Add trim analysis for implicit constructors

src/libraries/System.Text.RegularExpressions/src/System/Text/RegularExpressions/RegexLWCGCompiler.cs

@@ -8,6 +8,7 @@
 
 namespace System.Text.RegularExpressions
 {
+    [RequiresDynamicCode("Compiling a RegEx requires dynamic code.")]
     internal sealed class RegexLWCGCompiler : RegexCompiler
     {
         /// <summary>
@@ -31,7 +32,6 @@ internal sealed class RegexLWCGCompiler : RegexCompiler
         private static int s_regexCount;
 
         /// <summary>The top-level driver. Initializes everything then calls the Generate* methods.</summary>
-        [RequiresDynamicCode("Compiling a RegEx requires dynamic code.")]
         public RegexRunnerFactory? FactoryInstanceFromCode(string pattern, RegexTree regexTree, RegexOptions options, bool hasTimeout)
         {
             if (!regexTree.Root.SupportsCompilation(out _))
@@ -67,7 +67,6 @@ internal sealed class RegexLWCGCompiler : RegexCompiler
         }
 
         /// <summary>Begins the definition of a new method (no args) with a specified return value.</summary>
-        [RequiresDynamicCode("Compiling a RegEx requires dynamic code.")]
         private DynamicMethod DefineDynamicMethod(string methname, Type? returntype, Type hostType, Type[] paramTypes)
         {
             // We're claiming that these are static methods, but really they are instance methods.

src/tools/illink/src/ILLink.RoslynAnalyzer/RequiresAnalyzerBase.cs

@@ -128,6 +128,9 @@ public override void Initialize(AnalysisContext context)
                 foreach (var extraSyntaxNodeAction in ExtraSyntaxNodeActions)
                     context.RegisterSyntaxNodeAction(extraSyntaxNodeAction.Action, extraSyntaxNodeAction.SyntaxKind);
 
+                // Register the implicit base constructor analysis for all analyzers
+                context.RegisterSymbolAction(AnalyzeImplicitBaseCtor, SymbolKind.NamedType);
+
                 foreach (var extraSymbolAction in ExtraSymbolActions)
                     context.RegisterSymbolAction(extraSymbolAction.Action, extraSymbolAction.SymbolKind);
 
@@ -197,6 +200,33 @@ internal void CheckAndCreateRequiresDiagnostic(
             CreateRequiresDiagnostic(member, requiresAttribute, diagnosticContext);
         }
 
+        private void AnalyzeImplicitBaseCtor(SymbolAnalysisContext context)
+        {
+            var typeSymbol = (INamedTypeSymbol)context.Symbol;
+
+            if (typeSymbol.TypeKind != TypeKind.Class || typeSymbol.BaseType == null)
+                return;
+
+            if (typeSymbol.InstanceConstructors.Length != 1 || !typeSymbol.InstanceConstructors[0].IsImplicitlyDeclared)
+                return;
+
+            var implicitCtor = typeSymbol.InstanceConstructors[0];
+
+            var baseCtor = typeSymbol.BaseType.InstanceConstructors.FirstOrDefault(ctor => ctor.Parameters.IsEmpty);
+            if (baseCtor == null)
+                return;
+
+            var diagnosticContext = new DiagnosticContext(
+                typeSymbol.Locations[0],
+                context.ReportDiagnostic);
+
+            CheckAndCreateRequiresDiagnostic(
+                baseCtor,
+                implicitCtor,
+                ImmutableArray<ISymbol>.Empty,
+                diagnosticContext);
+        }
+
         [Flags]
         protected enum DiagnosticTargets
         {

src/tools/illink/test/Mono.Linker.Tests.Cases/RequiresCapability/RequiresExcludeStatics.cs

@@ -145,6 +145,10 @@ public static void Test()
             }
         }
 
+        [ExpectedWarning("IL2026", "BaseWithRequires.BaseWithRequires()", "--BaseWithRequires--", Tool.Analyzer, "")]
+        [ExpectedWarning("IL2026", "BaseWithRequires.BaseWithRequires()", "--BaseWithRequires--", Tool.Trimmer | Tool.NativeAot, "", CompilerGeneratedCode = true)]
+        [ExpectedWarning("IL3050", "BaseWithRequires.BaseWithRequires()", "--BaseWithRequires--", Tool.Analyzer, "NativeAOT Specific warning")]
+        [ExpectedWarning("IL3050", "BaseWithRequires.BaseWithRequires()", "--BaseWithRequires--", Tool.NativeAot, "NativeAOT Specific warning", CompilerGeneratedCode = true)]
         class DerivedWithoutRequires : BaseWithRequires
         {
             [ExpectedWarning("IL2026", "--Requires--")]
@@ -157,6 +161,9 @@ public static void Test()
             {
                 StaticMethod();
                 DerivedStaticMethod();
+
+                 // Instantiate for linker test consistency
+                new DerivedWithoutRequires();
             }
         }
 

src/tools/illink/test/Mono.Linker.Tests.Cases/RequiresCapability/RequiresOnClass.cs

@@ -36,6 +36,10 @@ public static void Main()
             AttributeParametersAndProperties.Test();
             MembersOnClassWithRequires<int>.Test();
             ConstFieldsOnClassWithRequires.Test();
+
+            // Instantiate classes so linker warnings match analyzer warnings
+            new TestUnconditionalSuppressMessage();
+            new DerivedWithoutRequiresOnType();
         }
 
         [RequiresUnreferencedCode("Message for --ClassWithRequires--")]
@@ -128,6 +132,10 @@ public DerivedFromNestedInRequiresClass() { }
             public static void StaticMethod() { }
         }
 
+        [ExpectedWarning("IL2026", "ClassWithRequires.ClassWithRequires()", "--ClassWithRequires--", Tool.Analyzer, "")]
+        [ExpectedWarning("IL2026", "ClassWithRequires.ClassWithRequires()", "--ClassWithRequires--", Tool.Trimmer | Tool.NativeAot, "", CompilerGeneratedCode = true)]
+        [ExpectedWarning("IL3050", "ClassWithRequires.ClassWithRequires()", "--ClassWithRequires--", Tool.Analyzer, "NativeAOT Specific warning")]
+        [ExpectedWarning("IL3050", "ClassWithRequires.ClassWithRequires()", "--ClassWithRequires--", Tool.NativeAot, "NativeAOT Specific warning", CompilerGeneratedCode = true)]
         class TestUnconditionalSuppressMessage : ClassWithRequires
         {
             public static void StaticMethodInTestSuppressionClass() { }
@@ -339,6 +347,10 @@ class BaseWithRequiresOnType
             public virtual void Method() { }
         }
 
+        [ExpectedWarning("IL2026", "BaseWithRequiresOnType.BaseWithRequiresOnType()", "RUC", Tool.Analyzer, "")]
+        [ExpectedWarning("IL2026", "BaseWithRequiresOnType.BaseWithRequiresOnType()", "RUC", Tool.Trimmer | Tool.NativeAot, "", CompilerGeneratedCode = true)]
+        [ExpectedWarning("IL3050", "BaseWithRequiresOnType.BaseWithRequiresOnType()", "RDC", Tool.Analyzer, "NativeAOT Specific warning")]
+        [ExpectedWarning("IL3050", "BaseWithRequiresOnType.BaseWithRequiresOnType()", "RDC", Tool.NativeAot, "NativeAOT Specific warning", CompilerGeneratedCode = true)]
         class DerivedWithoutRequiresOnType : BaseWithRequiresOnType
         {
             public override void Method() { }
@@ -694,6 +706,10 @@ class WithRequiresOnlyInstanceFields
                 public int InstanceField;
             }
 
+            [ExpectedWarning("IL2026", "WithRequires.WithRequires()", "--WithRequires--", Tool.Analyzer, "")]
+            [ExpectedWarning("IL2026", "WithRequires.WithRequires()", "--WithRequires--", Tool.Trimmer | Tool.NativeAot, "", CompilerGeneratedCode = true)]
+            [ExpectedWarning("IL3050", "WithRequires.WithRequires()", "--WithRequires--", Tool.Analyzer, "NativeAOT Specific warning")]
+            [ExpectedWarning("IL3050", "WithRequires.WithRequires()", "--WithRequires--", Tool.NativeAot, "NativeAOT Specific warning", CompilerGeneratedCode = true)]
             class DerivedWithoutRequires : WithRequires
             {
                 public static int DerivedStaticField;
@@ -831,6 +847,9 @@ public static void Test()
                 TestDAMOnTypeAccessInRUCScope(new DAMAnnotatedClassAccessedFromRUCScope());
                 TestDAMAccessOnOpenGeneric();
                 TestDAMAccessOnInstantiatedGeneric();
+
+                // Instantiate for linker test consistency
+                new DerivedWithoutRequires();
             }
         }
 
@@ -854,6 +873,10 @@ class DerivedRequires : WithRequires
                 private event EventHandler DerivedPrivateInstanceEvent;
             }
 
+            [ExpectedWarning("IL2026", "WithRequires.WithRequires()", "--WithRequires--", Tool.Analyzer, "")]
+            [ExpectedWarning("IL2026", "WithRequires.WithRequires()", "--WithRequires--", Tool.Trimmer | Tool.NativeAot, "", CompilerGeneratedCode = true)]
+            [ExpectedWarning("IL3050", "WithRequires.WithRequires()", "--WithRequires--", Tool.Analyzer, "NativeAOT Specific warning")]
+            [ExpectedWarning("IL3050", "WithRequires.WithRequires()", "--WithRequires--", Tool.NativeAot, "NativeAOT Specific warning", CompilerGeneratedCode = true)]
             class DerivedWithoutRequires : WithRequires
             {
                 public static event EventHandler DerivedStaticEvent;
@@ -1029,6 +1052,9 @@ public static void Test()
                 DerivedRequiresPublicEvents();
                 DerivedRequiresNonPublicEvents();
                 DerivedRequiresAllEvents();
+
+                // Instantiate for linker test consistency
+                new DerivedWithoutRequires();
             }
         }
 
@@ -1050,6 +1076,10 @@ class WithRequiresOnlyInstanceProperties
                 public int InstanceProperty { get; set; }
             }
 
+            [ExpectedWarning("IL2026", "WithRequires.WithRequires()", "--WithRequires--", Tool.Analyzer, "")]
+            [ExpectedWarning("IL2026", "WithRequires.WithRequires()", "--WithRequires--", Tool.Trimmer | Tool.NativeAot, "", CompilerGeneratedCode = true)]
+            [ExpectedWarning("IL3050", "WithRequires.WithRequires()", "--WithRequires--", Tool.Analyzer, "NativeAOT Specific warning")]
+            [ExpectedWarning("IL3050", "WithRequires.WithRequires()", "--WithRequires--", Tool.NativeAot, "NativeAOT Specific warning", CompilerGeneratedCode = true)]
             class DerivedWithoutRequires : WithRequires
             {
                 public static int DerivedStaticProperty { get; set; }
@@ -1217,6 +1247,9 @@ public static void Test()
                 TestDirectReflectionAccess();
                 TestDynamicDependencyAccess();
                 TestDAMOnTypeAccess(new DAMAnnotatedClass());
+
+                // Instantiate for linker test consistency
+                new DerivedWithoutRequires();
             }
         }