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Fix Feature Filter #64

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Merged
AngeloTadeucci merged 1 commit into from
May 4, 2026
Merged

Fix Feature Filter #64

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4 changes: 3 additions & 1 deletion Maple2.File.Generator/Resource/FeatureLocaleFilter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,9 @@ private static T Resolve<T>(this IEnumerable<T> enumerable) where T : IFeatureLo
}

int version = Features[entry.Feature];
if (version > maxVersion) {
if (version > maxVersion ||
// This is how the client resolves same version matches. Dumb as bricks.
(version == maxVersion && string.Compare(entry.Feature, result.Feature, StringComparison.Ordinal) > 0)) {
Comment on lines +68 to +70
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@coderabbitai coderabbitai Bot May 4, 2026

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⚠️ Potential issue | 🟡 Minor | ⚡ Quick win

Latent NullReferenceException when the first feature entry has version −1

result starts as default(T) — null for any reference-type T. The tie-breaker arm version == maxVersion fires the moment a feature entry's version matches the initial sentinel value of −1 (i.e. Features[entry.Feature] == -1). If that happens before any prior entry has set result, the expression result.Feature dereferences a null object and throws.

Note that string.Compare itself is null-safe for its string arguments (one or both comparands can be null — by definition, any string compares greater than a null reference), so the problem is specifically the member access on result, not the comparison call.

The correct guard also covers the semantics correctly: a null result should always be replaced by any feature entry at the same version (just as any feature beats no-feature).

🛡️ Proposed fix 
-            if (version > maxVersion ||
-                // This is how the client resolves same version matches. Dumb as bricks.
-                (version == maxVersion && string.Compare(entry.Feature, result.Feature, StringComparison.Ordinal) > 0)) {
+            if (version > maxVersion ||
+                // This is how the client resolves same version matches. Dumb as bricks.
+                (version == maxVersion && (result == null || string.Compare(entry.Feature, result.Feature, StringComparison.Ordinal) > 0))) {
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
if (version > maxVersion ||
// This is how the client resolves same version matches. Dumb as bricks.
(version == maxVersion && string.Compare(entry.Feature, result.Feature, StringComparison.Ordinal) > 0)) {
if (version > maxVersion ||
// This is how the client resolves same version matches. Dumb as bricks.
(version == maxVersion && (result == null || string.Compare(entry.Feature, result.Feature, StringComparison.Ordinal) > 0))) {
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@Maple2.File.Generator/Resource/FeatureLocaleFilter.cs` around lines 68 - 70,
The tie-breaker condition in FeatureLocaleFilter that reads (version ==
maxVersion && string.Compare(entry.Feature, result.Feature,
StringComparison.Ordinal) > 0) can dereference result (default(T) / null) when
the first seen entry has version == maxVersion (e.g. Features[entry.Feature] ==
-1); modify the condition to first check result == null before accessing
result.Feature so that any entry at the same version always replaces a null
result. In practice update the if in the method using variables version,
maxVersion, entry and result to: if (version > maxVersion || (version ==
maxVersion && (result == null || string.Compare(entry.Feature, result.Feature,
StringComparison.Ordinal) > 0))) so result is not dereferenced.

result = entry;
maxVersion = version;
}
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2 changes: 1 addition & 1 deletion Maple2.File.Parser/Maple2.File.Parser.csproj
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@
<PackageTags>MapleStory2, File, Parser, m2d, xml</PackageTags>
<!-- Use following lines to write the generated files to disk. -->
<EmitCompilerGeneratedFiles Condition=" '$(Configuration)' == 'Debug' ">true</EmitCompilerGeneratedFiles>
<PackageVersion>2.4.6</PackageVersion>
<PackageVersion>2.4.7</PackageVersion>
<TargetFramework>net8.0</TargetFramework>
<PackageReadmeFile>README.md</PackageReadmeFile>
<ImplicitUsings>enable</ImplicitUsings>
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