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Merge pull request #4761 from tamasvajk/feature/cil-enum-underlying
C#: Extract enum underlying type from IL
2 parents f95c480 + 2257a8d commit b649ccd

13 files changed

Lines changed: 7192 additions & 3005 deletions

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‎csharp/change-notes/2020-12-08-cil-enum-underlying-type.md‎

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@@ -0,0 +1,2 @@
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lgtm,codescanning
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* CIL extraction has been improved to store numeric underlying type of `enum` declarations.

‎csharp/extractor/Semmle.Extraction.CIL/Entities/TypeDefinitionType.cs‎

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@@ -212,6 +212,15 @@ public override IEnumerable<IExtractionProduct> Contents
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var @base = (Type)Cx.CreateGeneric(this, td.BaseType);
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yield return @base;
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yield return Tuples.cil_base_class(this, @base);
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if (IsSystemEnum(td.BaseType) &&
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GetUnderlyingEnumType() is var underlying &&
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underlying.HasValue)
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{
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var underlyingType = Cx.Create(underlying.Value);
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yield return underlyingType;
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yield return Tuples.cil_enum_underlying_type(this, underlyingType);
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}
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}
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foreach (var @interface in td.GetInterfaceImplementations().Select(i => Cx.MdReader.GetInterfaceImplementation(i)))
@@ -226,6 +235,59 @@ public override IEnumerable<IExtractionProduct> Contents
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}
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}
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private bool IsSystemEnum(EntityHandle baseType)
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{
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return baseType.Kind switch
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{
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HandleKind.TypeReference => IsSystemEnum((TypeReferenceHandle)baseType),
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HandleKind.TypeDefinition => IsSystemEnum((TypeDefinitionHandle)baseType),
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_ => false,
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};
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}
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private bool IsSystemEnum(TypeReferenceHandle baseType)
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{
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var baseTypeReference = Cx.MdReader.GetTypeReference(baseType);
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return IsSystemEnum(baseTypeReference.Name, baseTypeReference.Namespace);
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}
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private bool IsSystemEnum(TypeDefinitionHandle baseType)
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{
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var baseTypeDefinition = Cx.MdReader.GetTypeDefinition(baseType);
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return IsSystemEnum(baseTypeDefinition.Name, baseTypeDefinition.Namespace);
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}
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private bool IsSystemEnum(StringHandle typeName, StringHandle namespaceName)
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{
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return Cx.MdReader.StringComparer.Equals(typeName, "Enum") &&
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!namespaceName.IsNil &&
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Cx.MdReader.StringComparer.Equals(namespaceName, "System");
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}
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internal PrimitiveTypeCode? GetUnderlyingEnumType()
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{
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foreach (var handle in td.GetFields())
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{
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var field = Cx.MdReader.GetFieldDefinition(handle);
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if (field.Attributes.HasFlag(FieldAttributes.Static))
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{
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continue;
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}
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var blob = Cx.MdReader.GetBlobReader(field.Signature);
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if (blob.ReadSignatureHeader().Kind != SignatureKind.Field)
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{
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break;
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}
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return (PrimitiveTypeCode)blob.ReadByte();
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}
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return null;
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}
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internal override Method LookupMethod(StringHandle name, BlobHandle signature)
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{
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foreach (var h in td.GetMethods())

‎csharp/extractor/Semmle.Extraction.CIL/Tuples.cs‎

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@@ -32,6 +32,9 @@ internal static Tuple cil_array_type(ArrayType array, Type element, int rank) =>
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internal static Tuple cil_base_class(Type t, Type @base) =>
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new Tuple("cil_base_class", t, @base);
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internal static Tuple cil_enum_underlying_type(Type t, PrimitiveType underlying) =>
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new Tuple("cil_enum_underlying_type", t, underlying);
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internal static Tuple cil_base_interface(Type t, Type @base) =>
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new Tuple("cil_base_interface", t, @base);
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‎csharp/ql/src/semmle/code/cil/Type.qll‎

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@@ -79,7 +79,7 @@ class Type extends DotNet::Type, Declaration, TypeContainer, @cil_type {
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}
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/** Holds if this type is an `enum`. */
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predicate isEnum() { this.getBaseClass*().isSystemType("Enum") }
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predicate isEnum() { this.getBaseClass().isSystemType("Enum") }
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/** Holds if this type is public. */
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predicate isPublic() { cil_public(this) }

‎csharp/ql/src/semmle/code/cil/Types.qll‎

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@@ -47,8 +47,12 @@ class ValueOrRefType extends DotNet::ValueOrRefType, Type, @cil_valueorreftype {
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class Enum extends ValueOrRefType {
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Enum() { this.isEnum() }
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// Note that we don't actually use the proper internal representation yet.
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override IntType getUnderlyingType() { any() }
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override IntegralType getUnderlyingType() {
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cil_enum_underlying_type(this, result)
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or
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not cil_enum_underlying_type(this, _) and
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result instanceof IntType
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}
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}
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/** A `class`. */

‎csharp/ql/src/semmlecode.csharp.dbscheme‎

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@@ -1803,6 +1803,7 @@ cil_newslot(int id: @cil_method ref);
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cil_base_class(unique int id: @cil_type ref, int base: @cil_type ref);
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cil_base_interface(int id: @cil_type ref, int base: @cil_type ref);
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cil_enum_underlying_type(unique int id: @cil_type ref, int underlying: @cil_type ref);
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#keyset[unbound, index]
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cil_type_parameter(

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