C#: Only extract Public and Protected members from reference assemblies.

csharp/extractor/Semmle.Extraction.CSharp/CodeAnalysisExtensions/SymbolExtensions.cs

@@ -642,5 +642,40 @@ namespace Semmle.Extraction.CSharp
         /// </summary>
         public static IEnumerable<AnnotatedTypeSymbol> GetAnnotatedTypeArguments(this INamedTypeSymbol symbol) =>
             symbol.TypeArguments.Zip(symbol.TypeArgumentNullableAnnotations, (t, a) => new AnnotatedTypeSymbol(t, a));
+
+        /// <summary>
+        /// Returns true if the symbol is public, protected or protected internal.
+        /// </summary>
+        public static bool IsPublicOrProtected(this ISymbol symbol) =>
+            symbol.DeclaredAccessibility == Accessibility.Public
+            || symbol.DeclaredAccessibility == Accessibility.Protected
+            || symbol.DeclaredAccessibility == Accessibility.ProtectedOrInternal;
+
+        /// <summary>
+        /// Returns true if the given symbol should be extracted.
+        /// </summary>
+        public static bool ShouldExtractSymbol(this ISymbol symbol)
+        {
+            // Extract all source symbols and public/protected metadata symbols.
+            if (symbol.Locations.Any(x => !x.IsInMetadata) || symbol.IsPublicOrProtected())
+            {
+                return true;
+            }
+            if (symbol is IMethodSymbol method)
+            {
+                return method.ExplicitInterfaceImplementations.Any(m => m.ContainingType.DeclaredAccessibility == Accessibility.Public);
+            }
+            if (symbol is IPropertySymbol property)
+            {
+                return property.ExplicitInterfaceImplementations.Any(m => m.ContainingType.DeclaredAccessibility == Accessibility.Public);
+            }
+            return false;
+        }
+
+        /// <summary>
+        /// Returns the symbols that should be extracted.
+        /// </summary>
+        public static IEnumerable<T> ExtractionCandidates<T>(this IEnumerable<T> symbols) where T : ISymbol =>
+            symbols.Where(symbol => symbol.ShouldExtractSymbol());
     }
 }

csharp/extractor/Semmle.Extraction.CSharp/Entities/Method.cs

@@ -101,7 +101,7 @@ namespace Semmle.Extraction.CSharp.Entities
                 }
             }
 
-            if (Symbol.OverriddenMethod is not null)
+            if (Symbol.OverriddenMethod is not null && Symbol.OverriddenMethod.ShouldExtractSymbol())
             {
                 trapFile.overrides(this, Method.Create(Context, Symbol.OverriddenMethod));
             }

csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Type.cs

@@ -225,7 +225,7 @@ namespace Semmle.Extraction.CSharp.Entities
         }
 
         /// <summary>
-        /// Called to extract all members and nested types.
+        /// Called to extract members and nested types.
         /// This is called on each member of a namespace,
         /// in either source code or an assembly.
         /// </summary>
@@ -236,7 +236,7 @@ namespace Semmle.Extraction.CSharp.Entities
                 Context.BindComments(this, l);
             }
 
-            foreach (var member in Symbol.GetMembers())
+            foreach (var member in Symbol.GetMembers().ExtractionCandidates())
             {
                 switch (member.Kind)
                 {
@@ -262,16 +262,16 @@ namespace Semmle.Extraction.CSharp.Entities
 
                 var members = new List<ISymbol>();
 
-                foreach (var member in Symbol.GetMembers())
+                foreach (var member in Symbol.GetMembers().ExtractionCandidates())
                     members.Add(member);
-                foreach (var member in Symbol.GetTypeMembers())
+                foreach (var member in Symbol.GetTypeMembers().ExtractionCandidates())
                     members.Add(member);
 
                 // Mono extractor puts all BASE interface members as members of the current interface.
 
                 if (Symbol.TypeKind == TypeKind.Interface)
                 {
-                    foreach (var baseInterface in Symbol.Interfaces)
+                    foreach (var baseInterface in Symbol.Interfaces.ExtractionCandidates())
                     {
                         foreach (var member in baseInterface.GetMembers())
                             members.Add(member);
@@ -285,10 +285,10 @@ namespace Semmle.Extraction.CSharp.Entities
                     Context.CreateEntity(member);
                 }
 
-                if (Symbol.BaseType is not null)
+                if (Symbol.BaseType is not null && Symbol.BaseType.ShouldExtractSymbol())
                     Create(Context, Symbol.BaseType).PopulateGenerics();
 
-                foreach (var i in Symbol.Interfaces)
+                foreach (var i in Symbol.Interfaces.ExtractionCandidates())
                 {
                     Create(Context, i).PopulateGenerics();
                 }

csharp/extractor/Semmle.Extraction.CSharp/Extractor/Analyser.cs

@@ -269,7 +269,7 @@ namespace Semmle.Extraction.CSharp
                 AnalyseNamespace(cx, memberNamespace);
             }
 
-            foreach (var memberType in ns.GetTypeMembers())
+            foreach (var memberType in ns.GetTypeMembers().ExtractionCandidates())
             {
                 Entities.Type.Create(cx, memberType).ExtractRecursive();
             }

csharp/extractor/Semmle.Extraction.CSharp/Extractor/Extractor.cs

@@ -549,7 +549,6 @@ namespace Semmle.Extraction.CSharp
                         compilerArguments.CompilationOptions
                             .WithAssemblyIdentityComparer(DesktopAssemblyIdentityComparer.Default)
                             .WithStrongNameProvider(new DesktopStrongNameProvider(compilerArguments.KeyFileSearchPaths))
-                            .WithMetadataImportOptions(MetadataImportOptions.All)
                         );
                 },
                 (compilation, options) => analyser.EndInitialize(compilerArguments, options, compilation, cwd, args),