fix: Fix inlay hint resolution being broken

crates/rust-analyzer/src/handlers/request.rs

@@ -1508,11 +1508,18 @@ pub(crate) fn handle_inlay_hints_resolve(
         file_id,
         hint_position,
         resolve_data.hash,
+        |hint| {
+            std::hash::BuildHasher::hash_one(
+                &std::hash::BuildHasherDefault::<ide_db::FxHasher>::default(),
+                hint,
+            )
+            // json only supports numbers up to 2^53 - 1 as integers, so mask the rest
+            & ((1 << 53) - 1)
+        },
     )?;
 
-    let mut resolved_hints = resolve_hints
-        .into_iter()
-        .filter_map(|it| {
+    Ok(resolve_hints
+        .and_then(|it| {
             to_proto::inlay_hint(
                 &snap,
                 &forced_resolve_inlay_hints_config.fields_to_resolve,
@@ -1523,13 +1530,8 @@ pub(crate) fn handle_inlay_hints_resolve(
             .ok()
         })
         .filter(|hint| hint.position == original_hint.position)
-        .filter(|hint| hint.kind == original_hint.kind);
-    if let Some(resolved_hint) = resolved_hints.next() {
-        if resolved_hints.next().is_none() {
-            return Ok(resolved_hint);
-        }
-    }
-    Ok(original_hint)
+        .filter(|hint| hint.kind == original_hint.kind)
+        .unwrap_or(original_hint))
 }
 
 pub(crate) fn handle_call_hierarchy_prepare(

crates/rust-analyzer/src/lsp/ext.rs

@@ -463,13 +463,6 @@ pub struct TestInfo {
     pub runnable: Runnable,
 }
 
-#[derive(Serialize, Deserialize, Debug)]
-#[serde(rename_all = "camelCase")]
-pub struct InlayHintsParams {
-    pub text_document: TextDocumentIdentifier,
-    pub range: Option<lsp_types::Range>,
-}
-
 pub enum Ssr {}
 
 impl Request for Ssr {

crates/rust-analyzer/src/lsp/to_proto.rs

@@ -453,6 +453,8 @@ pub(crate) fn inlay_hint(
             &std::hash::BuildHasherDefault::<FxHasher>::default(),
             &inlay_hint,
         )
+        // json only supports numbers up to 2^53 - 1 as integers, so mask the rest
+         & ((1 << 53) - 1)
     });
 
     let mut something_to_resolve = false;

crates/rust-analyzer/tests/slow-tests/main.rs

@@ -23,12 +23,12 @@ use lsp_types::{
     notification::DidOpenTextDocument,
     request::{
         CodeActionRequest, Completion, Formatting, GotoTypeDefinition, HoverRequest,
-        WillRenameFiles, WorkspaceSymbolRequest,
+        InlayHintRequest, InlayHintResolveRequest, WillRenameFiles, WorkspaceSymbolRequest,
     },
     CodeActionContext, CodeActionParams, CompletionParams, DidOpenTextDocumentParams,
     DocumentFormattingParams, FileRename, FormattingOptions, GotoDefinitionParams, HoverParams,
-    PartialResultParams, Position, Range, RenameFilesParams, TextDocumentItem,
-    TextDocumentPositionParams, WorkDoneProgressParams,
+    InlayHint, InlayHintLabel, InlayHintParams, PartialResultParams, Position, Range,
+    RenameFilesParams, TextDocumentItem, TextDocumentPositionParams, WorkDoneProgressParams,
 };
 use rust_analyzer::lsp::ext::{OnEnter, Runnables, RunnablesParams, UnindexedProject};
 use serde_json::json;
@@ -75,6 +75,48 @@ use std::collections::Spam;
     assert!(res.to_string().contains("HashMap"));
 }
 
+#[test]
+fn resolves_inlay_hints() {
+    if skip_slow_tests() {
+        return;
+    }
+
+    let server = Project::with_fixture(
+        r#"
+//- /Cargo.toml
+[package]
+name = "foo"
+version = "0.0.0"
+
+//- /src/lib.rs
+struct Foo;
+fn f() {
+    let x = Foo;
+}
+"#,
+    )
+    .server()
+    .wait_until_workspace_is_loaded();
+
+    let res = server.send_request::<InlayHintRequest>(InlayHintParams {
+        range: Range::new(Position::new(0, 0), Position::new(3, 1)),
+        text_document: server.doc_id("src/lib.rs"),
+        work_done_progress_params: WorkDoneProgressParams::default(),
+    });
+    let mut hints = serde_json::from_value::<Option<Vec<InlayHint>>>(res).unwrap().unwrap();
+    let hint = hints.pop().unwrap();
+    assert!(hint.data.is_some());
+    assert!(
+        matches!(&hint.label, InlayHintLabel::LabelParts(parts) if parts[1].location.is_none())
+    );
+    let res = server.send_request::<InlayHintResolveRequest>(hint);
+    let hint = serde_json::from_value::<InlayHint>(res).unwrap();
+    assert!(hint.data.is_none());
+    assert!(
+        matches!(&hint.label, InlayHintLabel::LabelParts(parts) if parts[1].location.is_some())
+    );
+}
+
 #[test]
 fn test_runnables_project() {
     if skip_slow_tests() {

crates/rust-analyzer/tests/slow-tests/support.rs

@@ -159,6 +159,18 @@ impl Project<'_> {
                         content_format: Some(vec![lsp_types::MarkupKind::Markdown]),
                         ..Default::default()
                     }),
+                    inlay_hint: Some(lsp_types::InlayHintClientCapabilities {
+                        resolve_support: Some(lsp_types::InlayHintResolveClientCapabilities {
+                            properties: vec![
+                                "textEdits".to_owned(),
+                                "tooltip".to_owned(),
+                                "label.tooltip".to_owned(),
+                                "label.location".to_owned(),
+                                "label.command".to_owned(),
+                            ],
+                        }),
+                        ..Default::default()
+                    }),
                     ..Default::default()
                 }),
                 window: Some(lsp_types::WindowClientCapabilities {