Diagnostics for module initializers feature

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -6109,4 +6109,16 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
   <data name="IDS_FeatureModuleInitializers" xml:space="preserve">
     <value>module initializers</value>
   </data>
+  <data name="ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType" xml:space="preserve">
+    <value>Module initializer method '{0}' must be accessible at the module level</value>
+  </data>
+  <data name="ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid" xml:space="preserve">
+    <value>Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</value>
+  </data>
+  <data name="ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric" xml:space="preserve">
+    <value>Module initializer method '{0}' must not be generic and must not be contained in a generic type</value>
+  </data>
+  <data name="ERR_ModuleInitializerMethodMustBeOrdinary" xml:space="preserve">
+    <value>A module initializer must be an ordinary member method</value>
+  </data>
 </root>

src/Compilers/CSharp/Portable/Errors/ErrorCode.cs

@@ -1786,6 +1786,11 @@ internal enum ErrorCode
         WRN_GivenExpressionAlwaysMatchesPattern = 8793,
         WRN_IsPatternAlways = 8794,
 
+        ERR_ModuleInitializerMethodMustBeOrdinary = 8795,
+        ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType = 8796,
+        ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid = 8797,
+        ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric = 8798,
+
         #endregion diagnostics introduced for C# 9.0
 
         // Note: you will need to re-generate compiler code after adding warnings (eng\generate-compiler-code.cmd)

src/Compilers/CSharp/Portable/Symbols/Source/SourceMethodSymbolWithAttributes.cs

@@ -9,6 +9,7 @@
 using System.Linq;
 using System.Runtime.InteropServices;
 using System.Threading;
+using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Roslyn.Utilities;
 
@@ -485,8 +486,7 @@ private void DecodeWellKnownAttributeAppliedToMethod(ref DecodeWellKnownAttribut
             else if (attribute.IsTargetAttribute(this, AttributeDescription.ModuleInitializerAttribute))
             {
                 MessageID.IDS_FeatureModuleInitializers.CheckFeatureAvailability(arguments.Diagnostics, arguments.AttributeSyntaxOpt);
-                // PROTOTYPE(module-initializers): diagnostics
-                DeclaringCompilation.AddModuleInitializerMethod(this);
+                DecodeModuleInitializerAttribute(arguments);
             }
             else
             {
@@ -763,6 +763,46 @@ private void DecodeDllImportAttribute(ref DecodeWellKnownAttributeArguments<Attr
                     preserveSig);
             }
         }
+
+        private void DecodeModuleInitializerAttribute(DecodeWellKnownAttributeArguments<AttributeSyntax, CSharpAttributeData, AttributeLocation> arguments)
+        {
+            Debug.Assert(arguments.AttributeSyntaxOpt is object);
+
+            if (MethodKind != MethodKind.Ordinary)
+            {
+                arguments.Diagnostics.Add(ErrorCode.ERR_ModuleInitializerMethodMustBeOrdinary, arguments.AttributeSyntaxOpt.Location);
+                return;
+            }
+
+            Debug.Assert(ContainingType is object);
+            var hasError = false;
+
+            HashSet<DiagnosticInfo>? useSiteDiagnostics = null;
+            if (!AccessCheck.IsSymbolAccessible(this, ContainingAssembly, ref useSiteDiagnostics))
+            {
+                arguments.Diagnostics.Add(ErrorCode.ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType, arguments.AttributeSyntaxOpt.Location, Name);
+                hasError = true;
+            }
+
+            arguments.Diagnostics.Add(arguments.AttributeSyntaxOpt, useSiteDiagnostics);
+
+            if (!IsStatic || ParameterCount > 0 || !ReturnsVoid)
+            {
+                arguments.Diagnostics.Add(ErrorCode.ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid, arguments.AttributeSyntaxOpt.Location, Name);
+                hasError = true;
+            }
+
+            if (IsGenericMethod || ContainingType.IsGenericType)
+            {
+                arguments.Diagnostics.Add(ErrorCode.ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric, arguments.AttributeSyntaxOpt.Location, Name);
+                hasError = true;
+            }
+
+            if (!hasError && !CallsAreOmitted(arguments.AttributeSyntaxOpt.SyntaxTree))
+            {
+                DeclaringCompilation.AddModuleInitializerMethod(this);
+            }
+        }
 #nullable restore
 
         internal sealed override void PostDecodeWellKnownAttributes(ImmutableArray<CSharpAttributeData> boundAttributes, ImmutableArray<AttributeSyntax> allAttributeSyntaxNodes, DiagnosticBag diagnostics, AttributeLocation symbolPart, WellKnownAttributeData decodedData)

src/Compilers/CSharp/Portable/xlf/CSharpResources.cs.xlf

@@ -332,6 +332,26 @@
         <target state="translated">Chybějící vzor</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric">
+        <source>Module initializer method '{0}' must not be generic and must not be contained in a generic type</source>
+        <target state="new">Module initializer method '{0}' must not be generic and must not be contained in a generic type</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType">
+        <source>Module initializer method '{0}' must be accessible at the module level</source>
+        <target state="new">Module initializer method '{0}' must be accessible at the module level</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeOrdinary">
+        <source>A module initializer must be an ordinary member method</source>
+        <target state="new">A module initializer must be an ordinary member method</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid">
+        <source>Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</source>
+        <target state="new">Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_MultipleAnalyzerConfigsInSameDir">
         <source>Multiple analyzer config files cannot be in the same directory ('{0}').</source>
         <target state="translated">Ve stejném adresáři nemůže být více konfiguračních souborů analyzátoru ({0}).</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.de.xlf

@@ -332,6 +332,26 @@
         <target state="translated">Muster fehlt.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric">
+        <source>Module initializer method '{0}' must not be generic and must not be contained in a generic type</source>
+        <target state="new">Module initializer method '{0}' must not be generic and must not be contained in a generic type</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType">
+        <source>Module initializer method '{0}' must be accessible at the module level</source>
+        <target state="new">Module initializer method '{0}' must be accessible at the module level</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeOrdinary">
+        <source>A module initializer must be an ordinary member method</source>
+        <target state="new">A module initializer must be an ordinary member method</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid">
+        <source>Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</source>
+        <target state="new">Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_MultipleAnalyzerConfigsInSameDir">
         <source>Multiple analyzer config files cannot be in the same directory ('{0}').</source>
         <target state="translated">Dasselbe Verzeichnis ({0}) darf nicht mehrere Konfigurationsdateien des Analysetools enthalten.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.es.xlf

@@ -332,6 +332,26 @@
         <target state="translated">Falta un patrón.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric">
+        <source>Module initializer method '{0}' must not be generic and must not be contained in a generic type</source>
+        <target state="new">Module initializer method '{0}' must not be generic and must not be contained in a generic type</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType">
+        <source>Module initializer method '{0}' must be accessible at the module level</source>
+        <target state="new">Module initializer method '{0}' must be accessible at the module level</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeOrdinary">
+        <source>A module initializer must be an ordinary member method</source>
+        <target state="new">A module initializer must be an ordinary member method</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid">
+        <source>Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</source>
+        <target state="new">Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_MultipleAnalyzerConfigsInSameDir">
         <source>Multiple analyzer config files cannot be in the same directory ('{0}').</source>
         <target state="translated">No es posible que un mismo directorio ("{0}") contenga varios archivos de configuración del analizador.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.fr.xlf

@@ -332,6 +332,26 @@
         <target state="translated">Modèle manquant</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric">
+        <source>Module initializer method '{0}' must not be generic and must not be contained in a generic type</source>
+        <target state="new">Module initializer method '{0}' must not be generic and must not be contained in a generic type</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType">
+        <source>Module initializer method '{0}' must be accessible at the module level</source>
+        <target state="new">Module initializer method '{0}' must be accessible at the module level</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeOrdinary">
+        <source>A module initializer must be an ordinary member method</source>
+        <target state="new">A module initializer must be an ordinary member method</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid">
+        <source>Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</source>
+        <target state="new">Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_MultipleAnalyzerConfigsInSameDir">
         <source>Multiple analyzer config files cannot be in the same directory ('{0}').</source>
         <target state="translated">Plusieurs fichiers config d'analyseur ne peuvent pas figurer dans le même répertoire ('{0}').</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.it.xlf

@@ -332,6 +332,26 @@
         <target state="translated">Criterio mancante</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric">
+        <source>Module initializer method '{0}' must not be generic and must not be contained in a generic type</source>
+        <target state="new">Module initializer method '{0}' must not be generic and must not be contained in a generic type</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType">
+        <source>Module initializer method '{0}' must be accessible at the module level</source>
+        <target state="new">Module initializer method '{0}' must be accessible at the module level</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeOrdinary">
+        <source>A module initializer must be an ordinary member method</source>
+        <target state="new">A module initializer must be an ordinary member method</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid">
+        <source>Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</source>
+        <target state="new">Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_MultipleAnalyzerConfigsInSameDir">
         <source>Multiple analyzer config files cannot be in the same directory ('{0}').</source>
         <target state="translated">La stessa directory ('{0}') non può contenere più file di configurazione dell'analizzatore.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.ja.xlf

@@ -332,6 +332,26 @@
         <target state="translated">パターンがありません</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric">
+        <source>Module initializer method '{0}' must not be generic and must not be contained in a generic type</source>
+        <target state="new">Module initializer method '{0}' must not be generic and must not be contained in a generic type</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType">
+        <source>Module initializer method '{0}' must be accessible at the module level</source>
+        <target state="new">Module initializer method '{0}' must be accessible at the module level</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeOrdinary">
+        <source>A module initializer must be an ordinary member method</source>
+        <target state="new">A module initializer must be an ordinary member method</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid">
+        <source>Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</source>
+        <target state="new">Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_MultipleAnalyzerConfigsInSameDir">
         <source>Multiple analyzer config files cannot be in the same directory ('{0}').</source>
         <target state="translated">複数のアナライザー構成ファイルを同じディレクトリに入れることはできません ('{0}')。</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.ko.xlf

@@ -332,6 +332,26 @@
         <target state="translated">패턴이 없습니다.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric">
+        <source>Module initializer method '{0}' must not be generic and must not be contained in a generic type</source>
+        <target state="new">Module initializer method '{0}' must not be generic and must not be contained in a generic type</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType">
+        <source>Module initializer method '{0}' must be accessible at the module level</source>
+        <target state="new">Module initializer method '{0}' must be accessible at the module level</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeOrdinary">
+        <source>A module initializer must be an ordinary member method</source>
+        <target state="new">A module initializer must be an ordinary member method</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid">
+        <source>Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</source>
+        <target state="new">Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_MultipleAnalyzerConfigsInSameDir">
         <source>Multiple analyzer config files cannot be in the same directory ('{0}').</source>
         <target state="translated">분석기 구성 파일 여러 개가 동일한 디렉터리('{0}')에 있을 수 없습니다.</target>

src/Compilers/CSharp/Portable/xlf/CSharpResources.pl.xlf

@@ -332,6 +332,26 @@
         <target state="translated">Brak wzorca</target>
         <note />
       </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric">
+        <source>Module initializer method '{0}' must not be generic and must not be contained in a generic type</source>
+        <target state="new">Module initializer method '{0}' must not be generic and must not be contained in a generic type</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType">
+        <source>Module initializer method '{0}' must be accessible at the module level</source>
+        <target state="new">Module initializer method '{0}' must be accessible at the module level</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeOrdinary">
+        <source>A module initializer must be an ordinary member method</source>
+        <target state="new">A module initializer must be an ordinary member method</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid">
+        <source>Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</source>
+        <target state="new">Module initializer method '{0}' must be static, must have no parameters, and must return 'void'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="ERR_MultipleAnalyzerConfigsInSameDir">
         <source>Multiple analyzer config files cannot be in the same directory ('{0}').</source>
         <target state="translated">Wiele plików konfiguracji analizatora nie może znajdować się w tym samym katalogu („{0}”).</target>