PS: Fix toString on unknown static field access

powershell/ql/lib/semmle/code/powershell/ast/internal/MemberExpr.qll

@@ -29,22 +29,26 @@ class MemberExpr extends Expr, TMemberExpr {
 
   /** Gets the name of the member being looked up, if any. */
   string getMemberName() {
-    result = getRawAst(this).(Raw::MemberExpr).getMember().(Raw::StringConstExpr).getValue().getValue()
+    result =
+      getRawAst(this).(Raw::MemberExpr).getMember().(Raw::StringConstExpr).getValue().getValue()
   }
 
   predicate isNullConditional() { getRawAst(this).(Raw::MemberExpr).isNullConditional() }
 
   predicate isStatic() { getRawAst(this).(Raw::MemberExpr).isStatic() }
 
-  final override string toString() { result = this.getMemberName() }
+  final override string toString() {
+    result = this.getMemberName()
+    or
+    not exists(this.getMemberName()) and
+    result = "..."
+  }
 
   predicate isExplicitWrite(Ast assignment) {
     explicitAssignment(getRawAst(this), getRawAst(assignment))
   }
 
-  predicate isImplicitWrite() {
-    implicitAssignment(getRawAst(this))
-  }
+  predicate isImplicitWrite() { implicitAssignment(getRawAst(this)) }
 }
 
 /** A `MemberExpr` that is being written to. */

powershell/ql/test/library-tests/ast/Expressions/MemberExpression.ps1

@@ -0,0 +1,2 @@
+param($x)
+[DateTime]::$x

powershell/ql/test/library-tests/ast/Expressions/expressions.expected

@@ -5,6 +5,7 @@ cmdExpr
 | BinaryExpression.ps1:4:1:4:7 | [Stmt] result | BinaryExpression.ps1:4:1:4:7 | result |
 | ExpandableString.ps1:1:1:1:39 | [Stmt] Date: $([DateTime]::Now)\nName: $name | ExpandableString.ps1:1:1:1:39 | Date: $([DateTime]::Now)\nName: $name |
 | ExpandableString.ps1:1:23:1:37 | [Stmt] Now | ExpandableString.ps1:1:23:1:37 | Now |
+| MemberExpression.ps1:2:1:2:14 | [Stmt] ... | MemberExpression.ps1:2:1:2:14 | ... |
 | SubExpression.ps1:1:1:1:23 | [Stmt] Call to AddDays | SubExpression.ps1:1:1:1:23 | Call to AddDays |
 | SubExpression.ps1:1:3:1:10 | [Stmt] Call to Get-Date | SubExpression.ps1:1:3:1:10 | Call to Get-Date |
 | SubExpression.ps1:2:1:2:21 | [Stmt] Call to AddDays | SubExpression.ps1:2:1:2:21 | Call to AddDays |
@@ -13,3 +14,6 @@ invokeMemoryExpression
 | SubExpression.ps1:1:1:1:23 | Call to AddDays | SubExpression.ps1:1:1:1:11 | $(...) | 0 | SubExpression.ps1:1:21:1:22 | 10 |
 expandableString
 | ExpandableString.ps1:1:1:1:39 | Date: $([DateTime]::Now)\nName: $name | 1 | ExpandableString.ps1:1:21:1:38 | $(...) |
+memberExpr
+| ExpandableString.ps1:1:23:1:37 | Now | ExpandableString.ps1:1:23:1:32 | DateTime |
+| MemberExpression.ps1:2:1:2:14 | ... | MemberExpression.ps1:2:1:2:10 | DateTime |

powershell/ql/test/library-tests/ast/Expressions/expressions.ql

@@ -1,19 +1,19 @@
 import powershell
 
 query predicate binaryExpr(BinaryExpr e, Expr e1, Expr e2) {
-    e1 = e.getLeft() and
-    e2 = e.getRight()
+  e1 = e.getLeft() and
+  e2 = e.getRight()
 }
 
-query predicate cmdExpr(ExprStmt exprStmt, Expr e) {
-    e = exprStmt.getExpr()
-}
+query predicate cmdExpr(ExprStmt exprStmt, Expr e) { e = exprStmt.getExpr() }
 
 query predicate invokeMemoryExpression(InvokeMemberExpr invoke, Expr e, int i, Expr arg) {
-    e = invoke.getQualifier() and
-    arg = invoke.getArgument(i)
+  e = invoke.getQualifier() and
+  arg = invoke.getArgument(i)
 }
 
 query predicate expandableString(ExpandableStringExpr expandable, int i, Expr e) {
-    e = expandable.getExpr(i)
+  e = expandable.getExpr(i)
 }
+
+query predicate memberExpr(MemberExpr expr, Expr e) { e = expr.getQualifier() }