Summary
Semantic answers where an assistant would otherwise grep.
The difference shows up on the questions text search cannot answer at all: what implements this interface, which direction a call goes, and whether a rename is safe when a longer method name shares the prefix. Because it runs inside the IDE session, the answers reflect the solution as loaded, not as it appears on disk.
What it is
A Visual Studio extension that exposes the C# compiler's semantic model as tools. Symbol lookups, references, inheritance and renames are answered by Roslyn against your open solution, the same engine behind Go to Definition.
What you get
- A symbol's definition, its usages, and the symbol at any file position
- Symbol search across the solution, and the outline of a document
- Inheritance: what implements or derives from a type
- Call relationships in both directions — who calls a method and what it calls
- Renames carried out by the compiler across every call site
- Compiler diagnostics, document formatting, command execution and asynchronous test runs
- Debugger tools alongside the Roslyn ones, shipped as a preview
Requirements
Visual Studio with the extension installed from the Marketplace, and the solution open — the answers come from the same session you are editing in.