"Rename" refactor does not work on tuple fields

[mkrueger]

Got a bug report:

Refactoring of a tuple, does not update the tuple values:

var j = (int rune, int value);
j.rune

Refactoring rune above to a new name does not update the code below.

My use case was:

(int rune, int value) j = (5, 3);
j.rune = 5;

Got an exception on rename:

System.NullReferenceException: Object reference not set to an instance of an object
  at Microsoft.CodeAnalysis.Rename.ConflictEngine.ConflictResolver+<AddDeclarationConflictsAsync>d__9.MoveNext () [0x001cd] in <62ecf748d8c54ce99002ae42d41637ec>:0 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in /home/mkrueger/work/mono/mcs/class/referencesource/mscorlib/system/runtime/exceptionservices/exceptionservicescommon.cs:151 
  at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) [0x00037] in /home/mkrueger/work/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:187 
  at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) [0x00028] in /home/mkrueger/work/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:156 
  at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) [0x00008] in /home/mkrueger/work/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:128 
  at System.Runtime.CompilerServices.ConfiguredTaskAwaitable+ConfiguredTaskAwaiter.GetResult () [0x00000] in /home/mkrueger/work/mono/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/TaskAwaiter.cs:447 
  at Microsoft.CodeAnalysis.Rename.ConflictEngine.ConflictResolver+Session+<IdentifyConflictsAsync>d__19.MoveNext () [0x00d0b] in <62ecf748d8c54ce99002ae42d41637ec>:0 

[sharwell]

💭 I see other past bugs related to renaming tuple elements, but none that I can claim is a duplicate of this. Seems the current status of this feature is it's known to not work and supposed to show a dialog telling you so, but seems you saw a crash instead. Makes me wonder if someone tried to implement the functionality but missed this case.

[Pilchie]

@jcouv or @dpoeschl do you know the expected current state here?

[jcouv]

Two things:

• var j = (int rune, int value); is not valid code. Was that produced by the refactoring, or was that code you tried to refactor?
• renaming tuple element names is currently blocked (see Cannot rename named tuples #14115)

[mkrueger]

The thing is that I get code reported that is not valid. It's ok for a rename not working on invalid code.

But that shouldn't be done via an unhandled exception :).