add flag to disable deprecated code

26 files changed, 173 insertions, 55 deletions

diff --git a/build/common.targets b/build/common.targets
index 8b17c45a..92fd9a9a 100644
--- a/build/common.targets
+++ b/build/common.targets
@@ -5,6 +5,7 @@
     <Product>SMAPI</Product>
     <LangVersion>latest</LangVersion>
     <AssemblySearchPaths>$(AssemblySearchPaths);{GAC}</AssemblySearchPaths>
+    <DefineConstants>$(DefineConstants);SMAPI_DEPRECATED</DefineConstants>
 
     <!--enable nullable annotations, except in .NET Standard 2.0 where they aren't supported-->
     <Nullable Condition="'$(TargetFramework)' != 'netstandard2.0'">enable</Nullable>
@@ -20,14 +21,17 @@
     <!--
       suppress warnings that don't apply, so it's easier to spot actual issues.
 
-      warning | builds  | summary                                   | rationale
-      ┄┄┄┄┄┄┄ | ┄┄┄┄┄┄┄ | ┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄ | ┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄
-      CS0436  | all     | local type conflicts with imported type   | SMAPI needs to use certain low-level code during very early compatibility checks, before it's safe to load any other DLLs.
-      CA1416  | all     | platform code available on all platforms  | Compiler doesn't recognize the #if constants used by SMAPI.
-      CS0809  | all     | obsolete overload for non-onsolete member | This is deliberate to signal to mods that certain APIs are only implemented for the game and shouldn't be called by mods.
-      NU1701  | all     | NuGet package targets older .NET version  | All such packages are carefully tested to make sure they do work.
+      warning | builds     | summary                                   | rationale
+      ┄┄┄┄┄┄┄ | ┄┄┄┄┄┄┄┄┄┄ | ┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄ | ┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄
+      CS0436  | all        | local type conflicts with imported type   | SMAPI needs to use certain low-level code during very early compatibility checks, before it's safe to load any other DLLs.
+      CS0612  | deprecated | member is obsolete                        | internal references to deprecated code when deprecated code is enabled.
+      CS0618  | deprecated | member is obsolete (with message)         | internal references to deprecated code when deprecated code is enabled.
+      CA1416  | all        | platform code available on all platforms  | Compiler doesn't recognize the #if constants used by SMAPI.
+      CS0809  | all        | obsolete overload for non-obsolete member | This is deliberate to signal to mods that certain APIs are only implemented for the game and shouldn't be called by mods.
+      NU1701  | all        | NuGet package targets older .NET version  | All such packages are carefully tested to make sure they do work.
     -->
-    <NoWarn>$(NoWarn);CS0436;CA1416;CS0809;NU1701</NoWarn>
+      <NoWarn Condition="$(DefineConstants.Contains(SMAPI_DEPRECATED))">$(NoWarn);CS0612;CS0618</NoWarn>
+      <NoWarn>$(NoWarn);CS0436;CA1416;CS0809;NU1701</NoWarn>
   </PropertyGroup>
 
   <!--find game folder-->
diff --git a/docs/technical/smapi.md b/docs/technical/smapi.md
index 44b6e49f..90990ee4 100644
--- a/docs/technical/smapi.md
+++ b/docs/technical/smapi.md
@@ -62,6 +62,7 @@ SMAPI uses a small number of conditional compilation constants, which you can se
 flag | purpose
 ---- | -------
 `SMAPI_FOR_WINDOWS` | Whether SMAPI is being compiled for Windows; if not set, the code assumes Linux/macOS. Set automatically in `common.targets`.
+`SMAPI_DEPRECATED`  | Whether to include deprecated code in the build.
 
 ## Compile from source code
 ### Main project
diff --git a/src/SMAPI.Toolkit/Framework/ModData/ModWarning.cs b/src/SMAPI.Toolkit/Framework/ModData/ModWarning.cs
index 32c2ed6d..338192af 100644
--- a/src/SMAPI.Toolkit/Framework/ModData/ModWarning.cs
+++ b/src/SMAPI.Toolkit/Framework/ModData/ModWarning.cs
@@ -18,9 +18,11 @@ namespace StardewModdingAPI.Toolkit.Framework.ModData
         /// <summary>The mod patches the game in a way that may impact stability.</summary>
         PatchesGame = 4,
 
+#if SMAPI_FOR_WINDOWS
         /// <summary>The mod uses the <c>dynamic</c> keyword which won't work on Linux/macOS.</summary>
         [Obsolete("This value is no longer used by SMAPI and will be removed in the upcoming SMAPI 4.0.0.")]
         UsesDynamic = 8,
+#endif
 
         /// <summary>The mod references specialized 'unvalidated update tick' events which may impact stability.</summary>
         UsesUnvalidatedUpdateTick = 16,
@@ -37,6 +39,7 @@ namespace StardewModdingAPI.Toolkit.Framework.ModData
         /// <summary>Uses .NET APIs for shell or process access.</summary>
         AccessesShell = 256,
 
+#if SMAPI_DEPRECATED
         /// <summary>References the legacy <c>System.Configuration.ConfigurationManager</c> assembly and doesn't include a copy in the mod folder, so it'll break in SMAPI 4.0.0.</summary>
         DetectedLegacyConfigurationDll = 512,
 
@@ -45,5 +48,6 @@ namespace StardewModdingAPI.Toolkit.Framework.ModData
 
         /// <summary>References the legacy <c>System.Security.Permissions</c> assembly and doesn't include a copy in the mod folder, so it'll break in SMAPI 4.0.0.</summary>
         DetectedLegacyPermissionsDll = 2048
+#endif
     }
 }
diff --git a/src/SMAPI/Constants.cs b/src/SMAPI/Constants.cs
index db88563e..33468717 100644
--- a/src/SMAPI/Constants.cs
+++ b/src/SMAPI/Constants.cs
@@ -6,7 +6,9 @@ using System.Reflection;
 using Mono.Cecil;
 using StardewModdingAPI.Enums;
 using StardewModdingAPI.Framework;
+#if SMAPI_DEPRECATED
 using StardewModdingAPI.Framework.Deprecations;
+#endif
 using StardewModdingAPI.Framework.ModLoading;
 using StardewModdingAPI.Toolkit.Framework;
 using StardewModdingAPI.Toolkit.Utilities;
@@ -77,6 +79,7 @@ namespace StardewModdingAPI
         /// <summary>The game framework running the game.</summary>
         public static GameFramework GameFramework { get; } = EarlyConstants.GameFramework;
 
+#if SMAPI_DEPRECATED
         /// <summary>The path to the game folder.</summary>
         [Obsolete($"Use {nameof(Constants)}.{nameof(GamePath)} instead. This property will be removed in SMAPI 4.0.0.")]
         public static string ExecutionPath
@@ -93,6 +96,7 @@ namespace StardewModdingAPI
                 return Constants.GamePath;
             }
         }
+#endif
 
         /// <summary>The path to the game folder.</summary>
         public static string GamePath { get; } = EarlyConstants.GamePath;
diff --git a/src/SMAPI/Framework/Content/AssetInfo.cs b/src/SMAPI/Framework/Content/AssetInfo.cs
index 773e3126..43feed27 100644
--- a/src/SMAPI/Framework/Content/AssetInfo.cs
+++ b/src/SMAPI/Framework/Content/AssetInfo.cs
@@ -1,7 +1,9 @@
 using System;
 using System.Collections.Generic;
 using Microsoft.Xna.Framework.Graphics;
+#if SMAPI_DEPRECATED
 using StardewModdingAPI.Framework.Deprecations;
+#endif
 
 namespace StardewModdingAPI.Framework.Content
 {
@@ -30,6 +32,10 @@ namespace StardewModdingAPI.Framework.Content
         public IAssetName NameWithoutLocale => this.NameWithoutLocaleImpl ??= this.Name.GetBaseAssetName();
 
         /// <inheritdoc />
+        public Type DataType { get; }
+
+#if SMAPI_DEPRECATED
+        /// <inheritdoc />
         [Obsolete($"Use {nameof(AssetInfo.Name)} or {nameof(AssetInfo.NameWithoutLocale)} instead. This property will be removed in SMAPI 4.0.0.")]
         public string AssetName
         {
@@ -50,9 +56,7 @@ namespace StardewModdingAPI.Framework.Content
                 return this.NameWithoutLocale.Name;
             }
         }
-
-        /// <inheritdoc />
-        public Type DataType { get; }
+#endif
 
 
         /*********
@@ -71,6 +75,7 @@ namespace StardewModdingAPI.Framework.Content
             this.GetNormalizedPath = getNormalizedPath;
         }
 
+#if SMAPI_DEPRECATED
         /// <inheritdoc />
         [Obsolete($"Use {nameof(Name)}.{nameof(IAssetName.IsEquivalentTo)} or {nameof(AssetInfo.NameWithoutLocale)}.{nameof(IAssetName.IsEquivalentTo)} instead. This method will be removed in SMAPI 4.0.0.")]
         public bool AssetNameEquals(string path)
@@ -90,6 +95,7 @@ namespace StardewModdingAPI.Framework.Content
 
             return this.NameWithoutLocale.IsEquivalentTo(path);
         }
+#endif
 
 
         /*********
diff --git a/src/SMAPI/Framework/Content/AssetInterceptorChange.cs b/src/SMAPI/Framework/Content/AssetInterceptorChange.cs
index f3d4f3f4..3b5068dc 100644
--- a/src/SMAPI/Framework/Content/AssetInterceptorChange.cs
+++ b/src/SMAPI/Framework/Content/AssetInterceptorChange.cs
@@ -1,8 +1,8 @@
+#if SMAPI_DEPRECATED
 using System;
 using System.Reflection;
 using StardewModdingAPI.Internal;
 
-#pragma warning disable CS0618 // obsolete asset interceptors deliberately supported here
 namespace StardewModdingAPI.Framework.Content
 {
     /// <summary>A wrapper for <see cref="IAssetEditor"/> and <see cref="IAssetLoader"/> for internal cache invalidation.</summary>
@@ -103,3 +103,4 @@ namespace StardewModdingAPI.Framework.Content
         }
     }
 }
+#endif
diff --git a/src/SMAPI/Framework/ContentCoordinator.cs b/src/SMAPI/Framework/ContentCoordinator.cs
index 3e09ac62..9e044b44 100644
--- a/src/SMAPI/Framework/ContentCoordinator.cs
+++ b/src/SMAPI/Framework/ContentCoordinator.cs
@@ -12,7 +12,9 @@ using StardewModdingAPI.Framework.Content;
 using StardewModdingAPI.Framework.ContentManagers;
 using StardewModdingAPI.Framework.Reflection;
 using StardewModdingAPI.Framework.Utilities;
+#if SMAPI_DEPRECATED
 using StardewModdingAPI.Internal;
+#endif
 using StardewModdingAPI.Metadata;
 using StardewModdingAPI.Toolkit.Serialization;
 using StardewModdingAPI.Toolkit.Utilities.PathLookups;
@@ -84,6 +86,7 @@ namespace StardewModdingAPI.Framework
         /// <summary>The cached asset load/edit operations to apply, indexed by asset name.</summary>
         private readonly TickCacheDictionary<IAssetName, AssetOperationGroup?> AssetOperationsByKey = new();
 
+#if SMAPI_DEPRECATED
         /// <summary>A cache of asset operation groups created for legacy <see cref="IAssetLoader"/> implementations.</summary>
         [Obsolete("This only exists to support legacy code and will be removed in SMAPI 4.0.0.")]
         private readonly Dictionary<IAssetLoader, Dictionary<Type, AssetLoadOperation>> LegacyLoaderCache = new(ReferenceEqualityComparer.Instance);
@@ -91,6 +94,7 @@ namespace StardewModdingAPI.Framework
         /// <summary>A cache of asset operation groups created for legacy <see cref="IAssetEditor"/> implementations.</summary>
         [Obsolete("This only exists to support legacy code and will be removed in SMAPI 4.0.0.")]
         private readonly Dictionary<IAssetEditor, Dictionary<Type, AssetEditOperation>> LegacyEditorCache = new(ReferenceEqualityComparer.Instance);
+#endif
 
 
         /*********
@@ -102,6 +106,7 @@ namespace StardewModdingAPI.Framework
         /// <summary>The current language as a constant.</summary>
         public LocalizedContentManager.LanguageCode Language => this.MainContentManager.Language;
 
+#if SMAPI_DEPRECATED
         /// <summary>Interceptors which provide the initial versions of matching assets.</summary>
         [Obsolete("This only exists to support legacy code and will be removed in SMAPI 4.0.0.")]
         public IList<ModLinked<IAssetLoader>> Loaders { get; } = new List<ModLinked<IAssetLoader>>();
@@ -109,6 +114,7 @@ namespace StardewModdingAPI.Framework
         /// <summary>Interceptors which edit matching assets after they're loaded.</summary>
         [Obsolete("This only exists to support legacy code and will be removed in SMAPI 4.0.0.")]
         public IList<ModLinked<IAssetEditor>> Editors { get; } = new List<ModLinked<IAssetEditor>>();
+#endif
 
         /// <summary>The absolute path to the <see cref="ContentManager.RootDirectory"/>.</summary>
         public string FullRootDirectory { get; }
@@ -498,15 +504,25 @@ namespace StardewModdingAPI.Framework
             return invalidatedAssets.Keys;
         }
 
+#if SMAPI_DEPRECATED
         /// <summary>Get the asset load and edit operations to apply to a given asset if it's (re)loaded now.</summary>
         /// <typeparam name="T">The asset type.</typeparam>
         /// <param name="info">The asset info to load or edit.</param>
         public AssetOperationGroup? GetAssetOperations<T>(IAssetInfo info)
             where T : notnull
+#else
+        /// <summary>Get the asset load and edit operations to apply to a given asset if it's (re)loaded now.</summary>
+        /// <param name="info">The asset info to load or edit.</param>
+        public AssetOperationGroup? GetAssetOperations(IAssetInfo info)
+#endif
         {
             return this.AssetOperationsByKey.GetOrSet(
                 info.Name,
+#if SMAPI_DEPRECATED
                 () => this.GetAssetOperationsWithoutCache<T>(info)
+#else
+                () => this.RequestAssetOperations(info)
+#endif
             );
         }
 
@@ -629,6 +645,7 @@ namespace StardewModdingAPI.Framework
             return map;
         }
 
+#if SMAPI_DEPRECATED
         /// <summary>Get the asset load and edit operations to apply to a given asset if it's (re)loaded now, ignoring the <see cref="AssetOperationsByKey"/> cache.</summary>
         /// <typeparam name="T">The asset type.</typeparam>
         /// <param name="info">The asset info to load or edit.</param>
@@ -639,7 +656,6 @@ namespace StardewModdingAPI.Framework
             AssetOperationGroup? group = this.RequestAssetOperations(info);
 
             // legacy load operations
-#pragma warning disable CS0612, CS0618 // deprecated code
             if (this.Editors.Count > 0 || this.Loaders.Count > 0)
             {
                 IAssetInfo legacyInfo = this.GetLegacyAssetInfo(info);
@@ -738,7 +754,6 @@ namespace StardewModdingAPI.Framework
                     );
                 }
             }
-#pragma warning restore CS0612, CS0618
 
             return group;
         }
@@ -818,5 +833,6 @@ namespace StardewModdingAPI.Framework
             // else no change needed
             return asset;
         }
+#endif
     }
 }
diff --git a/src/SMAPI/Framework/ContentManagers/GameContentManager.cs b/src/SMAPI/Framework/ContentManagers/GameContentManager.cs
index 446f4a67..df7bdc59 100644
--- a/src/SMAPI/Framework/ContentManagers/GameContentManager.cs
+++ b/src/SMAPI/Framework/ContentManagers/GameContentManager.cs
@@ -76,7 +76,11 @@ namespace StardewModdingAPI.Framework.ContentManagers
             // custom asset from a loader
             string locale = this.GetLocale();
             IAssetInfo info = new AssetInfo(locale, assetName, typeof(T), this.AssertAndNormalizeAssetName);
-            AssetOperationGroup? operations = this.Coordinator.GetAssetOperations<T>(info);
+            AssetOperationGroup? operations = this.Coordinator.GetAssetOperations
+#if SMAPI_DEPRECATED
+                <T>
+#endif
+                (info);
             if (operations?.LoadOperations.Count > 0)
             {
                 if (!this.AssertMaxOneRequiredLoader(info, operations.LoadOperations, out string? error))
@@ -129,7 +133,11 @@ namespace StardewModdingAPI.Framework.ContentManagers
                 data = this.AssetsBeingLoaded.Track(assetName.Name, () =>
                 {
                     IAssetInfo info = new AssetInfo(assetName.LocaleCode, assetName, typeof(T), this.AssertAndNormalizeAssetName);
-                    AssetOperationGroup? operations = this.Coordinator.GetAssetOperations<T>(info);
+                    AssetOperationGroup? operations = this.Coordinator.GetAssetOperations
+#if SMAPI_DEPRECATED
+                        <T>
+#endif
+                        (info);
                     IAssetData asset =
                         this.ApplyLoader<T>(info, operations?.LoadOperations)
                         ?? new AssetDataForObject(info, this.RawLoad<T>(assetName, useCache), this.AssertAndNormalizeAssetName, this.Reflection);
@@ -294,7 +302,11 @@ namespace StardewModdingAPI.Framework.ContentManagers
                 ? $"Multiple mods want to provide the '{info.Name}' asset: {string.Join(", ", loaderNames)}"
                 : $"The '{loaderNames[0]}' mod wants to provide the '{info.Name}' asset multiple times";
 
-            error = $"{errorPhrase}. An asset can't be loaded multiple times, so SMAPI will use the default asset instead. Uninstall one of the mods to fix this. (Message for modders: you should avoid {nameof(AssetLoadPriority)}.{nameof(AssetLoadPriority.Exclusive)} and {nameof(IAssetLoader)} if possible to avoid conflicts.)";
+            error = $"{errorPhrase}. An asset can't be loaded multiple times, so SMAPI will use the default asset instead. Uninstall one of the mods to fix this. (Message for modders: you should avoid {nameof(AssetLoadPriority)}.{nameof(AssetLoadPriority.Exclusive)}"
+#if SMAPI_DEPRECATED
+                + " and {nameof(IAssetLoader)}"
+#endif
+                + " if possible to avoid conflicts.)";
             return false;
         }
 
@@ -349,6 +361,7 @@ namespace StardewModdingAPI.Framework.ContentManagers
                     // handle mismatch
                     if (loadedMap.TileSheets.Count <= vanillaSheet.Index || loadedMap.TileSheets[vanillaSheet.Index].Id != vanillaSheet.Id)
                     {
+#if SMAPI_DEPRECATED
                         // only show warning if not farm map
                         // This is temporary: mods shouldn't do this for any vanilla map, but these are the ones we know will crash. Showing a warning for others instead gives modders time to update their mods, while still simplifying troubleshooting.
                         bool isFarmMap = info.Name.IsEquivalentTo("Maps/Farm") || info.Name.IsEquivalentTo("Maps/Farm_Combat") || info.Name.IsEquivalentTo("Maps/Farm_Fishing") || info.Name.IsEquivalentTo("Maps/Farm_Foraging") || info.Name.IsEquivalentTo("Maps/Farm_FourCorners") || info.Name.IsEquivalentTo("Maps/Farm_Island") || info.Name.IsEquivalentTo("Maps/Farm_Mining");
@@ -361,7 +374,12 @@ namespace StardewModdingAPI.Framework.ContentManagers
                             mod.LogAsMod($"SMAPI blocked a '{info.Name}' map load: {reason}", LogLevel.Error);
                             return false;
                         }
+
                         mod.LogAsMod($"SMAPI found an issue with a '{info.Name}' map load: {reason}", LogLevel.Warn);
+#else
+                        mod.LogAsMod($"SMAPI found an issue with a '{info.Name}' map load: {this.GetOnBehalfOfLabel(loader.OnBehalfOf, parenthetical: false) ?? "mod"} reordered the original tilesheets, which often causes crashes.\nTechnical details for mod author: Expected order: {string.Join(", ", vanillaTilesheetRefs.Select(p => p.Id))}. See https://stardewvalleywiki.com/Modding:Maps#Tilesheet_order for help.", LogLevel.Error);
+                        return false;
+#endif
                     }
                 }
             }
diff --git a/src/SMAPI/Framework/ContentPack.cs b/src/SMAPI/Framework/ContentPack.cs
index 70fe51f8..a1d977e4 100644
--- a/src/SMAPI/Framework/ContentPack.cs
+++ b/src/SMAPI/Framework/ContentPack.cs
@@ -96,6 +96,7 @@ namespace StardewModdingAPI.Framework
             }
         }
 
+#if SMAPI_DEPRECATED
         /// <inheritdoc />
         [Obsolete($"Use {nameof(IContentPack.ModContent)}.{nameof(IModContentHelper.Load)} instead. This method will be removed in SMAPI 4.0.0.")]
         public T LoadAsset<T>(string key)
@@ -110,6 +111,7 @@ namespace StardewModdingAPI.Framework
         {
             return this.ModContent.GetInternalAssetName(key).Name;
         }
+#endif
 
 
         /*********
diff --git a/src/SMAPI/Framework/ModHelpers/CommandHelper.cs b/src/SMAPI/Framework/ModHelpers/CommandHelper.cs
index ddbd618a..21435f62 100644
--- a/src/SMAPI/Framework/ModHelpers/CommandHelper.cs
+++ b/src/SMAPI/Framework/ModHelpers/CommandHelper.cs
@@ -1,5 +1,7 @@
 using System;
+#if SMAPI_DEPRECATED
 using StardewModdingAPI.Framework.Deprecations;
+#endif
 
 namespace StardewModdingAPI.Framework.ModHelpers
 {
@@ -32,6 +34,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
             return this;
         }
 
+#if SMAPI_DEPRECATED
         /// <inheritdoc />
         [Obsolete("Use mod-provided APIs to integrate with mods instead. This method will be removed in SMAPI 4.0.0.")]
         public bool Trigger(string name, string[] arguments)
@@ -45,5 +48,6 @@ namespace StardewModdingAPI.Framework.ModHelpers
 
             return this.CommandManager.Trigger(name, arguments);
         }
+#endif
     }
 }
diff --git a/src/SMAPI/Framework/ModHelpers/ContentHelper.cs b/src/SMAPI/Framework/ModHelpers/ContentHelper.cs
index 427adac2..9992cb52 100644
--- a/src/SMAPI/Framework/ModHelpers/ContentHelper.cs
+++ b/src/SMAPI/Framework/ModHelpers/ContentHelper.cs
@@ -1,3 +1,4 @@
+#if SMAPI_DEPRECATED
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
@@ -249,3 +250,4 @@ namespace StardewModdingAPI.Framework.ModHelpers
         }
     }
 }
+#endif
diff --git a/src/SMAPI/Framework/ModHelpers/ModHelper.cs b/src/SMAPI/Framework/ModHelpers/ModHelper.cs
index 48973691..9ac3b6f7 100644
--- a/src/SMAPI/Framework/ModHelpers/ModHelper.cs
+++ b/src/SMAPI/Framework/ModHelpers/ModHelper.cs
@@ -1,7 +1,9 @@
 using System;
 using System.IO;
 using StardewModdingAPI.Events;
+#if SMAPI_DEPRECATED
 using StardewModdingAPI.Framework.Deprecations;
+#endif
 using StardewModdingAPI.Framework.Input;
 
 namespace StardewModdingAPI.Framework.ModHelpers
@@ -9,12 +11,14 @@ namespace StardewModdingAPI.Framework.ModHelpers
     /// <summary>Provides simplified APIs for writing mods.</summary>
     internal class ModHelper : BaseHelper, IModHelper, IDisposable
     {
+#if SMAPI_DEPRECATED
         /*********
         ** Fields
         *********/
         /// <summary>The backing field for <see cref="Content"/>.</summary>
         [Obsolete("This only exists to support legacy code and will be removed in SMAPI 4.0.0.")]
         private readonly ContentHelper ContentImpl;
+#endif
 
 
         /*********
@@ -26,6 +30,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
         /// <inheritdoc />
         public IModEvents Events { get; }
 
+#if SMAPI_DEPRECATED
         /// <inheritdoc />
         [Obsolete($"Use {nameof(IGameContentHelper)} or {nameof(IModContentHelper)} instead.")]
         public IContentHelper Content
@@ -42,6 +47,7 @@ namespace StardewModdingAPI.Framework.ModHelpers
                 return this.ContentImpl;
             }
         }
+#endif
 
         /// <inheritdoc />
         public IGameContentHelper GameContent { get; }
@@ -82,7 +88,6 @@ namespace StardewModdingAPI.Framework.ModHelpers
         /// <param name="modDirectory">The full path to the mod's folder.</param>
         /// <param name="currentInputState">Manages the game's input state for the current player instance. That may not be the main player in split-screen mode.</param>
         /// <param name="events">Manages access to events raised by SMAPI.</param>
-        /// <param name="contentHelper">An API for loading content assets.</param>
         /// <param name="gameContentHelper">An API for loading content assets from the game's <c>Content</c> folder or via <see cref="IModEvents.Content"/>.</param>
         /// <param name="modContentHelper">An API for loading content assets from your mod's files.</param>
         /// <param name="contentPackHelper">An API for managing content packs.</param>
@@ -96,9 +101,9 @@ namespace StardewModdingAPI.Framework.ModHelpers
         /// <exception cref="InvalidOperationException">The <paramref name="modDirectory"/> path does not exist on disk.</exception>
         public ModHelper(
             IModMetadata mod, string modDirectory, Func<SInputState> currentInputState, IModEvents events,
-#pragma warning disable CS0612 // deprecated code
+#if SMAPI_DEPRECATED
             ContentHelper contentHelper,
-#pragma warning restore CS0612
+#endif
             IGameContentHelper gameContentHelper, IModContentHelper modContentHelper, IContentPackHelper contentPackHelper, ICommandHelper commandHelper, IDataHelper dataHelper, IModRegistry modRegistry, IReflectionHelper reflectionHelper, IMultiplayerHelper multiplayer, ITranslationHelper translationHelper
         )
             : base(mod)
@@ -111,9 +116,9 @@ namespace StardewModdingAPI.Framework.ModHelpers
 
             // initialize
             this.DirectoryPath = modDirectory;
-#pragma warning disable CS0612 // deprecated code
+#if SMAPI_DEPRECATED
             this.ContentImpl = contentHelper ?? throw new ArgumentNullException(nameof(contentHelper));
-#pragma warning restore CS0612
+#endif
             this.GameContent = gameContentHelper ?? throw new ArgumentNullException(nameof(gameContentHelper));
             this.ModContent = modContentHelper ?? throw new ArgumentNullException(nameof(modContentHelper));
             this.ContentPacks = contentPackHelper ?? throw new ArgumentNullException(nameof(contentPackHelper));
@@ -127,12 +132,14 @@ namespace StardewModdingAPI.Framework.ModHelpers
             this.Events = events;
         }
 
+#if SMAPI_DEPRECATED
         /// <summary>Get the underlying instance for <see cref="IContentHelper"/>.</summary>
         [Obsolete("This only exists to support legacy code and will be removed in SMAPI 4.0.0.")]
         public ContentHelper GetLegacyContentHelper()
         {
             return this.ContentImpl;
         }
+#endif
 
         /****
         ** Mod config file
diff --git a/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs b/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
index e5aaa8ee..eb940c41 100644
--- a/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
+++ b/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
@@ -163,6 +163,7 @@ namespace StardewModdingAPI.Framework.ModLoading
                 this.AssemblyDefinitionResolver.Add(assembly.Definition);
             }
 
+#if SMAPI_DEPRECATED
             // special case: clear legacy-DLL warnings if the mod bundles a copy
             if (mod.Warnings.HasFlag(ModWarning.DetectedLegacyCachingDll))
             {
@@ -185,6 +186,7 @@ namespace StardewModdingAPI.Framework.ModLoading
                 if (File.Exists(Path.Combine(mod.DirectoryPath, "System.Security.Permissions.dll")))
                     mod.RemoveWarning(ModWarning.DetectedLegacyPermissionsDll);
             }
+#endif
 
             // throw if incompatibilities detected
             if (!assumeCompatible && mod.Warnings.HasFlag(ModWarning.BrokenCodeLoaded))
@@ -452,6 +454,7 @@ namespace StardewModdingAPI.Framework.ModLoading
                     mod.SetWarning(ModWarning.AccessesShell);
                     break;
 
+#if SMAPI_DEPRECATED
                 case InstructionHandleResult.DetectedLegacyCachingDll:
                     template = $"{logPrefix}Detected reference to System.Runtime.Caching.dll, which will be removed in SMAPI 4.0.0.";
                     mod.SetWarning(ModWarning.DetectedLegacyCachingDll);
@@ -466,6 +469,7 @@ namespace StardewModdingAPI.Framework.ModLoading
                     template = $"{logPrefix}Detected reference to System.Security.Permissions.dll, which will be removed in SMAPI 4.0.0.";
                     mod.SetWarning(ModWarning.DetectedLegacyPermissionsDll);
                     break;
+#endif
 
                 case InstructionHandleResult.None:
                     break;
diff --git a/src/SMAPI/Framework/ModLoading/Finders/LegacyAssemblyFinder.cs b/src/SMAPI/Framework/ModLoading/Finders/LegacyAssemblyFinder.cs
index d3437b05..77380907 100644
--- a/src/SMAPI/Framework/ModLoading/Finders/LegacyAssemblyFinder.cs
+++ b/src/SMAPI/Framework/ModLoading/Finders/LegacyAssemblyFinder.cs
@@ -1,3 +1,4 @@
+#if SMAPI_DEPRECATED
 using Mono.Cecil;
 using StardewModdingAPI.Framework.ModLoading.Framework;
 
@@ -47,3 +48,4 @@ namespace StardewModdingAPI.Framework.ModLoading.Finders
         }
     }
 }
+#endif
diff --git a/src/SMAPI/Framework/ModLoading/InstructionHandleResult.cs b/src/SMAPI/Framework/ModLoading/InstructionHandleResult.cs
index 476c30d0..189ca64e 100644
--- a/src/SMAPI/Framework/ModLoading/InstructionHandleResult.cs
+++ b/src/SMAPI/Framework/ModLoading/InstructionHandleResult.cs
@@ -32,6 +32,7 @@ namespace StardewModdingAPI.Framework.ModLoading
         /// <summary>The instruction accesses the OS shell or processes directly.</summary>
         DetectedShellAccess,
 
+#if SMAPI_DEPRECATED
         /// <summary>The module references the legacy <c>System.Configuration.ConfigurationManager</c> assembly and doesn't include a copy in the mod folder, so it'll break in SMAPI 4.0.0.</summary>
         DetectedLegacyConfigurationDll,
 
@@ -40,5 +41,6 @@ namespace StardewModdingAPI.Framework.ModLoading
 
         /// <summary>The module references the legacy <c>System.Security.Permissions</c> assembly and doesn't include a copy in the mod folder, so it'll break in SMAPI 4.0.0.</summary>
         DetectedLegacyPermissionsDll
+#endif
     }
 }
diff --git a/src/SMAPI/Framework/SCore.cs b/src/SMAPI/Framework/SCore.cs
index 385a94ea..ff3eadf5 100644
--- a/src/SMAPI/Framework/SCore.cs
+++ b/src/SMAPI/Framework/SCore.cs
@@ -32,7 +32,9 @@ using StardewModdingAPI.Framework.Networking;
 using StardewModdingAPI.Framework.Reflection;
 using StardewModdingAPI.Framework.Rendering;
 using StardewModdingAPI.Framework.Serialization;
+#if SMAPI_DEPRECATED
 using StardewModdingAPI.Framework.StateTracking.Comparers;
+#endif
 using StardewModdingAPI.Framework.StateTracking.Snapshots;
 using StardewModdingAPI.Framework.Utilities;
 using StardewModdingAPI.Internal;
@@ -139,8 +141,10 @@ namespace StardewModdingAPI.Framework
         /// <summary>The maximum number of consecutive attempts SMAPI should make to recover from an update error.</summary>
         private readonly Countdown UpdateCrashTimer = new(60); // 60 ticks = roughly one second
 
+#if SMAPI_DEPRECATED
         /// <summary>Asset interceptors added or removed since the last tick.</summary>
         private readonly List<AssetInterceptorChange> ReloadAssetInterceptorsQueue = new();
+#endif
 
         /// <summary>A list of queued commands to parse and execute.</summary>
         /// <remarks>This property must be thread-safe, since it's accessed from a separate console input thread.</remarks>
@@ -483,6 +487,7 @@ namespace StardewModdingAPI.Framework
                     return;
                 }
 
+#if SMAPI_DEPRECATED
                 /*********
                 ** Reload assets when interceptors are added/removed
                 *********/
@@ -515,6 +520,7 @@ namespace StardewModdingAPI.Framework
                     // reload affected assets
                     this.ContentCore.InvalidateCache(asset => interceptors.Any(p => p.CanIntercept(asset)));
                 }
+#endif
 
                 /*********
                 ** Parse commands
@@ -1646,9 +1652,9 @@ namespace StardewModdingAPI.Framework
 
             // initialize loaded non-content-pack mods
             this.Monitor.Log("Launching mods...", LogLevel.Debug);
-#pragma warning disable CS0612, CS0618 // deprecated code
             foreach (IModMetadata metadata in loadedMods)
             {
+#if SMAPI_DEPRECATED
                 // add interceptors
                 if (metadata.Mod?.Helper is ModHelper helper)
                 {
@@ -1684,7 +1690,6 @@ namespace StardewModdingAPI.Framework
                     content.ObservableAssetEditors.CollectionChanged += (_, e) => this.OnAssetInterceptorsChanged(metadata, e.NewItems?.Cast<IAssetEditor>(), e.OldItems?.Cast<IAssetEditor>(), this.ContentCore.Editors);
                     content.ObservableAssetLoaders.CollectionChanged += (_, e) => this.OnAssetInterceptorsChanged(metadata, e.NewItems?.Cast<IAssetLoader>(), e.OldItems?.Cast<IAssetLoader>(), this.ContentCore.Loaders);
                 }
-#pragma warning restore CS0612, CS0618
 
                 // log deprecation warnings
                 if (metadata.HasWarnings(ModWarning.DetectedLegacyCachingDll, ModWarning.DetectedLegacyConfigurationDll, ModWarning.DetectedLegacyPermissionsDll))
@@ -1710,6 +1715,7 @@ namespace StardewModdingAPI.Framework
                         );
                     }
                 }
+#endif
 
                 // call entry method
                 Context.HeuristicModsRunningCode.Push(metadata);
@@ -1750,6 +1756,7 @@ namespace StardewModdingAPI.Framework
             this.Monitor.Log("Mods loaded and ready!", LogLevel.Debug);
         }
 
+#if SMAPI_DEPRECATED
         /// <summary>Raised after a mod adds or removes asset interceptors.</summary>
         /// <typeparam name="T">The asset interceptor type (one of <see cref="IAssetEditor"/> or <see cref="IAssetLoader"/>).</typeparam>
         /// <param name="mod">The mod metadata.</param>
@@ -1772,6 +1779,7 @@ namespace StardewModdingAPI.Framework
                     list.Remove(entry);
             }
         }
+#endif
 
         /// <summary>Load a given mod.</summary>
         /// <param name="mod">The mod to load.</param>
@@ -1915,9 +1923,9 @@ namespace StardewModdingAPI.Framework
                     {
                         IModEvents events = new ModEvents(mod, this.EventManager);
                         ICommandHelper commandHelper = new CommandHelper(mod, this.CommandManager);
-#pragma warning disable CS0612 // deprecated code
+#if SMAPI_DEPRECATED
                         ContentHelper contentHelper = new(contentCore, mod.DirectoryPath, mod, monitor, this.Reflection);
-#pragma warning restore CS0612
+#endif
                         GameContentHelper gameContentHelper = new(contentCore, mod, mod.DisplayName, monitor, this.Reflection);
                         IModContentHelper modContentHelper = new ModContentHelper(contentCore, mod.DirectoryPath, mod, mod.DisplayName, gameContentHelper.GetUnderlyingContentManager(), this.Reflection);
                         IContentPackHelper contentPackHelper = new ContentPackHelper(
@@ -1930,7 +1938,11 @@ namespace StardewModdingAPI.Framework
                         IModRegistry modRegistryHelper = new ModRegistryHelper(mod, this.ModRegistry, proxyFactory, monitor);
                         IMultiplayerHelper multiplayerHelper = new MultiplayerHelper(mod, this.Multiplayer);
 
-                        modHelper = new ModHelper(mod, mod.DirectoryPath, () => this.GetCurrentGameInstance().Input, events, contentHelper, gameContentHelper, modContentHelper, contentPackHelper, commandHelper, dataHelper, modRegistryHelper, reflectionHelper, multiplayerHelper, translationHelper);
+                        modHelper = new ModHelper(mod, mod.DirectoryPath, () => this.GetCurrentGameInstance().Input, events,
+#if SMAPI_DEPRECATED
+                            contentHelper,
+#endif
+                            gameContentHelper, modContentHelper, contentPackHelper, commandHelper, dataHelper, modRegistryHelper, reflectionHelper, multiplayerHelper, translationHelper);
                     }
 
                     // init mod
diff --git a/src/SMAPI/GameFramework.cs b/src/SMAPI/GameFramework.cs
index 60fbe56e..009865fe 100644
--- a/src/SMAPI/GameFramework.cs
+++ b/src/SMAPI/GameFramework.cs
@@ -1,13 +1,17 @@
+#if SMAPI_DEPRECATED
 using System;
+#endif
 
 namespace StardewModdingAPI
 {
     /// <summary>The game framework running the game.</summary>
     public enum GameFramework
     {
+#if SMAPI_DEPRECATED
         /// <summary>The XNA Framework, previously used on Windows.</summary>
         [Obsolete("Stardew Valley no longer uses XNA Framework on any supported platform.  This value will be removed in SMAPI 4.0.0.")]
         Xna,
+#endif
 
         /// <summary>The MonoGame framework.</summary>
         MonoGame
diff --git a/src/SMAPI/IAssetEditor.cs b/src/SMAPI/IAssetEditor.cs
index 9f22ed83..f3238ba9 100644
--- a/src/SMAPI/IAssetEditor.cs
+++ b/src/SMAPI/IAssetEditor.cs
@@ -1,3 +1,4 @@
+#if SMAPI_DEPRECATED
 using System;
 using StardewModdingAPI.Events;
 
@@ -19,3 +20,4 @@ namespace StardewModdingAPI
         void Edit<T>(IAssetData asset);
     }
 }
+#endif
diff --git a/src/SMAPI/IAssetInfo.cs b/src/SMAPI/IAssetInfo.cs
index 44fd91a5..20064946 100644
--- a/src/SMAPI/IAssetInfo.cs
+++ b/src/SMAPI/IAssetInfo.cs
@@ -8,25 +8,34 @@ namespace StardewModdingAPI
         /*********
         ** Accessors
         *********/
+#if SMAPI_DEPRECATED
         /// <summary>The content's locale code, if the content is localized.</summary>
         /// <remarks>LEGACY NOTE: when reading this field from an <see cref="IAssetLoader"/> or <see cref="IAssetEditor"/> implementation, for non-localized assets it will return the current game locale (or an empty string for English) instead of null.</remarks>
+#else
+        /// <summary>The content's locale code, if the content is localized.</summary>
+#endif
         string? Locale { get; }
 
+#if SMAPI_DEPRECATED
         /// <summary>The asset name being read.</summary>
         /// <remarks>LEGACY NOTE: when reading this field from an <see cref="IAssetLoader"/> or <see cref="IAssetEditor"/> implementation, it's always equivalent to <see cref="NameWithoutLocale"/> for backwards compatibility.</remarks>
+#else
+        /// <summary>The asset name being read.</summary>
+#endif
         public IAssetName Name { get; }
 
         /// <summary>The <see cref="Name"/> with any locale codes stripped.</summary>
         /// <remarks>For example, if <see cref="Name"/> contains a locale like <c>Data/Bundles.fr-FR</c>, this will be the name without locale like <c>Data/Bundles</c>. If the name has no locale, this field is equivalent.</remarks>
         public IAssetName NameWithoutLocale { get; }
 
+        /// <summary>The content data type.</summary>
+        Type DataType { get; }
+
+#if SMAPI_DEPRECATED
         /// <summary>The normalized asset name being read. The format may change between platforms; see <see cref="AssetNameEquals"/> to compare with a known path.</summary>
         [Obsolete($"Use {nameof(Name)} or {nameof(NameWithoutLocale)} instead. This property will be removed in SMAPI 4.0.0.")]
         string AssetName { get; }
 
-        /// <summary>The content data type.</summary>
-        Type DataType { get; }
-
 
         /*********
         ** Public methods
@@ -35,5 +44,6 @@ namespace StardewModdingAPI
         /// <param name="path">The expected asset path, relative to the game's content folder and without the .xnb extension or locale suffix (like 'Data\ObjectInformation').</param>
         [Obsolete($"Use {nameof(Name)}.{nameof(IAssetName.IsEquivalentTo)} or {nameof(NameWithoutLocale)}.{nameof(IAssetName.IsEquivalentTo)} instead. This method will be removed in SMAPI 4.0.0.")]
         bool AssetNameEquals(string path);
+#endif
     }
 }
diff --git a/src/SMAPI/IAssetLoader.cs b/src/SMAPI/IAssetLoader.cs
index 96b98793..205980a7 100644
--- a/src/SMAPI/IAssetLoader.cs
+++ b/src/SMAPI/IAssetLoader.cs
@@ -1,3 +1,4 @@
+#if SMAPI_DEPRECATED
 using System;
 using StardewModdingAPI.Events;
 
@@ -19,3 +20,4 @@ namespace StardewModdingAPI
         T Load<T>(IAssetInfo asset);
     }
 }
+#endif
diff --git a/src/SMAPI/ICommandHelper.cs b/src/SMAPI/ICommandHelper.cs
index 9f1c345c..c92a09c2 100644
--- a/src/SMAPI/ICommandHelper.cs
+++ b/src/SMAPI/ICommandHelper.cs
@@ -17,11 +17,13 @@ namespace StardewModdingAPI
         /// <exception cref="ArgumentException">There's already a command with that name.</exception>
         ICommandHelper Add(string name, string documentation, Action<string, string[]> callback);
 
+#if SMAPI_DEPRECATED
         /// <summary>Trigger a command.</summary>
         /// <param name="name">The command name.</param>
         /// <param name="arguments">The command arguments.</param>
         /// <returns>Returns whether a matching command was triggered.</returns>
         [Obsolete("Use mod-provided APIs to integrate with mods instead. This method will be removed in SMAPI 4.0.0.")]
         bool Trigger(string name, string[] arguments);
+#endif
     }
 }
diff --git a/src/SMAPI/IContentHelper.cs b/src/SMAPI/IContentHelper.cs
index 7637edf0..b0e30a82 100644
--- a/src/SMAPI/IContentHelper.cs
+++ b/src/SMAPI/IContentHelper.cs
@@ -1,3 +1,4 @@
+#if SMAPI_DEPRECATED
 using System;
 using System.Collections.Generic;
 using System.Diagnostics.Contracts;
@@ -80,3 +81,4 @@ namespace StardewModdingAPI
             where T : notnull;
     }
 }
+#endif
diff --git a/src/SMAPI/IContentPack.cs b/src/SMAPI/IContentPack.cs
index 73b1a860..5047b172 100644
--- a/src/SMAPI/IContentPack.cs
+++ b/src/SMAPI/IContentPack.cs
@@ -1,7 +1,9 @@
 using System;
+#if SMAPI_DEPRECATED
 using Microsoft.Xna.Framework.Content;
 using Microsoft.Xna.Framework.Graphics;
 using xTile;
+#endif
 
 namespace StardewModdingAPI
 {
@@ -47,6 +49,7 @@ namespace StardewModdingAPI
         void WriteJsonFile<TModel>(string path, TModel data)
             where TModel : class;
 
+#if SMAPI_DEPRECATED
         /// <summary>Load content from the content pack folder (if not already cached), and return it. When loading a <c>.png</c> file, this must be called outside the game's draw loop.</summary>
         /// <typeparam name="T">The expected data type. The main supported types are <see cref="Map"/>, <see cref="Texture2D"/>, <see cref="IRawTextureData"/>, and data structures; other types may be supported by the game's content pipeline.</typeparam>
         /// <param name="key">The relative file path within the content pack (case-insensitive).</param>
@@ -61,5 +64,6 @@ namespace StardewModdingAPI
         /// <exception cref="ArgumentException">The <paramref name="key"/> is empty or contains invalid characters.</exception>
         [Obsolete($"Use {nameof(IContentPack.ModContent)}.{nameof(IModContentHelper.GetInternalAssetName)} instead. This method will be removed in SMAPI 4.0.0.")]
         string GetActualAssetKey(string key);
+#endif
     }
 }
diff --git a/src/SMAPI/IModHelper.cs b/src/SMAPI/IModHelper.cs
index 15e4ed8d..a44d92c1 100644
--- a/src/SMAPI/IModHelper.cs
+++ b/src/SMAPI/IModHelper.cs
@@ -1,4 +1,6 @@
+#if SMAPI_DEPRECATED
 using System;
+#endif
 using StardewModdingAPI.Events;
 
 namespace StardewModdingAPI
@@ -25,9 +27,11 @@ namespace StardewModdingAPI
         /// <remarks>This API is intended for reading content assets from the mod files (like game data, images, etc); see also <see cref="Data"/> which is intended for persisting internal mod data.</remarks>
         IModContentHelper ModContent { get; }
 
+#if SMAPI_DEPRECATED
         /// <summary>An API for loading content assets.</summary>
         [Obsolete($"Use {nameof(IGameContentHelper)} or {nameof(IModContentHelper)} instead.")]
         IContentHelper Content { get; }
+#endif
 
         /// <summary>An API for managing content packs.</summary>
         IContentPackHelper ContentPacks { get; }
diff --git a/src/SMAPI/Metadata/InstructionMetadata.cs b/src/SMAPI/Metadata/InstructionMetadata.cs
index dce0c6b1..efa91d20 100644
--- a/src/SMAPI/Metadata/InstructionMetadata.cs
+++ b/src/SMAPI/Metadata/InstructionMetadata.cs
@@ -54,8 +54,10 @@ namespace StardewModdingAPI.Metadata
                 // detect Harmony & rewrite for SMAPI 3.12 (Harmony 1.x => 2.0 update)
                 yield return new HarmonyRewriter();
 
+#if SMAPI_DEPRECATED
                 // detect issues for SMAPI 4.0.0
                 yield return new LegacyAssemblyFinder();
+#endif
             }
             else
                 yield return new HarmonyRewriter(shouldRewrite: false);
diff --git a/src/SMAPI/Utilities/PerScreen.cs b/src/SMAPI/Utilities/PerScreen.cs
index b86310b8..54657ade 100644
--- a/src/SMAPI/Utilities/PerScreen.cs
+++ b/src/SMAPI/Utilities/PerScreen.cs
@@ -1,8 +1,10 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+#if SMAPI_DEPRECATED
 using StardewModdingAPI.Framework;
 using StardewModdingAPI.Framework.Deprecations;
+#endif
 
 namespace StardewModdingAPI.Utilities
 {
@@ -41,12 +43,31 @@ namespace StardewModdingAPI.Utilities
         /// <summary>Construct an instance.</summary>
         /// <remarks><strong>Limitation with nullable reference types:</strong> when the underlying type <typeparamref name="T"/> is nullable, this sets the default value to null regardless of whether you marked the type parameter nullable. To avoid that, set the default value with the 'createNewState' argument instead.</remarks>
         public PerScreen()
-            : this(null, nullExpected: true) { }
+        {
+            this.CreateNewState = (() => default!);
+        }
 
         /// <summary>Construct an instance.</summary>
         /// <param name="createNewState">Create the initial state for a screen.</param>
         public PerScreen(Func<T> createNewState)
-            : this(createNewState, nullExpected: false) { }
+        {
+            if (createNewState is null)
+            {
+#if SMAPI_DEPRECATED
+                createNewState = (() => default!);
+                SCore.DeprecationManager.Warn(
+                    null,
+                    $"calling the {nameof(PerScreen<T>)} constructor with null",
+                    "3.14.0",
+                    DeprecationLevel.Notice
+                );
+#else
+                throw new ArgumentNullException(nameof(createNewState));
+#endif
+            }
+
+            this.CreateNewState = createNewState;
+        }
 
         /// <summary>Get all active values by screen ID. This doesn't initialize the value for a screen ID if it's not created yet.</summary>
         public IEnumerable<KeyValuePair<int, T>> GetActiveValues()
@@ -84,30 +105,6 @@ namespace StardewModdingAPI.Utilities
         /*********
         ** Private methods
         *********/
-        /// <summary>Construct an instance.</summary>
-        /// <param name="createNewState">Create the initial state for a screen.</param>
-        /// <param name="nullExpected">Whether a null <paramref name="createNewState"/> value is expected.</param>
-        /// <remarks>This constructor only exists to maintain backwards compatibility. In SMAPI 4.0.0, the overload that passes <c>nullExpected: false</c> should throw an exception instead.</remarks>
-        private PerScreen(Func<T>? createNewState, bool nullExpected)
-        {
-            if (createNewState is null)
-            {
-                createNewState = (() => default!);
-
-                if (!nullExpected)
-                {
-                    SCore.DeprecationManager.Warn(
-                        null,
-                        $"calling the {nameof(PerScreen<T>)} constructor with null",
-                        "3.14.0",
-                        DeprecationLevel.Notice
-                    );
-                }
-            }
-
-            this.CreateNewState = createNewState;
-        }
-
         /// <summary>Remove screens which are no longer active.</summary>
         private void RemoveDeadScreens()
         {