Swift: prototype implementation of type inference in QL

Author: hvitved

rust/ql/lib/codeql/rust/internal/typeinference/Type.qll

@@ -357,7 +357,7 @@ class PtrConstType extends PtrType {
 
 /**
  * A special pseudo type used to indicate that the actual type may have to be
- * inferred by propagating type information back into call arguments.
+ * inferred by propagating type information top-down.
  *
  * For example, in
  *
@@ -374,8 +374,8 @@ class PtrConstType extends PtrType {
  * parameter of `Vec`.
  *
  * Unknown types are used to restrict when type information is allowed to flow
- * into call arguments (including method call receivers), in order to avoid
- * combinatorial explosions.
+ * top-down (including method call receivers), in order to avoid combinatorial
+ * explosions.
  */
 class UnknownType extends Type, TUnknownType {
   override TypeParameter getPositionalTypeParameter(int i) { none() }

rust/ql/lib/codeql/rust/internal/typeinference/TypeInference.qll

@@ -219,8 +219,6 @@ private module Input2Common {
 }
 
 private module PreInput2 implements InputSig2<PreTypeMention> {
-  PreTypeMention getABaseTypeMention(Type t) { none() }
-
   PreTypeMention getATypeParameterConstraint(TypeParameter tp) {
     result = Input2Common::getATypeParameterConstraint(tp)
   }
@@ -245,8 +243,6 @@ private module PreInput2 implements InputSig2<PreTypeMention> {
 module PreM2 = Make2<PreTypeMention, PreInput2>;
 
 private module Input2 implements InputSig2<TypeMention> {
-  TypeMention getABaseTypeMention(Type t) { none() }
-
   TypeMention getATypeParameterConstraint(TypeParameter tp) {
     result = Input2Common::getATypeParameterConstraint(tp)
   }