Rust: Model namespaces in path resolution

rust/ql/lib/codeql/rust/AstConsistency.qll

@@ -78,6 +78,12 @@ private import codeql.rust.elements.internal.PathResolution
 /** Holds if `p` may resolve to multiple items including `i`. */
 query predicate multiplePathResolutions(Path p, ItemNode i) {
   i = resolvePath(p) and
+  // `use foo::bar` may use both a type `bar` and a value `bar`
+  not p =
+    any(UseTree use |
+      not use.isGlob() and
+      not use.hasUseTreeList()
+    ).getPath() and
   strictcount(resolvePath(p)) > 1
 }
 

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

@@ -5,6 +5,31 @@
 private import rust
 private import codeql.rust.elements.internal.generated.ParentChild
 
+private newtype TNamespace =
+  TTypeNamespace() or
+  TValueNamespace()
+
+/**
+ * A namespace.
+ *
+ * Either the _value_ namespace or the _type_ namespace, see
+ * https://doc.rust-lang.org/reference/names/namespaces.html.
+ */
+final class Namespace extends TNamespace {
+  /** Holds if this is the value namespace. */
+  predicate isValue() { this = TValueNamespace() }
+
+  /** Holds if this is the type namespace. */
+  predicate isType() { this = TTypeNamespace() }
+
+  /** Gets a textual representation of this namespace. */
+  string toString() {
+    this.isValue() and result = "value"
+    or
+    this.isType() and result = "type"
+  }
+}
+
 /**
  * An item that may be referred to by a path, and which is a node in
  * the _item graph_.
@@ -46,11 +71,15 @@ private import codeql.rust.elements.internal.generated.ParentChild
  * - https://doc.rust-lang.org/reference/names/scopes.html
  * - https://doc.rust-lang.org/reference/paths.html
  * - https://doc.rust-lang.org/reference/visibility-and-privacy.html
+ * - https://doc.rust-lang.org/reference/names/namespaces.html
  */
 abstract class ItemNode extends AstNode {
   /** Gets the (original) name of this item. */
   abstract string getName();
 
+  /** Gets the namespace that this item belongs to, if any. */
+  abstract Namespace getNamespace();
+
   /** Gets the visibility of this item, if any. */
   abstract Visibility getVisibility();
 
@@ -143,30 +172,44 @@ abstract private class ModuleLikeNode extends ItemNode {
 private class SourceFileItemNode extends ModuleLikeNode, SourceFile {
   override string getName() { result = "(source file)" }
 
+  override Namespace getNamespace() {
+    result.isType() // can be referenced with `super`
+  }
+
   override Visibility getVisibility() { none() }
 }
 
 private class ConstItemNode extends ItemNode instanceof Const {
   override string getName() { result = Const.super.getName().getText() }
 
+  override Namespace getNamespace() { result.isValue() }
+
   override Visibility getVisibility() { result = Const.super.getVisibility() }
 }
 
 private class EnumItemNode extends ItemNode instanceof Enum {
   override string getName() { result = Enum.super.getName().getText() }
 
+  override Namespace getNamespace() { result.isType() }
+
   override Visibility getVisibility() { result = Enum.super.getVisibility() }
 }
 
 private class VariantItemNode extends ItemNode instanceof Variant {
   override string getName() { result = Variant.super.getName().getText() }
 
+  override Namespace getNamespace() {
+    if super.getFieldList() instanceof RecordFieldList then result.isType() else result.isValue()
+  }
+
   override Visibility getVisibility() { result = Variant.super.getVisibility() }
 }
 
 private class FunctionItemNode extends ItemNode instanceof Function {
   override string getName() { result = Function.super.getName().getText() }
 
+  override Namespace getNamespace() { result.isValue() }
+
   override Visibility getVisibility() { result = Function.super.getVisibility() }
 }
 
@@ -184,57 +227,92 @@ abstract private class ImplOrTraitItemNode extends ItemNode {
   }
 }
 
-private class ImplItemNode extends ImplOrTraitItemNode instanceof Impl {
+class ImplItemNode extends ImplOrTraitItemNode instanceof Impl {
+  ItemNode resolveSelfTy() { result = resolvePath(super.getSelfTy().(PathTypeRepr).getPath()) }
+
   override string getName() { result = "(impl)" }
 
+  override Namespace getNamespace() {
+    result.isType() // can be referenced with `Self`
+  }
+
   override Visibility getVisibility() { result = Impl.super.getVisibility() }
 }
 
 private class MacroCallItemNode extends ItemNode instanceof MacroCall {
   override string getName() { result = "(macro call)" }
 
+  override Namespace getNamespace() { none() }
+
   override Visibility getVisibility() { none() }
 }
 
 private class ModuleItemNode extends ModuleLikeNode instanceof Module {
   override string getName() { result = Module.super.getName().getText() }
 
+  override Namespace getNamespace() { result.isType() }
+
   override Visibility getVisibility() { result = Module.super.getVisibility() }
 }
 
 private class StructItemNode extends ItemNode instanceof Struct {
   override string getName() { result = Struct.super.getName().getText() }
 
+  override Namespace getNamespace() {
+    result.isType() // the struct itself
+    or
+    not super.getFieldList() instanceof RecordFieldList and
+    result.isValue() // the constructor
+  }
+
   override Visibility getVisibility() { result = Struct.super.getVisibility() }
 }
 
-private class TraitItemNode extends ImplOrTraitItemNode instanceof Trait {
+class TraitItemNode extends ImplOrTraitItemNode instanceof Trait {
   override string getName() { result = Trait.super.getName().getText() }
 
+  override Namespace getNamespace() { result.isType() }
+
   override Visibility getVisibility() { result = Trait.super.getVisibility() }
 }
 
+class TypeAliasItemNode extends ItemNode instanceof TypeAlias {
+  override string getName() { result = TypeAlias.super.getName().getText() }
+
+  override Namespace getNamespace() { result.isType() }
+
+  override Visibility getVisibility() { result = TypeAlias.super.getVisibility() }
+}
+
 private class UnionItemNode extends ItemNode instanceof Union {
   override string getName() { result = Union.super.getName().getText() }
 
+  override Namespace getNamespace() { result.isType() }
+
   override Visibility getVisibility() { result = Union.super.getVisibility() }
 }
 
 private class UseItemNode extends ItemNode instanceof Use {
   override string getName() { result = "(use)" }
 
+  override Namespace getNamespace() { none() }
+
   override Visibility getVisibility() { none() }
 }
 
 private class BlockExprItemNode extends ItemNode instanceof BlockExpr {
   override string getName() { result = "(block expr)" }
 
+  override Namespace getNamespace() { none() }
+
   override Visibility getVisibility() { none() }
 }
 
 private class TypeParamItemNode extends ItemNode instanceof TypeParam {
   override string getName() { result = TypeParam.super.getName().getText() }
 
+  override Namespace getNamespace() { result.isType() }
+
   override Visibility getVisibility() { none() }
 }
 
@@ -320,19 +398,22 @@ private predicate useTreeDeclares(UseTree tree, string name) {
 }
 
 /**
- * Holds if `item` explicitly declares a sub item named `name`. This includes
- * items declared by `use` statements, except for glob imports.
+ * Holds if `item` explicitly declares a sub item named `name` in the
+ * namespace `ns`. This includes items declared by `use` statements,
+ * except for glob imports.
  */
 pragma[nomagic]
-private predicate declares(ItemNode item, string name) {
+private predicate declares(ItemNode item, Namespace ns, string name) {
   exists(ItemNode child | child.getImmediateParent() = item |
-    child.getName() = name
+    child.getName() = name and
+    child.getNamespace() = ns
     or
-    useTreeDeclares(child.(Use).getUseTree(), name)
+    useTreeDeclares(child.(Use).getUseTree(), name) and
+    exists(ns) // `use foo::bar` can refer to both a value and a type
   )
   or
   exists(MacroCallItemNode call |
-    declares(call, name) and
+    declares(call, ns, name) and
     call.getImmediateParent() = item
   )
 }
@@ -351,19 +432,20 @@ private class RelevantPath extends Path {
 
 /**
  * Holds if the unqualified path `p` references an item named `name`, and `name`
- * may be looked up inside enclosing item `encl`.
+ * may be looked up in the `ns` namespace inside enclosing item `encl`.
  */
 pragma[nomagic]
-private predicate unqualifiedPathLookup(RelevantPath p, string name, ItemNode encl) {
+private predicate unqualifiedPathLookup(RelevantPath p, string name, Namespace ns, ItemNode encl) {
   exists(ItemNode encl0 |
     // lookup in the immediately enclosing item
     p.isUnqualified(name) and
-    encl0.getADescendant() = p
+    encl0.getADescendant() = p and
+    exists(ns)
     or
     // lookup in an outer scope, but only if the item is not declared in inner scope
     exists(ItemNode mid |
-      unqualifiedPathLookup(p, name, mid) and
-      not declares(mid, name)
+      unqualifiedPathLookup(p, name, ns, mid) and
+      not declares(mid, ns, name)
     |
       // nested modules do not have unqualified access to items from outer modules,
       // except for items declared at top-level in the source file
@@ -374,16 +456,30 @@ private predicate unqualifiedPathLookup(RelevantPath p, string name, ItemNode en
   |
     // functions in `impl` blocks need to use explicit `Self::` to access other
     // functions in the `impl` block
-    if encl0 instanceof ImplOrTraitItemNode then encl = encl0.getImmediateParent() else encl = encl0
+    if encl0 instanceof ImplOrTraitItemNode and ns.isValue()
+    then encl = encl0.getImmediateParent()
+    else encl = encl0
   )
 }
 
-/** Gets the item that `path` resolves to, if any. */
-cached
-ItemNode resolvePath(RelevantPath path) {
-  exists(ItemNode encl, string name |
-    unqualifiedPathLookup(path, name, encl) and
-    result = encl.getASuccessor(name)
+pragma[nomagic]
+private ItemNode getASuccessor(ItemNode pred, string name, Namespace ns) {
+  result = pred.getASuccessor(name) and
+  ns = result.getNamespace()
+}
+
+pragma[nomagic]
+private ItemNode resolvePath0(RelevantPath path) {
+  exists(ItemNode encl, Namespace ns, string name, ItemNode res |
+    unqualifiedPathLookup(path, name, ns, encl) and
+    res = getASuccessor(encl, name, ns)
+  |
+    if
+      not any(RelevantPath parent).getQualifier() = path and
+      name = "Self" and
+      res instanceof ImplItemNode
+    then result = res.(ImplItemNode).resolveSelfTy()
+    else result = res
   )
   or
   exists(ItemNode q, string name |
@@ -394,6 +490,47 @@ ItemNode resolvePath(RelevantPath path) {
   result = resolveUseTreeListItem(_, _, path)
 }
 
+/** Holds if path `p` must be looked up in namespace `n`. */
+private predicate pathUsesNamespace(Path p, Namespace n) {
+  n.isValue() and
+  (
+    p = any(PathExpr pe).getPath()
+    or
+    p = any(TupleStructPat tsp).getPath()
+  )
+  or
+  n.isType() and
+  (
+    p = any(Visibility v).getPath()
+    or
+    p = any(RecordExpr re).getPath()
+    or
+    p = any(PathTypeRepr ptr).getPath()
+    or
+    p = any(RecordPat rp).getPath()
+    or
+    p =
+      any(UseTree use |
+        use.isGlob()
+        or
+        use.hasUseTreeList()
+      ).getPath()
+    or
+    p = any(Path parent).getQualifier()
+  )
+}
+
+/** Gets the item that `path` resolves to, if any. */
+cached
+ItemNode resolvePath(RelevantPath path) {
+  result = resolvePath0(path) and
+  (
+    pathUsesNamespace(path, result.getNamespace())
+    or
+    not pathUsesNamespace(path, _)
+  )
+}
+
 pragma[nomagic]
 private ItemNode resolvePathQualifier(RelevantPath path, string name) {
   result = resolvePath(path.getQualifier()) and
@@ -452,14 +589,14 @@ pragma[nomagic]
 private predicate useImportEdge(Use use, string name, ItemNode item) {
   exists(UseTree tree, ItemNode used |
     used = resolveUseTreeListItem(use, tree) and
-    not exists(tree.getUseTreeList()) and
+    not tree.hasUseTreeList() and
     if tree.isGlob()
     then
-      exists(ItemNode encl |
+      exists(ItemNode encl, Namespace ns |
         encl.getADescendant() = use and
-        item = used.getASuccessor(name) and
+        item = getASuccessor(used, name, ns) and
         // glob imports can be shadowed
-        not declares(encl, name)
+        not declares(encl, ns, name)
       )
     else item = used
   |