Guard nil address (#36)

EmergeTools · Sep 6, 2023 · c8b8f59 · c8b8f59
1 parent 6cf6355
commit c8b8f59
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Showing 3 changed files with 84 additions and 2 deletions.
diff --git a/DemoApp/DemoApp.xcodeproj/xcshareddata/xcschemes/DemoApp.xcscheme b/DemoApp/DemoApp.xcodeproj/xcshareddata/xcschemes/DemoApp.xcscheme
@@ -0,0 +1,77 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "1500"
+   version = "1.7">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "FA1671BE2A5367A800A42DB0"
+               BuildableName = "DemoApp.app"
+               BlueprintName = "DemoApp"
+               ReferencedContainer = "container:DemoApp.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      shouldAutocreateTestPlan = "YES">
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "FA1671BE2A5367A800A42DB0"
+            BuildableName = "DemoApp.app"
+            BlueprintName = "DemoApp"
+            ReferencedContainer = "container:DemoApp.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "FA1671BE2A5367A800A42DB0"
+            BuildableName = "DemoApp.app"
+            BlueprintName = "DemoApp"
+            ReferencedContainer = "container:DemoApp.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Debug"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>
diff --git a/Sources/SnapshotPreviewsCore/ConformanceLookup.swift b/Sources/SnapshotPreviewsCore/ConformanceLookup.swift
@@ -49,6 +49,11 @@ private func parseConformance(conformance: UnsafePointer<ProtocolConformanceDesc
   let descriptorOffset = Int(conformance.pointee.protocolDescriptor & ~1)
   let jumpPtr = UnsafeRawPointer(conformance).advanced(by: MemoryLayout<ProtocolConformanceDescriptor>.offset(of: \.protocolDescriptor)!).advanced(by: descriptorOffset)
   let address = jumpPtr.load(as: UInt64.self)
+
+  // Address will be 0 if the protocol is not available (such as only defined on a newer OS)
+  guard address != 0 else {
+    return nil
+  }
   let protoPtr = UnsafeRawPointer(bitPattern: UInt(address))!
   let proto = protoPtr.load(as: ProtocolDescriptor.self)
   let namePtr = protoPtr.advanced(by: MemoryLayout<ProtocolDescriptor>.offset(of: \.name)!).advanced(by: Int(proto.name))

diff --git a/Sources/SnapshotPreviewsCore/PrecisionModifier.swift b/Sources/SnapshotPreviewsCore/PrecisionModifier.swift
@@ -9,15 +9,15 @@ import Foundation
 import SwiftUI
 
 public struct EmergePrecisionModifier: ViewModifier {
-  let precision: Float
+  let precision: Float?
 
   public func body(content: Content) -> some View {
     content
   }
 }
 
 extension View {
-  public func emergeSnapshotPrecision(_ precision: Float) -> some View {
+  public func emergeSnapshotPrecision(_ precision: Float?) -> some View {
     modifier(EmergePrecisionModifier(precision: precision))
   }
 }