detect broken assembly references not covered by a dependency, and flag as incompatible (#356)

2 files changed, 29 insertions, 1 deletions

diff --git a/docs/release-notes.md b/docs/release-notes.md
index adf161b4..80f6e604 100644
--- a/docs/release-notes.md
+++ b/docs/release-notes.md
@@ -27,8 +27,9 @@
   * Fixed launch issue for Linux players with some terminals. (Thanks to HanFox and kurumushi!)
   * Fixed issue where a mod crashing in `CanEdit` or `CanLoad` could cause an abort-retry loop.
   * Fixed many mods not working if the player name is blank.
+  * Fixed repeated errors in some cases when a mod references a missing assembly.
   * Renamed `install.exe` to `install on Windows.exe` to avoid confusion.
-  * Removed the `player_setspeed` and `player_setlevel` commands, which weren't implemented in a useful way. Use a mod like CJB Cheats Menu if you need those.
+  * Removed the `player_setlevel` and `player_setspeed` commands, which weren't implemented in a useful way. Use a mod like CJB Cheats Menu if you need those.
   * Updated compatibility list.
 
 * For modders:
diff --git a/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs b/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
index ba4c3f5c..8f5a8316 100644
--- a/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
+++ b/src/SMAPI/Framework/ModLoading/AssemblyLoader.cs
@@ -99,6 +99,19 @@ namespace StardewModdingAPI.Framework.ModLoading
                 // rewrite assembly
                 bool changed = this.RewriteAssembly(mod, assembly.Definition, assumeCompatible, loggedMessages, logPrefix: "      ");
 
+                // detect broken assembly reference
+                foreach (AssemblyNameReference reference in assembly.Definition.MainModule.AssemblyReferences)
+                {
+                    if (!this.IsAssemblyLoaded(reference))
+                    {
+                        this.Monitor.LogOnce(loggedMessages, $"      Broken code in {assembly.File.Name}: reference to missing assembly '{reference.FullName}'.");
+                        if (!assumeCompatible)
+                            throw new IncompatibleInstructionException($"assembly reference to {reference.FullName}", $"Found a reference to missing assembly '{reference.FullName}' while loading assembly {assembly.File.Name}.");
+                        mod.SetWarning(ModWarning.BrokenCodeLoaded);
+                        break;
+                    }
+                }
+
                 // load assembly
                 if (changed)
                 {
@@ -126,6 +139,20 @@ namespace StardewModdingAPI.Framework.ModLoading
             return lastAssembly;
         }
 
+        /// <summary>Get whether an assembly is loaded.</summary>
+        /// <param name="reference">The assembly name reference.</param>
+        public bool IsAssemblyLoaded(AssemblyNameReference reference)
+        {
+            try
+            {
+                return this.AssemblyDefinitionResolver.Resolve(reference) != null;
+            }
+            catch (AssemblyResolutionException)
+            {
+                return false;
+            }
+        }
+
         /// <summary>Resolve an assembly by its name.</summary>
         /// <param name="name">The assembly name.</param>
         /// <remarks>