C#: Only use getTypeRef when there is not already a type available

Author: hvitved

csharp/ql/lib/semmle/code/csharp/AnnotatedType.qll

@@ -251,15 +251,21 @@ private int getElementTypeFlags(@has_type_annotation element) {
   result = strictsum(int b | type_annotation(element, b) | b)
 }
 
+private predicate specificTypeParameterNullability(
+  TypeParameterConstraints constraints, Type type, @nullability n
+) {
+  specific_type_parameter_nullability(constraints, type, n)
+  or
+  specific_type_parameter_nullability(constraints, getTypeRef(type), n)
+}
+
 private Annotations::Nullability getTypeParameterNullability(
   TypeParameterConstraints constraints, Type type
 ) {
-  if specific_type_parameter_nullability(constraints, getTypeRef(type), _)
-  then
-    specific_type_parameter_nullability(constraints, getTypeRef(type),
-      Annotations::getNullability(result))
+  if specificTypeParameterNullability(constraints, type, _)
+  then specificTypeParameterNullability(constraints, type, Annotations::getNullability(result))
   else (
-    specific_type_parameter_constraints(constraints, getTypeRef(type)) and
+    type = constraints.getATypeConstraint() and
     result instanceof Annotations::NoNullability
   )
 }

csharp/ql/lib/semmle/code/csharp/Attribute.qll

@@ -62,7 +62,12 @@ private string getAttributeName(Attribute a) {
  */
 class Attribute extends TopLevelExprParent, @attribute {
   /** Gets the type of this attribute. */
-  Class getType() { attributes(this, _, getTypeRef(result), _) }
+  Class getType() {
+    attributes(this, _, result, _)
+    or
+    not attributes(this, _, any(Type t), _) and
+    attributes(this, _, getTypeRef(result), _)
+  }
 
   /** Gets the element that this attribute is attached to. */
   Attributable getTarget() { attributes(this, _, _, result) }

csharp/ql/lib/semmle/code/csharp/Callable.qll

@@ -236,7 +236,12 @@ class Method extends Callable, Virtualizable, Attributable, @method {
 
   override ValueOrRefType getDeclaringType() { methods(this, _, result, _, _) }
 
-  override Type getReturnType() { methods(this, _, _, getTypeRef(result), _) }
+  override Type getReturnType() {
+    methods(this, _, _, result, _)
+    or
+    not methods(this, _, _, any(Type t), _) and
+    methods(this, _, _, getTypeRef(result), _)
+  }
 
   override Method getUnboundDeclaration() { methods(this, _, _, _, result) }
 
@@ -453,7 +458,12 @@ class Operator extends Callable, Member, Attributable, Overridable, @operator {
 
   override ValueOrRefType getDeclaringType() { operators(this, _, _, result, _, _) }
 
-  override Type getReturnType() { operators(this, _, _, _, getTypeRef(result), _) }
+  override Type getReturnType() {
+    operators(this, _, _, _, result, _)
+    or
+    not operators(this, _, _, _, any(Type t), _) and
+    operators(this, _, _, _, getTypeRef(result), _)
+  }
 
   override Operator getUnboundDeclaration() { operators(this, _, _, _, _, result) }
 

csharp/ql/lib/semmle/code/csharp/Event.qll

@@ -23,7 +23,12 @@ class Event extends DeclarationWithAccessors, @event {
 
   override ValueOrRefType getDeclaringType() { events(this, _, result, _, _) }
 
-  override DelegateType getType() { events(this, _, _, getTypeRef(result), _) }
+  override DelegateType getType() {
+    events(this, _, _, result, _)
+    or
+    not events(this, _, _, any(Type t), _) and
+    events(this, _, _, getTypeRef(result), _)
+  }
 
   /** Gets an `add` or `remove` accessor of this event, if any. */
   EventAccessor getAnEventAccessor() { result.getDeclaration() = this }

csharp/ql/lib/semmle/code/csharp/Generics.qll

@@ -261,7 +261,11 @@ class TypeParameter extends DotNet::TypeParameter, Type, @type_parameter {
  */
 class TypeParameterConstraints extends Element, @type_parameter_constraints {
   /** Gets a specific type constraint, if any. */
-  Type getATypeConstraint() { specific_type_parameter_constraints(this, getTypeRef(result)) }
+  Type getATypeConstraint() {
+    specific_type_parameter_constraints(this, result)
+    or
+    specific_type_parameter_constraints(this, getTypeRef(result))
+  }
 
   /** Gets an annotated specific type constraint, if any. */
   AnnotatedType getAnAnnotatedTypeConstraint() { result.appliesToTypeConstraint(this) }
@@ -413,9 +417,19 @@ class ConstructedType extends ValueOrRefType, ConstructedGeneric {
 
   override Location getALocation() { result = this.getUnboundDeclaration().getALocation() }
 
-  override Type getTypeArgument(int n) { type_arguments(getTypeRef(result), n, this) }
+  override Type getTypeArgument(int n) {
+    type_arguments(result, n, this)
+    or
+    not type_arguments(any(Type t), n, this) and
+    type_arguments(getTypeRef(result), n, this)
+  }
 
-  override UnboundGenericType getUnboundGeneric() { constructed_generic(this, getTypeRef(result)) }
+  override UnboundGenericType getUnboundGeneric() {
+    constructed_generic(this, result)
+    or
+    not constructed_generic(this, any(Type t)) and
+    constructed_generic(this, getTypeRef(result))
+  }
 
   final override Type getChild(int n) { result = this.getTypeArgument(n) }
 
@@ -587,7 +601,12 @@ class UnboundGenericMethod extends Method, UnboundGeneric {
 class ConstructedMethod extends Method, ConstructedGeneric {
   override Location getALocation() { result = this.getUnboundDeclaration().getALocation() }
 
-  override Type getTypeArgument(int n) { type_arguments(getTypeRef(result), n, this) }
+  override Type getTypeArgument(int n) {
+    type_arguments(result, n, this)
+    or
+    not type_arguments(any(Type t), n, this) and
+    type_arguments(getTypeRef(result), n, this)
+  }
 
   override UnboundGenericMethod getUnboundGeneric() { constructed_generic(this, result) }
 

csharp/ql/lib/semmle/code/csharp/Member.qll

@@ -215,7 +215,12 @@ class Overridable extends Declaration, TOverridable {
    * to members that can be declared on an interface, i.e. methods, properties,
    * indexers and events.
    */
-  Interface getExplicitlyImplementedInterface() { explicitly_implements(this, getTypeRef(result)) }
+  Interface getExplicitlyImplementedInterface() {
+    explicitly_implements(this, result)
+    or
+    not explicitly_implements(this, any(Interface i)) and
+    explicitly_implements(this, getTypeRef(result))
+  }
 
   /**
    * Holds if this member implements an interface member explicitly.

csharp/ql/lib/semmle/code/csharp/Property.qll

@@ -120,7 +120,12 @@ class Property extends DotNet::Property, DeclarationWithGetSetAccessors, @proper
 
   override ValueOrRefType getDeclaringType() { properties(this, _, result, _, _) }
 
-  override Type getType() { properties(this, _, _, getTypeRef(result), _) }
+  override Type getType() {
+    properties(this, _, _, result, _)
+    or
+    not properties(this, _, _, any(Type t), _) and
+    properties(this, _, _, getTypeRef(result), _)
+  }
 
   /**
    * Holds if this property is automatically implemented. For example, `P1`
@@ -260,7 +265,12 @@ class Indexer extends DeclarationWithGetSetAccessors, Parameterizable, @indexer
 
   override ValueOrRefType getDeclaringType() { indexers(this, _, result, _, _) }
 
-  override Type getType() { indexers(this, _, _, getTypeRef(result), _) }
+  override Type getType() {
+    indexers(this, _, _, result, _)
+    or
+    not indexers(this, _, _, any(Type t), _) and
+    indexers(this, _, _, getTypeRef(result), _)
+  }
 
   override IndexerAccess getAnAccess() { result.getTarget() = this }
 

csharp/ql/lib/semmle/code/csharp/Stmt.qll

@@ -984,7 +984,12 @@ class CatchClause extends Stmt, @catch {
    * }
    * ```
    */
-  ExceptionClass getCaughtExceptionType() { catch_type(this, getTypeRef(result), _) }
+  ExceptionClass getCaughtExceptionType() {
+    catch_type(this, result, _)
+    or
+    not catch_type(this, any(Type t), _) and
+    catch_type(this, getTypeRef(result), _)
+  }
 
   /**
    * Gets the `catch` filter clause, if any. For example, the filter expression

csharp/ql/lib/semmle/code/csharp/Type.qll

@@ -110,9 +110,16 @@ class ValueOrRefType extends DotNet::ValueOrRefType, Type, Attributable, @value_
     parent_namespace_declaration(this, result)
   }
 
+  private Class getExplicitBaseClass() {
+    extend(this, result)
+    or
+    not extend(this, any(Class c)) and
+    extend(this, getTypeRef(result))
+  }
+
   /** Gets the immediate base class of this class, if any. */
   final Class getBaseClass() {
-    extend(this, getTypeRef(result))
+    result = this.getExplicitBaseClass()
     or
     not extend(this, _) and
     not isObjectClass(this) and
@@ -122,7 +129,11 @@ class ValueOrRefType extends DotNet::ValueOrRefType, Type, Attributable, @value_
   }
 
   /** Gets an immediate base interface of this type, if any. */
-  Interface getABaseInterface() { implement(this, getTypeRef(result)) }
+  Interface getABaseInterface() {
+    implement(this, result)
+    or
+    implement(this, getTypeRef(result))
+  }
 
   /** Gets an immediate base type of this type, if any. */
   override ValueOrRefType getABaseType() {
@@ -672,7 +683,12 @@ class Enum extends ValueType, @enum_type {
    * }
    * ```
    */
-  IntegralType getUnderlyingType() { enum_underlying_type(this, getTypeRef(result)) }
+  IntegralType getUnderlyingType() {
+    enum_underlying_type(this, result)
+    or
+    not enum_underlying_type(this, any(Type t)) and
+    enum_underlying_type(this, getTypeRef(result))
+  }
 
   /**
    * Gets an `enum` constant declared in this `enum`, for example `Even`
@@ -855,7 +871,12 @@ class Interface extends RefType, @interface_type {
  */
 class DelegateType extends RefType, Parameterizable, @delegate_type {
   /** Gets the return type of this delegate. */
-  Type getReturnType() { delegate_return_type(this, getTypeRef(result)) }
+  Type getReturnType() {
+    delegate_return_type(this, result)
+    or
+    not delegate_return_type(this, any(Type t)) and
+    delegate_return_type(this, getTypeRef(result))
+  }
 
   /** Gets the annotated return type of this delegate. */
   AnnotatedType getAnnotatedReturnType() { result.appliesTo(this) }
@@ -939,7 +960,12 @@ class UnmanagedCallingConvention extends CallingConvention {
  */
 class FunctionPointerType extends Type, Parameterizable, @function_pointer_type {
   /** Gets the return type of this function pointer. */
-  Type getReturnType() { function_pointer_return_type(this, getTypeRef(result)) }
+  Type getReturnType() {
+    function_pointer_return_type(this, result)
+    or
+    not function_pointer_return_type(this, any(Type t)) and
+    function_pointer_return_type(this, getTypeRef(result))
+  }
 
   /** Gets the calling convention. */
   CallingConvention getCallingConvention() {
@@ -950,6 +976,9 @@ class FunctionPointerType extends Type, Parameterizable, @function_pointer_type
 
   /** Gets the unmanaged calling convention at index `i`. */
   Type getUnmanagedCallingConvention(int i) {
+    has_unmanaged_calling_conventions(this, i, result)
+    or
+    not has_unmanaged_calling_conventions(this, i, any(Type t)) and
     has_unmanaged_calling_conventions(this, i, getTypeRef(result))
   }
 
@@ -979,7 +1008,12 @@ class NullableType extends ValueType, ConstructedType, @nullable_type {
    * Gets the underlying value type of this nullable type.
    * For example `int` in `int?`.
    */
-  Type getUnderlyingType() { nullable_underlying_type(this, getTypeRef(result)) }
+  Type getUnderlyingType() {
+    nullable_underlying_type(this, result)
+    or
+    not nullable_underlying_type(this, any(Type t)) and
+    nullable_underlying_type(this, getTypeRef(result))
+  }
 
   override UnboundGenericStruct getUnboundGeneric() {
     result.hasQualifiedName("System", "Nullable<>")
@@ -1021,7 +1055,12 @@ class ArrayType extends DotNet::ArrayType, RefType, @array_type {
   predicate isMultiDimensional() { this.getRank() > 1 }
 
   /** Gets the element type of this array, for example `int` in `int[]`. */
-  override Type getElementType() { array_element_type(this, _, _, getTypeRef(result)) }
+  override Type getElementType() {
+    array_element_type(this, _, _, result)
+    or
+    not array_element_type(this, _, _, any(Type t)) and
+    array_element_type(this, _, _, getTypeRef(result))
+  }
 
   /** Holds if this array type has the same shape (dimension and rank) as `that` array type. */
   predicate hasSameShapeAs(ArrayType that) {
@@ -1076,7 +1115,12 @@ class ArrayType extends DotNet::ArrayType, RefType, @array_type {
  * A pointer type, for example `char*`.
  */
 class PointerType extends DotNet::PointerType, Type, @pointer_type {
-  override Type getReferentType() { pointer_referent_type(this, getTypeRef(result)) }
+  override Type getReferentType() {
+    pointer_referent_type(this, result)
+    or
+    not pointer_referent_type(this, any(Type t)) and
+    pointer_referent_type(this, getTypeRef(result))
+  }
 
   override string toStringWithTypes() { result = DotNet::PointerType.super.toStringWithTypes() }
 
@@ -1134,7 +1178,12 @@ class UnknownType extends Type, @unknown_type {
  */
 class TupleType extends ValueType, @tuple_type {
   /** Gets the underlying type of this tuple, which is of type `System.ValueTuple`. */
-  Struct getUnderlyingType() { tuple_underlying_type(this, getTypeRef(result)) }
+  Struct getUnderlyingType() {
+    tuple_underlying_type(this, result)
+    or
+    not tuple_underlying_type(this, any(Type t)) and
+    tuple_underlying_type(this, getTypeRef(result))
+  }
 
   /**
    * Gets the `n`th element of this tuple, indexed from 0.
@@ -1196,7 +1245,11 @@ class TypeMention extends @type_mention {
   Type type;
   @type_mention_parent parent;
 
-  TypeMention() { type_mention(this, getTypeRef(type), parent) }
+  TypeMention() {
+    type_mention(this, type, parent)
+    or
+    type_mention(this, getTypeRef(type), parent)
+  }
 
   /** Gets the type being mentioned. */
   Type getType() { result = type }

csharp/ql/lib/semmle/code/csharp/TypeRef.qll

@@ -8,10 +8,13 @@ import csharp
 
 /** A typeref is a reference to a type in some assembly. */
 private class TypeRef extends @typeref {
+  /** Gets the name of type being referenced. */
   string getName() { typerefs(this, result) }
 
+  /** Gets a textual representation of this type reference. */
   string toString() { result = this.getName() }
 
+  /** Gets the type being referenced. */
   Type getReferencedType() {
     typeref_type(this, result)
     or
@@ -27,8 +30,4 @@ private class TypeRef extends @typeref {
  * This is used for extensionals that can be supplied
  * as either type references or types.
  */
-@type_or_ref getTypeRef(Type type) {
-  result = type
-  or
-  result.(TypeRef).getReferencedType() = type
-}
+TypeRef getTypeRef(Type type) { result.getReferencedType() = type }