C#: Address review comments

calumgrant · calumgrant · commit a868456628dd · 2020-01-22T14:21:12.000Z
diff --git a/csharp/ql/src/semmle/code/csharp/dataflow/Nullness.qll b/csharp/ql/src/semmle/code/csharp/dataflow/Nullness.qll
@@ -181,7 +181,7 @@ private predicate isMaybeNullArgument(Ssa::ExplicitDefinition def, MaybeNullExpr
   )
 }
 
-private predicate isNullDefaultArgument(Ssa::ExplicitDefinition def, MaybeNullExpr arg) {
+private predicate isNullDefaultArgument(Ssa::ExplicitDefinition def, AlwaysNullExpr arg) {
   exists(AssignableDefinitions::ImplicitParameterDefinition pdef, Parameter p |
     pdef = def.getADefinition()
   |
diff --git a/csharp/ql/test/query-tests/Nullness/E.cs b/csharp/ql/test/query-tests/Nullness/E.cs
@@ -364,6 +364,8 @@ static void Ex33(string s, object o)
     }
 
     static int Ex34(string s = null) => s.Length; // BAD (maybe)
+
+    static int Ex35(string s = "null") => s.Length; // GOOD
 }
 
 public static class Extensions

Original file line number	Diff line number	Diff line change
`@@ -181,7 +181,7 @@ private predicate isMaybeNullArgument(Ssa::ExplicitDefinition def, MaybeNullExpr`
`181`	`181`	`)`
`182`	`182`	`}`
`183`	`183`
`184`		`-private predicate isNullDefaultArgument(Ssa::ExplicitDefinition def, MaybeNullExpr arg) {`
	`184`	`+private predicate isNullDefaultArgument(Ssa::ExplicitDefinition def, AlwaysNullExpr arg) {`
`185`	`185`	`exists(AssignableDefinitions::ImplicitParameterDefinition pdef, Parameter p \|`
`186`	`186`	`pdef = def.getADefinition()`
`187`	`187`	`\|`
Original file line number	Diff line number	Diff line change
`@@ -364,6 +364,8 @@ static void Ex33(string s, object o)`
`364`	`364`	`}`
`365`	`365`
`366`	`366`	`static int Ex34(string s = null) => s.Length; // BAD (maybe)`
	`367`	`+`
	`368`	`+ static int Ex35(string s = "null") => s.Length; // GOOD`
`367`	`369`	`}`
`368`	`370`
`369`	`371`	`public static class Extensions`