Java: Reinstate useless null check results for fields that are no longer tracked as SSA variables.

aschackmull · aschackmull · commit 3a30e2a2db0e · 2025-11-11T15:28:45.000+01:00
diff --git a/java/ql/lib/semmle/code/java/dataflow/NullGuards.qll b/java/ql/lib/semmle/code/java/dataflow/NullGuards.qll
@@ -105,6 +105,13 @@ Expr clearlyNotNullExpr(Expr reason) {
     result = v.getARead() and
     not result = baseNotNullExpr()
   )
+  or
+  exists(Field f |
+    result = f.getAnAccess() and
+    f.isFinal() and
+    f.getInitializer() = clearlyNotNullExpr(reason) and
+    not result = baseNotNullExpr()
+  )
 }
 
 /** Holds if `v` is an SSA variable that is provably not `null`. */

Original file line number	Diff line number	Diff line change
`@@ -105,6 +105,13 @@ Expr clearlyNotNullExpr(Expr reason) {`
`105`	`105`	`result = v.getARead() and`
`106`	`106`	`not result = baseNotNullExpr()`
`107`	`107`	`)`
	`108`	`+ or`
	`109`	`+ exists(Field f \|`
	`110`	`+ result = f.getAnAccess() and`
	`111`	`+ f.isFinal() and`
	`112`	`+ f.getInitializer() = clearlyNotNullExpr(reason) and`
	`113`	`+ not result = baseNotNullExpr()`
	`114`	`+ )`
`108`	`115`	`}`
`109`	`116`
`110`	`117`	/** Holds if `v` is an SSA variable that is provably not `null`. */