Preview 2:

• Intellisense (@333fred)
  • Public API
  • Display inferred nullability of variables, fields, properties, type arguments
  • Should we display some hint about oblivious vs. non-null?
• Nullable Specification (Mads)
• #nullable
  • binding (no more scoped context) Remove remaining artifacts of symbol-centric NonNullTypes context. #31607
  • #pragma warning nullable (enable|disable|restore) PR Add support for restore and safeonly for #nullable directive. #31806
  • Code fixer
• Tuples Track nullable state for tuple items #29970
• More attributes e.g.: [MaybeNull]
  • Finalize BCL types
• ! suppress conversion warnings ! should suppress conversion warnings #30376
• e switch { … }, switch (e) { … } Nullable reference types: no nullability flow check in switch statements. #23944
• Avoid inferring unspeakable type arguments (PR Use speakable annotations in method type re-inference #31813)
• Dogfood
  • WPFRunner
  • CodeAnalysis
• Nullable value types Track Nullable Value Type Null State #29817, PR Track nullability of nullable value types #31499
• [Nullable] metadata encoding (PR Adjust the way nullable annotations are represented in metadata #31212)
  • Sync with F# on format
• Analyze yield return Null warnings not reported for iterator methods #23701

Non-blocking:

• Annotations Need mechanism for injecting annotations #29821
  • File format, MSBuild and loading logic
  • Some IDE support
• Intellisense
  • Display member annotations QuickInfo doesn't display nullability on properties #26830
  • Display member annotations from metadata even when feature disabled
• Codegen for null-check on parameter!
• Lambdas: track nullability of captured variables Analyze captured variables at the location lambda is converted to a delegate #29617
• Local functions: track nullability of captured variables Analyze local functions in NullableWalker #27233
• Other annotations
  • Other attributes (NullEquals, NullInNullOut, NotNulled) Recognize annotations on methods that affect nullability analysis #26761
• [Nullable]
  • Include NullableAttribute in framework? See Use synthesized attribute infrastructure for System.NullableAttribute #22820 (comment)
• Add attribute types to Core 3
• Port attribute types to mono
• Coordinate integration with Razor
• NullableAttribute: Store flags into a field NullableAttribute constructor parameter should be stored in a field #30143
• Codefixer to add #nullable enable and NullableReferenceTypes Nullable: Fixer to add #nullable and project-level setting #30099
  • project system property or API Add support for Nullable build setting project-system#4058
• Other annotations
  • Nullable property with non-nullable setter Need annotation for nullable property with non-nullable setter #26621
• TypeSymbolWithAnnotations
  • Revert properties (MethodSymbol.ReturnType, etc.) to TypeSymbol and add TypeSymbolWithAnnotations properties
  • Review use of TypeMap.AsTypeSymbol and TypeMap.AsTypeSymbolWithAnnotations for cases where nullability is dropped (@jcouv)
• SymbolDisplay
  • Include ?
  • Include ! and ~ Add SymbolDisplay option to append suffix for unannotated reference types #28242
• Conversions
  • Allow variance of out parameter: void M(out string x) invoked with M(out string? x);
  • Infer nullability in out var out var treated as non-nullable #25347
  • Infer nullability in deconstruction Nullability should be inferred from deconstruction #29618
  • Which conversions remain?
• Flow analysis
  • De-reference should update null state Should not report warning for second dereference of nullable value #26749
  • case patterns (case null:, case string:, case string s:) Nullable reference types: no nullability flow check in switch statements. #23944
  • x in var x = obliviousListOfString; should be List<string!>!
  • Anonymous types Inferred nullability should flow into anonymous type fields #24018
  • Query clauses and range variables Implement nullability analysis in LINQ queries #29863
  • foreach (var x in maybeNull) { } Report warning using foreach with a nullable value #23493
  • No warnings in unreachable code Handle unreachable code in the nullable walker #28798
• Fields and properties
  • Report uninitialized warnings for static fields and properties Nullable Reference Types: CS8618 and/or CS8625 should be consistently reported for static fields/properties. #27014
  • Track nullability of fields and properties
  • Report warning for null initializer null initializer for non-nullable property (or field) should warn #26628
  • Report warning before assignment Nullable Reference Types: A warning should be reported when dereferencing a field/property before it is assigned #27016
  • No warnings for constructor that throws exception Reporting "field is uninitialized" for constructor that throws an exception #25529
• Use VisitType to implement ContainsNullableReferenceTypes. See TestDeepTypeAccessibilityBug18018 test.
• ! operator
  • Warning for unnecessary !? Report hidden diagnostic for unnecessary ! #25372
  • Error for !!. See StaticNullChecking.SuppressNullableWarning_Multiple !! should be disallowed #29902
  • Error for a! = b;. See StaticNullChecking.SuppressNullableWarning_Assignment and InvalidOperationException in StackOptimizerPass1.IsIndirectAssignment with x! = null; #28377
  • ERR_NotNullableOperatorNotReferenceType should be a warning not an error
• Method type inference
  • MergeDynamic and MergeTupleNames ignore nullability
  • InferExtensionMethodTypeArguments ignores nullability
  • MethodGroupReturnTypeInference ignores nullability
• Flow analysis
  • Intersection with other C# 8.0 features (switch expression, null-coalescing assignment, ...)
    • ??=
    • recursive patterns
• Dogfood
  • Update public API of Microsoft.CodeAnalysis.dll and Microsoft.CSharp.CodeAnalysis.dll
  • Update tool for tracking public APIs
• EE
  • Include ? annotations in Type for Locals and Watch

Productivity Migrated to project https://github.com/dotnet/roslyn/projects/43

• QuickInfo

• Authoring experience for external annotations

• Can we make it easier to see what context we're in?

• null assignment suggests declaring as nullable Add a DeclareAsNullable fixer #26630

• null test suggests declaring as nullable Add DeclareAsNullable refactoring #26661

• Fix interface implementation or override Nullability fixer for interface implementations #26833

• Grey out unnecessary ! Gray out unnecessary non-null suppression operator #26736

• Grey out unnecessary ?

• Using ? or ! suggests turning feature on (issue Nullable: Fixer to add #nullable and project-level setting #30099)

  • locally Create AddNonNullTypes code fixer #30098
  • globally

• help move #nullable up/down the scopes

• classify #nullable (PR Add syntax classification for nullable directives #31579)

• Indent #nullable to the margin

• Marshalling options in OOP process (PR add new compilation options to data sync to OOP. #32726)

• Performance

  • Measure performance compiling Roslyn

• IDE: Metadata view

Work related to project-system:

• project-system API for CPS Add NullableReferenceTypes property project-system#4277
• project-system API for csproj/legacy
• add drop-down in UI
• SDK work to set default value
• Code fixer to set NullableReferenceTypes project property (setting Project.Configuration.Properties["NullableReferenceTypes"] and declaring that "NullableReferenceTypes" BooleanProperty)

Preview 1:

• Fix installer Installing NonNullable Reference Types preview fails #29987
• Merge back to a preview branch
  • Remove/replace PROTOTYPE markers
  • IDE test pass
• [NonNullTypes]
  • Disable warnings with [NonNullTypes(Warnings=false)] Add NonNullTypesAttribute.Warnings property #29616 (no longer applicable)
  • Fix/verify [NonNullTypes] in PE symbols (no longer applicable)
  • Injecting NonNullTypesAttribute Inject NonNullTypesAttribute #29180
  • Use explicit NonNullTypes context in every TSWA Every TypeSymbolWithAnnotations should have an explicit NonNullTypes context #28766
  • Warning for ! if no attribute (needs a new solution)
  • Enable warnings with [NonNullTypes]
  • Warning for ? if no attribute or if [NonNullTypes(false)]
  • Remove syntax-based cycle breaking (modules, types, members)
  • Enable feature with [NonNullTypes] or [NonNullTypes(value)] (
    Bind NonNullTypes for types #28491)
• Method type inference
  • Incorrect nullability arguments include ~ Incorrect nullability from method type inference #27961
• Flow analysis
  • (object)x != null Warnings reported after comparing with object == or != #27928
  • L-values Suppression operator on L-values #27522
  • t.ToString(); for unconstrained T
  • tuples Missing warning on tuple nullability #28951
  • ?. Infer nullability of receiver and member from ?. expression #25870
  • s is string Pattern test should inform nullability #26745
  • is patterns
    • x is C y
    • x is K where K is a constant other than null
• Type parameters
  • Substitution with ~ and ? or ! (oblivious doesn't survive, LDM 7-11)
  • Support object constraint; use object? for unconstrained Support Object type as a generic type constraint. #29809
  • Check constraints No warning for mismatched nullability in constraint #27742
  • Error for T? unless T is constrained to a reference type or a value type Report error for T? when T is unconstrained #28804
  • Support class? constraint
• Switch old tests to C# 8 (update default test options)
• Track nullability of unconstrained type parameters Track nullability of unconstrained type parameters #28956
• Performance
  • Close allocation gap with null unaware C#
• Merge 15.8 branch
• Compiler command-line switch Add "Nullable" compilation option. #30479 and MSBuild setting