PS: Rename getExpr to getBase on ConvertExpr.

powershell/ql/lib/semmle/code/powershell/ConvertExpr.qll

@@ -5,7 +5,7 @@ class ConvertExpr extends @convert_expression, Expr {
 
   override SourceLocation getLocation() { convert_expression_location(this, result) }
 
-  Expr getExpr() { convert_expression(this, _, result, _, _) }
+  Expr getBase() { convert_expression(this, _, result, _, _) }
 
   TypeConstraint getType() { convert_expression(this, _, _, result, _) }
 

powershell/ql/lib/semmle/code/powershell/controlflow/CfgNodes.qll

@@ -485,6 +485,22 @@ module ExprNodes {
       )
     }
   }
+
+  class ConvertExprChildMapping extends ExprChildMapping, ConvertExpr {
+    override predicate relevantChild(Ast n) { n = this.getBase() }
+  }
+
+  class ConvertCfgNode extends ExprCfgNode {
+    override string getAPrimaryQlClass() { result = "ConvertCfgNode" }
+
+    override ConvertExprChildMapping e;
+
+    override ConvertExpr getExpr() { result = e }
+
+    final ExprCfgNode getBase() { e.hasCfgChild(e.getBase(), this, result) }
+
+    TypeConstraint getType() { result = e.getType() }
+  }
 }
 
 module StmtNodes {

powershell/ql/lib/semmle/code/powershell/controlflow/internal/ControlFlowGraphImpl.qll

@@ -589,7 +589,7 @@ module Trees {
   class ScriptBlockExprTree extends LeafTree instanceof ScriptBlockExpr { }
 
   class ConvertExprTree extends StandardPostOrderTree instanceof ConvertExpr {
-    override AstNode getChildNode(int i) { i = 0 and result = super.getExpr() }
+    override AstNode getChildNode(int i) { i = 0 and result = super.getBase() }
   }
 
   class IndexExprTree extends StandardPostOrderTree instanceof IndexExpr {

powershell/ql/lib/semmle/code/powershell/internal/ExplicitWrite.qll

@@ -10,7 +10,7 @@ module Private {
   predicate isExplicitWrite(Expr e, AssignStmt assign) {
     e = assign.getLeftHandSide()
     or
-    e = any(ConvertExpr convert | isExplicitWrite(convert, assign)).getExpr()
+    e = any(ConvertExpr convert | isExplicitWrite(convert, assign)).getBase()
     or
     e = any(ArrayLiteral array | isExplicitWrite(array, assign)).getAnElement()
   }