Rust: Handle unqualified UseTrees in path resolution

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

@@ -1457,6 +1457,24 @@ private predicate crateDependencyEdge(SourceFileItemNode file, string name, Crat
   not hasDeclOrDep(file, name)
 }
 
+/**
+ * Gets a `UseTree` that is nested under `tree`, and which needs to be resolved
+ * relative to the path of `tree`.
+ *
+ * `tree` is restricted to either having a path or being a direct child of some
+ * `use` statement without a path.
+ */
+private UseTree getAUseTreeUseTree(UseTree tree) {
+  result = tree.getUseTreeList().getAUseTree() and
+  (if tree.hasPath() then any() else tree = any(Use u).getUseTree())
+  or
+  exists(UseTree mid |
+    mid = getAUseTreeUseTree(tree) and
+    not mid.hasPath() and
+    result = mid.getUseTreeList().getAUseTree()
+  )
+}
+
 private predicate useTreeDeclares(UseTree tree, string name) {
   not tree.isGlob() and
   not exists(tree.getUseTreeList()) and
@@ -1470,7 +1488,7 @@ private predicate useTreeDeclares(UseTree tree, string name) {
   or
   exists(UseTree mid |
     useTreeDeclares(mid, name) and
-    mid = tree.getUseTreeList().getAUseTree()
+    mid = getAUseTreeUseTree(tree)
   )
 }
 
@@ -1511,7 +1529,10 @@ class RelevantPath extends Path {
   pragma[nomagic]
   predicate isUnqualified(string name) {
     not exists(this.getQualifier()) and
-    not this = any(UseTreeList list).getAUseTree().getPath().getQualifier*() and
+    not exists(UseTree tree |
+      tree.hasPath() and
+      this = getAUseTreeUseTree(tree).getPath().getQualifier*()
+    ) and
     name = this.getText()
   }
 
@@ -1990,7 +2011,7 @@ private ItemNode resolveUseTreeListItem(Use use, UseTree tree, RelevantPath path
   exists(UseOption useOpt | checkQualifiedVisibility(use, result, kind, useOpt) |
     exists(UseTree midTree, ItemNode mid, string name |
       mid = resolveUseTreeListItem(use, midTree) and
-      tree = midTree.getUseTreeList().getAUseTree() and
+      tree = getAUseTreeUseTree(midTree) and
       isUseTreeSubPathUnqualified(tree, path, pragma[only_bind_into](name)) and
       result = mid.getASuccessor(pragma[only_bind_into](name), kind, useOpt)
     )
@@ -2010,14 +2031,31 @@ private ItemNode resolveUseTreeListItemQualifier(
   name = path.getText()
 }
 
+private UseTree getAUseUseTree(Use use) {
+  exists(UseTree root | root = use.getUseTree() |
+    result = root
+    or
+    not root.hasPath() and
+    result = getAUseTreeUseTree(root)
+  )
+}
+
 pragma[nomagic]
 private ItemNode resolveUseTreeListItem(Use use, UseTree tree) {
   exists(Path path | path = tree.getPath() |
-    tree = use.getUseTree() and
+    tree = getAUseUseTree(use) and
     result = resolvePathCand(path)
     or
     result = resolveUseTreeListItem(use, tree, path, _)
   )
+  or
+  exists(UseTree midTree |
+    // `use foo::{bar, *}`; midTree = `foo` and tree = `*`
+    result = resolveUseTreeListItem(use, midTree) and
+    tree = getAUseTreeUseTree(midTree) and
+    tree.isGlob() and
+    not tree.hasPath()
+  )
 }
 
 /** Holds if `use` imports `item` as `name`. */
@@ -2159,6 +2197,16 @@ private module Debug {
     result = resolvePath(path)
   }
 
+  ItemNode debugResolveUseTreeListItem(Use use, UseTree tree, RelevantPath path, SuccessorKind kind) {
+    use = getRelevantLocatable() and
+    result = resolveUseTreeListItem(use, tree, path, kind)
+  }
+
+  ItemNode debugResolveUseTreeListItem(Use use, UseTree tree) {
+    use = getRelevantLocatable() and
+    result = resolveUseTreeListItem(use, tree)
+  }
+
   predicate debugUseImportEdge(Use use, string name, ItemNode item, SuccessorKind kind) {
     use = getRelevantLocatable() and
     useImportEdge(use, name, item, kind)

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

@@ -1,6 +1,6 @@
 multipleCallTargets
-| main.rs:125:9:125:11 | f(...) |
-| main.rs:365:9:367:16 | ...::f(...) |
-| main.rs:368:9:370:16 | ...::f(...) |
-| main.rs:447:9:451:16 | ...::f(...) |
-| main.rs:452:9:456:16 | ...::f(...) |
+| main.rs:126:9:126:11 | f(...) |
+| main.rs:366:9:368:16 | ...::f(...) |
+| main.rs:369:9:371:16 | ...::f(...) |
+| main.rs:448:9:452:16 | ...::f(...) |
+| main.rs:453:9:457:16 | ...::f(...) |

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

@@ -1,6 +1,7 @@
 mod my; // I1
 
-use my::*; // $ item=I1
+#[rustfmt::skip]
+use {{{my::{{self as my_alias, *}}}}}; // $ item=I1
 
 use my::nested::nested1::nested2::*; // $ item=I3
 
@@ -816,6 +817,7 @@ fn main() {
     nested8::f(); // $ item=I119
     my3::f(); // $ item=I200
     nested_f(); // $ item=I201
+    my_alias::nested_f(); // $ item=I201
     m18::m19::m20::g(); // $ item=I103
     m23::f(); // $ item=I108
     m24::f(); // $ item=I121