MIDL Language Support installs statistics

MIDL Language Support for VS Code

A complete MIDL3 development environment — catch errors as you type, get context-aware completions, and ship correct WinRT APIs faster.

⚡ Real-Time Diagnostics

Errors and warnings surface instantly as you type — no build step required. Syntax errors, undefined types, MIDL2/MIDL3 migration issues, and duplicate definitions are caught with precise source locations and actionable messages.

🧠 Context-Aware IntelliSense

Completions adapt to where your cursor is. Inside an attribute bracket on a runtimeclass? You'll see activatable, composable, contract. Inside a struct body? Only value types that are valid there. Inside attribute arguments like [threading(|? You'll get sta, mta, both.

Includes WinRT primitives, collection/async types, external .winmd types, and trigger characters on . and space.

🎯 Code Quality

16 built-in code quality rules with one-click quick fixers — enforce WinRT naming conventions, simplify verbose patterns, and catch common mistakes.

Async Naming Convention

Methods returning IAsyncOperation or IAsyncAction should follow the Async suffix convention. WinMIDL detects violations and offers one-click renames.

🔗 Navigation

Go to Definition — F12 into Decompiled WinMD

F12 on any Windows SDK type jumps to a decompiled IDL view straight from the .winmd — no source code needed.

F2 Rename Symbol

Rename a symbol and all its references in one shot. Works across interface declarations, requires clauses, and return types.

🌐 Windows SDK Integration

Namespace Drill-In

Type a dot after any Windows namespace and IntelliSense walks you through the hierarchy — Windows. → UI. → Composition, Core, Xaml…

Microsoft Learn Integration

Hover any Windows SDK type to see its documentation inline, with a direct link to Microsoft Learn. The side panel shows full API docs without leaving VS Code.

Features

🎨 Syntax Highlighting

Full TextMate grammar covering both MIDL3 and classic MIDL syntax:

• Keywords — namespace, runtimeclass, interface, delegate, struct, enum, event, import, apicontract, and classic keywords like coclass, library, typedef, union • Types — WinRT primitives (Boolean, Int32, String, Guid, Object, …) and classic types (HRESULT, BSTR, IUnknown, IDispatch, …) • Qualified type names — Dotted names like Windows.Foundation.Uri highlighted as types • Attributes — Keywords inside [...] brackets (e.g., uuid, contract, activatable, composable, threading, deprecated, and many more) • GUIDs — Inline GUID literals colorized as constants • Strings, numbers, comments — Double-quoted strings with escape sequences, hex (0xFF) and decimal literals, line (//) and block (/* */) comments • Storage modifiers — static, partial, unsealed, protected, overridable, get, set, out, ref, const

📝 Code Snippets

19 snippets for common MIDL3 patterns — type a prefix and press Tab:

| Prefix | Description |

| namespace | Namespace declaration | | runtimeclass | Runtime class with default constructor | | unsealedruntimeclass | Unsealed (composable) runtime class with base class | | staticruntimeclass | Static-only runtime class | | interface | Interface declaration | | interfacerequires | Interface with requires clause | | delegate | Delegate type | | struct | Struct with fields | | enum | Enumeration | | flagsenum | Flags enumeration with [flags] attribute | | propget | Read-only property ({ get; }) | | proprw | Read-write property (shorthand) | | event | Typed event (TypedEventHandler) | | asyncmethod | Async method returning IAsyncOperation | | asyncaction | Async method returning IAsyncAction | | contract | Contract version attribute | | apicontract | API contract definition with [contractversion] | | versionedblock | Versioned member block with contract attribute | | import | Import directive |

🖱️ Hover Information

Hover over any token for contextual documentation — keywords, built-in types, user-defined types, and external .winmd symbols.

🔗 Go to Definition

Ctrl+Click or F12 on any type or member name to jump to its declaration. Also works on attribute names — F12 on [threading] or [contract] navigates to the SDK attribute type definition (decompiled from .winmd).

🔎 Find All References

Shift+F12 to find every usage of a symbol in the document.

✍️ Signature Help

Parameter hints triggered by ( and , — shows full method/constructor/delegate signatures with active parameter highlighting. Also works inside attribute arguments: [contract(| shows (ContractName, version), [composable(| shows (FactoryType, access, version), etc.

📂 Code Folding

Collapse namespaces, runtime classes, interfaces, structs, enums, and versioned blocks using the editor fold controls.

🎯 Semantic Highlighting

14 semantic token types with declaration/static modifiers — identifiers resolved against the compilation for precise highlighting.

📐 Document Formatting

Shift+Alt+F — consistent 4-space indentation, normalized spacing, blank lines between declarations, trailing whitespace cleanup.

📋 Document Outline

Hierarchical symbol tree in Outline view and Breadcrumbs — namespaces, types, and members.

🔢 Namespace Type Count Code Lens

Each namespace block shows a summary of its contained types — e.g., 2 enums, 3 classes, 1 interface.

📝 Doc Comments (///, //!, /** */)

Both XML doc comments and Doxygen-style comments are supported:

XML (XDC) style:

Doxygen style:

Supported Doxygen tags: @brief/\brief, @param/\param (including @param[in]), @return/\returns, @see, @note, @deprecated.

• Hover shows summary text for documented types and members • Syntax highlighting for Doxygen @tags inside doc comments • Autocomplete generates and skeletons • /doc CLI switch emits .xdc XML doc comment files

🖥️ Inactive Region Graying

Code inside #ifdef / #ifndef blocks that are inactive (based on defined macros) is rendered with reduced opacity. Configure active defines via midl.defines in settings.

📊 Interactive Class Diagram

Command: MIDL: Show Class Diagram…

Description from the VS Code Marketplace listing.