C#: When creating conditionally accessed expressions, use the typeinfo from the conditional expression to ensure correct flow state and type nullability.

calumgrant · calumgrant · commit bcd8dca78099 · 2020-01-07T18:39:51.000Z
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expression.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expression.cs
@@ -292,7 +292,7 @@ abstract class Expression<SyntaxNode> : Expression
         protected Expression(ExpressionNodeInfo info)
             : base(info)
         {
-            Syntax = (SyntaxNode)info.Node;
+           Syntax = (SyntaxNode)info.Node;
         }
 
         /// <summary>
@@ -374,7 +374,8 @@ class ExpressionInfo : IExpressionInfo
         public bool IsCompilerGenerated { get; }
         public string ExprValue { get; }
 
-        public ExpressionInfo(Context cx, AnnotatedType type, Extraction.Entities.Location location, ExprKind kind, IExpressionParentEntity parent, int child, bool isCompilerGenerated, string value)
+        public ExpressionInfo(Context cx, AnnotatedType type, Extraction.Entities.Location location, ExprKind kind,
+            IExpressionParentEntity parent, int child, bool isCompilerGenerated, string value)
         {
             Context = cx;
             Type = type;
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/MemberAccess.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/MemberAccess.cs
@@ -30,7 +30,7 @@ private MemberAccess(ExpressionNodeInfo info, ExpressionSyntax qualifier, ISymbo
         public static Expression Create(ExpressionNodeInfo info, ConditionalAccessExpressionSyntax node) =>
             // The qualifier is located by walking the syntax tree.
             // `node.WhenNotNull` will contain a MemberBindingExpressionSyntax, calling the method below.
-            Create(info.Context, node.WhenNotNull, info.Parent, info.Child);
+            CreateFromNode(new ExpressionNodeInfo(info.Context, node.WhenNotNull, info.Parent, info.Child, info.TypeInfo));
 
         public static Expression Create(ExpressionNodeInfo info, MemberBindingExpressionSyntax node)
         {

Original file line number	Diff line number	Diff line change
`@@ -292,7 +292,7 @@ abstract class Expression<SyntaxNode> : Expression`
`292`	`292`	`protected Expression(ExpressionNodeInfo info)`
`293`	`293`	`: base(info)`
`294`	`294`	`{`
`295`		`- Syntax = (SyntaxNode)info.Node;`
	`295`	`+ Syntax = (SyntaxNode)info.Node;`
`296`	`296`	`}`
`297`	`297`
`298`	`298`	`/// <summary>`
`@@ -374,7 +374,8 @@ class ExpressionInfo : IExpressionInfo`
`374`	`374`	`public bool IsCompilerGenerated { get; }`
`375`	`375`	`public string ExprValue { get; }`
`376`	`376`
`377`		`- public ExpressionInfo(Context cx, AnnotatedType type, Extraction.Entities.Location location, ExprKind kind, IExpressionParentEntity parent, int child, bool isCompilerGenerated, string value)`
	`377`	`+ public ExpressionInfo(Context cx, AnnotatedType type, Extraction.Entities.Location location, ExprKind kind,`
	`378`	`+ IExpressionParentEntity parent, int child, bool isCompilerGenerated, string value)`
`378`	`379`	`{`
`379`	`380`	`Context = cx;`
`380`	`381`	`Type = type;`
Original file line number	Diff line number	Diff line change
`@@ -30,7 +30,7 @@ private MemberAccess(ExpressionNodeInfo info, ExpressionSyntax qualifier, ISymbo`
`30`	`30`	`public static Expression Create(ExpressionNodeInfo info, ConditionalAccessExpressionSyntax node) =>`
`31`	`31`	`// The qualifier is located by walking the syntax tree.`
`32`	`32`	// `node.WhenNotNull` will contain a MemberBindingExpressionSyntax, calling the method below.
`33`		`- Create(info.Context, node.WhenNotNull, info.Parent, info.Child);`
	`33`	`+ CreateFromNode(new ExpressionNodeInfo(info.Context, node.WhenNotNull, info.Parent, info.Child, info.TypeInfo));`
`34`	`34`
`35`	`35`	`public static Expression Create(ExpressionNodeInfo info, MemberBindingExpressionSyntax node)`
`36`	`36`	`{`