Rust: Unify logic in MethodResolution; remove TypeQualifierIsInstantiationOfImplSelf logic

rust/ql/lib/codeql/rust/elements/internal/InvocationExprImpl.qll

@@ -8,21 +8,31 @@ module Impl {
     TPositionalArgumentPosition(int i) {
       i in [0 .. max([any(ParamList l).getNumberOfParams(), any(ArgList l).getNumberOfArgs()]) - 1]
     } or
-    TSelfArgumentPosition()
+    TSelfArgumentPosition() or
+    TTypeQualifierArgumentPosition()
 
   /** An argument position in a call. */
   class ArgumentPosition extends TArgumentPosition {
     /** Gets the index of the argument in the call, if this is a positional argument. */
     int asPosition() { this = TPositionalArgumentPosition(result) }
 
     /** Holds if this call position is a self argument. */
-    predicate isSelf() { this instanceof TSelfArgumentPosition }
+    predicate isSelf() { this = TSelfArgumentPosition() }
+
+    /**
+     * Holds if this call position is a type qualifier, that is, not an actual
+     * argument, but rather an annotation that is needed to resolve the call target,
+     * just like actual arguments may be need to resolve the call target.
+     */
+    predicate isTypeQualifier() { this = TTypeQualifierArgumentPosition() }
 
     /** Gets a string representation of this argument position. */
     string toString() {
       result = this.asPosition().toString()
       or
       this.isSelf() and result = "self"
+      or
+      this.isTypeQualifier() and result = "type qualifier"
     }
   }
 

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

@@ -86,7 +86,7 @@ predicate traitTypeParameterOccurrence(
   TypeParameter traitTp
 ) {
   f = trait.getAssocItem(functionName) and
-  traitTp = getAssocFunctionTypeInclNonMethodSelfAt(f, trait, pos, path) and
+  traitTp = getAssocFunctionTypeAt(f, trait, pos, path) and
   traitTp = trait.(TraitTypeAbstraction).getATypeParameter()
 }
 
@@ -124,7 +124,7 @@ private predicate functionResolutionDependsOnArgumentCand(
     implHasSibling(impl, trait) and
     traitTypeParameterOccurrence(trait, _, functionName, pos, path, traitTp) and
     f = impl.getASuccessor(functionName) and
-    not pos.isSelf()
+    not pos.isSelfOrTypeQualifier()
   )
 }
 
@@ -141,7 +141,7 @@ pragma[nomagic]
 private Type getAssocFunctionNonTypeParameterTypeAt(
   ImplItemNode impl, Function f, FunctionPosition pos, TypePath path
 ) {
-  result = getAssocFunctionTypeInclNonMethodSelfAt(f, impl, pos, path) and
+  result = getAssocFunctionTypeAt(f, impl, pos, path) and
   not result instanceof TypeParameter
 }
 

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

@@ -23,6 +23,10 @@ class FunctionPosition extends TFunctionPosition {
 
   ArgumentPosition asArgumentPosition() { this = TArgumentFunctionPosition(result) }
 
+  predicate isTypeQualifier() { this.asArgumentPosition().isTypeQualifier() }
+
+  predicate isSelfOrTypeQualifier() { this.isSelf() or this.isTypeQualifier() }
+
   predicate isReturn() { this = TReturnFunctionPosition() }
 
   /** Gets the corresponding position when `f` is invoked via a function call. */
@@ -82,9 +86,9 @@ private newtype TAssocFunctionType =
     // through `i`. This ensures that `parent` is either a supertrait of `i` or
     // `i` in an `impl` block implementing `parent`.
     (parent = i or BaseTypes::rootTypesSatisfaction(_, TTrait(parent), i, _, _)) and
-    // We always include the `self` position, even for non-methods, where it is used
+    // We always include the type qualifer position, even for non-methods, where it is used
     // to match type qualifiers against the `impl` or trait type, such as in `Vec::new`.
-    (exists(pos.getTypeMention(f)) or pos.isSelf())
+    (exists(pos.getTypeMention(f)) or pos.isTypeQualifier())
   }
 
 bindingset[abs, constraint, tp]
@@ -116,21 +120,9 @@ Type getAssocFunctionTypeAt(Function f, ImplOrTraitItemNode i, FunctionPosition
       else result = getTraitConstraintTypeAt(i, constraint, tp, suffix)
     )
   )
-}
-
-/**
- * Same as `getAssocFunctionTypeAt`, but also includes types at the `self` position
- * for non-methods.
- */
-pragma[nomagic]
-Type getAssocFunctionTypeInclNonMethodSelfAt(
-  Function f, ImplOrTraitItemNode i, FunctionPosition pos, TypePath path
-) {
-  result = getAssocFunctionTypeAt(f, i, pos, path)
   or
   f = i.getASuccessor(_) and
-  not f.hasSelfParam() and
-  pos.isSelf() and
+  pos.isTypeQualifier() and
   result = resolveImplOrTraitType(i, path)
 }
 
@@ -192,7 +184,7 @@ class AssocFunctionType extends MkAssocFunctionType {
   Type getTypeAt(TypePath path) {
     exists(Function f, FunctionPosition pos, ImplOrTraitItemNode i, Type t |
       this.appliesTo(f, i, pos) and
-      t = getAssocFunctionTypeInclNonMethodSelfAt(f, i, pos, path)
+      t = getAssocFunctionTypeAt(f, i, pos, path)
     |
       not t instanceof SelfTypeParameter and
       result = t