Update to non-optional leading/trailingTrivia swift-syntax API

Author: bnbarham

Sources/SwiftFormatCore/SyntaxProtocol+Convenience.swift

@@ -25,7 +25,6 @@ extension SyntaxProtocol {
   ///   be returned.
   /// - Returns: The absolute position of the trivia piece.
   public func position(ofLeadingTriviaAt index: Trivia.Index) -> AbsolutePosition {
-    let leadingTrivia = self.leadingTrivia ?? []
     guard leadingTrivia.indices.contains(index) else {
       preconditionFailure("Index was out of bounds in the node's leading trivia.")
     }

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -876,7 +876,7 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     // The node's content is either a `DictionaryElementListSyntax` or a `TokenSyntax` for a colon
     // token (for an empty dictionary).
     if !(node.content.as(DictionaryElementListSyntax.self)?.isEmpty ?? true)
-      || node.content.leadingTrivia?.numberOfComments ?? 0 > 0
+      || node.content.leadingTrivia.numberOfComments > 0
       || node.rightSquare.leadingTrivia.numberOfComments > 0
     {
       after(node.leftSquare, tokens: .break(.open, size: 0), .open)
@@ -2161,7 +2161,7 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
       appendToken(.syntax(segmentText))
     }
 
-    if node.trailingTrivia?.containsBackslashes == true {
+    if node.trailingTrivia.containsBackslashes {
       // Segments with trailing backslashes won't end with a literal newline; the backslash is
       // considered trivia. To preserve the original text and wrapping, we need to manually render
       // the backslash and a break into the token stream.

Sources/SwiftFormatRules/NoAssignmentInExpressions.swift

@@ -68,7 +68,7 @@ public final class NoAssignmentInExpressions: SyntaxFormatRule {
             semicolon: nil
           )
           .with(\.leadingTrivia, [.newlines(1)])
-          .with(\.trailingTrivia, returnStmt.trailingTrivia?.withoutLeadingSpaces() ?? []))
+          .with(\.trailingTrivia, returnStmt.trailingTrivia.withoutLeadingSpaces()))
 
       default:
         newItems.append(newItem)

Sources/SwiftFormatRules/NoCasesWithOnlyFallthrough.swift

@@ -194,13 +194,7 @@ public final class NoCasesWithOnlyFallthrough: SyntaxFormatRule {
 
     // Only the first violation case can have displaced trivia, because any non-whitespace
     // trivia in the other violation cases would've prevented collapsing.
-    if let displacedLeadingTrivia = cases.first!.leadingTrivia?.withoutLastLine() {
-      let existingLeadingTrivia = newCase.leadingTrivia ?? []
-      let mergedLeadingTrivia = displacedLeadingTrivia + existingLeadingTrivia
-      return newCase.with(\.leadingTrivia, mergedLeadingTrivia)
-    } else {
-      return newCase
-    }
+    return newCase.with(\.leadingTrivia, cases.first!.leadingTrivia.withoutLastLine() + newCase.leadingTrivia)
   }
 }
 

Sources/SwiftFormatRules/OrderedImports.swift

@@ -491,8 +491,7 @@ fileprivate class Line {
     // description includes all leading and trailing trivia. It would be unusual to have any
     // non-whitespace trivia on the components of the import. Trim off the leading trivia, where
     // comments could be, and trim whitespace that might be after the import.
-    let leadingText = importDecl.leadingTrivia?.reduce(into: "") { $1.write(to: &$0) } ?? ""
-    return importDecl.description.dropFirst(leadingText.count)
+    return importDecl.with(\.leadingTrivia, []).description
       .trimmingCharacters(in: .whitespacesAndNewlines)
   }