Rust: Cross-crate path resolution

Author: hvitved

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

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

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 @@ final class Namespace extends TNamespace {
  * - 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();
 
@@ -96,6 +96,18 @@ abstract class ItemNode extends AstNode {
   Element getADescendant() {
     getImmediateParent(result) = this
     or
+    // for path resolution, we pretend that the crate is the immediate parent of the
+    // entry module/source file, which means that lookup via crate dependencies will
+    // only happen when inner scopes do not shadow
+    this =
+      any(CrateItemNode c |
+        // entry module/entry source file
+        result = c.getModuleNode()
+        or
+        // entry/transitive source file
+        result = c.getASourceFile()
+      )
+    or
     exists(Element mid |
       mid = this.getADescendant() and
       getImmediateParent(result) = mid and
@@ -122,6 +134,10 @@ abstract class ItemNode extends AstNode {
     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
@@ -180,7 +196,10 @@ abstract class ItemNode extends AstNode {
     this = result.(ImplOrTraitItemNode).getAnItemInSelfScope()
     or
     name = "crate" and
-    result.(SourceFileItemNode).getFile() = this.getFile()
+    exists(CrateItemNode crate |
+      this = crate.getASourceFile() and
+      result = crate.getModuleNode()
+    )
   }
 
   /** Gets the location of this item. */
@@ -214,6 +233,51 @@ private class SourceFileItemNode extends ModuleLikeNode, SourceFile {
   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 TypeParam getTypeParam(int i) { none() }
+}
+
 /** 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. */
@@ -595,6 +659,22 @@ private predicate fileImportEdge(Module mod, string name, ItemNode item) {
   )
 }
 
+/**
+ * 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
+  i.isPublic()
+}
+
+/**
+ * Holds if `source` depends on crate `dep` named `name`.
+ */
+private predicate crateDependencyEdge(Crate source, string name, CrateItemNode dep) {
+  dep = source.getDependency(name)
+}
+
 private predicate useTreeDeclares(UseTree tree, string name) {
   not tree.isGlob() and
   not exists(tree.getUseTreeList()) and
@@ -832,3 +912,48 @@ private predicate useImportEdge(Use use, string name, ItemNode item) {
     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/test/extractor-tests/canonical_path/CONSISTENCY/PathResolutionConsistency.expected

@@ -0,0 +1,3 @@
+multipleStaticCallTargets
+| regular.rs:29:5:29:9 | s.g(...) | anonymous.rs:15:9:15:22 | fn g |
+| regular.rs:29:5:29:9 | s.g(...) | regular.rs:13:5:13:18 | fn g |

rust/ql/test/extractor-tests/canonical_path_disabled/CONSISTENCY/PathResolutionConsistency.expected

@@ -0,0 +1,3 @@
+multipleStaticCallTargets
+| regular.rs:32:5:32:9 | s.g(...) | anonymous.rs:18:9:18:22 | fn g |
+| regular.rs:32:5:32:9 | s.g(...) | regular.rs:16:5:16:18 | fn g |

rust/ql/test/library-tests/path-resolution/path-resolution.expected

@@ -129,7 +129,7 @@ resolvePath
 | main.rs:274:16:274:16 | T | main.rs:268:7:268:7 | T |
 | main.rs:275:14:275:17 | Self | main.rs:266:5:276:5 | trait MyParamTrait |
 | main.rs:275:14:275:33 | ...::AssociatedType | main.rs:270:9:270:28 | TypeAlias |
-| main.rs:284:13:284:17 | crate | main.rs:1:1:499:2 | SourceFile |
+| main.rs:284:13:284:17 | crate | main.rs:1:1:500:2 | SourceFile |
 | main.rs:284:13:284:22 | ...::m13 | main.rs:279:1:292:1 | mod m13 |
 | main.rs:284:13:284:25 | ...::f | main.rs:280:5:280:17 | fn f |
 | main.rs:284:13:284:25 | ...::f | main.rs:280:19:281:19 | struct f |
@@ -220,7 +220,7 @@ resolvePath
 | main.rs:479:5:479:32 | ...::f | my2/nested2.rs:3:9:5:9 | fn f |
 | main.rs:480:5:480:5 | f | my2/nested2.rs:3:9:5:9 | fn f |
 | main.rs:481:5:481:5 | g | my2/nested2.rs:7:9:9:9 | fn g |
-| main.rs:482:5:482:9 | crate | main.rs:1:1:499:2 | SourceFile |
+| main.rs:482:5:482:9 | crate | main.rs:1:1:500:2 | SourceFile |
 | main.rs:482:5:482:12 | ...::h | main.rs:50:1:69:1 | fn h |
 | main.rs:483:5:483:6 | m1 | main.rs:13:1:37:1 | mod m1 |
 | main.rs:483:5:483:10 | ...::m2 | main.rs:18:5:36:5 | mod m2 |