C#: Take null conditional assignments into account in MaybeNullExpr.

michaelnebel · michaelnebel · commit 3d9c0cbb9b2f · 2026-01-07T15:22:11.000+01:00
diff --git a/csharp/ql/lib/semmle/code/csharp/dataflow/Nullness.qll b/csharp/ql/lib/semmle/code/csharp/dataflow/Nullness.qll
@@ -43,6 +43,12 @@ private Expr maybeNullExpr(Expr reason) {
     )
   or
   result.(NullCoalescingExpr).getRightOperand() = maybeNullExpr(reason)
+  or
+  result =
+    any(QualifiableExpr qe |
+      qe.isConditional() and
+      qe.getQualifier() = maybeNullExpr(reason)
+    )
 }
 
 /** An expression that may be `null`. */

Original file line number	Diff line number	Diff line change
`@@ -43,6 +43,12 @@ private Expr maybeNullExpr(Expr reason) {`
`43`	`43`	`)`
`44`	`44`	`or`
`45`	`45`	`result.(NullCoalescingExpr).getRightOperand() = maybeNullExpr(reason)`
	`46`	`+ or`
	`47`	`+ result =`
	`48`	`+ any(QualifiableExpr qe \|`
	`49`	`+ qe.isConditional() and`
	`50`	`+ qe.getQualifier() = maybeNullExpr(reason)`
	`51`	`+ )`
`46`	`52`	`}`
`47`	`53`
`48`	`54`	/** An expression that may be `null`. */