Merge pull request #20736 from github/copilot/add-constaccess-class

Rust: Add ConstAccess class with getConst() predicate

Author: hvitved

rust/ql/.generated.list

@@ -0,0 +1,7 @@
+/**
+ * This module provides the public class `ConstAccess`.
+ */
+
+private import internal.ConstImpl
+
+final class ConstAccess = Impl::ConstAccess;

rust/ql/.gitattributes

@@ -1,17 +1,19 @@
-// generated by codegen, remove this comment if you wish to edit this file
 /**
  * This module provides a hand-modifiable wrapper around the generated class `Const`.
  *
  * INTERNAL: Do not use.
  */
 
 private import codeql.rust.elements.internal.generated.Const
+private import codeql.rust.elements.internal.PathExprImpl::Impl as PathExprImpl
+private import codeql.rust.internal.PathResolution
 
 /**
  * INTERNAL: This module contains the customizable definition of `Const` and should not
  * be referenced directly.
  */
 module Impl {
+  // the following QLdoc is generated: if you need to edit it, do it in the schema file
   /**
    * A constant item declaration.
    *
@@ -21,4 +23,27 @@ module Impl {
    * ```
    */
   class Const extends Generated::Const { }
+
+  /**
+   * A constant access.
+   *
+   * For example:
+   * ```rust
+   * const X: i32 = 42;
+   *
+   * fn main() {
+   *     println!("{}", X);
+   * }
+   * ```
+   */
+  class ConstAccess extends PathExprImpl::PathExpr {
+    private Const c;
+
+    ConstAccess() { c = resolvePath(this.getPath()) }
+
+    /** Gets the constant being accessed. */
+    Const getConst() { result = c }
+
+    override string getAPrimaryQlClass() { result = "ConstAccess" }
+  }
 }

rust/ql/lib/codeql/rust/elements/ConstAccess.qll

@@ -9,6 +9,7 @@ import codeql.rust.elements.ArithmeticOperation
 import codeql.rust.elements.AssignmentOperation
 import codeql.rust.elements.BitwiseOperation
 import codeql.rust.elements.ComparisonOperation
+import codeql.rust.elements.ConstAccess
 import codeql.rust.elements.DerefExpr
 import codeql.rust.elements.LiteralExprExt
 import codeql.rust.elements.LogicalOperation

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

@@ -1043,7 +1043,7 @@ macro_expansion.rs:
 #   98|             getParamList(): [ParamList] ParamList
 #   99|             getFunctionBody(): [BlockExpr] { ... }
 #   99|               getStmtList(): [StmtList] StmtList
-#   99|                 getTailExpr(): [PathExpr] CONST_MyDeriveUnion
+#   99|                 getTailExpr(): [ConstAccess] CONST_MyDeriveUnion
 #   99|                   getPath(): [Path] CONST_MyDeriveUnion
 #   99|                     getSegment(): [PathSegment] CONST_MyDeriveUnion
 #   99|                       getIdentifier(): [NameRef] CONST_MyDeriveUnion

rust/ql/lib/rust.qll

@@ -0,0 +1,8 @@
+testFailures
+constAccess
+| main.rs:17:13:17:24 | GLOBAL_CONST | main.rs:1:1:1:29 | Const |
+| main.rs:19:13:19:24 | STRING_CONST | main.rs:2:1:2:35 | Const |
+| main.rs:21:13:21:33 | ...::ASSOC_CONST | main.rs:9:5:9:33 | Const |
+| main.rs:23:13:23:35 | ...::MODULE_CONST | main.rs:13:5:13:38 | Const |
+| main.rs:25:8:25:19 | GLOBAL_CONST | main.rs:1:1:1:29 | Const |
+| main.rs:29:16:29:36 | ...::ASSOC_CONST | main.rs:9:5:9:33 | Const |

rust/ql/test/extractor-tests/macro-expansion/PrintAst.expected

@@ -0,0 +1,21 @@
+import rust
+import utils.test.InlineExpectationsTest
+import TestUtils
+
+query predicate constAccess(ConstAccess ca, Const c) { toBeTested(ca) and c = ca.getConst() }
+
+module ConstAccessTest implements TestSig {
+  string getARelevantTag() { result = "const_access" }
+
+  predicate hasActualResult(Location location, string element, string tag, string value) {
+    exists(ConstAccess ca |
+      toBeTested(ca) and
+      location = ca.getLocation() and
+      element = ca.toString() and
+      tag = "const_access" and
+      value = ca.getConst().getName().getText()
+    )
+  }
+}
+
+import MakeTest<ConstAccessTest>

rust/ql/test/library-tests/const_access/Cargo.lock

@@ -0,0 +1,34 @@
+const GLOBAL_CONST: i32 = 42;
+const STRING_CONST: &str = "hello";
+
+struct MyStruct {
+    value: i32,
+}
+
+impl MyStruct {
+    const ASSOC_CONST: i32 = 100;
+}
+
+mod my_module {
+    pub const MODULE_CONST: i32 = 200;
+}
+
+fn use_consts() {
+    let x = GLOBAL_CONST; // $ const_access=GLOBAL_CONST
+    
+    let s = STRING_CONST; // $ const_access=STRING_CONST
+    
+    let y = MyStruct::ASSOC_CONST; // $ const_access=ASSOC_CONST
+    
+    let z = my_module::MODULE_CONST; // $ const_access=MODULE_CONST
+    
+    if GLOBAL_CONST > 0 { // $ const_access=GLOBAL_CONST
+        println!("positive");
+    }
+    
+    let arr = [MyStruct::ASSOC_CONST; 5]; // $ const_access=ASSOC_CONST
+}
+
+fn main() {
+    use_consts();
+}