Merge pull request #20096 from paldepind/rust/path-resolution-associated-type-fix

Rust: Path resolution associated type fix

Author: paldepind

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

@@ -112,13 +112,18 @@ abstract class ItemNode extends Locatable {
     result = this.(SourceFileItemNode).getSuper()
   }
 
+  pragma[nomagic]
+  private ItemNode getAChildSuccessor(string name) {
+    this = result.getImmediateParent() and
+    name = result.getName()
+  }
+
   cached
   ItemNode getASuccessorRec(string name) {
     Stages::PathResolutionStage::ref() and
     sourceFileEdge(this, name, result)
     or
-    this = result.getImmediateParent() and
-    name = result.getName()
+    result = this.getAChildSuccessor(name)
     or
     fileImportEdge(this, name, result)
     or
@@ -224,6 +229,38 @@ abstract class ItemNode extends Locatable {
     result.(CrateItemNode).isPotentialDollarCrateTarget()
   }
 
+  /**
+   * Holds if the successor `item` with the name `name` is not available locally
+   * for unqualified paths.
+   *
+   * This has the effect that a path of the form `name` inside `this` will not
+   * resolve to `item`.
+   */
+  pragma[nomagic]
+  predicate excludedLocally(string name, ItemNode item) {
+    // Associated items in an impl or trait block are not directly available
+    // inside the block, they require a qualified path with a `Self` prefix.
+    item = this.getAChildSuccessor(name) and
+    this instanceof ImplOrTraitItemNode and
+    item instanceof AssocItemNode
+  }
+
+  /**
+   * Holds if the successor `item` with the name `name` is not available
+   * externally for qualified paths that resolve to this item.
+   *
+   * This has the effect that a path of the form `Qualifier::name`, where
+   * `Qualifier` resolves to this item, will not resolve to `item`.
+   */
+  pragma[nomagic]
+  predicate excludedExternally(string name, ItemNode item) {
+    // Type parameters for an `impl` or trait block are not available outside of
+    // the block.
+    item = this.getAChildSuccessor(name) and
+    this instanceof ImplOrTraitItemNode and
+    item instanceof TypeParamItemNode
+  }
+
   pragma[nomagic]
   private predicate hasSourceFunction(string name) {
     this.getASuccessorFull(name).(Function).fromSource()
@@ -1145,7 +1182,9 @@ pragma[nomagic]
 private predicate declares(ItemNode item, Namespace ns, string name) {
   exists(ItemNode child | child.getImmediateParent() = item |
     child.getName() = name and
-    child.getNamespace() = ns
+    child.getNamespace() = ns and
+    // If `item` is excluded locally then it does not declare `name`.
+    not item.excludedLocally(name, child)
     or
     useTreeDeclares(child.(Use).getUseTree(), name) and
     exists(ns) // `use foo::bar` can refer to both a value and a type
@@ -1193,38 +1232,27 @@ private ItemNode getOuterScope(ItemNode i) {
   result = i.getImmediateParent()
 }
 
-pragma[nomagic]
-private ItemNode getAdjustedEnclosing(ItemNode encl0, Namespace ns) {
-  // functions in `impl` blocks need to use explicit `Self::` to access other
-  // functions in the `impl` block
-  if encl0 instanceof ImplOrTraitItemNode and ns.isValue()
-  then result = encl0.getImmediateParent()
-  else result = encl0
-}
-
 /**
  * Holds if the unqualified path `p` references an item named `name`, and `name`
  * may be looked up in the `ns` namespace inside enclosing item `encl`.
  */
 pragma[nomagic]
 private predicate unqualifiedPathLookup(ItemNode encl, string name, Namespace ns, RelevantPath p) {
-  exists(ItemNode encl0 | encl = getAdjustedEnclosing(encl0, ns) |
-    // lookup in the immediately enclosing item
-    p.isUnqualified(name) and
-    encl0.getADescendant() = p and
-    exists(ns) and
-    not name = ["crate", "$crate", "super", "self"]
-    or
-    // lookup in an outer scope, but only if the item is not declared in inner scope
-    exists(ItemNode mid |
-      unqualifiedPathLookup(mid, name, ns, p) and
-      not declares(mid, ns, name) and
-      not (
-        name = "Self" and
-        mid = any(ImplOrTraitItemNode i).getAnItemInSelfScope()
-      ) and
-      encl0 = getOuterScope(mid)
-    )
+  // lookup in the immediately enclosing item
+  p.isUnqualified(name) and
+  encl.getADescendant() = p and
+  exists(ns) and
+  not name = ["crate", "$crate", "super", "self"]
+  or
+  // lookup in an outer scope, but only if the item is not declared in inner scope
+  exists(ItemNode mid |
+    unqualifiedPathLookup(mid, name, ns, p) and
+    not declares(mid, ns, name) and
+    not (
+      name = "Self" and
+      mid = any(ImplOrTraitItemNode i).getAnItemInSelfScope()
+    ) and
+    encl = getOuterScope(mid)
   )
 }
 
@@ -1245,10 +1273,10 @@ private predicate sourceFileHasCratePathTc(ItemNode i1, ItemNode i2) =
 
 /**
  * Holds if the unqualified path `p` references a keyword item named `name`, and
- * `name` may be looked up in the `ns` namespace inside enclosing item `encl`.
+ * `name` may be looked up inside enclosing item `encl`.
  */
 pragma[nomagic]
-private predicate keywordLookup(ItemNode encl, string name, Namespace ns, RelevantPath p) {
+private predicate keywordLookup(ItemNode encl, string name, RelevantPath p) {
   // For `($)crate`, jump directly to the root module
   exists(ItemNode i | p.isCratePath(name, i) |
     encl instanceof SourceFile and
@@ -1259,18 +1287,17 @@ private predicate keywordLookup(ItemNode encl, string name, Namespace ns, Releva
   or
   name = ["super", "self"] and
   p.isUnqualified(name) and
-  exists(ItemNode encl0 |
-    encl0.getADescendant() = p and
-    encl = getAdjustedEnclosing(encl0, ns)
-  )
+  encl.getADescendant() = p
 }
 
 pragma[nomagic]
 private ItemNode unqualifiedPathLookup(RelevantPath p, Namespace ns) {
-  exists(ItemNode encl, string name | result = getASuccessorFull(encl, name, ns) |
+  exists(ItemNode encl, string name |
+    result = getASuccessorFull(encl, name, ns) and not encl.excludedLocally(name, result)
+  |
     unqualifiedPathLookup(encl, name, ns, p)
     or
-    keywordLookup(encl, name, ns, p)
+    keywordLookup(encl, name, p) and exists(ns)
   )
 }
 
@@ -1291,7 +1318,8 @@ private ItemNode resolvePath0(RelevantPath path, Namespace ns) {
   or
   exists(ItemNode q, string name |
     q = resolvePathQualifier(path, name) and
-    result = getASuccessorFull(q, name, ns)
+    result = getASuccessorFull(q, name, ns) and
+    not q.excludedExternally(name, result)
   )
   or
   result = resolveUseTreeListItem(_, _, path) and

rust/ql/test/library-tests/path-resolution/main.rs

@@ -636,6 +636,60 @@ impl AStruct // $ item=I123
     pub fn z(&self) {} // I125
 }
 
+mod associated_types {
+    use std::marker::PhantomData; // $ item=PhantomData
+    use std::result::Result; // $ item=Result
+
+    trait Reduce {
+        type Input; // ReduceInput
+        type Error; // ReduceError
+        type Output; // ReduceOutput
+        fn feed(
+            &mut self,
+            item: Self::Input, // $ item=ReduceInput
+        ) -> Result<Self::Output, Self::Error>; // $ item=Result item=ReduceOutput item=ReduceError
+    } // IReduce
+
+    struct MyImpl<Input, Error> {
+        _input: PhantomData<Input>, // $ item=PhantomData item=Input
+        _error: PhantomData<Error>, // $ item=PhantomData item=Error
+    } // MyImpl
+
+    #[rustfmt::skip]
+    impl<
+            Input, // IInput
+            Error, // IError
+        > Reduce // $ item=IReduce
+        for MyImpl<
+            Input, // $ item=IInput
+            Error, // $ item=IError
+        > // $ item=MyImpl
+    {
+        type Input = Result<
+            Input,       // $ item=IInput
+            Self::Error, // $ item=IErrorAssociated
+        > // $ item=Result
+        ; // IInputAssociated
+        type Error = Option<
+          Error // $ item=IError
+        > // $ item=Option
+        ; // IErrorAssociated
+        type Output =
+            Input // $ item=IInput
+        ; // IOutputAssociated
+
+        fn feed(
+            &mut self,
+            item: Self::Input // $ item=IInputAssociated
+        ) -> Result<
+            Self::Output, // $ item=IOutputAssociated
+            Self::Error // $ item=IErrorAssociated
+        > { // $ item=Result
+            item
+        }
+    }
+}
+
 use std::{self as ztd}; // $ item=std
 
 fn use_ztd(x: ztd::string::String) {} // $ item=String