Simplify lookup from guard ... else handling.

Author: MAJKFL

Sources/SwiftLexicalLookup/LookupState.swift

@@ -15,9 +15,5 @@ import Foundation
 /// Represents internal state for lookup.
 /// It shouldn't be used by clients.
 @_spi(Experimental) public struct LookupState {
-  /// Specifies scopes that introduce names to their parent and
-  /// should be skipped during lookup in sequential scopes.
-  var skipSequentialIntroductionFrom: IntroducingToSequentialParentScopeSyntax?
-
   init() {}
 }

Sources/SwiftLexicalLookup/ScopeImplementations.swift

@@ -301,12 +301,26 @@ import SwiftSyntax
 }
 
 @_spi(Experimental) extension GuardStmtSyntax: IntroducingToSequentialParentScopeSyntax {
+  /// Returns names matching lookup.
+  /// Lookup triggered from inside of `else`
+  /// returns no names.
+  ///
+  /// Example:
+  /// ```swift
+  /// guard let a = x else {
+  ///   return // a is not visible here
+  /// }
+  /// // a is visible here
+  /// ```
   @_spi(Experimental) public func introducesToSequentialParent(
     for identifier: Identifier?,
     at origin: SyntaxProtocol,
     with config: LookupConfig,
     state: LookupState
   ) -> [LookupResult] {
+    guard body.position > origin.position || body.endPosition < origin.position
+    else { return [] }
+    
     let names = conditions.flatMap { element in
       LookupName.getNames(from: element.condition, accessibleAfter: element.endPosition)
     }.filter { introducedName in
@@ -319,32 +333,6 @@ import SwiftSyntax
   @_spi(Experimental) public var introducedNames: [LookupName] {
     []
   }
-
-  /// Returns names matching lookup.
-  /// Lookup triggered from inside of `else`
-  /// clause is immediately forwarded to parent scope.
-  ///
-  /// Example:
-  /// ```swift
-  /// guard let a = x else {
-  ///   return // a is not visible here
-  /// }
-  /// // a is visible here
-  /// ```
-  @_spi(Experimental) public func _lookup(
-    for identifier: Identifier?,
-    at origin: SyntaxProtocol,
-    with config: LookupConfig,
-    state: LookupState
-  ) -> [LookupResult] {
-    if body.position <= origin.position && body.endPosition >= origin.position {
-      var newState = state
-      newState.skipSequentialIntroductionFrom = self
-      return lookupInParent(for: identifier, at: origin, with: config, state: newState)
-    } else {
-      return defaultLookupImplementation(for: identifier, at: origin, with: config, state: state)
-    }
-  }
 }
 
 @_spi(Experimental) extension ActorDeclSyntax: TypeScopeSyntax {}

Sources/SwiftLexicalLookup/SequentialScopeSyntax.swift

@@ -69,13 +69,6 @@ extension SequentialScopeSyntax {
       if let introducingToParentScope = Syntax(codeBlockItem.item).asProtocol(SyntaxProtocol.self)
         as? IntroducingToSequentialParentScopeSyntax
       {
-        // Check if the enocountered scope should be ignored.
-        if let scopeToSkip = state.skipSequentialIntroductionFrom,
-          scopeToSkip.id == introducingToParentScope.id
-        {
-          continue
-        }
-
         // Get results from encountered scope.
         let introducedResults = introducingToParentScope.introducesToSequentialParent(
           for: identifier,