Error messsage should mention C# 7.0 not C# 7 (#22255)

src/Compilers/CSharp/Portable/CSharpResources.Designer.cs

@@ -4598,7 +4598,7 @@ internal class CSharpResources {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Feature &apos;{0}&apos; is not available in C# 7. Please use language version {1} or greater..
+        ///   Looks up a localized string similar to Feature &apos;{0}&apos; is not available in C# 7.0. Please use language version {1} or greater..
         /// </summary>
         internal static string ERR_FeatureNotAvailableInVersion7 {
             get {

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -4402,7 +4402,7 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
     <value>Feature '{0}' is not available in C# 6. Please use language version {1} or greater.</value>
   </data>
   <data name="ERR_FeatureNotAvailableInVersion7" xml:space="preserve">
-    <value>Feature '{0}' is not available in C# 7. Please use language version {1} or greater.</value>
+    <value>Feature '{0}' is not available in C# 7.0. Please use language version {1} or greater.</value>
   </data>
   <data name="ERR_FeatureIsExperimental" xml:space="preserve">
     <value>Feature '{0}' is experimental and unsupported; use '/features:{1}' to enable.</value>

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

@@ -659,11 +659,12 @@ async static Task Main(string[] args)
 }";
             var compilation = CreateCompilationWithMscorlib45(source, options: TestOptions.DebugExe, parseOptions: TestOptions.Regular.WithLanguageVersion(LanguageVersion.CSharp7));
             compilation.VerifyDiagnostics(
-                // (6,18): error CS8107: Feature 'async main' is not available in C# 7. Please use language version 7.1 or greater.
+                // (6,18): error CS8107: Feature 'async main' is not available in C# 7.0. Please use language version 7.1 or greater.
                 //     async static Task Main(string[] args)
                 Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7, "Task").WithArguments("async main", "7.1").WithLocation(6, 18),
                 // error CS5001: Program does not contain a static 'Main' method suitable for an entry point
-                Diagnostic(ErrorCode.ERR_NoEntryPoint).WithLocation(1, 1));
+                Diagnostic(ErrorCode.ERR_NoEntryPoint).WithLocation(1, 1)
+                );
         }
 
         [Fact]

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

@@ -3427,15 +3427,17 @@ async public static Task Main()
     {
     }
 }";
-            CreateCompilationWithMscorlib45(source, options: TestOptions.ReleaseExe, parseOptions: TestOptions.Regular.WithLanguageVersion(LanguageVersion.CSharp7)).VerifyDiagnostics(
+            var comp = CreateCompilationWithMscorlib45(source, options: TestOptions.ReleaseExe, parseOptions: TestOptions.Regular.WithLanguageVersion(LanguageVersion.CSharp7));
+            comp.VerifyDiagnostics(
                 // (5,30): warning CS1998: This async method lacks 'await' operators and will run synchronously. Consider using the 'await' operator to await non-blocking API calls, or 'await Task.Run(...)' to do CPU-bound work on a background thread.
                 //     async public static Task Main()
                 Diagnostic(ErrorCode.WRN_AsyncLacksAwaits, "Main").WithLocation(5, 30),
-                // (5,25): error CS8107: Feature 'async main' is not available in C# 7. Please use language version 7.1 or greater.
+                // (5,25): error CS8107: Feature 'async main' is not available in C# 7.0. Please use language version 7.1 or greater.
                 //     async public static Task Main()
                 Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7, "Task").WithArguments("async main", "7.1").WithLocation(5, 25),
                 // error CS5001: Program does not contain a static 'Main' method suitable for an entry point
-                Diagnostic(ErrorCode.ERR_NoEntryPoint).WithLocation(1, 1));
+                Diagnostic(ErrorCode.ERR_NoEntryPoint).WithLocation(1, 1)
+                );
         }
 
         [Fact, WorkItem(547088, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/547088")]

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

@@ -26,7 +26,7 @@ static void Main()
 ";
             var comp = CreateStandardCompilation(source, parseOptions: TestOptions.Regular7);
             comp.VerifyDiagnostics(
-                // (6,17): error CS8107: Feature 'default literal' is not available in C# 7. Please use language version 7.1 or greater.
+                // (6,17): error CS8107: Feature 'default literal' is not available in C# 7.0. Please use language version 7.1 or greater.
                 //         int x = default;
                 Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7, "default").WithArguments("default literal", "7.1").WithLocation(6, 17)
                 );
@@ -47,7 +47,7 @@ class C
 ";
             var comp = CreateCompilationWithMscorlib46(source,parseOptions: TestOptions.Regular7 );
             comp.VerifyDiagnostics(
-                // (7,40): error CS8107: Feature 'default literal' is not available in C# 7. Please use language version 7.1 or greater.
+                // (7,40): error CS8107: Feature 'default literal' is not available in C# 7.0. Please use language version 7.1 or greater.
                 //     async Task M(CancellationToken t = default) { await Task.Delay(0); }
                 Diagnostic(ErrorCode.ERR_FeatureNotAvailableInVersion7, "default").WithArguments("default literal", "7.1").WithLocation(7, 40)
                 );