ParameterInfo.Name needs to be checked for null before usage (#1375)

filmor · web-flow · commit d86bf3ceba5f · 2021-02-04T12:33:19.000-08:00
This occured in trying to use F# code from Python. As the `.Name` property returns `null`, `ContainsKey` fails. Related documentation: https://docs.microsoft.com/en-us/dotnet/api/system.reflection.parameterinfo.name
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -56,6 +56,7 @@ or the DLL must be loaded in advance. This must be done before calling any other
 -   `import` may now raise errors with more detail than "No module named X"
 -   Exception stacktraces on `PythonException.StackTrace` are now properly formatted
 -   Providing an invalid type parameter to a generic type or method produces a helpful Python error
+-   Empty parameter names (as can be generated from F#) do not cause crashes
 
 ### Removed
 
diff --git a/src/runtime/methodbinder.cs b/src/runtime/methodbinder.cs
@@ -622,7 +622,7 @@ static object[] TryConvertArguments(ParameterInfo[] pi, bool paramsArray,
             for (int paramIndex = 0; paramIndex < pi.Length; paramIndex++)
             {
                 var parameter = pi[paramIndex];
-                bool hasNamedParam = kwargDict.ContainsKey(parameter.Name);
+                bool hasNamedParam = parameter.Name != null ? kwargDict.ContainsKey(parameter.Name) : false;
                 bool isNewReference = false;
 
                 if (paramIndex >= pyArgCount && !(hasNamedParam || (paramsArray && paramIndex == arrayStart)))

Original file line number	Diff line number	Diff line change
`@@ -622,7 +622,7 @@ static object[] TryConvertArguments(ParameterInfo[] pi, bool paramsArray,`
`622`	`622`	`for (int paramIndex = 0; paramIndex < pi.Length; paramIndex++)`
`623`	`623`	`{`
`624`	`624`	`var parameter = pi[paramIndex];`
`625`		`- bool hasNamedParam = kwargDict.ContainsKey(parameter.Name);`
	`625`	`+ bool hasNamedParam = parameter.Name != null ? kwargDict.ContainsKey(parameter.Name) : false;`
`626`	`626`	`bool isNewReference = false;`
`627`	`627`
`628`	`628`	`if (paramIndex >= pyArgCount && !(hasNamedParam \|\| (paramsArray && paramIndex == arrayStart)))`