Use LangVersion 8 in tests rather than Preview (#39421)

src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncIteratorTests.cs

@@ -267,7 +267,7 @@ static async System.Collections.Generic.IAsyncEnumerable<int> M()
             var comp = CreateCompilationWithTasksExtensions(new[] { source }, parseOptions: TestOptions.Regular7_3);
             comp.VerifyDiagnostics(expected);
 
-            comp = CreateCompilationWithTasksExtensions(new[] { source }, parseOptions: TestOptions.RegularPreview);
+            comp = CreateCompilationWithTasksExtensions(new[] { source }, parseOptions: TestOptions.Regular8);
             comp.VerifyDiagnostics(
                 // (4,45): error CS0234: The type or namespace name 'IAsyncEnumerable<>' does not exist in the namespace 'System.Collections.Generic' (are you missing an assembly reference?)
                 //     static async System.Collections.Generic.IAsyncEnumerable<int> M()
@@ -1290,7 +1290,7 @@ async System.Collections.Generic.IAsyncEnumerator<int> M()
             var comp = CreateCompilationWithTasksExtensions(new[] { source, AsyncStreamsTypes }, parseOptions: TestOptions.Regular7_3);
             comp.VerifyDiagnostics(expected);
 
-            comp = CreateCompilationWithTasksExtensions(new[] { source, AsyncStreamsTypes }, parseOptions: TestOptions.RegularPreview);
+            comp = CreateCompilationWithTasksExtensions(new[] { source, AsyncStreamsTypes }, parseOptions: TestOptions.Regular8);
             comp.VerifyDiagnostics();
         }
 

src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAwaitForeachTests.cs

@@ -38,7 +38,7 @@ IAsyncEnumerator<int> IAsyncEnumerable<int>.GetAsyncEnumerator(System.Threading.
             var comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, parseOptions: TestOptions.Regular7_3);
             comp.VerifyDiagnostics(expected);
 
-            comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, parseOptions: TestOptions.RegularPreview);
+            comp = CreateCompilationWithTasksExtensions(new[] { source, s_IAsyncEnumerable }, parseOptions: TestOptions.Regular8);
             comp.VerifyDiagnostics();
         }
 

src/Compilers/CSharp/Test/Semantic/Semantics/IndexAndRangeTests.cs

@@ -991,7 +991,7 @@ void M()
     }
 }";
             var compilation = CreateCompilationWithIndex(source, parseOptions: TestOptions.Regular7_3).VerifyDiagnostics(expected);
-            compilation = CreateCompilationWithIndex(source, parseOptions: TestOptions.RegularPreview).VerifyDiagnostics();
+            compilation = CreateCompilationWithIndex(source, parseOptions: TestOptions.Regular8).VerifyDiagnostics();
         }
 
         [Fact]
@@ -1474,7 +1474,7 @@ void M()
                 Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "..").WithArguments("range operator", "8.0").WithLocation(9, 17)
             };
             CreateCompilationWithIndexAndRange(source, parseOptions: TestOptions.Regular7_3).VerifyDiagnostics(expected);
-            CreateCompilationWithIndexAndRange(source, parseOptions: TestOptions.RegularPreview).VerifyDiagnostics();
+            CreateCompilationWithIndexAndRange(source, parseOptions: TestOptions.Regular8).VerifyDiagnostics();
         }
 
         [Fact]

src/Compilers/CSharp/Test/Semantic/Semantics/NullableReferenceTypesTests.cs

@@ -7598,7 +7598,7 @@ void M(string z)
             var c = CreateCompilation(new[] { source });
             c.VerifyDiagnostics(expected);
 
-            c = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
+            c = CreateCompilation(source, parseOptions: TestOptions.Regular8);
             c.VerifyDiagnostics(expected);
 
             expected = new[]

src/Compilers/CSharp/Test/Semantic/Semantics/NullableTests.cs

@@ -65,7 +65,7 @@ static void Main()
             };
             var comp = CreateCompilation(source, parseOptions: TestOptions.Regular7_3);
             comp.VerifyDiagnostics(expected);
-            comp = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
+            comp = CreateCompilation(source, parseOptions: TestOptions.Regular8);
             comp.VerifyDiagnostics(
                 // (7,11): warning CS8632: The annotation for nullable reference types should only be used in code within a '#nullable' context.
                 //     string? s1 = null;

src/Compilers/CSharp/Test/Semantic/Semantics/PatternMatchingTests2.cs

@@ -384,7 +384,7 @@ public static void Main()
                 Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7_3, "1 switch { _ => 0, }").WithArguments("recursive patterns", "8.0").WithLocation(5, 17)
                 );
 
-            CreateCompilation(source, options: TestOptions.DebugExe, parseOptions: TestOptions.RegularPreview).VerifyDiagnostics();
+            CreateCompilation(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular8).VerifyDiagnostics();
         }
 
         [Fact]
@@ -1093,7 +1093,7 @@ class _ {}
             var compilation = CreatePatternCompilation(source);
             compilation.VerifyDiagnostics(expected);
 
-            compilation = CreateCompilation(source, parseOptions: TestOptions.RegularPreview);
+            compilation = CreateCompilation(source, parseOptions: TestOptions.Regular8);
             compilation.VerifyDiagnostics(expected);
 
             expected = new[]

src/Compilers/CSharp/Test/Semantic/Semantics/UsingDeclarationTests.cs

@@ -670,7 +670,7 @@ static void Main()
 
             CreateCompilation(source, parseOptions: TestOptions.Regular7_3).VerifyDiagnostics(expected);
 
-            CreateCompilation(source, parseOptions: TestOptions.RegularPreview).VerifyDiagnostics();
+            CreateCompilation(source, parseOptions: TestOptions.Regular8).VerifyDiagnostics();
         }
 
         [Fact]
@@ -696,7 +696,7 @@ static async Task Main()
 
             CreateCompilationWithTasksExtensions(new[] { source, IAsyncDisposableDefinition }, parseOptions: TestOptions.Regular7_3).VerifyDiagnostics(expected);
 
-            CreateCompilationWithTasksExtensions(new[] { source, IAsyncDisposableDefinition }, parseOptions: TestOptions.RegularPreview).VerifyDiagnostics();
+            CreateCompilationWithTasksExtensions(new[] { source, IAsyncDisposableDefinition }, parseOptions: TestOptions.Regular8).VerifyDiagnostics();
         }
 
         [Fact]
@@ -772,7 +772,7 @@ static void Main()
     }
 }
 ";
-            CreateCompilation(source, parseOptions: TestOptions.RegularPreview).VerifyDiagnostics(
+            CreateCompilation(source, parseOptions: TestOptions.Regular8).VerifyDiagnostics(
                 // (7,15): error CS0106: The modifier 'public' is not valid for this item
                 //         using public readonly var x = (IDisposable)null;
                 Diagnostic(ErrorCode.ERR_BadMemberFlag, "public").WithArguments("public").WithLocation(7, 15),

src/Compilers/CSharp/Test/Syntax/Parsing/PatternParsingTests.cs

@@ -1847,7 +1847,7 @@ public void ParenthesizedExpression_03()
             UsingStatement(@"switch (e) { case (x: ((3))): ; }", TestOptions.RegularWithoutRecursivePatterns, expect);
             checkNodes();
 
-            UsingStatement(@"switch (e) { case (x: ((3))): ; }", TestOptions.RegularPreview);
+            UsingStatement(@"switch (e) { case (x: ((3))): ; }", TestOptions.Regular8);
             checkNodes();
 
             void checkNodes()