[Macros] Add an overload of findSyntaxNodeInSourceFile that accepts

a predicate.

The new overload is used during macro expansion to find the nearest
syntax node that is either a `DeclSyntax` or a `ClosureExprSyntax`.
This avoids an issue where calling the overload that accepts a
specific type may find an outer, unrelated declaration or closure.

Author: hborla

lib/ASTGen/Sources/ASTGen/SourceFile.swift

@@ -249,13 +249,11 @@ public func emitParserDiagnostics(
   }
 }
 
-/// Retrieve a syntax node in the given source file, with the given type.
-public func findSyntaxNodeInSourceFile<Node: SyntaxProtocol>(
-  sourceFilePtr: UnsafeRawPointer,
-  sourceLocationPtr: UnsafePointer<UInt8>?,
-  type: Node.Type,
-  wantOutermost: Bool = false
-) -> Node? {
+/// Find a token in the given source file at the given location.
+func findToken(
+  in sourceFilePtr: UnsafeRawPointer,
+  at sourceLocationPtr: UnsafePointer<UInt8>?
+) -> TokenSyntax? {
   guard let sourceLocationPtr = sourceLocationPtr else {
     return nil
   }
@@ -277,6 +275,20 @@ public func findSyntaxNodeInSourceFile<Node: SyntaxProtocol>(
     return nil
   }
 
+  return token
+}
+
+/// Retrieve a syntax node in the given source file, with the given type.
+public func findSyntaxNodeInSourceFile<Node: SyntaxProtocol>(
+  sourceFilePtr: UnsafeRawPointer,
+  sourceLocationPtr: UnsafePointer<UInt8>?,
+  type: Node.Type,
+  wantOutermost: Bool = false
+) -> Node? {
+  guard let token = findToken(in: sourceFilePtr, at: sourceLocationPtr) else {
+    return nil
+  }
+
   var currentSyntax = Syntax(token)
   var resultSyntax: Node? = nil
   while let parentSyntax = currentSyntax.parent {
@@ -309,6 +321,28 @@ public func findSyntaxNodeInSourceFile<Node: SyntaxProtocol>(
   return resultSyntax
 }
 
+/// Retrieve a syntax node in the given source file that satisfies the
+/// given predicate.
+public func findSyntaxNodeInSourceFile(
+  sourceFilePtr: UnsafeRawPointer,
+  sourceLocationPtr: UnsafePointer<UInt8>?,
+  where predicate: (Syntax) -> Bool
+) -> Syntax? {
+  guard let token = findToken(in: sourceFilePtr, at: sourceLocationPtr) else {
+    return nil
+  }
+
+  var currentSyntax = Syntax(token)
+  while let parentSyntax = currentSyntax.parent {
+    currentSyntax = parentSyntax
+    if predicate(currentSyntax) {
+      return currentSyntax
+    }
+  }
+
+  return nil
+}
+
 @_cdecl("swift_ASTGen_virtualFiles")
 @usableFromInline
 func getVirtualFiles(

lib/ASTGen/Sources/MacroEvaluation/Macros.swift

@@ -583,22 +583,15 @@ func expandAttachedMacro(
     return 1
   }
 
-  func findNode<T: SyntaxProtocol>(type: T.Type) -> T? {
-    findSyntaxNodeInSourceFile(
-      sourceFilePtr: declarationSourceFilePtr,
-      sourceLocationPtr: declarationSourceLocPointer,
-      type: T.self
-    )
-  }
-
   // Dig out the node for the closure or declaration to which the custom
   // attribute is attached.
-  let node: Syntax
-  if let closureNode = findNode(type: ClosureExprSyntax.self) {
-    node = Syntax(closureNode)
-  } else if let declNode = findNode(type: DeclSyntax.self) {
-    node = Syntax(declNode)
-  } else {
+  let node = findSyntaxNodeInSourceFile(
+    sourceFilePtr: declarationSourceFilePtr,
+    sourceLocationPtr: declarationSourceLocPointer,
+    where: { $0.is(DeclSyntax.self) || $0.is(ClosureExprSyntax.self) }
+  )
+
+  guard let node else {
     return 1
   }