Merge pull request #41639 from CyrusNajmabadi/blockStackFrames

Increase the amount of recursive parsing calls for statements+blocks.

Author: msftbot[bot]

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

@@ -2450,7 +2450,7 @@ private void ParseBlockAndExpressionBodiesWithSemicolon(
 
             if (this.CurrentToken.Kind == SyntaxKind.OpenBraceToken)
             {
-                blockBody = this.ParseBlock(isMethodBody: true);
+                blockBody = this.ParseMethodOrAccessorBodyBlock(isAccessorBody: false);
             }
 
             if (this.CurrentToken.Kind == SyntaxKind.EqualsGreaterThanToken)
@@ -2477,25 +2477,6 @@ private void ParseBlockAndExpressionBodiesWithSemicolon(
             }
         }
 
-        private void ParseBodyOrSemicolon(out BlockSyntax body, out SyntaxToken semicolon)
-        {
-            if (this.CurrentToken.Kind == SyntaxKind.OpenBraceToken)
-            {
-                body = this.ParseBlock(isMethodBody: true);
-
-                semicolon = null;
-                if (this.CurrentToken.Kind == SyntaxKind.SemicolonToken)
-                {
-                    semicolon = this.EatTokenWithPrejudice(ErrorCode.ERR_UnexpectedSemicolon);
-                }
-            }
-            else
-            {
-                semicolon = this.EatToken(SyntaxKind.SemicolonToken);
-                body = null;
-            }
-        }
-
         private bool IsEndOfTypeParameterList()
         {
             if (this.CurrentToken.Kind == SyntaxKind.OpenParenToken)
@@ -3305,7 +3286,7 @@ private AccessorDeclarationSyntax ParseAccessorDeclaration(bool isEvent)
                     {
                         if (!IsTerminator())
                         {
-                            blockBody = this.ParseBlock(isMethodBody: true, isAccessorBody: true);
+                            blockBody = this.ParseMethodOrAccessorBodyBlock(isAccessorBody: true);
                         }
                         else
                         {
@@ -6943,54 +6924,66 @@ private bool IsPossibleNewExpression()
             return null;
         }
 
-        // If "isMethodBody" is true, then this is the immediate body of a method/accessor.
-        // In this case, we create a many-child list if the body is not a small single statement.
-        // This then allows a "with many weak children" red node when the red node is created.
-        // If "isAccessorBody" is true, then we produce a special diagnostic if the open brace is
-        // missing.  Also, "isMethodBody" must be true.
-        private BlockSyntax ParseBlock(bool isMethodBody = false, bool isAccessorBody = false)
+        /// <summary>
+        /// Used to parse the block-body for a method or accessor.  For blocks that appear *inside*
+        /// method bodies, call <see cref="ParseBlock"/>.
+        /// </summary>
+        /// <param name="isAccessorBody">If is true, then we produce a special diagnostic if the
+        /// open brace is missing.</param>
+        private BlockSyntax ParseMethodOrAccessorBodyBlock(bool isAccessorBody)
         {
-            // Check again for incremental re-use, since ParseBlock is called from a bunch of places
-            // other than ParseStatementCore()
+            // Check again for incremental re-use.  This way if a method signature is edited we can
+            // still quickly re-sync on the body.
             if (this.IsIncrementalAndFactoryContextMatches && this.CurrentNodeKind == SyntaxKind.Block)
-            {
                 return (BlockSyntax)this.EatNode();
-            }
 
             // There's a special error code for a missing token after an accessor keyword
-            var openBrace = isAccessorBody && this.CurrentToken.Kind != SyntaxKind.OpenBraceToken
+            CSharpSyntaxNode openBrace = isAccessorBody && this.CurrentToken.Kind != SyntaxKind.OpenBraceToken
                 ? this.AddError(
                     SyntaxFactory.MissingToken(SyntaxKind.OpenBraceToken),
                     IsFeatureEnabled(MessageID.IDS_FeatureExpressionBodiedAccessor)
-                            ? ErrorCode.ERR_SemiOrLBraceOrArrowExpected
-                            : ErrorCode.ERR_SemiOrLBraceExpected)
+                        ? ErrorCode.ERR_SemiOrLBraceOrArrowExpected
+                        : ErrorCode.ERR_SemiOrLBraceExpected)
                 : this.EatToken(SyntaxKind.OpenBraceToken);
 
             var statements = _pool.Allocate<StatementSyntax>();
-            try
-            {
-                CSharpSyntaxNode tmp = openBrace;
-                this.ParseStatements(ref tmp, statements, stopOnSwitchSections: false);
-                openBrace = (SyntaxToken)tmp;
-                var closeBrace = this.EatToken(SyntaxKind.CloseBraceToken);
+            this.ParseStatements(ref openBrace, statements, stopOnSwitchSections: false);
 
-                SyntaxList<StatementSyntax> statementList;
-                if (isMethodBody && IsLargeEnoughNonEmptyStatementList(statements))
-                {
-                    // Force creation a many-children list, even if only 1, 2, or 3 elements in the statement list.
-                    statementList = new SyntaxList<StatementSyntax>(SyntaxList.List(((SyntaxListBuilder)statements).ToArray()));
-                }
-                else
-                {
-                    statementList = statements;
-                }
+            var block = _syntaxFactory.Block(
+                (SyntaxToken)openBrace,
+                // Force creation a many-children list, even if only 1, 2, or 3 elements in the statement list.
+                IsLargeEnoughNonEmptyStatementList(statements)
+                    ? new SyntaxList<StatementSyntax>(SyntaxList.List(((SyntaxListBuilder)statements).ToArray()))
+                    : statements,
+                this.EatToken(SyntaxKind.CloseBraceToken));
 
-                return _syntaxFactory.Block(openBrace, statementList, closeBrace);
-            }
-            finally
-            {
-                _pool.Free(statements);
-            }
+            _pool.Free(statements);
+            return block;
+        }
+
+        /// <summary>
+        /// Used to parse normal blocks that appear inside method bodies.  For the top level block
+        /// of a method/accessor use <see cref="ParseMethodOrAccessorBodyBlock"/>.
+        /// </summary>
+        private BlockSyntax ParseBlock()
+        {
+            // Check again for incremental re-use, since ParseBlock is called from a bunch of places
+            // other than ParseStatementCore()
+            if (this.IsIncrementalAndFactoryContextMatches && this.CurrentNodeKind == SyntaxKind.Block)
+                return (BlockSyntax)this.EatNode();
+
+            CSharpSyntaxNode openBrace = this.EatToken(SyntaxKind.OpenBraceToken);
+
+            var statements = _pool.Allocate<StatementSyntax>();
+            this.ParseStatements(ref openBrace, statements, stopOnSwitchSections: false);
+
+            var block = _syntaxFactory.Block(
+                (SyntaxToken)openBrace,
+                statements,
+                this.EatToken(SyntaxKind.CloseBraceToken));
+
+            _pool.Free(statements);
+            return block;
         }
 
         // Is this statement list non-empty, and large enough to make using weak children beneficial?