Rust: Implement TypeMention for paths that access associated types on concrete types

Author: paldepind

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

@@ -75,7 +75,7 @@ abstract class Type extends TType {
   abstract TypeParameter getPositionalTypeParameter(int i);
 
   /** Gets the default type for the `i`th type parameter, if any. */
-  TypeMention getTypeParameterDefault(int i) { none() }
+  TypeRepr getTypeParameterDefault(int i) { none() }
 
   /**
    * Gets a type parameter of this type.
@@ -129,7 +129,7 @@ class DataType extends Type, TDataType {
     result = TTypeParamTypeParameter(typeItem.getGenericParamList().getTypeParam(i))
   }
 
-  override TypeMention getTypeParameterDefault(int i) {
+  override TypeRepr getTypeParameterDefault(int i) {
     result = typeItem.getGenericParamList().getTypeParam(i).getDefaultType()
   }
 
@@ -189,7 +189,7 @@ class TraitType extends Type, TTrait {
     result.(SelfTypeParameter).getTrait() = trait
   }
 
-  override TypeMention getTypeParameterDefault(int i) {
+  override TypeRepr getTypeParameterDefault(int i) {
     result = trait.getGenericParamList().getTypeParam(i).getDefaultType()
   }
 

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

@@ -134,8 +134,8 @@ class TypePath = M1::TypePath;
 
 module TypePath = M1::TypePath;
 
-private module Input2 implements InputSig2<TypeMention> {
-  TypeMention getABaseTypeMention(Type t) { none() }
+private module Input2 implements InputSig2<PreTypeMention> {
+  PreTypeMention getABaseTypeMention(Type t) { none() }
 
   Type getATypeParameterConstraint(TypeParameter tp, TypePath path) {
     exists(TypeMention tm | result = tm.getTypeAt(path) |
@@ -158,7 +158,7 @@ private module Input2 implements InputSig2<TypeMention> {
    * inference module for more information.
    */
   predicate conditionSatisfiesConstraint(
-    TypeAbstraction abs, TypeMention condition, TypeMention constraint, boolean transitive
+    TypeAbstraction abs, PreTypeMention condition, PreTypeMention constraint, boolean transitive
   ) {
     // `impl` blocks implementing traits
     transitive = false and
@@ -208,7 +208,7 @@ private module Input2 implements InputSig2<TypeMention> {
   }
 }
 
-private module M2 = Make2<TypeMention, Input2>;
+private module M2 = Make2<PreTypeMention, Input2>;
 
 import M2
 
@@ -1960,7 +1960,7 @@ private module MethodResolution {
     pragma[nomagic]
     predicate hasTypeQualifiedCandidate(ImplItemNode impl) {
       exists(getCallExprTypeQualifier(this, _)) and
-      CallExprImpl::getResolvedFunction(this) = impl.getASuccessor(_)
+      CallExprImpl::getResolvedFunction(this) = impl.getADescendant()
     }
 
     pragma[nomagic]

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

@@ -10,7 +10,11 @@ private import TypeInference::Consistency as Consistency
 import TypeInference::Consistency
 
 query predicate illFormedTypeMention(TypeMention tm) {
-  Consistency::illFormedTypeMention(tm) and
+  // NOTE: We do not use `illFormedTypeMention` from the shared library as it is
+  // instantiated with `PreTypeMention` and we are interested in inconsistencies
+  // for `TypeMention`.
+  not exists(tm.getTypeAt(TypePath::nil())) and
+  exists(tm.getLocation()) and
   // avoid overlap with `PathTypeMention`
   not tm instanceof PathTypeReprMention and
   // known limitation for type mentions that would mention an escaping type parameter