C# hover information in the alpha VS Code extension.
Hover and Quick Info
Hover over C# symbols to see type signatures and documentation from the Roslyn sidecar. F# hover support is part of the SharpLsp direction, but the current website screenshots reflect the VS Code extension's active alpha state.
What You See
When you hover a symbol, SharpLsp returns a Markdown-rendered tooltip containing:
| Section | Content |
|---|---|
| Signature | Fully qualified symbol signature with syntax highlighting |
| Containing type | ContainingType.Name for members |
| XML documentation | <summary>, <param>, <returns>, <remarks>, <example> |
| Exceptions | <exception> tags from XML docs |
| Nullability | Nullable annotation state |
| Accessibility | public, internal, protected, etc. |
| Deprecation | [Obsolete] message with warning |
C# Hover (Roslyn)
The C# sidecar resolves symbols via SemanticModel.GetSymbolInfo() and renders XML documentation from three sources in priority order:
- Source code
///comments - XML documentation files from NuGet packages (
.xmlfiles alongside assemblies) - Roslyn's built-in documentation provider
Special Cases
| Hover Target | Behavior |
|---|---|
var keyword |
Shows the inferred type with full signature |
await expression |
Shows the unwrapped Task<T> return type |
nameof(Foo) |
Shows the referenced symbol |
| String literals | Returns null (no tooltip) |
| Lambda parameters | Shows inferred parameter types |
| Tuple elements | Shows element names and types |
| Pattern variables | Shows the pattern-matched type |
[Obsolete] members |
Shows deprecation message |
Example
var result = Enumerable.Range(0, 10).Select(x => x * x).ToList();
// β hover shows:
// IEnumerable<int> Enumerable.Range(int start, int count)
// Generates a sequence of integral numbers within a specified range.
// Parameters:
// start: The value of the first integer in the sequence.
// count: The number of sequential integers to generate.F# Hover
F# hover is part of the SharpLsp roadmap and sidecar architecture. The current website does not present it as beta-ready.
Solution Explorer Hover
The Solution Explorer tree view uses the same hover pipeline as the code editor. When you hover a symbol in the tree, the tooltip is identical to the one shown in the code editor.
| Tree Node Type | Tooltip Source |
|---|---|
| Symbol (class, method, property, etc.) | LSP hover --- same as code editor |
| Namespace | LSP hover --- same as code editor |
| NuGet Package | Package name + version |
| Project Reference | Reference name |
Caching
Hover results are cached by the Rust host via salsa incremental computation.
| Cache Key | Invalidated When |
|---|---|
(document_uri, document_version, position) |
Document is edited |
A cache hit returns in under 1ms. Stale hover requests for superseded document versions are cancelled immediately.
Performance Targets
| Metric | Target |
|---|---|
| Hover latency (p50) | <150ms |
| Hover latency (p95) | <300ms |
| Cached position | <1ms |
| Tree-sitter pre-validation (skip whitespace) | <1ms |
Error Handling
Hover never returns errors or blocks the editor. On any failure β sidecar not ready, symbol resolution failure, IPC timeout β SharpLsp returns null (no tooltip). Sidecar crashes trigger automatic recovery within 3 seconds.