Merge master into features/function-pointers

.gitignore

@@ -186,9 +186,6 @@ $RECYCLE.BIN/
 # Mac desktop service store files
 .DS_Store
 
-# Visual Studio Code
-.vscode/
-
 # JetBrains Rider
 .idea/
 

.vscode/tasks.json

@@ -0,0 +1,39 @@
+{
+  // See https://go.microsoft.com/fwlink/?LinkId=733558
+  // for the documentation about the tasks.json format
+  "version": "2.0.0",
+  "tasks": [
+    {
+        "label": "build",
+        "command": "./build.cmd",
+        "type": "shell",
+        "args": [
+        ],
+        "problemMatcher": "$msCompile",
+        "group": "build"
+    },
+    {
+        "label": "build skip analyzers",
+        "command": "./build.cmd",
+        "type": "shell",
+        "args": [
+          "-skipAnalyzers"
+        ],
+        "problemMatcher": "$msCompile",
+        "group": "build"
+    },
+    {
+        "label": "build csc skip analyzers",
+        "command": "dotnet",
+        "type": "shell",
+        "args": [
+          "msbuild",
+          "-p:UseRoslynAnalyzers=false",
+          "-p:GenerateFullPaths=true",
+          "src/Compilers/CSharp/csc/csc.csproj"
+        ],
+        "problemMatcher": "$msCompile",
+        "group": "build"
+    }
+  ]
+}

NuGet.config

@@ -4,6 +4,7 @@
   <packageSources>
     <clear />
     <add key="dotnet-core" value="https://dotnetfeed.blob.core.windows.net/dotnet-core/index.json" />
+    <add key="dotnet-eng" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json" />
     <add key="system-commandline" value="https://dotnet.myget.org/F/system-commandline/api/v3/index.json" />
     <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
     <add key="myget-dotnet-coreclr" value="https://dotnet.myget.org/F/dotnet-coreclr/api/v3/index.json" />

docs/Language Feature Status.md

@@ -18,11 +18,12 @@ efforts behind them.
 | [Relax ordering of `ref` and `partial` modifiers](https://github.com/dotnet/csharplang/issues/946) | [ref-partial](https://github.com/dotnet/roslyn/tree/features/ref-partial)               | In Progress                                                  | [alrz](https://github.com/alrz)                                              | [gafter](https://github.com/gafter)                                                | [jcouv](https://github.com/jcouv)       |
 | [Parameter null-checking](https://github.com/dotnet/csharplang/issues/2145)                        | [param-nullchecking](https://github.com/dotnet/roslyn/tree/features/param-nullchecking) | [In Progress](https://github.com/dotnet/roslyn/issues/36024) | [fayrose](https://github.com/fayrose)                                        | [agocke](https://github.com/agocke)                                                | [jaredpar](https://github.com/jaredpar) |
 | [Skip locals init](https://github.com/dotnet/csharplang/issues/1738)                               | [localsinit](https://github.com/dotnet/roslyn/tree/features/localsinit)                 | [In Progress](https://github.com/dotnet/roslyn/issues/25780) | [t-camaia](https://github.com/t-camaia), [agocke](https://github.com/agocke) | [jaredpar](https://github.com/jaredpar)                                            | [agocke](https://github.com/agocke)     |
-| [Lambda discard parameters](https://github.com/dotnet/csharplang/issues/111)                       | master                                                                                  | [In Progress](https://github.com/dotnet/roslyn/issues/38820) | [jcouv](https://github.com/jcouv)                                            | [AlekseyTs](https://github.com/AlekseyTs), [chsienki](https://github.com/chsienki) | [jcouv](https://github.com/jcouv)       |
-| [Native ints](https://github.com/dotnet/csharplang/issues/435)                                     | TBD                                                                                     | [In Progress](https://github.com/dotnet/roslyn/issues/38821) | [cston](https://github.com/cston)                                            | [333fred](https://github.com/333fred), [gafter](https://github.com/gafter)         | [jaredpar](https://github.com/jaredpar) |
-| [Attributes on local functions](https://github.com/dotnet/csharplang/issues/1888)                  | TBD                                                                                     | [In Progress](https://github.com/dotnet/roslyn/issues/38801) | [RikkiGibson](https://github.com/RikkiGibson)                                | [agocke](https://github.com/agocke)                                                | [agocke](https://github.com/agocke)     |
+| [Lambda discard parameters](https://github.com/dotnet/csharplang/issues/111)                       | master                                                                                  | [Merged](https://github.com/dotnet/roslyn/issues/38820) | [jcouv](https://github.com/jcouv)                                            | [AlekseyTs](https://github.com/AlekseyTs), [chsienki](https://github.com/chsienki) | [jcouv](https://github.com/jcouv)       |
+| [Native ints](https://github.com/dotnet/csharplang/issues/435)                                     | [features/NativeInt](https://github.com/dotnet/roslyn/tree/features/NativeInt)                           | [In Progress](https://github.com/dotnet/roslyn/issues/38821) | [cston](https://github.com/cston)                                            | [333fred](https://github.com/333fred), [gafter](https://github.com/gafter)         | [jaredpar](https://github.com/jaredpar) |
+| [Attributes on local functions](https://github.com/dotnet/csharplang/issues/1888)                  | [features/local-function-attributes](https://github.com/dotnet/roslyn/tree/features/local-function-attributes)                                                                                     | [In Progress](https://github.com/dotnet/roslyn/issues/38801) | [RikkiGibson](https://github.com/RikkiGibson)                                | [agocke](https://github.com/agocke)                                                | [agocke](https://github.com/agocke)     |
 | [Function pointers](https://github.com/dotnet/csharplang/issues/191)                               | [function-pointers](https://github.com/dotnet/roslyn/tree/features/function-pointers)   | [In Progress](https://github.com/dotnet/roslyn/issues/38830) | [333fred](https://github.com/333fred)                                        | [AlekseyTs](https://github.com/AlekseyTs)                                          | [jaredpar](https://github.com/jaredpar) |
 | [Pattern matching improvements](https://github.com/dotnet/csharplang/issues/2850)                 | [features/patterns3](https://github.com/dotnet/roslyn/tree/features/patterns3)          | In progress                                                  | [gafter](https://github.com/gafter)                                          | [RikkiGibson](https://github.com/RikkiGibson),[agocke](https://github.com/agocke)  | [gafter](https://github.com/gafter)     |
+| [Static lambdas](https://github.com/dotnet/csharplang/issues/275)                 | [features/static-lambdas](https://github.com/dotnet/roslyn/tree/features/static-lambdas)          | [In progress](https://github.com/dotnet/roslyn/issues/39606)                                                  | [CyrusNajmabadi](https://github.com/CyrusNajmabadi)                                           | [jcouv](https://github.com/jcouv)  | [jcouv](https://github.com/jcouv)     |
 
 # C# 8.0
 

docs/compilers/CSharp/Compiler Breaking Changes - post VS2019.md

@@ -78,3 +78,26 @@ could be different than the one that compiler used to find.
     ```
 
 11. Previously, the language version was not checked for `this ref` and `this in` orderings of parameter modifiers. In *Visual Studio 2019 version 16.4* these orderings produce an error with langversion below 7.2. See https://github.com/dotnet/roslyn/issues/38486
+
+12. https://github.com/dotnet/roslyn/issues/40092 Previously, the compiler allowed `extern event` declarations to have initializers, in violation of the C# language specification. In *Visual Studio 2019 version 16.5* such declarations produce compile errors.
+    ```C#
+    class C
+    {
+        extern event System.Action E = null; // error
+    }
+    ```
+
+13. https://github.com/dotnet/roslyn/issues/10492 Under some circumstances, the compiler would accept an expression that does not obey the rules of the language grammar.  Examples include
+    - `e is {} + c`
+    - `e is T t + c`
+
+    These all have in common that the left operand is of looser precedence than the `+` operator, but the left operand does not end in an expression so it cannot "consume" the addition.  Such expressions will no longer be permitted in Visual Studio 2019 version 16.5 and later.
+
+14. In Visual Studio version 15.0 and onwards, the compiler would allow compiling some malformed definitions of the `System.ValueTuple` types. For instance, one with a private `Item1` field. In *Visual Studio 2019 version 16.5* such definitions produce warnings.
+
+15. In Visual Studio version 15.0 and onwards, the compiler APIs would produce non-generic tuple symbols (`Arity` would be 0, would have no type arguments, would be original definitions). In *Visual Studio 2019 version 16.5* a 2-tuple symbol has `Arity` 2, and a 9-tuple symbol has `Arity` 8 (since it is a `ValueTuple'8`).
+
+
+16. In *Visual Studio 2019 version 16.5* and language version 8.0 and later, the compiler will no longer accept `throw null` when there is no type `System.Exception`.
+
+17. https://github.com/dotnet/roslyn/issues/39852 Previously the compiler would allow an invocation of an implicit index or range indexer to specify any named argument. In *Visual Studio 2019 version 16.5* argument names are no longer permitted for these invocations.

docs/compilers/Design/Bound Node Design.md

@@ -0,0 +1,18 @@
+Bound Node Design
+=================
+
+This document discusses design principles for the bound nodes.
+
+### The shape of the bound tree should correspond to the shape of the program's static semantics
+
+Generally speaking, that means that there is an isomorphism between the syntax and bound nodes, except when there is a mismatch between the shape of the syntax and semantics, in which case they model the shape of the semantics.  When possible, we prefer the correspondence be as direct as possible.  Here are two examples that illustrate this:
+1. Parenthesized expressions do not appear in the bound nodes because they have no semantic meaning.
+2. Query expressions are given a semantic meaning by correspondence to a translated form, so the bound nodes may model the translated form.
+
+### Bound nodes should capture all semantic information embedded in the syntax
+
+A consumer of the bound nodes should not need to examine the syntax from which they were produced to understand the meaning of the bound nodes.  All relevant semantic information that comes from the syntax should be summarized in the fields of the bound node.  If a consumer of a bound node needs to refer to the syntax to affect the meaning of the code, that is a design smell.
+
+### Every bound node type is either abstract or sealed
+
+In `BoundNodes.xml`, a `Node` should have a base that is `BoundNode` or a node type declared `AbstractNode`. Do not inherit a concrete node type from another concrete node type.

docs/contributing/Compiler Test Plan.md

@@ -40,7 +40,7 @@ This document provides guidance for thinking about language interactions and tes
     - events (including add/remove accessors)
 - Parameter modifiers (ref, out, in, params)
 - Attributes (including security attribute)
-- Generics (type arguments, variance, constraints including `class`, `struct`, `new()`, `unmanaged`)
+- Generics (type arguments, variance, constraints including `class`, `struct`, `new()`, `unmanaged`, `notnull`, types and interfaces with nullability)
 - Default and constant values
 - Partial classes
 - Literals
@@ -62,6 +62,7 @@ This document provides guidance for thinking about language interactions and tes
 - Dynamic
 - Ref structs, Readonly structs
 - Readonly members on structs (methods, property/indexer accessors, custom event accessors)
+- SkipLocalsInit
 
 # Code
 - Operators (see Eric's list below)

docs/features/skiplocalsinit.md

@@ -0,0 +1,24 @@
+
+# Feature design for SkipLocalsInit
+
+The feature is to add a new well-known attribute to the compiler, System.Runtime.CompilerServices.SkipLocalsInit that causes method bodies nested "inside" the scope of the attribute to elide the ".locals init" CIL directive that causes the CLR to zero-init local variables and space reserved using the "localloc" instruction. "Nested inside the scope of the attribute" is a concept defined as follows:
+
+1. When the attribute is applied to a module, all emitted methods inside that module, including generated methods, will skip local initialization.
+
+2. When the attribute is applied to a type (including interfaces), all methods transitively inside that type, including generated methods, will skip local initialization. This includes nested types.
+
+3. When the attribute is applied to a method, the method and all methods generated by the compiler which contain user-influenced code inside that method (e.g., local functions, lambdas, async methods) will skip local initialization.
+
+For the above, generated methods will skip local initialization only if they have user code inside them, or a significant number of
+compiler-generated locals. For example, the MoveNext method of an async method will skip local initialization, but the constructor of
+a display class probably will not, as the display class constructor likely has no locals anyway.
+
+Some notable decisions:
+
+1. Although SkipLocalsInit does not require unsafe code blocks, it does require the `unsafe` flag to be passed to the compiler. This
+   is to signal that in some cases code could view unassigned memory, including `stackalloc`. 
+
+2. Due to the compiler not controlling localsinit for other modules when emitting to a netmodule, SkipLocalsInit is not respected on
+   the assembly level, even if the AttributeUsage of the SkipLocalsInitAttribute is specified that it is allowed.
+
+3. The `Inherited` property of the SkipLocalsInitAttribute is not respected. SkipLocalsInit does not propagate through inheritance.

eng/Version.Details.xml

@@ -3,9 +3,9 @@
   <ProductDependencies>
   </ProductDependencies>
   <ToolsetDependencies>
-    <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="5.0.0-beta.19601.1">
+    <Dependency Name="Microsoft.DotNet.Arcade.Sdk" Version="5.0.0-beta.20054.1">
       <Uri>https://github.com/dotnet/arcade</Uri>
-      <Sha>c0b56ff3569e3c7475070486c40543ea4c6f6dc7</Sha>
+      <Sha>96ab522b32ff4d0f7bfc18074fd5ae3673c59d0a</Sha>
     </Dependency>
   </ToolsetDependencies>
 </Dependencies>