Rust: Remove {get,has}Trait from Call

Author: hvitved

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

@@ -34,12 +34,6 @@ module Impl {
    * called in Rust.
    */
   abstract class Call extends ExprImpl::Expr {
-    /** Gets the trait targeted by this call, if any. */
-    abstract Trait getTrait();
-
-    /** Holds if this call targets a trait. */
-    predicate hasTrait() { exists(this.getTrait()) }
-
     /** Gets the name of the method called if this call is a method call. */
     abstract string getMethodName();
 
@@ -75,18 +69,6 @@ module Impl {
     qualifier = path.getQualifier()
   }
 
-  private predicate callHasTraitQualifier(CallExpr call, Trait qualifier) {
-    exists(RelevantPath qualifierPath |
-      callHasQualifier(call, _, qualifierPath) and
-      qualifier = resolvePath(qualifierPath) and
-      // When the qualifier is `Self` and resolves to a trait, it's inside a
-      // trait method's default implementation. This is not a dispatch whose
-      // target is inferred from the type of the receiver, but should always
-      // resolve to the function in the trait block as path resolution does.
-      not qualifierPath.isUnqualified("Self")
-    )
-  }
-
   /** Holds if the call expression dispatches to a method. */
   private predicate callIsMethodCall(
     CallExpr call, Path qualifier, string methodName, boolean selfIsRef
@@ -107,8 +89,6 @@ module Impl {
 
     override string getMethodName() { none() }
 
-    override Trait getTrait() { callHasTraitQualifier(this, result) }
-
     override Expr getArgument(ArgumentPosition pos) {
       result = super.getArgList().getArg(pos.asPosition())
     }
@@ -129,8 +109,6 @@ module Impl {
 
     override string getMethodName() { result = methodName }
 
-    override Trait getTrait() { callHasTraitQualifier(this, result) }
-
     override Expr getArgument(ArgumentPosition pos) {
       pos.isSelf() and result = super.getArgList().getArg(0)
       or
@@ -141,8 +119,6 @@ module Impl {
   private class MethodCallExprCall extends Call instanceof MethodCallExpr {
     override string getMethodName() { result = super.getIdentifier().getText() }
 
-    override Trait getTrait() { none() }
-
     override Expr getArgument(ArgumentPosition pos) {
       pos.isSelf() and result = this.(MethodCallExpr).getReceiver()
       or
@@ -159,8 +135,6 @@ module Impl {
 
     override string getMethodName() { result = methodName }
 
-    override Trait getTrait() { result = trait }
-
     override Expr getArgument(ArgumentPosition pos) {
       pos.isSelf() and result = super.getOperand(0)
       or
@@ -171,8 +145,6 @@ module Impl {
   private class IndexCall extends Call instanceof IndexExpr {
     override string getMethodName() { result = "index" }
 
-    override Trait getTrait() { result.getCanonicalPath() = "core::ops::index::Index" }
-
     override Expr getArgument(ArgumentPosition pos) {
       pos.isSelf() and result = super.getBase()
       or

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

@@ -961,6 +961,24 @@ private Type getCallExprTypeQualifier(CallExpr ce, TypePath path) {
   )
 }
 
+/**
+ * Gets the trait qualifier of function call `ce`, if any.
+ *
+ * For example, the trait qualifier of `Default::<i32>::default()` is `Default`.
+ */
+pragma[nomagic]
+private Trait getCallExprTraitQualifier(CallExpr ce) {
+  exists(RelevantPath qualifierPath |
+    qualifierPath = getCallExprPathQualifier(ce) and
+    result = resolvePath(qualifierPath) and
+    // When the qualifier is `Self` and resolves to a trait, it's inside a
+    // trait method's default implementation. This is not a dispatch whose
+    // target is inferred from the type of the receiver, but should always
+    // resolve to the function in the trait block as path resolution does.
+    not qualifierPath.isUnqualified("Self")
+  )
+}
+
 /**
  * Provides functionality related to context-based typing of calls.
  */
@@ -1244,14 +1262,17 @@ private module MethodResolution {
 
   pragma[nomagic]
   private predicate methodCallTraitCandidate(Element mc, Trait trait) {
-    exists(string name, int arity |
-      mc.(MethodCall).hasNameAndArity(name, arity) and
-      methodTraitInfo(name, arity, trait)
-    |
-      not mc.(Call).hasTrait()
-      or
-      trait = mc.(Call).getTrait()
-    )
+    mc =
+      any(MethodCall mc0 |
+        exists(string name, int arity |
+          mc0.hasNameAndArity(name, arity) and
+          methodTraitInfo(name, arity, trait)
+        |
+          not mc0.hasTrait()
+          or
+          trait = mc0.getTrait()
+        )
+      )
   }
 
   private module MethodTraitIsVisible = TraitIsVisible<methodCallTraitCandidate/2>;
@@ -1296,7 +1317,7 @@ private module MethodResolution {
       or
       methodCallVisibleTraitCandidate(mc, i)
       or
-      i.(ImplItemNode).resolveTraitTy() = mc.(Call).getTrait()
+      i.(ImplItemNode).resolveTraitTy() = mc.getTrait()
     )
   }
 
@@ -1323,7 +1344,7 @@ private module MethodResolution {
     |
       methodCallVisibleImplTraitCandidate(mc, impl)
       or
-      impl.resolveTraitTy() = mc.(Call).getTrait()
+      impl.resolveTraitTy() = mc.getTrait()
     )
   }
 
@@ -1354,6 +1375,12 @@ private module MethodResolution {
 
     abstract predicate supportsAutoDerefAndBorrow();
 
+    /** Gets the trait targeted by this call, if any. */
+    abstract Trait getTrait();
+
+    /** Holds if this call targets a trait. */
+    predicate hasTrait() { exists(this.getTrait()) }
+
     AstNode getNodeAt(FunctionPosition apos) {
       result = this.getArgument(apos.asArgumentPosition())
       or
@@ -1611,6 +1638,8 @@ private module MethodResolution {
     }
 
     override predicate supportsAutoDerefAndBorrow() { any() }
+
+    override Trait getTrait() { none() }
   }
 
   private class MethodCallIndexExpr extends MethodCall, IndexExpr {
@@ -1629,6 +1658,8 @@ private module MethodResolution {
     }
 
     override predicate supportsAutoDerefAndBorrow() { any() }
+
+    override Trait getTrait() { result.getCanonicalPath() = "core::ops::index::Index" }
   }
 
   private class MethodCallCallExpr extends MethodCall, CallExpr {
@@ -1672,6 +1703,8 @@ private module MethodResolution {
     }
 
     override predicate supportsAutoDerefAndBorrow() { none() }
+
+    override Trait getTrait() { result = getCallExprTraitQualifier(this) }
   }
 
   final class MethodCallOperation extends MethodCall, Operation {
@@ -1712,6 +1745,8 @@ private module MethodResolution {
     }
 
     override predicate supportsAutoDerefAndBorrow() { none() }
+
+    override Trait getTrait() { this.isOverloaded(result, _, _) }
   }
 
   pragma[nomagic]
@@ -2282,14 +2317,17 @@ private module NonMethodResolution {
 
   pragma[nomagic]
   private predicate blanketLikeCallTraitCandidate(Element fc, Trait trait) {
-    exists(string name, int arity |
-      fc.(NonMethodCall).hasNameAndArity(name, arity) and
-      functionInfoBlanketLikeRelevantPos(_, name, arity, _, trait, _, _, _, _)
-    |
-      not fc.(Call).hasTrait()
-      or
-      trait = fc.(Call).getTrait()
-    )
+    fc =
+      any(NonMethodCall nmc |
+        exists(string name, int arity |
+          nmc.hasNameAndArity(name, arity) and
+          functionInfoBlanketLikeRelevantPos(_, name, arity, _, trait, _, _, _, _)
+        |
+          not nmc.hasTrait()
+          or
+          trait = nmc.getTrait()
+        )
+      )
   }
 
   private module BlanketTraitIsVisible = TraitIsVisible<blanketLikeCallTraitCandidate/2>;
@@ -2331,9 +2369,15 @@ private module NonMethodResolution {
       )
     }
 
+    /** Gets the trait targeted by this call, if any. */
+    Trait getTrait() { result = getCallExprTraitQualifier(this) }
+
+    /** Holds if this call targets a trait. */
+    predicate hasTrait() { exists(this.getTrait()) }
+
     pragma[nomagic]
     NonMethodFunction resolveAssocCallTargetCand(ImplItemNode i) {
-      not this.(Call).hasTrait() and
+      not this.hasTrait() and
       result = this.getPathResolutionResolved() and
       result = i.getASuccessor(_)
       or
@@ -2366,15 +2410,15 @@ private module NonMethodResolution {
     pragma[nomagic]
     predicate hasTraitResolved(TraitItemNode trait, NonMethodFunction resolved) {
       resolved = this.getPathResolutionResolved() and
-      trait = this.(Call).getTrait()
+      trait = this.getTrait()
     }
 
     /**
      * Gets the target of this call, which can be resolved using only path resolution.
      */
     pragma[nomagic]
     ItemNode resolveCallTargetViaPathResolution() {
-      not this.(Call).hasTrait() and
+      not this.hasTrait() and
       result = this.getPathResolutionResolved() and
       not FunctionOverloading::functionResolutionDependsOnArgument(_, result, _, _, _)
     }
@@ -2399,7 +2443,7 @@ private module NonMethodResolution {
 
     pragma[nomagic]
     NonMethodFunction resolveTraitFunctionViaPathResolution(TraitItemNode trait) {
-      this.(Call).hasTrait() and
+      this.hasTrait() and
       result = this.getPathResolutionResolved() and
       result = trait.getASuccessor(_)
     }