C++: fix typedef resolution in ArrayType

cpp/ql/lib/change-notes/2025-06-17-arraytype-typedefs.md

@@ -0,0 +1,4 @@
+---
+category: fix
+---
+* `resolveTypedefs` now properly resolves typedefs for `ArrayType`s.

cpp/ql/lib/semmle/code/cpp/Type.qll

@@ -1589,6 +1589,11 @@ class ArrayType extends DerivedType {
    * Holds if this array is a variable-length array (VLA).
    */
   predicate isVla() { type_is_vla(underlyingElement(this)) }
+
+  override Type resolveTypedefs() {
+    result.(ArrayType).getBaseType() = this.getBaseType().resolveTypedefs() and
+    result.(ArrayType).getArraySize() = this.getArraySize()
+  }
 }
 
 /**

cpp/ql/test/library-tests/resolve_typedefs/ArrayTypedefs.cpp

@@ -0,0 +1,7 @@
+typedef int int_t;
+int_t g1[10];
+int_t g2[2][4];
+
+typedef float float_t;
+float_t arr1[5];
+float_t (*a_pointer)[10];

cpp/ql/test/library-tests/resolve_typedefs/ArrayTypedefs.expected

@@ -0,0 +1,5 @@
+| file://:0:0:0:0 | float_t[5] | file://:0:0:0:0 | float[5] | ArrayTypedefs.cpp:6:9:6:12 | definition of arr1 |
+| file://:0:0:0:0 | float_t[10] | file://:0:0:0:0 | float[10] | ArrayTypedefs.cpp:7:11:7:19 | definition of a_pointer |
+| file://:0:0:0:0 | int_t[2][4] | file://:0:0:0:0 | int[2][4] | ArrayTypedefs.cpp:3:7:3:8 | definition of g2 |
+| file://:0:0:0:0 | int_t[4] | file://:0:0:0:0 | int[4] | ArrayTypedefs.cpp:3:7:3:8 | definition of g2 |
+| file://:0:0:0:0 | int_t[10] | file://:0:0:0:0 | int[10] | ArrayTypedefs.cpp:2:7:2:8 | definition of g1 |

cpp/ql/test/library-tests/resolve_typedefs/ArrayTypedefs.ql

@@ -0,0 +1,4 @@
+import cpp
+
+from ArrayType type
+select type, type.resolveTypedefs(), type.getATypeNameUse()