miscellaneous small feedback

src/Features/CSharp/Portable/BraceCompletion/InterpolatedStringBraceCompletionService.cs

@@ -48,10 +48,7 @@ protected override bool IsValidClosingBraceToken(SyntaxToken rightToken)
             => rightToken.IsKind(SyntaxKind.InterpolatedStringEndToken);
 
         protected override Task<bool> IsValidOpenBraceTokenAtPositionAsync(SyntaxToken token, int position, Document document, CancellationToken cancellationToken)
-        {
-            return Task.FromResult(IsValidOpeningBraceToken(token)
-                && token.Span.End - 1 == position);
-        }
+            => Task.FromResult(IsValidOpeningBraceToken(token) && token.Span.End - 1 == position);
 
         /// <summary>
         /// Returns true when the input position could be starting an interpolated string if opening quotes were typed.

src/Features/CSharp/Portable/BraceCompletion/ParenthesisBraceCompletionService.cs

@@ -37,27 +37,28 @@ public override Task<bool> AllowOverTypeAsync(BraceCompletionContext context, Ca
         protected override async Task<bool> IsValidOpenBraceTokenAtPositionAsync(SyntaxToken token, int position, Document document, CancellationToken cancellationToken)
         {
             var syntaxFactsService = document.GetRequiredLanguageService<ISyntaxFactsService>();
-            if (ParentIsSkippedTokensTrivia(syntaxFactsService, token) ||
-                !IsValidOpeningBraceToken(token) ||
-                token.SpanStart != position || token.Parent == null)
+            if (ParentIsSkippedTokensTrivia(syntaxFactsService, token)
+                || !IsValidOpeningBraceToken(token)
+                || token.SpanStart != position
+                || token.Parent == null)
             {
                 return false;
             }
 
             // now check whether parser think whether there is already counterpart closing parenthesis
             var (openBrace, closeBrace) = token.Parent.GetParentheses();
 
-            // If the completed pair is on the same line, then the closing parenthesis must belong to a different
-            // brace completion session higher up on the stack.  If that's the case then we can
-            // complete the opening brace here, so return this as valid for completion.
-            var text = await document.GetTextAsync(cancellationToken).ConfigureAwait(false);
-            if (text.Lines.GetLineFromPosition(openBrace.SpanStart) == text.Lines.GetLineFromPosition(closeBrace.Span.End))
+            // We can complete the brace if the closing brace is missing or the incorrect kind.
+            if (closeBrace.Kind() != SyntaxKind.CloseParenToken || closeBrace.Span.Length == 0)
             {
                 return true;
             }
 
-            // We can complete the brace if the closing brace is missing or the incorrect kind.
-            return closeBrace.Kind() != SyntaxKind.CloseParenToken || closeBrace.Span.Length == 0;
+            // If the completed pair is on the same line, then the closing parenthesis must belong to a different
+            // brace completion session higher up on the stack.  If that's the case then we can
+            // complete the opening brace here, so return this as valid for completion.
+            var text = await document.GetTextAsync(cancellationToken).ConfigureAwait(false);
+            return text.Lines.GetLineFromPosition(openBrace.SpanStart) == text.Lines.GetLineFromPosition(closeBrace.Span.End);
         }
     }
 }

src/Features/Core/Portable/BraceCompletion/AbstractBraceCompletionService.cs

@@ -70,11 +70,16 @@ internal abstract class AbstractBraceCompletionService : IBraceCompletionService
 
         public virtual async Task<bool> CanProvideBraceCompletionAsync(char brace, int openingPosition, Document document, CancellationToken cancellationToken)
         {
+            if (OpeningBrace != brace)
+            {
+                return false;
+            }
+
             // check that the user is not typing in a string literal or comment
             var tree = await document.GetRequiredSyntaxTreeAsync(cancellationToken).ConfigureAwait(false);
             var syntaxFactsService = document.GetRequiredLanguageService<ISyntaxFactsService>();
 
-            return OpeningBrace == brace && !syntaxFactsService.IsInNonUserCode(tree, openingPosition, cancellationToken);
+            return !syntaxFactsService.IsInNonUserCode(tree, openingPosition, cancellationToken);
         }
 
         public async Task<BraceCompletionContext?> GetCompletedBraceContextAsync(Document document, int caretLocation, CancellationToken cancellationToken)
@@ -97,15 +102,13 @@ public virtual async Task<bool> CanProvideBraceCompletionAsync(char brace, int o
         /// </summary>
         protected virtual Task<bool> IsValidOpenBraceTokenAtPositionAsync(SyntaxToken token, int position, Document document, CancellationToken cancellationToken)
         {
-            var syntaxFactsService = document.GetRequiredLanguageService<ISyntaxFactsService>();
-
-            // The open token is typed in skipped token trivia, we should not attempt to complete it.
-            if (ParentIsSkippedTokensTrivia(syntaxFactsService, token))
+            if (token.SpanStart != position)
             {
                 return SpecializedTasks.False;
             }
 
-            return Task.FromResult(token.SpanStart == position && IsValidOpeningBraceToken(token));
+            var syntaxFactsService = document.GetRequiredLanguageService<ISyntaxFactsService>();
+            return Task.FromResult(IsValidOpeningBraceToken(token) && !ParentIsSkippedTokensTrivia(syntaxFactsService, token));
         }
 
         /// <summary>
@@ -181,6 +184,11 @@ public static class SingleQuote
             public const char CloseCharacter = '\'';
         }
 
+        /// <summary>
+        /// Determines if inserting the opening brace at the location could be an attempt to
+        /// escape a previously inserted opening brace.
+        /// E.g. they are trying to type $"{{"
+        /// </summary>
         protected static async Task<bool> CouldEscapePreviousOpenBraceAsync(char openingBrace, int position, Document document, CancellationToken cancellationToken)
         {
             var text = await document.GetTextAsync(cancellationToken).ConfigureAwait(false);