Export getNodeForTarget in ast exports (#8652)

Author: timotheeguerin

.chronus/changes/expose-get-node-for-target-2025-9-2-20-36-17.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: feature
+packages:
+  - "@typespec/compiler"
+---
+
+[API] Export `getNodeForTarget` in `@typespec/compiler/ast` exports

packages/compiler/src/ast/index.ts

@@ -11,6 +11,7 @@
 
 export { NodeFlags, SyntaxKind } from "../core/types.js";
 
+export { getNodeForTarget } from "../core/diagnostics.js";
 export { printTypeSpecNode } from "../core/formatter.js";
 export {
   exprIsBareIdentifier,

packages/compiler/src/core/diagnostics.ts

@@ -44,8 +44,18 @@ export function getRelatedLocations(diagnostic: Diagnostic): RelatedSourceLocati
 }
 
 /**
- * Find the syntax node for a typespec diagnostic target.
- * Returns undefined if target is a type or symbol without a node.
+ * Find the syntax node for a TypeSpec diagnostic target.
+ *
+ * This function extracts the AST node from various types of diagnostic targets:
+ * - For template instance targets: returns the node of the template declaration
+ * - For symbols: returns the first declaration node (or symbol source for using symbols)
+ * - For AST nodes: returns the node itself
+ * - For types: returns the node associated with the type
+ *
+ * @param target The diagnostic target to extract a node from. Can be a template instance,
+ *               symbol, AST node, or type.
+ * @returns The AST node associated with the target, or undefined if the target is a type
+ *          or symbol that doesn't have an associated node.
  */
 export function getNodeForTarget(target: TypeSpecDiagnosticTarget): Node | undefined {
   if (!("kind" in target) && !("entityKind" in target)) {