Merge pull request #16087 from CyrusNajmabadi/parserDiagnostics

Move diagnostic from parser to later phase.

src/Compilers/CSharp/Portable/Binder/Imports.cs

@@ -138,6 +138,11 @@ internal string GetDebuggerDisplay()
 
                     if (usingDirective.Alias != null)
                     {
+                        if (usingDirective.Alias.Name.Identifier.ContextualKind() == SyntaxKind.GlobalKeyword)
+                        {
+                            diagnostics.Add(ErrorCode.WRN_GlobalAliasDefn, usingDirective.Alias.Name.Location);
+                        }
+
                         if (usingDirective.StaticKeyword != default(SyntaxToken))
                         {
                             diagnostics.Add(ErrorCode.ERR_NoAliasHere, usingDirective.Alias.Name.Location);

src/Compilers/CSharp/Portable/Parser/LanguageParser.cs

@@ -59,11 +59,6 @@ private static bool IsName(CSharpSyntaxNode node, SyntaxKind kind)
             }
         }
 
-        private static bool IsNameGlobal(CSharpSyntaxNode node)
-        {
-            return IsName(node, SyntaxKind.GlobalKeyword);
-        }
-
         private static bool IsNameGet(CSharpSyntaxNode node)
         {
             return IsName(node, SyntaxKind.GetKeyword);
@@ -865,20 +860,12 @@ private ExternAliasDirectiveSyntax ParseExternAliasDirective()
             return _syntaxFactory.ExternAliasDirective(externToken, aliasToken, name, semicolon);
         }
 
-        private NameEqualsSyntax ParseNameEquals(bool warnOnGlobal = false)
+        private NameEqualsSyntax ParseNameEquals()
         {
             Debug.Assert(this.IsNamedAssignment());
-
-            var id = this.ParseIdentifierToken();
-            var equals = this.EatToken(SyntaxKind.EqualsToken);
-
-            // Warn on "using global = X".
-            if (warnOnGlobal && IsNameGlobal(id))
-            {
-                id = this.AddError(id, ErrorCode.WRN_GlobalAliasDefn);
-            }
-
-            return _syntaxFactory.NameEquals(_syntaxFactory.IdentifierName(id), equals);
+            return _syntaxFactory.NameEquals(
+                _syntaxFactory.IdentifierName(this.ParseIdentifierToken()),
+                this.EatToken(SyntaxKind.EqualsToken));
         }
 
         private UsingDirectiveSyntax ParseUsingDirective()
@@ -898,11 +885,7 @@ private UsingDirectiveSyntax ParseUsingDirective()
                 staticToken = this.EatToken(SyntaxKind.StaticKeyword);
             }
 
-            NameEqualsSyntax alias = null;
-            if (this.IsNamedAssignment())
-            {
-                alias = ParseNameEquals(warnOnGlobal: true);
-            }
+            var alias = this.IsNamedAssignment() ? ParseNameEquals() : null;
 
             NameSyntax name;
             SyntaxToken semicolon;

src/Compilers/CSharp/Test/Syntax/LexicalAndXml/PreprocessorTests.cs

@@ -3326,18 +3326,21 @@ public void TestPragmaWarningDisableWithMultipleCodes()
         [Trait("Feature", "Directives")]
         public void TestRegressPragmaWarningDisableWithWarningCode()
         {
-            var text = @"#pragma warning disable 440
-using global = A; // CS0440
+            var text = @"
 class A
 {
-static void Main() { }
+    static void Main(bool b)
+    {
+#pragma warning disable 642
+        if (b);{}
+    }
 }
 ";
             // verify that error still appears in GetDiagnostics
             var tree = SyntaxFactory.ParseSyntaxTree(text);
             var diagnostic = tree.GetDiagnostics().Single();
             Assert.Equal(DiagnosticSeverity.Warning, diagnostic.Severity);
-            Assert.Equal(440, diagnostic.Code);
+            Assert.Equal(642, diagnostic.Code);
 
             // verify pragma information
             var node = tree.GetCompilationUnitRoot();
@@ -3346,7 +3349,7 @@ class A
                 PragmaKind = SyntaxKind.PragmaWarningDirectiveTrivia,
                 WarningOrChecksumKind = SyntaxKind.WarningKeyword,
                 DisableOrRestoreKind = SyntaxKind.DisableKeyword,
-                WarningList = new[] { "440" }
+                WarningList = new[] { "642" }
             });
 
             // verify that GetParseDiagnostics filters disabled warning

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

@@ -4543,7 +4543,13 @@ static void Main()
 }
 ";
 
-            ParseAndValidate(test, Diagnostic(ErrorCode.WRN_GlobalAliasDefn, "global"));
+            CreateCompilationWithMscorlib(test).VerifyDiagnostics(
+                // (2,7): warning CS0440: Defining an alias named 'global' is ill-advised since 'global::' always references the global namespace and not an alias
+                // using global = MyClass;   // CS0440
+                Diagnostic(ErrorCode.WRN_GlobalAliasDefn, "global").WithLocation(2, 7),
+                // (2,1): hidden CS8019: Unnecessary using directive.
+                // using global = MyClass;   // CS0440
+                Diagnostic(ErrorCode.HDN_UnusedUsingDirective, "using global = MyClass;").WithLocation(2, 1));
         }
 
         [Fact]