Draft completion hashing

7 files changed, 133 insertions, 23 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 52f6bedaaa9..8878fbbea30 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/item.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/item.rs
@@ -346,8 +346,7 @@ pub enum CompletionItemKind {
 impl_from!(SymbolKind for CompletionItemKind);
 
 impl CompletionItemKind {
-    #[cfg(test)]
-    pub(crate) fn tag(self) -> &'static str {
+    pub fn tag(self) -> &'static str {
         match self {
             CompletionItemKind::SymbolKind(kind) => match kind {
                 SymbolKind::Attribute => "at",
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 cffdfa29f1a..14f42b40055 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/lib.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/lib.rs
@@ -34,6 +34,7 @@ pub use crate::{
     config::{CallableSnippets, CompletionConfig},
     item::{
         CompletionItem, CompletionItemKind, CompletionRelevance, CompletionRelevancePostfixMatch,
+        CompletionRelevanceReturnType, CompletionRelevanceTypeMatch,
     },
     snippet::{Snippet, SnippetScope},
 };
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/Cargo.toml b/src/tools/rust-analyzer/crates/rust-analyzer/Cargo.toml
index 2dd2f2242a0..022b0a0ecf1 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/Cargo.toml
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/Cargo.toml
@@ -24,6 +24,7 @@ anyhow.workspace = true
 crossbeam-channel.workspace = true
 dirs = "5.0.1"
 dissimilar.workspace = true
+ide-completion.workspace = true
 itertools.workspace = true
 scip = "0.5.1"
 lsp-types = { version = "=0.95.0", features = ["proposed"] }
@@ -34,6 +35,7 @@ rayon.workspace = true
 rustc-hash.workspace = true
 serde_json = { workspace = true, features = ["preserve_order"] }
 serde.workspace = true
+tenthash = "0.4.0"
 num_cpus = "1.15.0"
 mimalloc = { version = "0.1.30", default-features = false, optional = true }
 lsp-server.workspace = true
@@ -90,13 +92,13 @@ jemalloc = ["jemallocator", "profile/jemalloc"]
 force-always-assert = ["always-assert/force"]
 sysroot-abi = []
 in-rust-tree = [
-  "sysroot-abi",
-  "syntax/in-rust-tree",
-  "parser/in-rust-tree",
-  "hir/in-rust-tree",
-  "hir-def/in-rust-tree",
-  "hir-ty/in-rust-tree",
-  "load-cargo/in-rust-tree",
+    "sysroot-abi",
+    "syntax/in-rust-tree",
+    "parser/in-rust-tree",
+    "hir/in-rust-tree",
+    "hir-def/in-rust-tree",
+    "hir-ty/in-rust-tree",
+    "load-cargo/in-rust-tree",
 ]
 
 [lints]
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/request.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/request.rs
index 0fadfa6c420..9dd6dc999b4 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/request.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/request.rs
@@ -36,6 +36,7 @@ use triomphe::Arc;
 use vfs::{AbsPath, AbsPathBuf, FileId, VfsPath};
 
 use crate::{
+    completion_item_hash,
     config::{Config, RustfmtConfig, WorkspaceSymbolConfig},
     diagnostics::convert_diagnostic,
     global_state::{FetchWorkspaceRequest, GlobalState, GlobalStateSnapshot},
@@ -1122,12 +1123,15 @@ pub(crate) fn handle_completion_resolve(
         return Ok(original_completion);
     };
     let source_root = snap.analysis.source_root_id(file_id)?;
+    let Some(completion_hash_for_resolve) = &resolve_data.completion_item_hash else {
+        return Ok(original_completion);
+    };
 
     let mut forced_resolve_completions_config = snap.config.completion(Some(source_root));
     forced_resolve_completions_config.fields_to_resolve = CompletionFieldsToResolve::empty();
 
     let position = FilePosition { file_id, offset };
-    let Some(resolved_completions) = snap.analysis.completions(
+    let Some(completions) = snap.analysis.completions(
         &forced_resolve_completions_config,
         position,
         resolve_data.trigger_character,
@@ -1135,6 +1139,14 @@ pub(crate) fn handle_completion_resolve(
     else {
         return Ok(original_completion);
     };
+
+    let Some(corresponding_completion) = completions.into_iter().find(|completion_item| {
+        let hash = completion_item_hash(&completion_item, resolve_data.for_ref);
+        &hash == completion_hash_for_resolve
+    }) else {
+        return Ok(original_completion);
+    };
+
     let mut resolved_completions = to_proto::completion_items(
         &snap.config,
         &forced_resolve_completions_config.fields_to_resolve,
@@ -1142,15 +1154,11 @@ pub(crate) fn handle_completion_resolve(
         snap.file_version(position.file_id),
         resolve_data.position,
         resolve_data.trigger_character,
-        resolved_completions,
+        vec![corresponding_completion],
     );
-
-    let mut resolved_completion =
-        if resolved_completions.get(resolve_data.completion_item_index).is_some() {
-            resolved_completions.swap_remove(resolve_data.completion_item_index)
-        } else {
-            return Ok(original_completion);
-        };
+    let Some(mut resolved_completion) = resolved_completions.pop() else {
+        return Ok(original_completion);
+    };
 
     if !resolve_data.imports.is_empty() {
         let additional_edits = snap
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 234204695cb..8f74e75d3d3 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 +47,9 @@ use self::lsp::ext as lsp_ext;
 #[cfg(test)]
 mod integrated_benchmarks;
 
+use ide::{CompletionItem, CompletionRelevance, TextEdit, TextRange};
 use serde::de::DeserializeOwned;
+use tenthash::TentHasher;
 
 pub use crate::{
     lsp::capabilities::server_capabilities, main_loop::main_loop, reload::ws_to_crate_graph,
@@ -61,3 +63,90 @@ pub fn from_json<T: DeserializeOwned>(
     serde_json::from_value(json.clone())
         .map_err(|e| anyhow::format_err!("Failed to deserialize {what}: {e}; {json}"))
 }
+
+fn completion_item_hash(item: &CompletionItem, is_ref_completion: bool) -> [u8; 20] {
+    fn hash_text_range(hasher: &mut TentHasher, text_range: &TextRange) {
+        hasher.update(u32::from(text_range.start()).to_le_bytes());
+        hasher.update(u32::from(text_range.end()).to_le_bytes());
+    }
+
+    fn hash_text_edit(hasher: &mut TentHasher, edit: &TextEdit) {
+        for indel in edit.iter() {
+            hasher.update(&indel.insert);
+            hash_text_range(hasher, &indel.delete);
+        }
+    }
+
+    fn has_completion_relevance(hasher: &mut TentHasher, relevance: &CompletionRelevance) {
+        use ide_completion::{
+            CompletionRelevancePostfixMatch, CompletionRelevanceReturnType,
+            CompletionRelevanceTypeMatch,
+        };
+
+        if let Some(type_match) = &relevance.type_match {
+            let label = match type_match {
+                CompletionRelevanceTypeMatch::CouldUnify => "could_unify",
+                CompletionRelevanceTypeMatch::Exact => "exact",
+            };
+            hasher.update(label);
+        }
+        hasher.update(&[u8::from(relevance.exact_name_match), u8::from(relevance.is_local)]);
+        if let Some(trait_) = &relevance.trait_ {
+            hasher.update(&[u8::from(trait_.is_op_method), u8::from(trait_.notable_trait)]);
+        }
+        hasher.update(&[
+            u8::from(relevance.is_name_already_imported),
+            u8::from(relevance.requires_import),
+            u8::from(relevance.is_private_editable),
+        ]);
+        if let Some(postfix_match) = &relevance.postfix_match {
+            let label = match postfix_match {
+                CompletionRelevancePostfixMatch::NonExact => "non_exact",
+                CompletionRelevancePostfixMatch::Exact => "exact",
+            };
+            hasher.update(label);
+        }
+        if let Some(function) = &relevance.function {
+            hasher.update(&[u8::from(function.has_params), u8::from(function.has_self_param)]);
+            let label = match function.return_type {
+                CompletionRelevanceReturnType::Other => "other",
+                CompletionRelevanceReturnType::DirectConstructor => "direct_constructor",
+                CompletionRelevanceReturnType::Constructor => "constructor",
+                CompletionRelevanceReturnType::Builder => "builder",
+            };
+            hasher.update(label);
+        }
+    }
+
+    let mut hasher = TentHasher::new();
+    hasher.update(&[
+        u8::from(is_ref_completion),
+        u8::from(item.is_snippet),
+        u8::from(item.deprecated),
+        u8::from(item.trigger_call_info),
+    ]);
+    hasher.update(&item.label);
+    if let Some(label_detail) = &item.label_detail {
+        hasher.update(label_detail);
+    }
+    hash_text_range(&mut hasher, &item.source_range);
+    hash_text_edit(&mut hasher, &item.text_edit);
+    hasher.update(item.kind.tag());
+    hasher.update(&item.lookup);
+    if let Some(detail) = &item.detail {
+        hasher.update(detail);
+    }
+    if let Some(documentation) = &item.documentation {
+        hasher.update(documentation.as_str());
+    }
+    has_completion_relevance(&mut hasher, &item.relevance);
+    if let Some((mutability, text_size)) = &item.ref_match {
+        hasher.update(mutability.as_keyword_for_ref());
+        hasher.update(u32::from(*text_size).to_le_bytes());
+    }
+    for (import_path, import_name) in &item.import_to_add {
+        hasher.update(import_path);
+        hasher.update(import_name);
+    }
+    hasher.finalize()
+}
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/lsp/ext.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/lsp/ext.rs
index 6ddfe118d5e..7d60ae703b2 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/lsp/ext.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/lsp/ext.rs
@@ -826,7 +826,8 @@ pub struct CompletionResolveData {
     pub imports: Vec<CompletionImport>,
     pub version: Option<i32>,
     pub trigger_character: Option<char>,
-    pub completion_item_index: usize,
+    pub for_ref: bool,
+    pub completion_item_hash: Option<[u8; 20]>,
 }
 
 #[derive(Debug, Serialize, Deserialize)]
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/lsp/to_proto.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/lsp/to_proto.rs
index d444f90a131..97caed8f08c 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/lsp/to_proto.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/lsp/to_proto.rs
@@ -21,6 +21,7 @@ use serde_json::to_value;
 use vfs::AbsPath;
 
 use crate::{
+    completion_item_hash,
     config::{CallInfoConfig, Config},
     global_state::GlobalStateSnapshot,
     line_index::{LineEndings, LineIndex, PositionEncoding},
@@ -274,6 +275,11 @@ fn completion_item(
     completion_trigger_character: Option<char>,
     item: CompletionItem,
 ) {
+    let original_completion_item = if fields_to_resolve == &CompletionFieldsToResolve::empty() {
+        None
+    } else {
+        Some(item.clone())
+    };
     let insert_replace_support = config.insert_replace_support().then_some(tdpp.position);
     let ref_match = item.ref_match();
 
@@ -393,16 +399,17 @@ fn completion_item(
             Vec::new()
         };
     let (ref_resolve_data, resolve_data) = if something_to_resolve || !imports.is_empty() {
-        let mut item_index = acc.len();
         let ref_resolve_data = if ref_match.is_some() {
             let ref_resolve_data = lsp_ext::CompletionResolveData {
                 position: tdpp.clone(),
                 imports: Vec::new(),
                 version,
                 trigger_character: completion_trigger_character,
-                completion_item_index: item_index,
+                for_ref: true,
+                completion_item_hash: original_completion_item
+                    .as_ref()
+                    .map(|item| completion_item_hash(item, true)),
             };
-            item_index += 1;
             Some(to_value(ref_resolve_data).unwrap())
         } else {
             None
@@ -412,7 +419,10 @@ fn completion_item(
             imports,
             version,
             trigger_character: completion_trigger_character,
-            completion_item_index: item_index,
+            for_ref: false,
+            completion_item_hash: original_completion_item
+                .as_ref()
+                .map(|item| completion_item_hash(item, false)),
         };
         (ref_resolve_data, Some(to_value(resolve_data).unwrap()))
     } else {