ty == *expected_without_ref) {
             cov_mark::hit!(suggest_ref);
             let mutability = if expected_type.is_mutable_reference() {
                 hir::Mutability::Mut
             } else {
                 hir::Mutability::Shared
             };
-            return Some(mutability);
-        };
+            return Some(CompletionItemRefMode::Reference(mutability));
+        }
+    }
+
+    if let Some(completion_without_ref) = completion_without_ref {
+        if completion_without_ref == *expected_type && completion_without_ref.is_copy(ctx.db) {
+            cov_mark::hit!(suggest_deref);
+            return Some(CompletionItemRefMode::Dereference);
+        }
     }
+
     None
 }
 
@@ -664,16 +679,16 @@ fn path_ref_match(
     if let Some(original_path) = &path_ctx.original_path {
         // At least one char was typed by the user already, in that case look for the original path
         if let Some(original_path) = completion.sema.original_ast_node(original_path.clone()) {
-            if let Some(ref_match) = compute_ref_match(completion, ty) {
-                item.ref_match(ref_match, original_path.syntax().text_range().start());
+            if let Some(ref_mode) = compute_ref_match(completion, ty) {
+                item.ref_match(ref_mode, original_path.syntax().text_range().start());
             }
         }
     } else {
         // completion requested on an empty identifier, there is no path here yet.
         // FIXME: This might create inconsistent completions where we show a ref match in macro inputs
         // as long as nothing was typed yet
-        if let Some(ref_match) = compute_ref_match(completion, ty) {
-            item.ref_match(ref_match, completion.position.offset);
+        if let Some(ref_mode) = compute_ref_match(completion, ty) {
+            item.ref_match(ref_mode, completion.position.offset);
         }
     }
 }
@@ -2065,7 +2080,42 @@ fn main() {
     }
 
     #[test]
-    fn suggest_deref() {
+    fn suggest_deref_copy() {
+        cov_mark::check!(suggest_deref);
+        check_relevance(
+            r#"
+//- minicore: copy
+struct Foo;
+
+impl Copy for Foo {}
+impl Clone for Foo {
+    fn clone(&self) -> Self { *self }
+}
+
+fn bar(x: Foo) {}
+
+fn main() {
+    let foo = &Foo;
+    bar($0);
+}
+"#,
+            expect![[r#"
+                st Foo Foo [type]
+                st Foo Foo [type]
+                ex Foo  [type]
+                lc foo &Foo [local]
+                lc *foo [type+local]
+                fn bar(…) fn(Foo) []
+                fn main() fn() []
+                md core  []
+                tt Clone  []
+                tt Copy  []
+            "#]],
+        );
+    }
+
+    #[test]
+    fn suggest_deref_trait() {
         check_relevance(
             r#"
 //- minicore: deref
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/render/function.rs b/src/tools/rust-analyzer/crates/ide-completion/src/render/function.rs
index a859d79e243..96a58aaa815 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/render/function.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/render/function.rs
@@ -143,8 +143,8 @@ fn render(
         }
         FuncKind::Method(DotAccess { receiver: Some(receiver), .. }, _) => {
             if let Some(original_expr) = completion.sema.original_ast_node(receiver.clone()) {
-                if let Some(ref_match) = compute_ref_match(completion, &ret_type) {
-                    item.ref_match(ref_match, original_expr.syntax().text_range().start());
+                if let Some(ref_mode) = compute_ref_match(completion, &ret_type) {
+                    item.ref_match(ref_mode, original_expr.syntax().text_range().start());
                 }
             }
         }
diff --git a/src/tools/rust-analyzer/crates/ide/src/lib.rs b/src/tools/rust-analyzer/crates/ide/src/lib.rs
index 183962be281..043e8542154 100644
--- a/src/tools/rust-analyzer/crates/ide/src/lib.rs
+++ b/src/tools/rust-analyzer/crates/ide/src/lib.rs
@@ -120,7 +120,7 @@ pub use ide_assists::{
 };
 pub use ide_completion::{
     CallableSnippets, CompletionConfig, CompletionFieldsToResolve, CompletionItem,
-    CompletionItemKind, CompletionRelevance, Snippet, SnippetScope,
+    CompletionItemKind, CompletionItemRefMode, CompletionRelevance, Snippet, SnippetScope,
 };
 pub use ide_db::text_edit::{Indel, TextEdit};
 pub use ide_db::{
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/lib.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/lib.rs
index e7f5a7f5e78..61ec576dd4f 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/lib.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/lib.rs
@@ -47,7 +47,8 @@ use self::lsp::ext as lsp_ext;
 #[cfg(test)]
 mod integrated_benchmarks;
 
-use ide::{CompletionItem, CompletionRelevance};
+use hir::Mutability;
+use ide::{CompletionItem, CompletionItemRefMode, CompletionRelevance};
 use serde::de::DeserializeOwned;
 use tenthash::TentHasher;
 
@@ -132,8 +133,13 @@ fn completion_item_hash(item: &CompletionItem, is_ref_completion: bool) -> [u8;
         hasher.update(detail);
     }
     hash_completion_relevance(&mut hasher, &item.relevance);
-    if let Some((mutability, text_size)) = &item.ref_match {
-        hasher.update(mutability.as_keyword_for_ref());
+    if let Some((ref_mode, text_size)) = &item.ref_match {
+        let prefix = match ref_mode {
+            CompletionItemRefMode::Reference(Mutability::Shared) => "&",
+            CompletionItemRefMode::Reference(Mutability::Mut) => "&mut ",
+            CompletionItemRefMode::Dereference => "*",
+        };
+        hasher.update(prefix);
         hasher.update(u32::from(*text_size).to_le_bytes());
     }
     for (import_path, import_name) in &item.import_to_add {