Remove force unwrapping for source location

Companion of swiftlang/swift-syntax#1532

Author: kimdv

lib/ASTGen/Sources/ASTGen/PluginHost.swift

@@ -380,7 +380,7 @@ extension PluginMessage.Syntax {
         fileID: fileID,
         fileName: fileName,
         offset: loc.offset,
-        line: loc.line!,
-        column: loc.column!))
+        line: loc.line,
+        column: loc.column))
   }
 }

test/Macros/Inputs/syntax_macro_definitions.swift

@@ -38,13 +38,11 @@ public struct FileIDMacro: ExpressionMacro {
     of macro: Node,
     in context: Context
   ) throws -> ExprSyntax {
-    guard let sourceLoc = context.location(of: macro),
-      let fileID = sourceLoc.file
-    else {
+    guard let sourceLoc = context.location(of: macro) else {
       throw CustomError.message("can't find location for macro")
     }
 
-    let fileLiteral: ExprSyntax = "\(literal: fileID)"
+    let fileLiteral: ExprSyntax = "\(literal: sourceLoc.file)"
     return fileLiteral
   }
 }
@@ -746,7 +744,7 @@ public enum LeftHandOperandFinderMacro: ExpressionMacro {
         fatalError("missing source location information")
       }
 
-      print("Source range for LHS is \(lhsStartLoc.file!): \(lhsStartLoc.line!):\(lhsStartLoc.column!)-\(lhsEndLoc.line!):\(lhsEndLoc.column!)")
+      print("Source range for LHS is \(lhsStartLoc.file): \(lhsStartLoc.line):\(lhsStartLoc.column)-\(lhsEndLoc.line):\(lhsEndLoc.column)")
 
       return .visitChildren
     }