suppress non-applicable code warnings

build/common.targets

@@ -9,6 +9,21 @@
     <!--set platform-->
     <DefineConstants Condition="$(OS) == 'Windows_NT'">$(DefineConstants);SMAPI_FOR_WINDOWS</DefineConstants>
     <CopyToGameFolder>true</CopyToGameFolder>
+
+    <!-- allow mods to be compiled as AnyCPU for compatibility with older platforms -->
+    <ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch>None</ResolveAssemblyWarnOrErrorOnTargetArchitectureMismatch>
+
+    <!--
+      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.
+    -->
+    <NoWarn>$(NoWarn);CS0436;CA1416;CS0809;NU1701</NoWarn>
   </PropertyGroup>
 
   <!--find game folder-->

src/SMAPI/Framework/ModLoading/RewriteFacades/AccessToolsFacade.cs

@@ -4,6 +4,8 @@ using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using HarmonyLib;
 
+#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member: This is internal code to support rewriters that shouldn't be called directly.
+
 namespace StardewModdingAPI.Framework.ModLoading.RewriteFacades
 {
     /// <summary>Maps Harmony 1.x <see cref="AccessTools"/> methods to Harmony 2.x to avoid breaking older mods.</summary>

src/SMAPI/Framework/ModLoading/RewriteFacades/HarmonyInstanceFacade.cs

@@ -5,6 +5,8 @@ using System.Reflection;
 using System.Reflection.Emit;
 using HarmonyLib;
 
+#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member: This is internal code to support rewriters that shouldn't be called directly.
+
 namespace StardewModdingAPI.Framework.ModLoading.RewriteFacades
 {
     /// <summary>Maps Harmony 1.x <code>HarmonyInstance</code> methods to Harmony 2.x's <see cref="Harmony"/> to avoid breaking older mods.</summary>

src/SMAPI/Framework/ModLoading/RewriteFacades/HarmonyMethodFacade.cs

@@ -3,6 +3,8 @@ using System.Diagnostics.CodeAnalysis;
 using System.Reflection;
 using HarmonyLib;
 
+#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member: This is internal code to support rewriters that shouldn't be called directly.
+
 namespace StardewModdingAPI.Framework.ModLoading.RewriteFacades
 {
     /// <summary>Maps Harmony 1.x <see cref="HarmonyMethod"/> methods to Harmony 2.x to avoid breaking older mods.</summary>

src/SMAPI/Framework/ModLoading/RewriteFacades/SpriteBatchFacade.cs

@@ -2,6 +2,9 @@ using System.Diagnostics.CodeAnalysis;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
 
+#pragma warning disable CS0109 // Member does not hide an inherited member, new keyword is not required: This is deliberate to support legacy XNA Framework platforms.
+#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member: This is internal code to support rewriters that shouldn't be called directly.
+
 namespace StardewModdingAPI.Framework.ModLoading.RewriteFacades
 {
     /// <summary>Provides <see cref="SpriteBatch"/> method signatures that can be injected into mod code for compatibility with mods written for XNA Framework before Stardew Valley 1.5.5.</summary>

src/SMAPI/Utilities/Keybind.cs

@@ -105,7 +105,9 @@ namespace StardewModdingAPI.Utilities
         /// <summary>Get the keybind state relative to the previous tick.</summary>
         public SButtonState GetState()
         {
+#pragma warning disable CS0618 // Type or member is obsolete: deliberate call to GetButtonState() for unit tests
             SButtonState[] states = this.Buttons.Select(this.GetButtonState).Distinct().ToArray();
+#pragma warning restore CS0618
 
             // single state
             if (states.Length == 1)