Rust: Path resolution improvements

rust/ql/integration-tests/hello-workspace/exe/src/main.rs

@@ -1,7 +1,7 @@
-use lib::a_module::hello;
+use lib::a_module::hello; // $ item=HELLO
 
 mod a_module;
 
 fn main() {
-    hello();
+    hello(); // $ item=HELLO
 }

rust/ql/integration-tests/hello-workspace/lib/src/a_module/mod.rs

@@ -1,3 +1,3 @@
 pub fn hello() {
     println!("Hello, world!");
-}
+} // HELLO

rust/ql/integration-tests/hello-workspace/path-resolution.ql

@@ -0,0 +1 @@
+import utils.test.PathResolutionInlineExpectationsTest

rust/ql/integration-tests/hello-workspace/rust-project.json

@@ -2,14 +2,23 @@
   "sysroot_src": "filled by the rust_project fixture",
   "crates": [
     {
+      "display_name": "exe",
+      "version": "0.1.0",
       "root_module": "exe/src/main.rs",
       "edition": "2021",
-      "deps": [{"crate": 1, "name": "lib"}]
+      "deps": [
+        {
+          "crate": 1,
+          "name": "lib"
+        }
+      ]
     },
     {
+      "display_name": "lib",
+      "version": "0.1.0",
       "root_module": "lib/src/lib.rs",
       "edition": "2021",
       "deps": []
     }
   ]
-}
+}

rust/ql/integration-tests/hello-workspace/summary.cargo.expected

@@ -1,4 +1,4 @@
-| Elements extracted | 87 |
+| Elements extracted | 90 |
 | Elements unextracted | 0 |
 | Extraction errors | 0 |
 | Extraction warnings | 0 |

rust/ql/integration-tests/hello-workspace/summary.rust-project.expected

@@ -1,4 +1,4 @@
-| Elements extracted | 87 |
+| Elements extracted | 90 |
 | Elements unextracted | 0 |
 | Extraction errors | 0 |
 | Extraction warnings | 0 |

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

@@ -13,6 +13,7 @@ private import codeql.rust.elements.internal.generated.Crate
 module Impl {
   private import rust
   private import codeql.rust.elements.internal.NamedCrate
+  private import codeql.rust.internal.PathResolution
 
   class Crate extends Generated::Crate {
     override string toStringImpl() {
@@ -58,6 +59,14 @@ module Impl {
      */
     Crate getADependency() { result = this.getDependency(_) }
 
+    /** Gets the source file that defines this crate, if any. */
+    SourceFile getSourceFile() { result.getFile() = this.getModule().getFile() }
+
+    /**
+     * Gets a source file that belongs to this crate, if any.
+     */
+    SourceFile getASourceFile() { result = this.(CrateItemNode).getASourceFile() }
+
     override Location getLocation() { result = this.getModule().getLocation() }
   }
 }

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

@@ -73,7 +73,7 @@
  * - https://doc.rust-lang.org/reference/visibility-and-privacy.html
  * - https://doc.rust-lang.org/reference/names/namespaces.html
  */
-abstract class ItemNode extends AstNode {
+abstract class ItemNode extends Locatable {
   /** Gets the (original) name of this item. */
   abstract string getName();
 
@@ -109,7 +109,11 @@
 
   /** Gets the immediately enclosing module (or source file) of this item. */
   pragma[nomagic]
-  ModuleLikeNode getImmediateParentModule() { this = result.getAnItemInScope() }
+  ModuleLikeNode getImmediateParentModule() {
+    this = result.getAnItemInScope()
+    or
+    result = this.(SourceFileItemNode).getSuper()
+  }
 
   pragma[nomagic]
   private ItemNode getASuccessorRec(string name) {
@@ -122,6 +126,10 @@
     or
     useImportEdge(this, name, result)
     or
+    crateDefEdge(this, name, result)
+    or
+    crateDependencyEdge(this, name, result)
+    or
     // items made available through `use` are available to nodes that contain the `use`
     exists(UseItemNode use |
       use = this.getASuccessorRec(_) and
@@ -168,19 +176,18 @@
     result = this.getASuccessorRec(name)
     or
     name = "super" and
-    if this instanceof Module
+    if this instanceof Module or this instanceof SourceFile
     then result = this.getImmediateParentModule()
     else result = this.getImmediateParentModule().getImmediateParentModule()
     or
     name = "self" and
-    not this instanceof Module and
-    result = this.getImmediateParentModule()
+    if this instanceof Module then result = this else result = this.getImmediateParentModule()
     or
     name = "Self" and
     this = result.(ImplOrTraitItemNode).getAnItemInSelfScope()
     or
     name = "crate" and
-    result.(SourceFileItemNode).getFile() = this.getFile()
+    this = result.(CrateItemNode).getASourceFile()
   }
 
   /** Gets the location of this item. */
@@ -203,6 +210,14 @@
 }
 
 private class SourceFileItemNode extends ModuleLikeNode, SourceFile {
+  pragma[nomagic]
+  ModuleLikeNode getSuper() {
+    exists(ModuleItemNode mod |
+      fileImport(mod, this) and
+      result = mod.getASuccessor("super")
+    )
+  }
+
   override string getName() { result = "(source file)" }
 
   override Namespace getNamespace() {
@@ -211,6 +226,55 @@
 
   override Visibility getVisibility() { none() }
 
+  override predicate isPublic() { any() }
+
+  override TypeParam getTypeParam(int i) { none() }
+}
+
+class CrateItemNode extends ItemNode instanceof Crate {
+  /**
+   * Gets the module node that defines this crate.
+   *
+   * This is either a source file, when the crate is defined in source code,
+   * or a module, when the crate is defined in a dependency.
+   */
+  pragma[nomagic]
+  ModuleLikeNode getModuleNode() {
+    result = super.getSourceFile()
+    or
+    not exists(super.getSourceFile()) and
+    result = super.getModule()
+  }
+
+  /**
+   * Gets a source file that belongs to this crate, if any.
+   *
+   * This is calculated as those source files that can be reached from the entry
+   * file of this crate using zero or more `mod` imports, without going through
+   * the entry point of some other crate.
+   */
+  pragma[nomagic]
+  SourceFileItemNode getASourceFile() {
+    result = super.getSourceFile()
+    or
+    exists(SourceFileItemNode mid, Module mod |
+      mid = this.getASourceFile() and
+      mod.getFile() = mid.getFile() and
+      fileImport(mod, result) and
+      not result = any(Crate other).getSourceFile()
+    )
+  }
+
+  override string getName() { result = Crate.super.getName() }
+
+  override Namespace getNamespace() {
+    result.isType() // can be referenced with `crate`
+  }
+
+  override Visibility getVisibility() { none() }
+
+  override predicate isPublic() { any() }
+
   override TypeParam getTypeParam(int i) { none() }
 }
 
@@ -460,7 +524,7 @@
 
   override Namespace getNamespace() { none() }
 
-  override Visibility getVisibility() { none() }
+  override Visibility getVisibility() { result = Use.super.getVisibility() }
 
   override TypeParam getTypeParam(int i) { none() }
 }
@@ -586,11 +650,33 @@
  * Holds if `mod` is a `mod name;` item targeting a file resulting in `item` being
  * in scope under the name `name`.
  */
+pragma[nomagic]
 private predicate fileImportEdge(Module mod, string name, ItemNode item) {
-  item.isPublic() and
-  exists(SourceFile f |
+  exists(SourceFileItemNode f |
     fileImport(mod, f) and
-    sourceFileEdge(f, name, item)
+    item = f.getASuccessor(name)
+  )
+}
+
+/**
+ * Holds if crate `c` defines the item `i` named `name`.
+ */
+pragma[nomagic]
+private predicate crateDefEdge(CrateItemNode c, string name, ItemNode i) {
+  i = c.getModuleNode().getASuccessor(name) and
+  not i instanceof Crate
+}
+
+/**
+ * Holds if `m` depends on crate `dep` named `name`.
+ */
+private predicate crateDependencyEdge(ModuleLikeNode m, string name, CrateItemNode dep) {
+  exists(CrateItemNode c | dep = c.(Crate).getDependency(name) |
+    // entry module/entry source file
+    m = c.getModuleNode()
+    or
+    // entry/transitive source file
+    m = c.getASourceFile()
   )
 }
 
@@ -745,13 +831,54 @@
   )
 }
 
-/** Gets the item that `path` resolves to, if any. */
-cached
-ItemNode resolvePath(RelevantPath path) {
+pragma[nomagic]
+private ItemNode resolvePath1(RelevantPath path) {
   exists(Namespace ns | result = resolvePath0(path, ns) |
     pathUsesNamespace(path, ns)
     or
-    not pathUsesNamespace(path, _)
+    not pathUsesNamespace(path, _) and
+    not path = any(MacroCall mc).getPath()
+  )
+}
+
+pragma[nomagic]
+private ItemNode resolvePathPrivate(
+  RelevantPath path, ModuleLikeNode itemParent, ModuleLikeNode pathParent
+) {
+  result = resolvePath1(path) and
+  itemParent = result.getImmediateParentModule() and
+  not result.isPublic() and
+  (
+    pathParent.getADescendant() = path
+    or
+    pathParent = any(ItemNode mid | path = mid.getADescendant()).getImmediateParentModule()
+  )
+}
+
+/**
+ * Gets a module that has access to private items defined inside `itemParent`.
+ *
+ * According to
+ *
+ * https://web.mit.edu/rust-lang_v1.25/arch/amd64_ubuntu1404/share/doc/rust/html/book/second-edition/ch07-02-controlling-visibility-with-pub.html#privacy-rules
+ *
+ * this is either `itemParent` itself or any (transitive) child of `itemParent`.
+ */
+pragma[nomagic]
+private ModuleLikeNode getAPrivateVisibleModule(ModuleLikeNode itemParent) {
+  exists(resolvePathPrivate(_, itemParent, _)) and
+  result.getImmediateParentModule*() = itemParent
+}
+
+/** Gets the item that `path` resolves to, if any. */
+cached
+ItemNode resolvePath(RelevantPath path) {
+  result = resolvePath1(path) and
+  result.isPublic()
+  or
+  exists(ModuleLikeNode itemParent, ModuleLikeNode pathParent |
+    result = resolvePathPrivate(path, itemParent, pathParent) and
+    pathParent = getAPrivateVisibleModule(itemParent)
   )
 }
 
@@ -762,9 +889,9 @@
 }
 
 private predicate isUseTreeSubPath(UseTree tree, RelevantPath path) {
   path = tree.getPath()
   or
   exists(RelevantPath mid |
     isUseTreeSubPath(tree, mid) and
     path = mid.getQualifier()
   )
@@ -831,3 +958,48 @@
     name != "_"
   )
 }
+
+/** Provides predicates for debugging the path resolution implementation. */
+private module Debug {
+  private Locatable getRelevantLocatable() {
+    exists(string filepath, int startline, int startcolumn, int endline, int endcolumn |
+      result.getLocation().hasLocationInfo(filepath, startline, startcolumn, endline, endcolumn) and
+      // filepath.matches("%/compile.rs") and
+      // startline = 1986
+      // filepath.matches("%/build_steps/mod.rs") and
+      // startline = 17
+      filepath.matches("%/main.rs") and
+      startline = 1
+    )
+  }
+
+  predicate debugUnqualifiedPathLookup(RelevantPath p, string name, Namespace ns, ItemNode encl) {
+    p = getRelevantLocatable() and
+    unqualifiedPathLookup(p, name, ns, encl)
+  }
+
+  ItemNode debugResolvePath(RelevantPath path) {
+    path = getRelevantLocatable() and
+    result = resolvePath(path)
+  }
+
+  predicate debugUseImportEdge(Use use, string name, ItemNode item) {
+    use = getRelevantLocatable() and
+    useImportEdge(use, name, item)
+  }
+
+  ItemNode debugGetASuccessorRec(ItemNode i, string name) {
+    i = getRelevantLocatable() and
+    result = i.getASuccessor(name)
+  }
+
+  predicate debugFileImportEdge(Module mod, string name, ItemNode item) {
+    mod = getRelevantLocatable() and
+    fileImportEdge(mod, name, item)
+  }
+
+  predicate debugFileImport(Module m, SourceFile f) {
+    m = getRelevantLocatable() and
+    fileImport(m, f)
+  }
+}

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

@@ -7,6 +7,7 @@ private import PathResolution
 
 /** Holds if `p` may resolve to multiple items including `i`. */
 query predicate multiplePathResolutions(Path p, ItemNode i) {
+  p.fromSource() and
   i = resolvePath(p) and
   // `use foo::bar` may use both a type `bar` and a value `bar`
   not p =