18.13

Issues

• Speculative semantic model for a parameter's default value incorrectly disables nullable analysis

  Area-CompilersFeature - Nullable Semantic Model
  Bug

  dotnet/roslyn#85806 · Filter by author martin-strecker-sonarsource opened on Sep 28, 2026 · 18.13
  

• Speculative semantic model for an isolated AttributeSyntax incorrectly disables nullable analysis

  Area-CompilersFeature - Nullable Semantic Model
  Bug

  dotnet/roslyn#85807 · Filter by author martin-strecker-sonarsource opened on Sep 28, 2026 · 18.13
  

• Investigate preferred UI culture for analyzer-config diagnostics

  Area-Compilers
  dotnet/roslyn#85858 · Filter by author mwiemer-microsoft opened on Sep 30, 2026 · 18.13
  

• Restore deep collection-expression operation coverage on .NET Framework

  Area-CompilersFeature - Collection ExpressionsTest-Gap
  dotnet/roslyn#85874 · Filter by author mwiemer-microsoft opened on Oct 1, 2026 · 18.13
  1

  

• Parameter post-conditions are unexpectedly applied through a user defined conversion used by the argument

  Area-CompilersFeature - Nullable Reference TypesFeature - Unions
  Bug

  dotnet/roslyn#86057 · Filter by author AlekseyTs opened on Oct 14, 2026 · 18.13
  5

  

• Filtered generator runs can omit shared post-init sources and poison the compilation cache

  Area-CompilersFeature - Source Generators
  Bug

  dotnet/roslyn#86062 · Filter by author rmarinho opened on Oct 14, 2026 · 18.13
  

• Definite-assignment error omitted for captured struct field through forward local-function call with many variable slots

  Area-CompilersFeature - Flow Analysis
  Bug

  dotnet/roslyn#86155 · Filter by author jjonescz opened on Oct 21, 2026 · 18.13
  

• An assert fires in RefSafetyAnalysis for an implicit indexer set access

  Area-CompilersFeature - Ref Fields
  Bug

  dotnet/roslyn#86166 · Filter by author AlekseyTs opened on Oct 21, 2026 · 18.13
  

• Taking address of an element of a captured inline-array should be disallowed

  Area-CompilersFeature - Inline ArraysFeature - Local Functions
  Bug

  dotnet/roslyn#86179 · Filter by author jjonescz opened on Oct 22, 2026 · 18.13
  

• Compiler output cache drops warnings and changes MSBuild -warnaserror results

  Area-CompilersFeature - Caching Compiler
  Bug

  dotnet/roslyn#86198 · Filter by author sbomer opened on Oct 23, 2026 · 18.13