Rust: Implement type inference support for non-universal impl blocks

Author: paldepind

rust/ql/lib/codeql/rust/internal/PathResolution.qll

@@ -413,61 +413,6 @@ class ImplItemNode extends ImplOrTraitItemNode instanceof Impl {
 
   TraitItemNode resolveTraitTy() { result = resolvePath(this.getTraitPath()) }
 
-  pragma[nomagic]
-  private TypeRepr getASelfTyArg() {
-    result =
-      this.getSelfPath().getSegment().getGenericArgList().getAGenericArg().(TypeArg).getTypeRepr()
-  }
-
-  /**
-   * Holds if this `impl` block is not fully parametric. That is, the implementing
-   * type is generic and the implementation is not parametrically polymorphic in all
-   * the implementing type's arguments.
-   *
-   * Examples:
-   *
-   * ```rust
-   * impl Foo { ... } // fully parametric
-   *
-   * impl<T> Foo<T> { ... } // fully parametric
-   *
-   * impl Foo<i64> { ... } // not fully parametric
-   *
-   * impl<T> Foo<Foo<T>> { ... } // not fully parametric
-   *
-   * impl<T: Trait> Foo<T> { ... } // not fully parametric
-   *
-   * impl<T> Foo<T> where T: Trait { ... } // not fully parametric
-   * ```
-   */
-  pragma[nomagic]
-  predicate isNotFullyParametric() {
-    exists(TypeRepr arg | arg = this.getASelfTyArg() |
-      not exists(resolveTypeParamPathTypeRepr(arg))
-      or
-      resolveTypeParamPathTypeRepr(arg).hasTraitBound()
-    )
-  }
-
-  /**
-   * Holds if this `impl` block is fully parametric. Examples:
-   *
-   * ```rust
-   * impl Foo { ... } // fully parametric
-   *
-   * impl<T> Foo<T> { ... } // fully parametric
-   *
-   * impl Foo<i64> { ... } // not fully parametric
-   *
-   * impl<T> Foo<Foo<T>> { ... } // not fully parametric
-   *
-   * impl<T: Trait> Foo<T> { ... } // not fully parametric
-   *
-   * impl<T> Foo<T> where T: Trait { ... } // not fully parametric
-   * ```
-   */
-  predicate isFullyParametric() { not this.isNotFullyParametric() }
-
   override AssocItemNode getAnAssocItem() { result = super.getAssocItemList().getAnAssocItem() }
 
   override string getName() { result = "(impl)" }

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

@@ -27,10 +27,6 @@ newtype TType =
  * types, such as traits and implementation blocks.
  */
 abstract class Type extends TType {
-  /** Gets the method `name` belonging to this type, if any. */
-  pragma[nomagic]
-  abstract Function getMethod(string name);
-
   /** Gets the struct field `name` belonging to this type, if any. */
   pragma[nomagic]
   abstract StructField getStructField(string name);
@@ -45,25 +41,6 @@ abstract class Type extends TType {
   /** Gets a type parameter of this type. */
   final TypeParameter getATypeParameter() { result = this.getTypeParameter(_) }
 
-  /**
-   * Gets an AST node that mentions a base type of this type, if any.
-   *
-   * Although Rust doesn't have traditional OOP-style inheritance, we model trait
-   * bounds and `impl` blocks as base types. Example:
-   *
-   * ```rust
-   * trait T1 {}
-   *
-   * trait T2 {}
-   *
-   * trait T3 : T1, T2 {}
-   * //    ^^ `this`
-   * //         ^^ `result`
-   * //             ^^ `result`
-   * ```
-   */
-  abstract TypeMention getABaseTypeMention();
-
   /** Gets a textual representation of this type. */
   abstract string toString();
 
@@ -73,21 +50,6 @@ abstract class Type extends TType {
 
 abstract private class StructOrEnumType extends Type {
   abstract ItemNode asItemNode();
-
-  final override Function getMethod(string name) {
-    result = this.asItemNode().getASuccessor(name) and
-    exists(ImplOrTraitItemNode impl | result = impl.getAnAssocItem() |
-      impl instanceof Trait
-      or
-      impl.(ImplItemNode).isFullyParametric()
-    )
-  }
-
-  /** Gets all of the fully parametric `impl` blocks that target this type. */
-  final override ImplMention getABaseTypeMention() {
-    this.asItemNode() = result.resolveSelfTy() and
-    result.isFullyParametric()
-  }
 }
 
 /** A struct type. */
@@ -138,8 +100,6 @@ class TraitType extends Type, TTrait {
 
   TraitType() { this = TTrait(trait) }
 
-  override Function getMethod(string name) { result = trait.(ItemNode).getASuccessor(name) }
-
   override StructField getStructField(string name) { none() }
 
   override TupleField getTupleField(int i) { none() }
@@ -151,14 +111,6 @@ class TraitType extends Type, TTrait {
       any(AssociatedTypeTypeParameter param | param.getTrait() = trait and param.getIndex() = i)
   }
 
-  pragma[nomagic]
-  private TypeReprMention getABoundMention() {
-    result = trait.getTypeBoundList().getABound().getTypeRepr()
-  }
-
-  /** Gets any of the trait bounds of this trait. */
-  override TypeMention getABaseTypeMention() { result = this.getABoundMention() }
-
   override string toString() { result = trait.toString() }
 
   override Location getLocation() { result = trait.getLocation() }
@@ -220,8 +172,6 @@ class ImplType extends Type, TImpl {
 
   ImplType() { this = TImpl(impl) }
 
-  override Function getMethod(string name) { result = impl.(ItemNode).getASuccessor(name) }
-
   override StructField getStructField(string name) { none() }
 
   override TupleField getTupleField(int i) { none() }
@@ -230,9 +180,6 @@ class ImplType extends Type, TImpl {
     result = TTypeParamTypeParameter(impl.getGenericParamList().getTypeParam(i))
   }
 
-  /** Get the trait implemented by this `impl` block, if any. */
-  override TypeMention getABaseTypeMention() { result = impl.getTrait() }
-
   override string toString() { result = impl.toString() }
 
   override Location getLocation() { result = impl.getLocation() }
@@ -247,8 +194,6 @@ class ImplType extends Type, TImpl {
 class ArrayType extends Type, TArrayType {
   ArrayType() { this = TArrayType() }
 
-  override Function getMethod(string name) { none() }
-
   override StructField getStructField(string name) { none() }
 
   override TupleField getTupleField(int i) { none() }
@@ -257,8 +202,6 @@ class ArrayType extends Type, TArrayType {
     none() // todo
   }
 
-  override TypeMention getABaseTypeMention() { none() }
-
   override string toString() { result = "[]" }
 
   override Location getLocation() { result instanceof EmptyLocation }
@@ -273,8 +216,6 @@ class ArrayType extends Type, TArrayType {
 class RefType extends Type, TRefType {
   RefType() { this = TRefType() }
 
-  override Function getMethod(string name) { none() }
-
   override StructField getStructField(string name) { none() }
 
   override TupleField getTupleField(int i) { none() }
@@ -284,17 +225,13 @@ class RefType extends Type, TRefType {
     i = 0
   }
 
-  override TypeMention getABaseTypeMention() { none() }
-
   override string toString() { result = "&" }
 
   override Location getLocation() { result instanceof EmptyLocation }
 }
 
 /** A type parameter. */
 abstract class TypeParameter extends Type {
-  override TypeMention getABaseTypeMention() { none() }
-
   override StructField getStructField(string name) { none() }
 
   override TupleField getTupleField(int i) { none() }
@@ -318,19 +255,9 @@ class TypeParamTypeParameter extends TypeParameter, TTypeParamTypeParameter {
 
   TypeParam getTypeParam() { result = typeParam }
 
-  override Function getMethod(string name) {
-    // NOTE: If the type parameter has trait bounds, then this finds methods
-    // on the bounding traits.
-    result = typeParam.(ItemNode).getASuccessor(name)
-  }
-
   override string toString() { result = typeParam.toString() }
 
   override Location getLocation() { result = typeParam.getLocation() }
-
-  final override TypeMention getABaseTypeMention() {
-    result = typeParam.getTypeBoundList().getABound().getTypeRepr()
-  }
 }
 
 /**
@@ -377,19 +304,13 @@ class AssociatedTypeTypeParameter extends TypeParameter, TAssociatedTypeTypePara
 
   int getIndex() { traitAliasIndex(_, result, typeAlias) }
 
-  override Function getMethod(string name) { none() }
-
   override string toString() { result = typeAlias.getName().getText() }
 
   override Location getLocation() { result = typeAlias.getLocation() }
-
-  override TypeMention getABaseTypeMention() { none() }
 }
 
 /** An implicit reference type parameter. */
 class RefTypeParameter extends TypeParameter, TRefTypeParameter {
-  override Function getMethod(string name) { none() }
-
   override string toString() { result = "&T" }
 
   override Location getLocation() { result instanceof EmptyLocation }
@@ -409,15 +330,34 @@ class SelfTypeParameter extends TypeParameter, TSelfTypeParameter {
 
   Trait getTrait() { result = trait }
 
-  override TypeMention getABaseTypeMention() { result = trait }
+  override string toString() { result = "Self [" + trait.toString() + "]" }
+
+  override Location getLocation() { result = trait.getLocation() }
+}
+
+/** A type abstraction. */
+abstract class TypeAbstraction extends AstNode {
+  abstract TypeParameter getATypeParameter();
+}
 
-  override Function getMethod(string name) {
-    // The `Self` type parameter is an implementation of the trait, so it has
-    // all the trait's methods.
-    result = trait.(ItemNode).getASuccessor(name)
+final class ImplTypeAbstraction extends TypeAbstraction, Impl {
+  override TypeParamTypeParameter getATypeParameter() {
+    result.getTypeParam() = this.getGenericParamList().getATypeParam()
   }
+}
 
-  override string toString() { result = "Self [" + trait.toString() + "]" }
+final class TraitTypeAbstraction extends TypeAbstraction, Trait {
+  override TypeParamTypeParameter getATypeParameter() {
+    result.getTypeParam() = this.getGenericParamList().getATypeParam()
+  }
+}
 
-  override Location getLocation() { result = trait.getLocation() }
+final class TypeBoundTypeAbstraction extends TypeAbstraction, TypeBound {
+  override TypeParamTypeParameter getATypeParameter() { none() }
+}
+
+final class SelfTypeBoundTypeAbstraction extends TypeAbstraction, Name {
+  SelfTypeBoundTypeAbstraction() { any(Trait trait).getName() = this }
+
+  override TypeParamTypeParameter getATypeParameter() { none() }
 }