Rust: Calculate canonical paths in QL

Author: hvitved

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

@@ -190,6 +190,33 @@ abstract class ItemNode extends Locatable {
     this = result.(CrateItemNode).getASourceFile()
   }
 
+  /**
+   * Gets the canonical path of this item, if any.
+   *
+   * See [The Rust Reference][1] for more details.
+   *
+   * [1]: https://doc.rust-lang.org/reference/paths.html#canonical-paths
+   */
+  cached
+  abstract string getCanonicalPath(Crate c);
+
+  /** Gets the canonical path prefix that this node provides for `child`. */
+  pragma[nomagic]
+  string getCanonicalPathPrefixFor(Crate c, ItemNode child) {
+    child.getImmediateParent() = this and
+    result = this.getCanonicalPath(c)
+  }
+
+  /** Gets the canonical path prefix of this node, if any. */
+  pragma[nomagic]
+  final string getCanonicalPathPrefix(Crate c) {
+    result = any(ItemNode parent).getCanonicalPathPrefixFor(c, this)
+  }
+
+  /** Gets the canonical path prefix of this node, if any. */
+  pragma[nomagic]
+  final Crate getACanonicalPathCrate() { exists(this.getCanonicalPathPrefix(result)) }
+
   /** Gets the location of this item. */
   Location getLocation() { result = super.getLocation() }
 }
@@ -226,6 +253,8 @@ private class SourceFileItemNode extends ModuleLikeNode, SourceFile {
   override predicate isPublic() { any() }
 
   override TypeParam getTypeParam(int i) { none() }
+
+  override string getCanonicalPath(Crate c) { none() }
 }
 
 class CrateItemNode extends ItemNode instanceof Crate {
@@ -273,12 +302,44 @@ class CrateItemNode extends ItemNode instanceof Crate {
   override predicate isPublic() { any() }
 
   override TypeParam getTypeParam(int i) { none() }
+
+  override string getCanonicalPath(Crate c) { c = this and result = Crate.super.getName() }
+
+  override string getCanonicalPathPrefixFor(Crate c, ItemNode child) {
+    exists(ModuleLikeNode m |
+      result = this.getCanonicalPath(c) and
+      m = this.getModuleNode()
+    |
+      child = m
+      or
+      child.getImmediateParent() = m.(SourceFile) and
+      not m = child.(SourceFileItemNode).getSuper()
+    )
+  }
 }
 
 /** An item that can occur in a trait or an `impl` block. */
 abstract private class AssocItemNode extends ItemNode, AssocItem {
   /** Holds if this associated item has an implementation. */
   abstract predicate hasImplementation();
+
+  bindingset[c]
+  private string getCanonicalPathPart(Crate c, int i) {
+    i = 0 and
+    result = this.getCanonicalPathPrefix(c)
+    or
+    i = 1 and
+    result = "::"
+    or
+    i = 2 and
+    result = this.getName()
+  }
+
+  language[monotonicAggregates]
+  override string getCanonicalPath(Crate c) {
+    c = this.getACanonicalPathCrate() and
+    result = strictconcat(int i | i in [0 .. 2] | this.getCanonicalPathPart(c, i) order by i)
+  }
 }
 
 private class ConstItemNode extends AssocItemNode instanceof Const {
@@ -301,6 +362,24 @@ private class EnumItemNode extends ItemNode instanceof Enum {
   override Visibility getVisibility() { result = Enum.super.getVisibility() }
 
   override TypeParam getTypeParam(int i) { result = super.getGenericParamList().getTypeParam(i) }
+
+  bindingset[c]
+  private string getCanonicalPathPart(Crate c, int i) {
+    i = 0 and
+    result = this.getCanonicalPathPrefix(c)
+    or
+    i = 1 and
+    result = "::"
+    or
+    i = 2 and
+    result = this.getName()
+  }
+
+  language[monotonicAggregates]
+  override string getCanonicalPath(Crate c) {
+    c = this.getACanonicalPathCrate() and
+    result = strictconcat(int i | i in [0 .. 2] | this.getCanonicalPathPart(c, i) order by i)
+  }
 }
 
 private class VariantItemNode extends ItemNode instanceof Variant {
@@ -315,6 +394,24 @@ private class VariantItemNode extends ItemNode instanceof Variant {
   }
 
   override Visibility getVisibility() { result = Variant.super.getVisibility() }
+
+  bindingset[c]
+  private string getCanonicalPathPart(Crate c, int i) {
+    i = 0 and
+    result = this.getCanonicalPathPrefix(c)
+    or
+    i = 1 and
+    result = "::"
+    or
+    i = 2 and
+    result = this.getName()
+  }
+
+  language[monotonicAggregates]
+  override string getCanonicalPath(Crate c) {
+    c = this.getACanonicalPathCrate() and
+    result = strictconcat(int i | i in [0 .. 2] | this.getCanonicalPathPart(c, i) order by i)
+  }
 }
 
 class FunctionItemNode extends AssocItemNode instanceof Function {
@@ -436,6 +533,47 @@ class ImplItemNode extends ImplOrTraitItemNode instanceof Impl {
   override TypeParam getTypeParam(int i) { result = super.getGenericParamList().getTypeParam(i) }
 
   override Visibility getVisibility() { result = Impl.super.getVisibility() }
+
+  pragma[nomagic]
+  private string getCanonicalPathTraitPart(Crate c) {
+    exists(Crate c2 | result = this.resolveTraitTy().getCanonicalPath(c2) |
+      c = c2
+      or
+      c2 = c.getADependency()
+    )
+  }
+
+  bindingset[c]
+  private string getCanonicalPathPart(Crate c, int i) {
+    i = 0 and
+    result = "<"
+    or
+    i = 1 and
+    result = this.resolveSelfTy().getCanonicalPath(c)
+    or
+    if exists(this.getTraitPath())
+    then
+      i = 2 and
+      result = " as "
+      or
+      i = 3 and
+      result = this.getCanonicalPathTraitPart(c)
+      or
+      i = 4 and
+      result = ">"
+    else (
+      i = 2 and
+      result = ">"
+    )
+  }
+
+  language[monotonicAggregates]
+  override string getCanonicalPath(Crate c) {
+    c = this.getACanonicalPathCrate() and
+    exists(int m | if exists(this.getTraitPath()) then m = 4 else m = 2 |
+      result = strictconcat(int i | i in [0 .. m] | this.getCanonicalPathPart(c, i) order by i)
+    )
+  }
 }
 
 private class MacroCallItemNode extends AssocItemNode instanceof MacroCall {
@@ -448,6 +586,8 @@ private class MacroCallItemNode extends AssocItemNode instanceof MacroCall {
   override TypeParam getTypeParam(int i) { none() }
 
   override Visibility getVisibility() { none() }
+
+  override string getCanonicalPath(Crate c) { none() }
 }
 
 private class ModuleItemNode extends ModuleLikeNode instanceof Module {
@@ -458,6 +598,44 @@ private class ModuleItemNode extends ModuleLikeNode instanceof Module {
   override Visibility getVisibility() { result = Module.super.getVisibility() }
 
   override TypeParam getTypeParam(int i) { none() }
+
+  bindingset[c]
+  private string getCanonicalPathPart(Crate c, int i) {
+    i = 0 and
+    result = this.getCanonicalPathPrefix(c)
+    or
+    i = 1 and
+    result = "::"
+    or
+    i = 2 and
+    result = this.getName()
+  }
+
+  language[monotonicAggregates]
+  override string getCanonicalPath(Crate c) {
+    c = this.getACanonicalPathCrate() and
+    result = strictconcat(int i | i in [0 .. 2] | this.getCanonicalPathPart(c, i) order by i)
+  }
+
+  pragma[nomagic]
+  private ItemNode getACanonicalPathChild() {
+    exists(SourceFile f |
+      fileImport(this, f) and
+      sourceFileEdge(f, _, result)
+    )
+    or
+    this = result.getImmediateParent()
+    or
+    exists(ItemNode mid |
+      mid = this.getACanonicalPathChild() and
+      mid.(MacroCallItemNode) = result.getImmediateParent()
+    )
+  }
+
+  override string getCanonicalPathPrefixFor(Crate c, ItemNode child) {
+    child = this.getACanonicalPathChild() and
+    result = this.getCanonicalPath(c)
+  }
 }
 
 private class StructItemNode extends ItemNode instanceof Struct {
@@ -473,6 +651,24 @@ private class StructItemNode extends ItemNode instanceof Struct {
   override Visibility getVisibility() { result = Struct.super.getVisibility() }
 
   override TypeParam getTypeParam(int i) { result = super.getGenericParamList().getTypeParam(i) }
+
+  bindingset[c]
+  private string getCanonicalPathPart(Crate c, int i) {
+    i = 0 and
+    result = this.getCanonicalPathPrefix(c)
+    or
+    i = 1 and
+    result = "::"
+    or
+    i = 2 and
+    result = this.getName()
+  }
+
+  language[monotonicAggregates]
+  override string getCanonicalPath(Crate c) {
+    c = this.getACanonicalPathCrate() and
+    result = strictconcat(int i | i in [0 .. 2] | this.getCanonicalPathPart(c, i) order by i)
+  }
 }
 
 class TraitItemNode extends ImplOrTraitItemNode instanceof Trait {
@@ -492,6 +688,36 @@ class TraitItemNode extends ImplOrTraitItemNode instanceof Trait {
   override Visibility getVisibility() { result = Trait.super.getVisibility() }
 
   override TypeParam getTypeParam(int i) { result = super.getGenericParamList().getTypeParam(i) }
+
+  bindingset[c]
+  private string getCanonicalPathPart(Crate c, int i) {
+    i = 0 and
+    result = "<_ as "
+    or
+    i = 1 and
+    result = this.getCanonicalPathPrefix(c)
+    or
+    i = 2 and
+    result = "::"
+    or
+    i = 3 and
+    result = this.getName()
+    or
+    i = 4 and
+    result = ">"
+  }
+
+  language[monotonicAggregates]
+  override string getCanonicalPath(Crate c) {
+    c = this.getACanonicalPathCrate() and
+    result = strictconcat(int i | i in [1 .. 3] | this.getCanonicalPathPart(c, i) order by i)
+  }
+
+  language[monotonicAggregates]
+  override string getCanonicalPathPrefixFor(Crate c, ItemNode child) {
+    result = strictconcat(int i | i in [0 .. 4] | this.getCanonicalPathPart(c, i) order by i) and
+    child = this.getAnAssocItem()
+  }
 }
 
 class TypeAliasItemNode extends AssocItemNode instanceof TypeAlias {
@@ -514,6 +740,24 @@ private class UnionItemNode extends ItemNode instanceof Union {
   override Visibility getVisibility() { result = Union.super.getVisibility() }
 
   override TypeParam getTypeParam(int i) { result = super.getGenericParamList().getTypeParam(i) }
+
+  bindingset[c]
+  private string getCanonicalPathPart(Crate c, int i) {
+    i = 0 and
+    result = this.getCanonicalPathPrefix(c)
+    or
+    i = 1 and
+    result = "::"
+    or
+    i = 2 and
+    result = this.getName()
+  }
+
+  language[monotonicAggregates]
+  override string getCanonicalPath(Crate c) {
+    c = this.getACanonicalPathCrate() and
+    result = strictconcat(int i | i in [0 .. 2] | this.getCanonicalPathPart(c, i) order by i)
+  }
 }
 
 private class UseItemNode extends ItemNode instanceof Use {
@@ -524,6 +768,8 @@ private class UseItemNode extends ItemNode instanceof Use {
   override Visibility getVisibility() { result = Use.super.getVisibility() }
 
   override TypeParam getTypeParam(int i) { none() }
+
+  override string getCanonicalPath(Crate c) { none() }
 }
 
 private class BlockExprItemNode extends ItemNode instanceof BlockExpr {
@@ -534,6 +780,8 @@ private class BlockExprItemNode extends ItemNode instanceof BlockExpr {
   override Visibility getVisibility() { none() }
 
   override TypeParam getTypeParam(int i) { none() }
+
+  override string getCanonicalPath(Crate c) { none() }
 }
 
 private class TypeParamItemNode extends ItemNode instanceof TypeParam {
@@ -589,6 +837,8 @@ private class TypeParamItemNode extends ItemNode instanceof TypeParam {
   override TypeParam getTypeParam(int i) { none() }
 
   override Location getLocation() { result = TypeParam.super.getName().getLocation() }
+
+  override string getCanonicalPath(Crate c) { none() }
 }
 
 /** Holds if `item` has the name `name` and is a top-level item inside `f`. */

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

@@ -36,6 +36,12 @@ query predicate multipleTupleFields(FieldExpr fe, TupleField field) {
   strictcount(fe.getTupleField()) > 1
 }
 
+/** Holds if `p` may resolve to multiple items including `i`. */
+query predicate multipleCanonicalPaths(ItemNode i, Crate c, string path) {
+  path = i.getCanonicalPath(c) and
+  strictcount(i.getCanonicalPath(c)) > 1
+}
+
 /**
  * Gets counts of path resolution inconsistencies of each type.
  */