Rust: Make path resolution tests work with Rust 1.96 and fix m::{self} when m is a trait

rust/ql/lib/change-notes/2026-09-07-self-path-trait.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* Fix path resolution for `m::{self}` paths where `m` is a trait.

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

@@ -427,7 +427,7 @@ abstract class ItemNode extends Locatable {
       if
         this instanceof Module or
         this instanceof Enum or
-        this instanceof Struct or
+        this instanceof Trait or
         this instanceof Crate
       then (
         kind.isBoth() and

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

@@ -4,3 +4,15 @@ struct A; // A1
 struct A; // A2
 
 fn f(x: A) {} // $ item=A2 (the latter occurence takes precedence)
+
+/// Test `m::{self}` where `m` is a struct. Per the Rust specification `m` must
+/// resolve to a module, trait, or enum:
+/// https://doc.rust-lang.org/reference/items/use-declarations.html#r-items.use.self.module
+mod self_import_from_struct {
+    struct MyStruct; // Struct
+
+    #[rustfmt::skip]
+    use self::MyStruct::{ // $ item=Struct
+        self // $ SPURIOUS: item=self_import_from_struct
+    };
+}

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

@@ -685,29 +685,38 @@ mod m18 {
     }
 }
 
-mod m21 {
-    mod m22 {
+/// Test importing modules, traits, and enums with `{self}`.
+mod self_imports {
+    mod definitions {
+        pub mod my_module {
+            pub fn f() {} // I107
+        } // I104
+        pub trait MyTrait {} // I105
         pub enum MyEnum {
-            A, // I104
-        } // I105
+            A, // I108
+        } // I106
+    }
 
-        pub struct MyStruct; // I106
-    } // I107
+    mod imports {
+        #[rustfmt::skip]
+        use super::definitions::my_module::{ // $ item=I104
+            self // $ item=I104
+        };
 
-    mod m33 {
         #[rustfmt::skip]
-        use super::m22::MyEnum::{ // $ item=I105
+        use super::definitions::MyTrait::{ // $ item=I105
             self // $ item=I105
         };
 
         #[rustfmt::skip]
-        use super::m22::MyStruct::{ // $ item=I106
+        use super::definitions::MyEnum::{ // $ item=I106
             self // $ item=I106
         };
 
-        fn f() {
-            let _ = MyEnum::A; // $ item=I104
-            let _ = MyStruct {}; // $ item=I106
+        #[rustfmt::skip]
+        fn f<T: MyTrait>() { // $ item=I105
+            my_module::f(); // $ item=I107
+            let _ = MyEnum::A; // $ item=I108
         }
     }
 }