Features/module initializers

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -6319,4 +6319,19 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
   <data name="ERR_DoesNotOverrideBaseEqualityContract" xml:space="preserve">
     <value>'{0}' does not override expected property from '{1}'.</value>
   </data>
+  <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/Compilation/CSharpCompilation.cs

@@ -17,6 +17,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Cci;
+using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CodeGen;
 using Microsoft.CodeAnalysis.CSharp.Emit;
 using Microsoft.CodeAnalysis.CSharp.Symbols;
@@ -2057,6 +2058,14 @@ private protected override bool IsSymbolAccessibleWithinCore(
             throw new NotImplementedException();
         }
 
+        private ConcurrentSet<MethodSymbol>? _moduleInitializerMethods;
+
+        internal void AddModuleInitializerMethod(MethodSymbol method)
+        {
+            Debug.Assert(!_declarationDiagnosticsFrozen);
+            LazyInitializer.EnsureInitialized(ref _moduleInitializerMethods).Add(method);
+        }
+
         #endregion
 
         #region Binding
@@ -2857,6 +2866,11 @@ internal override bool CompileMethods(
                     filterOpt: filterOpt,
                     cancellationToken: cancellationToken);
 
+                if (!hasDeclarationErrors && !CommonCompiler.HasUnsuppressableErrors(methodBodyDiagnosticBag))
+                {
+                    GenerateModuleInitializer(moduleBeingBuilt, methodBodyDiagnosticBag);
+                }
+
                 bool hasMethodBodyError = !FilterAndAppendAndFreeDiagnostics(diagnostics, ref methodBodyDiagnosticBag);
 
                 if (hasDeclarationErrors || hasMethodBodyError)
@@ -2868,6 +2882,30 @@ internal override bool CompileMethods(
             return true;
         }
 
+        private void GenerateModuleInitializer(PEModuleBuilder moduleBeingBuilt, DiagnosticBag methodBodyDiagnosticBag)
+        {
+            Debug.Assert(_declarationDiagnosticsFrozen);
+
+            if (_moduleInitializerMethods is object)
+            {
+                var ilBuilder = new ILBuilder(moduleBeingBuilt, new LocalSlotManager(slotAllocator: null), OptimizationLevel.Release, areLocalsZeroed: false);
+
+                foreach (MethodSymbol method in _moduleInitializerMethods.OrderBy<MethodSymbol>(LexicalOrderSymbolComparer.Instance))
+                {
+                    ilBuilder.EmitOpCode(ILOpCode.Call, stackAdjustment: 0);
+
+                    ilBuilder.EmitToken(
+                        moduleBeingBuilt.Translate(method, methodBodyDiagnosticBag, needDeclaration: true),
+                        CSharpSyntaxTree.Dummy.GetRoot(),
+                        methodBodyDiagnosticBag);
+                }
+
+                ilBuilder.EmitRet(isVoid: true);
+                ilBuilder.Realize();
+                moduleBeingBuilt.RootModuleType.SetStaticConstructorBody(ilBuilder.RealizedIL);
+            }
+        }
+
         internal override bool GenerateResourcesAndDocumentationComments(
             CommonPEModuleBuilder moduleBuilder,
             Stream? xmlDocStream,

src/Compilers/CSharp/Portable/Compilation/LexicalOrderSymbolComparer.cs

@@ -8,10 +8,11 @@
 
 namespace Microsoft.CodeAnalysis.CSharp
 {
-    /// <summary> This is an implementation of a special symbol comparer, which is supposed to be used  for 
-    /// sorting original definition symbols (explicitly or explicitly declared in source  within the same 
-    /// container) in lexical order of their declarations. It will not work on  anything that uses non-source locations. 
-    /// </summary>        
+    /// <summary>
+    /// This is an implementation of a special symbol comparer, which is supposed to be used for sorting
+    /// original definition symbols (explicitly or implicitly declared in source within the same compilation)
+    /// in lexical order of their declarations. It will not work on anything that uses non-source locations.
+    /// </summary>
     internal class LexicalOrderSymbolComparer : IComparer<Symbol>
     {
         public static readonly LexicalOrderSymbolComparer Instance = new LexicalOrderSymbolComparer();
@@ -30,6 +31,7 @@ public int Compare(Symbol x, Symbol y)
 
             var xSortKey = x.GetLexicalSortKey();
             var ySortKey = y.GetLexicalSortKey();
+            Debug.Assert((object)x.DeclaringCompilation == y.DeclaringCompilation);
 
             comparison = LexicalSortKey.Compare(xSortKey, ySortKey);
             if (comparison != 0)

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

@@ -1820,13 +1820,10 @@ internal enum ErrorCode
         ERR_CannotConvertAddressOfToDelegate = 8811,
         ERR_AddressOfToNonFunctionPointer = 8812,
 
-        ERR_8813 = 8813, // used by features/module-initializers
-
-        ERR_8814 = 8814, // used by features/module-initializers
-
-        ERR_8815 = 8815, // used by features/module-initializers
-
-        ERR_8816 = 8816, // used by features/module-initializers
+        ERR_ModuleInitializerMethodMustBeOrdinary = 8813,
+        ERR_ModuleInitializerMethodMustBeAccessibleOutsideTopLevelType = 8814,
+        ERR_ModuleInitializerMethodMustBeStaticParameterlessVoid = 8815,
+        ERR_ModuleInitializerMethodAndContainingTypesMustNotBeGeneric = 8816,
 
         ERR_PartialMethodReturnTypeDifference = 8817,
         ERR_PartialMethodRefReturnDifference = 8818,

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

@@ -207,6 +207,7 @@ internal enum MessageID
         IDS_FeatureInitOnlySetters = MessageBase + 12781,
         IDS_FeatureRecords = MessageBase + 12782,
         IDS_FeatureNullPointerConstantPattern = MessageBase + 12783,
+        IDS_FeatureModuleInitializers = MessageBase + 12784,
     }
 
     // Message IDs may refer to strings that need to be localized.
@@ -332,6 +333,7 @@ internal static LanguageVersion RequiredVersion(this MessageID feature)
                 case MessageID.IDS_FeatureInitOnlySetters: // semantic check
                 case MessageID.IDS_FeatureRecords:
                 case MessageID.IDS_FeatureStaticAnonymousFunction: // syntax check
+                case MessageID.IDS_FeatureModuleInitializers: // semantic check on method attribute
                     return LanguageVersion.Preview;
 
                 // C# 8.0 features.

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;
 
@@ -486,6 +487,11 @@ private void DecodeWellKnownAttributeAppliedToMethod(ref DecodeWellKnownAttribut
                 MessageID.IDS_FeatureMemberNotNull.CheckFeatureAvailability(arguments.Diagnostics, arguments.AttributeSyntaxOpt);
                 CSharpAttributeData.DecodeMemberNotNullWhenAttribute<MethodWellKnownAttributeData>(ContainingType, ref arguments);
             }
+            else if (attribute.IsTargetAttribute(this, AttributeDescription.ModuleInitializerAttribute))
+            {
+                MessageID.IDS_FeatureModuleInitializers.CheckFeatureAvailability(arguments.Diagnostics, arguments.AttributeSyntaxOpt);
+                DecodeModuleInitializerAttribute(arguments);
+            }
             else
             {
                 var compilation = this.DeclaringCompilation;
@@ -762,6 +768,46 @@ 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

@@ -497,6 +497,26 @@
         <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>
@@ -1284,6 +1304,11 @@
         <target state="new">MemberNotNull attribute</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureModuleInitializers">
+        <source>module initializers</source>
+        <target state="new">module initializers</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeatureNameShadowingInNestedFunctions">
         <source>name shadowing in nested functions</source>
         <target state="translated">skrývání názvů ve vnořených funkcích</target>

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

@@ -497,6 +497,26 @@
         <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>
@@ -1284,6 +1304,11 @@
         <target state="new">MemberNotNull attribute</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureModuleInitializers">
+        <source>module initializers</source>
+        <target state="new">module initializers</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeatureNameShadowingInNestedFunctions">
         <source>name shadowing in nested functions</source>
         <target state="translated">Namensshadowing in geschachtelten Funktionen</target>

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

@@ -497,6 +497,26 @@
         <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>
@@ -1284,6 +1304,11 @@
         <target state="new">MemberNotNull attribute</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureModuleInitializers">
+        <source>module initializers</source>
+        <target state="new">module initializers</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeatureNameShadowingInNestedFunctions">
         <source>name shadowing in nested functions</source>
         <target state="translated">sombreado de nombres en funciones anidadas</target>

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

@@ -497,6 +497,26 @@
         <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>
@@ -1284,6 +1304,11 @@
         <target state="new">MemberNotNull attribute</target>
         <note />
       </trans-unit>
+      <trans-unit id="IDS_FeatureModuleInitializers">
+        <source>module initializers</source>
+        <target state="new">module initializers</target>
+        <note />
+      </trans-unit>
       <trans-unit id="IDS_FeatureNameShadowingInNestedFunctions">
         <source>name shadowing in nested functions</source>
         <target state="translated">ombrage des noms dans les fonctions imbriquées</target>