Added RazorParserFeatureFlags and added support for minimized bool tag

helper bound attributes
 - Fixes #1678, #431

src/Microsoft.AspNetCore.Razor.Language/BoundAttributeDescriptor.cs

@@ -21,10 +21,14 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         public bool IsIndexerStringProperty { get; protected set; }
 
+        public bool IsIndexerBooleanProperty { get; protected set; }
+
         public bool IsEnum { get; protected set; }
 
         public bool IsStringProperty { get; protected set; }
 
+        public bool IsBooleanProperty { get; protected set; }
+
         public string Name { get; protected set; }
 
         public string IndexerNamePrefix { get; protected set; }

src/Microsoft.AspNetCore.Razor.Language/BoundAttributeDescriptorExtensions.cs

@@ -27,5 +27,27 @@ namespace Microsoft.AspNetCore.Razor.Language
 
             return string.Equals(attribute.Kind, TagHelperConventions.DefaultKind, StringComparison.Ordinal);
         }
+
+        internal static bool ExpectsStringValue(this BoundAttributeDescriptor attribute, string name)
+        {
+            if (attribute.IsStringProperty)
+            {
+                return true;
+            }
+
+            var isIndexerNameMatch = TagHelperMatchingConventions.SatisfiesBoundAttributeIndexer(name, attribute);
+            return isIndexerNameMatch && attribute.IsIndexerStringProperty;
+        }
+
+        internal static bool ExpectsBooleanValue(this BoundAttributeDescriptor attribute, string name)
+        {
+            if (attribute.IsBooleanProperty)
+            {
+                return true;
+            }
+
+            var isIndexerNameMatch = TagHelperMatchingConventions.SatisfiesBoundAttributeIndexer(name, attribute);
+            return isIndexerNameMatch && attribute.IsIndexerBooleanProperty;
+        }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/DefaultBoundAttributeDescriptor.cs

@@ -35,6 +35,9 @@ namespace Microsoft.AspNetCore.Razor.Language
 
             IsIndexerStringProperty = indexerTypeName == typeof(string).FullName || indexerTypeName == "string";
             IsStringProperty = typeName == typeof(string).FullName || typeName == "string";
+
+            IsIndexerBooleanProperty = indexerTypeName == typeof(bool).FullName || indexerTypeName == "bool";
+            IsBooleanProperty = typeName == typeof(bool).FullName || typeName == "bool";
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/DefaultRazorIntermediateNodeLoweringPhase.cs

@@ -39,7 +39,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             var imports = codeDocument.GetImportSyntaxTrees();
             if (imports != null)
             {
-                var importsVisitor = new ImportsVisitor(document, builder, namespaces);
+                var importsVisitor = new ImportsVisitor(document, builder, namespaces, syntaxTree.Options.FeatureFlags);
 
                 for (var j = 0; j < imports.Count; j++)
                 {
@@ -51,7 +51,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             }
 
             var tagHelperPrefix = tagHelperContext?.Prefix;
-            var visitor = new MainSourceVisitor(document, builder, namespaces, tagHelperPrefix)
+            var visitor = new MainSourceVisitor(document, builder, namespaces, tagHelperPrefix, syntaxTree.Options.FeatureFlags)
             {
                 FilePath = syntaxTree.Source.FilePath,
             };
@@ -151,12 +151,14 @@ namespace Microsoft.AspNetCore.Razor.Language
             protected readonly IntermediateNodeBuilder _builder;
             protected readonly DocumentIntermediateNode _document;
             protected readonly Dictionary<string, SourceSpan?> _namespaces;
+            protected readonly RazorParserFeatureFlags _featureFlags;
 
-            public LoweringVisitor(DocumentIntermediateNode document, IntermediateNodeBuilder builder, Dictionary<string, SourceSpan?> namespaces)
+            public LoweringVisitor(DocumentIntermediateNode document, IntermediateNodeBuilder builder, Dictionary<string, SourceSpan?> namespaces, RazorParserFeatureFlags featureFlags)
             {
                 _document = document;
                 _builder = builder;
                 _namespaces = namespaces;
+                _featureFlags = featureFlags;
             }
 
             public string FilePath { get; set; }
@@ -331,8 +333,7 @@ namespace Microsoft.AspNetCore.Razor.Language
 
             protected SourceSpan? BuildSourceSpanFromNode(SyntaxTreeNode node)
             {
-                var location = node.Start;
+                if (node == null || node.Start == SourceLocation.Undefined)
-                if (location == SourceLocation.Undefined)
                 {
                     return null;
                 }
@@ -351,8 +352,8 @@ namespace Microsoft.AspNetCore.Razor.Language
         {
             private readonly string _tagHelperPrefix;
 
-            public MainSourceVisitor(DocumentIntermediateNode document, IntermediateNodeBuilder builder, Dictionary<string, SourceSpan?> namespaces, string tagHelperPrefix)
+            public MainSourceVisitor(DocumentIntermediateNode document, IntermediateNodeBuilder builder, Dictionary<string, SourceSpan?> namespaces, string tagHelperPrefix, RazorParserFeatureFlags featureFlags)
-                : base(document, builder, namespaces)
+                : base(document, builder, namespaces, featureFlags)
             {
                 _tagHelperPrefix = tagHelperPrefix;
             }
@@ -670,10 +671,11 @@ namespace Microsoft.AspNetCore.Razor.Language
 
                     if (associatedDescriptors.Any() && renderedBoundAttributeNames.Add(attribute.Name))
                     {
-                        if (attributeValueNode == null)
+                        var isMinimizedAttribute = attributeValueNode == null;
+                        if (isMinimizedAttribute && !_featureFlags.AllowMinimizedBooleanTagHelperAttributes)
                         {
-                            // Minimized attributes are not valid for bound attributes. TagHelperBlockRewriter has already
+                            // Minimized attributes are not valid for non-boolean bound attributes. TagHelperBlockRewriter
-                            // logged an error if it was a bound attribute; so we can skip.
+                            // has already logged an error if it was a non-boolean bound attribute; so we can skip.
                             continue;
                         }
 
@@ -684,6 +686,14 @@ namespace Microsoft.AspNetCore.Razor.Language
                                 return TagHelperMatchingConventions.CanSatisfyBoundAttribute(attribute.Name, a);
                             });
 
+                            var expectsBooleanValue = associatedAttributeDescriptor.ExpectsBooleanValue(attribute.Name);
+
+                            if (isMinimizedAttribute && !expectsBooleanValue)
+                            {
+                                // We do not allow minimized non-boolean bound attributes.
+                                continue;
+                            }
+
                             var setTagHelperProperty = new TagHelperPropertyIntermediateNode()
                             {
                                 AttributeName = attribute.Name,
@@ -695,7 +705,7 @@ namespace Microsoft.AspNetCore.Razor.Language
                             };
 
                             _builder.Push(setTagHelperProperty);
-                            attributeValueNode.Accept(this);
+                            attributeValueNode?.Accept(this);
                             _builder.Pop();
                         }
                     }
@@ -720,8 +730,8 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         private class ImportsVisitor : LoweringVisitor
         {
-            public ImportsVisitor(DocumentIntermediateNode document, IntermediateNodeBuilder builder, Dictionary<string, SourceSpan?> namespaces)
+            public ImportsVisitor(DocumentIntermediateNode document, IntermediateNodeBuilder builder, Dictionary<string, SourceSpan?> namespaces, RazorParserFeatureFlags featureFlags)
-                : base(document, new ImportBuilder(builder), namespaces)
+                : base(document, new ImportBuilder(builder), namespaces, featureFlags)
             {
             }
 

src/Microsoft.AspNetCore.Razor.Language/DefaultRazorParserOptions.cs

@@ -8,7 +8,7 @@ namespace Microsoft.AspNetCore.Razor.Language
 {
     internal class DefaultRazorParserOptions : RazorParserOptions
     {
-        public DefaultRazorParserOptions(DirectiveDescriptor[] directives, bool designTime, bool parseLeadingDirectives)
+        public DefaultRazorParserOptions(DirectiveDescriptor[] directives, bool designTime, bool parseLeadingDirectives, RazorLanguageVersion version)
         {
             if (directives == null)
             {
@@ -18,6 +18,8 @@ namespace Microsoft.AspNetCore.Razor.Language
             Directives = directives;
             DesignTime = designTime;
             ParseLeadingDirectives = parseLeadingDirectives;
+            Version = version;
+            FeatureFlags = RazorParserFeatureFlags.Create(Version);
         }
 
         public override bool DesignTime { get; }
@@ -25,5 +27,9 @@ namespace Microsoft.AspNetCore.Razor.Language
         public override IReadOnlyCollection<DirectiveDescriptor> Directives { get; }
 
         public override bool ParseLeadingDirectives { get; }
+
+        public override RazorLanguageVersion Version { get; }
+
+        internal override RazorParserFeatureFlags FeatureFlags { get; }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/DefaultRazorParserOptionsBuilder.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
 
@@ -8,9 +9,10 @@ namespace Microsoft.AspNetCore.Razor.Language
 {
     internal class DefaultRazorParserOptionsBuilder : RazorParserOptionsBuilder
     {
-        public DefaultRazorParserOptionsBuilder(bool designTime)
+        public DefaultRazorParserOptionsBuilder(bool designTime, RazorLanguageVersion version)
         {
             DesignTime = designTime;
+            Version = version;
         }
 
         public override bool DesignTime { get; }
@@ -19,9 +21,11 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         public override bool ParseLeadingDirectives { get; set; }
 
+        public override RazorLanguageVersion Version { get; }
+
         public override RazorParserOptions Build()
         {
-            return new DefaultRazorParserOptions(Directives.ToArray(), DesignTime, ParseLeadingDirectives);
+            return new DefaultRazorParserOptions(Directives.ToArray(), DesignTime, ParseLeadingDirectives, Version);
         }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/DefaultRazorParserOptionsFeature.cs

@@ -8,11 +8,13 @@ namespace Microsoft.AspNetCore.Razor.Language
     internal class DefaultRazorParserOptionsFeature : RazorEngineFeatureBase, IRazorParserOptionsFeature
     {
         private readonly bool _designTime;
+        private readonly RazorLanguageVersion _version;
         private IConfigureRazorParserOptionsFeature[] _configureOptions;
 
-        public DefaultRazorParserOptionsFeature(bool designTime)
+        public DefaultRazorParserOptionsFeature(bool designTime, RazorLanguageVersion version)
         {
             _designTime = designTime;
+            _version = version;
         }
 
         protected override void OnInitialized()
@@ -22,7 +24,7 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         public RazorParserOptions GetOptions()
         {
-            var builder = new DefaultRazorParserOptionsBuilder(_designTime);
+            var builder = new DefaultRazorParserOptionsBuilder(_designTime, _version);
             for (var i = 0; i < _configureOptions.Length; i++)
             {
                 _configureOptions[i].Configure(builder);

src/Microsoft.AspNetCore.Razor.Language/DefaultRazorTagHelperBinderPhase.cs

@@ -53,7 +53,8 @@ namespace Microsoft.AspNetCore.Razor.Language
             }
 
             var errorSink = new ErrorSink();
-            var rewriter = new TagHelperParseTreeRewriter(tagHelperPrefix, descriptors);
+            var rewriter = new TagHelperParseTreeRewriter(tagHelperPrefix, descriptors, syntaxTree.Options.FeatureFlags);
+
             var root = syntaxTree.Root;
             root = rewriter.Rewrite(root, errorSink);
 

src/Microsoft.AspNetCore.Razor.Language/Extensions/DefaultTagHelperTargetExtension.cs

@@ -336,7 +336,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
             }
 
             // If we get there, this is the first time seeing this property so we need to evaluate the expression.
-            if (node.BoundAttribute.IsStringProperty || (node.IsIndexerNameMatch && node.BoundAttribute.IsIndexerStringProperty))
+            if (node.BoundAttribute.ExpectsStringValue(node.AttributeName))
             {
                 if (DesignTime)
                 {
@@ -407,7 +407,17 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                             context.CodeWriter.WriteStartAssignment(GetPropertyAccessor(node));
                         }
 
-                        RenderTagHelperAttributeInline(context, node, node.Source);
+                        if (node.Children.Count == 0 &&
+                            node.AttributeStructure == AttributeStructure.Minimized &&
+                            node.BoundAttribute.ExpectsBooleanValue(node.AttributeName))
+                        {
+                            // If this is a minimized boolean attribute, set the value to true.
+                            context.CodeWriter.Write("true");
+                        }
+                        else
+                        {
+                            RenderTagHelperAttributeInline(context, node, node.Source);
+                        }
 
                         context.CodeWriter.WriteLine(";");
                     }
@@ -429,7 +439,17 @@ namespace Microsoft.AspNetCore.Razor.Language.Extensions
                                 .Write(".");
                         }
 
-                        RenderTagHelperAttributeInline(context, node, node.Source);
+                        if (node.Children.Count == 0 &&
+                            node.AttributeStructure == AttributeStructure.Minimized &&
+                            node.BoundAttribute.ExpectsBooleanValue(node.AttributeName))
+                        {
+                            // If this is a minimized boolean attribute, set the value to true.
+                            context.CodeWriter.Write("true");
+                        }
+                        else
+                        {
+                            RenderTagHelperAttributeInline(context, node, node.Source);
+                        }
 
                         context.CodeWriter.WriteLine(";");
                     }

src/Microsoft.AspNetCore.Razor.Language/Legacy/TagHelperBlockRewriter.cs

@@ -16,13 +16,14 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
         public static TagHelperBlockBuilder Rewrite(
             string tagName,
             bool validStructure,
+            RazorParserFeatureFlags featureFlags,
             Block tag,
             TagHelperBinding bindingResult,
             ErrorSink errorSink)
         {
             // There will always be at least one child for the '<'.
             var start = tag.Children.First().Start;
-            var attributes = GetTagAttributes(tagName, validStructure, tag, bindingResult, errorSink);
+            var attributes = GetTagAttributes(tagName, validStructure, tag, bindingResult, errorSink, featureFlags);
             var tagMode = GetTagMode(tagName, tag, bindingResult, errorSink);
 
             return new TagHelperBlockBuilder(tagName, tagMode, start, attributes, bindingResult);
@@ -33,7 +34,8 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             bool validStructure,
             Block tagBlock,
             TagHelperBinding bindingResult,
-            ErrorSink errorSink)
+            ErrorSink errorSink,
+            RazorParserFeatureFlags featureFlags)
         {
             var attributes = new List<TagHelperAttributeNode>();
 
@@ -61,10 +63,15 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
                 {
                     SourceLocation? errorLocation = null;
 
-                    // Check if it's a bound attribute that is minimized or if it's a bound non-string attribute that
+                    // Check if it's a non-boolean bound attribute that is minimized or if it's a bound
-                    // is null or whitespace.
+                    // non-string attribute that has null or whitespace content.
-                    if ((result.IsBoundAttribute && result.AttributeValueNode == null) ||
+                    var isMinimized = result.AttributeValueNode == null;
-                        (result.IsBoundNonStringAttribute &&
+                    var isValidMinimizedAttribute = featureFlags.AllowMinimizedBooleanTagHelperAttributes && result.IsBoundBooleanAttribute;
+                    if ((isMinimized &&
+                        result.IsBoundAttribute &&
+                        !isValidMinimizedAttribute) ||
+                        (!isMinimized &&
+                        result.IsBoundNonStringAttribute &&
                          IsNullOrWhitespaceAttributeValue(result.AttributeValueNode)))
                     {
                         errorLocation = GetAttributeNameStartLocation(child);
@@ -690,9 +697,8 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
         {
             var firstBoundAttribute = FindFirstBoundAttribute(name, descriptors);
             var isBoundAttribute = firstBoundAttribute != null;
-            var isBoundNonStringAttribute = isBoundAttribute &&
+            var isBoundNonStringAttribute = isBoundAttribute && !firstBoundAttribute.ExpectsStringValue(name);
-                !(firstBoundAttribute.IsStringProperty ||
+            var isBoundBooleanAttribute = isBoundAttribute && firstBoundAttribute.ExpectsBooleanValue(name);
-                    (TagHelperMatchingConventions.SatisfiesBoundAttributeIndexer(name, firstBoundAttribute) && firstBoundAttribute.IsIndexerStringProperty));
             var isMissingDictionaryKey = isBoundAttribute &&
                 firstBoundAttribute.IndexerNamePrefix != null &&
                 name.Length == firstBoundAttribute.IndexerNamePrefix.Length;
@@ -709,6 +715,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
                 AttributeName = name,
                 IsBoundAttribute = isBoundAttribute,
                 IsBoundNonStringAttribute = isBoundNonStringAttribute,
+                IsBoundBooleanAttribute = isBoundBooleanAttribute,
                 IsMissingDictionaryKey = isMissingDictionaryKey,
                 IsDuplicateAttribute = isDuplicateAttribute
             };
@@ -766,6 +773,8 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
 
             public bool IsBoundNonStringAttribute { get; set; }
 
+            public bool IsBoundBooleanAttribute { get; set; }
+
             public bool IsMissingDictionaryKey { get; set; }
 
             public bool IsDuplicateAttribute { get; set; }

src/Microsoft.AspNetCore.Razor.Language/Legacy/TagHelperParseTreeRewriter.cs

@@ -44,8 +44,12 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
         private readonly Stack<BlockBuilder> _blockStack;
         private TagHelperBlockTracker _currentTagHelperTracker;
         private BlockBuilder _currentBlock;
+        private RazorParserFeatureFlags _featureFlags;
 
-        public TagHelperParseTreeRewriter(string tagHelperPrefix, IEnumerable<TagHelperDescriptor> descriptors)
+        public TagHelperParseTreeRewriter(
+            string tagHelperPrefix,
+            IEnumerable<TagHelperDescriptor> descriptors,
+            RazorParserFeatureFlags featureFlags)
         {
             _tagHelperPrefix = tagHelperPrefix;
             _tagHelperBinder = new TagHelperBinder(tagHelperPrefix, descriptors);
@@ -53,6 +57,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             _blockStack = new Stack<BlockBuilder>();
             _attributeValueBuilder = new StringBuilder();
             _htmlAttributeTracker = new List<KeyValuePair<string, string>>();
+            _featureFlags = featureFlags;
         }
 
         private TagBlockTracker CurrentTracker => _trackerStack.Count > 0 ? _trackerStack.Peek() : null;
@@ -225,6 +230,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
                 var builder = TagHelperBlockRewriter.Rewrite(
                     tagName,
                     validTagStructure,
+                    _featureFlags,
                     tagBlock,
                     tagHelperBinding,
                     errorSink);

src/Microsoft.AspNetCore.Razor.Language/Properties/Resources.Designer.cs

@@ -682,6 +682,20 @@ namespace Microsoft.AspNetCore.Razor.Language
         internal static string FormatTagHelperPrefixDirective_Description()
             => GetString("TagHelperPrefixDirective_Description");
 
+        /// <summary>
+        /// Provided value for razor language version is unsupported or invalid: '{0}'.
+        /// </summary>
+        internal static string InvalidRazorLanguageVersion
+        {
+            get => GetString("InvalidRazorLanguageVersion");
+        }
+
+        /// <summary>
+        /// Provided value for razor language version is unsupported or invalid: '{0}'.
+        /// </summary>
+        internal static string FormatInvalidRazorLanguageVersion(object p0)
+            => string.Format(CultureInfo.CurrentCulture, GetString("InvalidRazorLanguageVersion"), p0);
+
         private static string GetString(string name, params string[] formatterNames)
         {
             var value = _resourceManager.GetString(name);

src/Microsoft.AspNetCore.Razor.Language/RazorEngine.cs

@@ -102,7 +102,7 @@ namespace Microsoft.AspNetCore.Razor.Language
         internal static void AddRuntimeDefaults(IRazorEngineBuilder builder)
         {
             // Configure options
-            builder.Features.Add(new DefaultRazorParserOptionsFeature(designTime: false));
+            builder.Features.Add(new DefaultRazorParserOptionsFeature(designTime: false, version: RazorParserOptions.LatestRazorLanguageVersion));
             builder.Features.Add(new DefaultRazorCodeGenerationOptionsFeature(designTime: false));
 
             // Intermediate Node Passes
@@ -116,7 +116,7 @@ namespace Microsoft.AspNetCore.Razor.Language
         internal static void AddDesignTimeDefaults(IRazorEngineBuilder builder)
         {
             // Configure options
-            builder.Features.Add(new DefaultRazorParserOptionsFeature(designTime: true));
+            builder.Features.Add(new DefaultRazorParserOptionsFeature(designTime: true, version: RazorParserOptions.LatestRazorLanguageVersion));
             builder.Features.Add(new DefaultRazorCodeGenerationOptionsFeature(designTime: true));
             builder.Features.Add(new SuppressChecksumOptionsFeature());
 

src/Microsoft.AspNetCore.Razor.Language/RazorLanguageVersion.cs

@@ -0,0 +1,33 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Razor.Language
+{
+    public enum RazorLanguageVersion
+    {
+        Version1_0 = 1,
+
+        Version1_1 = 2,
+
+        Version2_0 = 3,
+
+        Version2_1 = 4,
+    }
+
+    internal static class RazorLanguageVersionExtensions
+    {
+        internal static bool IsValid(this RazorLanguageVersion version)
+        {
+            switch (version)
+            {
+                case RazorLanguageVersion.Version1_0:
+                case RazorLanguageVersion.Version1_1:
+                case RazorLanguageVersion.Version2_0:
+                case RazorLanguageVersion.Version2_1:
+                    return true;
+            }
+
+            return false;
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/RazorParserFeatureFlags.cs

@@ -0,0 +1,39 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+
+namespace Microsoft.AspNetCore.Razor.Language
+{
+    internal abstract class RazorParserFeatureFlags
+    {
+        public static RazorParserFeatureFlags Create(RazorLanguageVersion version)
+        {
+            if (!version.IsValid())
+            {
+                throw new ArgumentException(Resources.FormatInvalidRazorLanguageVersion(version.ToString()));
+            }
+
+            var allowMinimizedBooleanTagHelperAttributes = false;
+
+            if (version == RazorLanguageVersion.Version2_1)
+            {
+                allowMinimizedBooleanTagHelperAttributes = true;
+            }
+
+            return new DefaultRazorParserFeatureFlags(allowMinimizedBooleanTagHelperAttributes);
+        }
+
+        public abstract bool AllowMinimizedBooleanTagHelperAttributes { get; }
+
+        private class DefaultRazorParserFeatureFlags : RazorParserFeatureFlags
+        {
+            public DefaultRazorParserFeatureFlags(bool allowMinimizedBooleanTagHelperAttributes)
+            {
+                AllowMinimizedBooleanTagHelperAttributes = allowMinimizedBooleanTagHelperAttributes;
+            }
+
+            public override bool AllowMinimizedBooleanTagHelperAttributes { get; }
+        }
+    }
+}

src/Microsoft.AspNetCore.Razor.Language/RazorParserOptions.cs

@@ -8,9 +8,15 @@ namespace Microsoft.AspNetCore.Razor.Language
 {
     public abstract class RazorParserOptions
     {
+        internal static readonly RazorLanguageVersion LatestRazorLanguageVersion = RazorLanguageVersion.Version2_1;
+
         public static RazorParserOptions CreateDefault()
         {
-            return new DefaultRazorParserOptions(Array.Empty<DirectiveDescriptor>(), designTime: false, parseLeadingDirectives: false);
+            return new DefaultRazorParserOptions(
+                Array.Empty<DirectiveDescriptor>(),
+                designTime: false,
+                parseLeadingDirectives: false,
+                version: LatestRazorLanguageVersion);
         }
 
         public static RazorParserOptions Create(Action<RazorParserOptionsBuilder> configure)
@@ -20,7 +26,7 @@ namespace Microsoft.AspNetCore.Razor.Language
                 throw new ArgumentNullException(nameof(configure));
             }
 
-            var builder = new DefaultRazorParserOptionsBuilder(designTime: false);
+            var builder = new DefaultRazorParserOptionsBuilder(designTime: false, version: LatestRazorLanguageVersion);
             configure(builder);
             var options = builder.Build();
 
@@ -34,7 +40,7 @@ namespace Microsoft.AspNetCore.Razor.Language
                 throw new ArgumentNullException(nameof(configure));
             }
 
-            var builder = new DefaultRazorParserOptionsBuilder(designTime: true);
+            var builder = new DefaultRazorParserOptionsBuilder(designTime: true, version: LatestRazorLanguageVersion);
             configure(builder);
             var options = builder.Build();
 
@@ -54,5 +60,9 @@ namespace Microsoft.AspNetCore.Razor.Language
         /// In a future release this may be updated to include all leading directive content.
         /// </remarks>
         public abstract bool ParseLeadingDirectives { get; }
+
+        public virtual RazorLanguageVersion Version { get; } = LatestRazorLanguageVersion;
+
+        internal virtual RazorParserFeatureFlags FeatureFlags { get; }
     }
 }

src/Microsoft.AspNetCore.Razor.Language/RazorParserOptionsBuilder.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Collections.Generic;
 
 namespace Microsoft.AspNetCore.Razor.Language
@@ -13,6 +14,8 @@ namespace Microsoft.AspNetCore.Razor.Language
 
         public abstract bool ParseLeadingDirectives { get; set; }
 
+        public virtual RazorLanguageVersion Version { get; }
+
         public abstract RazorParserOptions Build();
     }
 }

src/Microsoft.AspNetCore.Razor.Language/Resources.resx

@@ -261,4 +261,7 @@
   <data name="TagHelperPrefixDirective_Description" xml:space="preserve">
     <value>Specify a prefix that is required in an element name for it to be included in Tag Helper processing.</value>
   </data>
+  <data name="InvalidRazorLanguageVersion" xml:space="preserve">
+    <value>Provided value for razor language version is unsupported or invalid: '{0}'.</value>
+  </data>
 </root>

test/Microsoft.AspNetCore.Razor.Language.Test/BoundAttributeDescriptorExtensionsTest.cs

@@ -95,5 +95,185 @@ namespace Microsoft.AspNetCore.Razor.Language
             // Assert
             Assert.False(isDefault);
         }
+
+        [Fact]
+        public void ExpectsStringValue_ReturnsTrue_ForStringProperty()
+        {
+            // Arrange
+            var tagHelperBuilder = new DefaultTagHelperDescriptorBuilder(TagHelperConventions.DefaultKind, "TestTagHelper", "Test");
+            tagHelperBuilder.TypeName("TestTagHelper");
+
+            var builder = new DefaultBoundAttributeDescriptorBuilder(tagHelperBuilder, TagHelperConventions.DefaultKind);
+            builder
+                .Name("test")
+                .PropertyName("BoundProp")
+                .TypeName(typeof(string).FullName);
+
+            var descriptor = builder.Build();
+
+            // Act
+            var result = descriptor.ExpectsStringValue("test");
+
+            // Assert
+            Assert.True(result);
+        }
+
+        [Fact]
+        public void ExpectsStringValue_ReturnsFalse_ForNonStringProperty()
+        {
+            // Arrange
+            var tagHelperBuilder = new DefaultTagHelperDescriptorBuilder(TagHelperConventions.DefaultKind, "TestTagHelper", "Test");
+            tagHelperBuilder.TypeName("TestTagHelper");
+
+            var builder = new DefaultBoundAttributeDescriptorBuilder(tagHelperBuilder, TagHelperConventions.DefaultKind);
+            builder
+                .Name("test")
+                .PropertyName("BoundProp")
+                .TypeName(typeof(bool).FullName);
+
+            var descriptor = builder.Build();
+
+            // Act
+            var result = descriptor.ExpectsStringValue("test");
+
+            // Assert
+            Assert.False(result);
+        }
+
+        [Fact]
+        public void ExpectsStringValue_ReturnsTrue_StringIndexerAndNameMatch()
+        {
+            // Arrange
+            var tagHelperBuilder = new DefaultTagHelperDescriptorBuilder(TagHelperConventions.DefaultKind, "TestTagHelper", "Test");
+            tagHelperBuilder.TypeName("TestTagHelper");
+
+            var builder = new DefaultBoundAttributeDescriptorBuilder(tagHelperBuilder, TagHelperConventions.DefaultKind);
+            builder
+                .Name("test")
+                .PropertyName("BoundProp")
+                .TypeName("System.Collection.Generic.IDictionary<string, string>")
+                .AsDictionary("prefix-test-", typeof(string).FullName);
+
+            var descriptor = builder.Build();
+
+            // Act
+            var result = descriptor.ExpectsStringValue("prefix-test-key");
+
+            // Assert
+            Assert.True(result);
+        }
+
+        [Fact]
+        public void ExpectsStringValue_ReturnsFalse_StringIndexerAndNameMismatch()
+        {
+            // Arrange
+            var tagHelperBuilder = new DefaultTagHelperDescriptorBuilder(TagHelperConventions.DefaultKind, "TestTagHelper", "Test");
+            tagHelperBuilder.TypeName("TestTagHelper");
+
+            var builder = new DefaultBoundAttributeDescriptorBuilder(tagHelperBuilder, TagHelperConventions.DefaultKind);
+            builder
+                .Name("test")
+                .PropertyName("BoundProp")
+                .TypeName("System.Collection.Generic.IDictionary<string, string>")
+                .AsDictionary("prefix-test-", typeof(string).FullName);
+
+            var descriptor = builder.Build();
+
+            // Act
+            var result = descriptor.ExpectsStringValue("test");
+
+            // Assert
+            Assert.False(result);
+        }
+
+        [Fact]
+        public void ExpectsBooleanValue_ReturnsTrue_ForBooleanProperty()
+        {
+            // Arrange
+            var tagHelperBuilder = new DefaultTagHelperDescriptorBuilder(TagHelperConventions.DefaultKind, "TestTagHelper", "Test");
+            tagHelperBuilder.TypeName("TestTagHelper");
+
+            var builder = new DefaultBoundAttributeDescriptorBuilder(tagHelperBuilder, TagHelperConventions.DefaultKind);
+            builder
+                .Name("test")
+                .PropertyName("BoundProp")
+                .TypeName(typeof(bool).FullName);
+
+            var descriptor = builder.Build();
+
+            // Act
+            var result = descriptor.ExpectsBooleanValue("test");
+
+            // Assert
+            Assert.True(result);
+        }
+
+        [Fact]
+        public void ExpectsBooleanValue_ReturnsFalse_ForNonBooleanProperty()
+        {
+            // Arrange
+            var tagHelperBuilder = new DefaultTagHelperDescriptorBuilder(TagHelperConventions.DefaultKind, "TestTagHelper", "Test");
+            tagHelperBuilder.TypeName("TestTagHelper");
+
+            var builder = new DefaultBoundAttributeDescriptorBuilder(tagHelperBuilder, TagHelperConventions.DefaultKind);
+            builder
+                .Name("test")
+                .PropertyName("BoundProp")
+                .TypeName(typeof(int).FullName);
+
+            var descriptor = builder.Build();
+
+            // Act
+            var result = descriptor.ExpectsBooleanValue("test");
+
+            // Assert
+            Assert.False(result);
+        }
+
+        [Fact]
+        public void ExpectsBooleanValue_ReturnsTrue_BooleanIndexerAndNameMatch()
+        {
+            // Arrange
+            var tagHelperBuilder = new DefaultTagHelperDescriptorBuilder(TagHelperConventions.DefaultKind, "TestTagHelper", "Test");
+            tagHelperBuilder.TypeName("TestTagHelper");
+
+            var builder = new DefaultBoundAttributeDescriptorBuilder(tagHelperBuilder, TagHelperConventions.DefaultKind);
+            builder
+                .Name("test")
+                .PropertyName("BoundProp")
+                .TypeName("System.Collection.Generic.IDictionary<string, bool>")
+                .AsDictionary("prefix-test-", typeof(bool).FullName);
+
+            var descriptor = builder.Build();
+
+            // Act
+            var result = descriptor.ExpectsBooleanValue("prefix-test-key");
+
+            // Assert
+            Assert.True(result);
+        }
+
+        [Fact]
+        public void ExpectsBooleanValue_ReturnsFalse_BooleanIndexerAndNameMismatch()
+        {
+            // Arrange
+            var tagHelperBuilder = new DefaultTagHelperDescriptorBuilder(TagHelperConventions.DefaultKind, "TestTagHelper", "Test");
+            tagHelperBuilder.TypeName("TestTagHelper");
+
+            var builder = new DefaultBoundAttributeDescriptorBuilder(tagHelperBuilder, TagHelperConventions.DefaultKind);
+            builder
+                .Name("test")
+                .PropertyName("BoundProp")
+                .TypeName("System.Collection.Generic.IDictionary<string, bool>")
+                .AsDictionary("prefix-test-", typeof(bool).FullName);
+
+            var descriptor = builder.Build();
+
+            // Act
+            var result = descriptor.ExpectsBooleanValue("test");
+
+            // Assert
+            Assert.False(result);
+        }
     }
 }

test/Microsoft.AspNetCore.Razor.Language.Test/DefaultRazorParsingPhaseTest.cs

@@ -15,7 +15,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             var engine = RazorEngine.CreateEmpty(builder =>
             {
                 builder.Phases.Add(phase);
-                builder.Features.Add(new DefaultRazorParserOptionsFeature(designTime: false));
+                builder.Features.Add(new DefaultRazorParserOptionsFeature(designTime: false, version: RazorParserOptions.LatestRazorLanguageVersion));
             });
 
             var codeDocument = TestRazorCodeDocument.CreateEmpty();
@@ -35,7 +35,7 @@ namespace Microsoft.AspNetCore.Razor.Language
             var engine = RazorEngine.CreateEmpty((builder) =>
             {
                 builder.Phases.Add(phase);
-                builder.Features.Add(new DefaultRazorParserOptionsFeature(designTime: false));
+                builder.Features.Add(new DefaultRazorParserOptionsFeature(designTime: false, version: RazorParserOptions.LatestRazorLanguageVersion));
                 builder.Features.Add(new MyParserOptionsFeature());
             });
 
@@ -58,9 +58,8 @@ namespace Microsoft.AspNetCore.Razor.Language
             var engine = RazorEngine.CreateEmpty((builder) =>
             {
                 builder.Phases.Add(phase);
-                builder.Features.Add(new DefaultRazorParserOptionsFeature(designTime: false));
+                builder.Features.Add(new DefaultRazorParserOptionsFeature(designTime: false, version: RazorParserOptions.LatestRazorLanguageVersion));
                 builder.Features.Add(new MyParserOptionsFeature());
-
             });
 
             var imports = new[]

test/Microsoft.AspNetCore.Razor.Language.Test/IntegrationTests/TestTagHelperDescriptors.cs

@@ -46,6 +46,43 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
             }
         }
 
+        public static IEnumerable<TagHelperDescriptor> MinimizedBooleanTagHelperDescriptors
+        {
+            get
+            {
+                return new[]
+                {
+                    CreateTagHelperDescriptor(
+                        tagName: "span",
+                        typeName: "SpanTagHelper",
+                        assemblyName: "TestAssembly"),
+                    CreateTagHelperDescriptor(
+                        tagName: "div",
+                        typeName: "DivTagHelper",
+                        assemblyName: "TestAssembly"),
+                    CreateTagHelperDescriptor(
+                        tagName: "input",
+                        typeName: "InputTagHelper",
+                        assemblyName: "TestAssembly",
+                        attributes: new Action<BoundAttributeDescriptorBuilder>[]
+                        {
+                            builder => builder
+                                .Name("value")
+                                .PropertyName("FooProp")
+                                .TypeName("System.String"),
+                            builder => builder
+                                .Name("bound")
+                                .PropertyName("BoundProp")
+                                .TypeName("System.Boolean"),
+                            builder => builder
+                                .Name("age")
+                                .PropertyName("AgeProp")
+                                .TypeName("System.Int32"),
+                        })
+                };
+            }
+        }
+
         public static IEnumerable<TagHelperDescriptor> CssSelectorTagHelperDescriptors
         {
             get
@@ -267,6 +304,22 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests
                                 .RequireAttributeDescriptor(attribute => attribute.Name("input-bound-required-string"))
                                 .RequireAttributeDescriptor(attribute => attribute.Name("input-unbound-required")),
                         }),
+                    CreateTagHelperDescriptor(
+                        tagName: "div",
+                        typeName: "DivTagHelper",
+                        assemblyName: "TestAssembly",
+                        attributes: new Action<BoundAttributeDescriptorBuilder>[]
+                        {
+                            builder => builder
+                                .Name("boundbool")
+                                .PropertyName("BoundBoolProp")
+                                .TypeName(typeof(bool).FullName),
+                            builder => builder
+                                .Name("booldict")
+                                .PropertyName("BoolDictProp")
+                                .TypeName("System.Collections.Generic.IDictionary<string, bool>")
+                                .AsDictionaryAttribute("booldict-prefix-", typeof(bool).FullName),
+                        }),
                 };
             }
         }

test/Microsoft.AspNetCore.Razor.Language.Test/Legacy/TagHelperBlockRewriterTest.cs

@@ -118,11 +118,11 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             var descriptors = new[]
             {
                 TagHelperDescriptorBuilder.Create("CatchAllTagHelper", "SomeAssembly")
-                    .TagMatchingRuleDescriptor(rule => 
+                    .TagMatchingRuleDescriptor(rule =>
                         rule
                         .RequireTagName("*")
                         .RequireAttributeDescriptor(attribute => attribute.Name("bound")))
-                    .BoundAttributeDescriptor(attribute => 
+                    .BoundAttributeDescriptor(attribute =>
                         attribute
                         .Name("[item]")
                         .PropertyName("ListItems")
@@ -222,7 +222,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             var descriptors = new TagHelperDescriptor[]
             {
                 TagHelperDescriptorBuilder.Create("InputTagHelper", "SomeAssembly")
-                    .TagMatchingRuleDescriptor(rule => 
+                    .TagMatchingRuleDescriptor(rule =>
                         rule
                         .RequireTagName("input")
                         .RequireTagStructure(TagStructure.WithoutEndTag))
@@ -320,7 +320,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             var descriptors = new TagHelperDescriptor[]
             {
                 TagHelperDescriptorBuilder.Create("InputTagHelper1", "SomeAssembly")
-                    .TagMatchingRuleDescriptor(rule => 
+                    .TagMatchingRuleDescriptor(rule =>
                         rule
                         .RequireTagName("input")
                         .RequireTagStructure(structure1))
@@ -2251,7 +2251,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             {
                 TagHelperDescriptorBuilder.Create("mythTagHelper", "SomeAssembly")
                     .TagMatchingRuleDescriptor(rule => rule.RequireTagName("myth"))
-                    .BoundAttributeDescriptor(attribute => 
+                    .BoundAttributeDescriptor(attribute =>
                         attribute
                         .Name("bound")
                         .PropertyName("Bound")
@@ -3901,7 +3901,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             var descriptors = new TagHelperDescriptor[]
             {
                 TagHelperDescriptorBuilder.Create("InputTagHelper1", "SomeAssembly")
-                    .TagMatchingRuleDescriptor(rule => 
+                    .TagMatchingRuleDescriptor(rule =>
                         rule
                         .RequireTagName("input")
                         .RequireAttributeDescriptor(attribute => attribute.Name("unbound-required")))
@@ -3959,5 +3959,107 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             // Act & Assert
             EvaluateData(descriptors, documentContent, (MarkupBlock)expectedOutput, (RazorError[])expectedErrors);
         }
+
+        [Fact]
+        public void Rewrite_UnderstandsMinimizedBooleanBoundAttributes()
+        {
+            // Arrange
+            var documentContent = "<input boundbool boundbooldict-key />";
+            var descriptors = new TagHelperDescriptor[]
+            {
+                TagHelperDescriptorBuilder.Create("InputTagHelper", "SomeAssembly")
+                    .TagMatchingRuleDescriptor(rule =>
+                        rule
+                        .RequireTagName("input"))
+                    .BoundAttributeDescriptor(attribute =>
+                        attribute
+                        .Name("boundbool")
+                        .PropertyName("BoundBoolProp")
+                        .TypeName(typeof(bool).FullName))
+                    .BoundAttributeDescriptor(attribute =>
+                        attribute
+                        .Name("boundbooldict")
+                        .PropertyName("BoundBoolDictProp")
+                        .TypeName("System.Collections.Generic.IDictionary<string, bool>")
+                        .AsDictionary("boundbooldict-", typeof(bool).FullName))
+                    .Build(),
+            };
+
+            var expectedOutput = new MarkupBlock(
+                new MarkupTagHelperBlock(
+                    "input",
+                    TagMode.SelfClosing,
+                    attributes: new List<TagHelperAttributeNode>()
+                    {
+                        new TagHelperAttributeNode("boundbool", null, AttributeStructure.Minimized),
+                        new TagHelperAttributeNode("boundbooldict-key", null, AttributeStructure.Minimized),
+                    }));
+
+            // Act & Assert
+            EvaluateData(descriptors, documentContent, expectedOutput, new RazorError[] { });
+        }
+
+        [Fact]
+        public void Rewrite_FeatureDisabled_AddsErrorForMinimizedBooleanBoundAttributes()
+        {
+            // Arrange
+            var documentContent = "<input boundbool boundbooldict-key />";
+            var descriptors = new TagHelperDescriptor[]
+            {
+                TagHelperDescriptorBuilder.Create("InputTagHelper", "SomeAssembly")
+                    .TagMatchingRuleDescriptor(rule =>
+                        rule
+                        .RequireTagName("input"))
+                    .BoundAttributeDescriptor(attribute =>
+                        attribute
+                        .Name("boundbool")
+                        .PropertyName("BoundBoolProp")
+                        .TypeName(typeof(bool).FullName))
+                    .BoundAttributeDescriptor(attribute =>
+                        attribute
+                        .Name("boundbooldict")
+                        .PropertyName("BoundBoolDictProp")
+                        .TypeName("System.Collections.Generic.IDictionary<string, bool>")
+                        .AsDictionary("boundbooldict-", typeof(bool).FullName))
+                    .Build(),
+            };
+
+            var featureFlags = new TestRazorParserFeatureFlags(allowMinimizedBooleanTagHelperAttributes: false);
+
+            var expectedOutput = new MarkupBlock(
+                new MarkupTagHelperBlock(
+                    "input",
+                    TagMode.SelfClosing,
+                    attributes: new List<TagHelperAttributeNode>()
+                    {
+                        new TagHelperAttributeNode("boundbool", null, AttributeStructure.Minimized),
+                        new TagHelperAttributeNode("boundbooldict-key", null, AttributeStructure.Minimized),
+                    }));
+
+            var expectedErrors = new[]
+            {
+                new RazorError(
+                    "Attribute 'boundbool' on tag helper element 'input' requires a value. Tag helper bound attributes of type 'System.Boolean' cannot be empty or contain only whitespace.",
+                    new SourceLocation(7, 0, 7),
+                    length: 9),
+                new RazorError(
+                    "Attribute 'boundbooldict-key' on tag helper element 'input' requires a value. Tag helper bound attributes of type 'System.Boolean' cannot be empty or contain only whitespace.",
+                    new SourceLocation(17, 0, 17),
+                    length: 17),
+            };
+
+            // Act & Assert
+            EvaluateData(descriptors, documentContent, expectedOutput, expectedErrors, featureFlags: featureFlags);
+        }
+
+        private class TestRazorParserFeatureFlags : RazorParserFeatureFlags
+        {
+            public TestRazorParserFeatureFlags(bool allowMinimizedBooleanTagHelperAttributes)
+            {
+                AllowMinimizedBooleanTagHelperAttributes = allowMinimizedBooleanTagHelperAttributes;
+            }
+
+            public override bool AllowMinimizedBooleanTagHelperAttributes { get; }
+        }
     }
 }

test/Microsoft.AspNetCore.Razor.Language.Test/Legacy/TagHelperParseTreeRewriterTest.cs

@@ -52,7 +52,7 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             var errorSink = new ErrorSink();
             var parseResult = ParseDocument(documentContent);
             var document = parseResult.Root;
-            var parseTreeRewriter = new TagHelperParseTreeRewriter(null, Enumerable.Empty<TagHelperDescriptor>());
+            var parseTreeRewriter = new TagHelperParseTreeRewriter(null, Enumerable.Empty<TagHelperDescriptor>(), parseResult.Options.FeatureFlags);
 
             // Assert - Guard
             var rootBlock = Assert.IsType<Block>(document);

test/Microsoft.AspNetCore.Razor.Language.Test/Legacy/TagHelperRewritingTestBase.cs

@@ -51,11 +51,16 @@ namespace Microsoft.AspNetCore.Razor.Language.Legacy
             string documentContent,
             MarkupBlock expectedOutput,
             IEnumerable<RazorError> expectedErrors,
-            string tagHelperPrefix = null)
+            string tagHelperPrefix = null,
+            RazorParserFeatureFlags featureFlags = null)
         {
             var syntaxTree = ParseDocument(documentContent);
             var errorSink = new ErrorSink();
-            var parseTreeRewriter = new TagHelperParseTreeRewriter(tagHelperPrefix, descriptors);
+            var parseTreeRewriter = new TagHelperParseTreeRewriter(
+                tagHelperPrefix,
+                descriptors,
+                featureFlags ?? syntaxTree.Options.FeatureFlags);
+
             var actualTree = parseTreeRewriter.Rewrite(syntaxTree.Root, errorSink);
 
             var allErrors = syntaxTree.Diagnostics.Concat(errorSink.Errors.Select(error => RazorDiagnostic.Create(error)));

test/Microsoft.AspNetCore.Razor.Language.Test/RazorParserFeatureFlagsTest.cs

@@ -0,0 +1,41 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Razor.Language
+{
+    public class RazorParserFeatureFlagsTest
+    {
+        [Fact]
+        public void Create_LatestVersion_AllowsMinimizedBooleanTagHelperAttributes()
+        {
+            // Arrange & Act
+            var context = RazorParserFeatureFlags.Create(RazorLanguageVersion.Version2_1);
+
+            // Assert
+            Assert.True(context.AllowMinimizedBooleanTagHelperAttributes);
+        }
+
+        [Fact]
+        public void Create_OlderVersion_DoesNotAllowMinimizedBooleanTagHelperAttributes()
+        {
+            // Arrange & Act
+            var context = RazorParserFeatureFlags.Create(RazorLanguageVersion.Version1_1);
+
+            // Assert
+            Assert.False(context.AllowMinimizedBooleanTagHelperAttributes);
+        }
+
+        [Fact]
+        public void Create_UnknownVersion_Throws()
+        {
+            // Arrange, Act & Assert
+            var exception = Assert.Throws<ArgumentException>(
+                () => RazorParserFeatureFlags.Create(0));
+
+            Assert.Equal("Provided value for razor language version is unsupported or invalid: '0'.", exception.Message);
+        }
+    }
+}

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/MinimizedTagHelpers.cshtml

@@ -15,4 +15,6 @@
                 input-unbound-required="hello2" 
            catchall-unbound-required 
            input-bound-required-string="world" />
+    <div boundbool booldict-prefix-key></div>
+    <div>Tag helper with unmatched bound boolean attributes.</div>
 </p>

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/MinimizedTagHelpers_DesignTime.codegen.cs

@@ -7,6 +7,7 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
     {
         private global::TestNamespace.CatchAllTagHelper __TestNamespace_CatchAllTagHelper;
         private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper;
+        private global::DivTagHelper __DivTagHelper;
         #pragma warning disable 219
         private void __RazorDirectiveTokenHelpers__() {
         ((System.Action)(() => {
@@ -32,6 +33,10 @@ global::System.Object __typeHelper = "*, TestAssembly";
             __TestNamespace_InputTagHelper = CreateTagHelper<global::TestNamespace.InputTagHelper>();
             __TestNamespace_CatchAllTagHelper = CreateTagHelper<global::TestNamespace.CatchAllTagHelper>();
             __TestNamespace_InputTagHelper.BoundRequiredString = "world";
+            __DivTagHelper = CreateTagHelper<global::DivTagHelper>();
+            __DivTagHelper.BoundBoolProp = true;
+            __DivTagHelper.BoolDictProp["key"] = true;
+            __DivTagHelper = CreateTagHelper<global::DivTagHelper>();
             __TestNamespace_CatchAllTagHelper = CreateTagHelper<global::TestNamespace.CatchAllTagHelper>();
         }
         #pragma warning restore 1998

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/MinimizedTagHelpers_DesignTime.ir.txt

@@ -4,6 +4,7 @@ Document -
             DefaultTagHelperRuntime - 
             FieldDeclaration -  - private - global::TestNamespace.CatchAllTagHelper - __TestNamespace_CatchAllTagHelper
             FieldDeclaration -  - private - global::TestNamespace.InputTagHelper - __TestNamespace_InputTagHelper
+            FieldDeclaration -  - private - global::DivTagHelper - __DivTagHelper
             DesignTimeDirective - 
                 DirectiveToken - (14:0,14 [17] MinimizedTagHelpers.cshtml) - "*, TestAssembly"
             CSharpCode - 
@@ -15,7 +16,7 @@ Document -
             MethodDeclaration -  - public async - System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (31:0,31 [4] MinimizedTagHelpers.cshtml)
                     IntermediateToken - (31:0,31 [4] MinimizedTagHelpers.cshtml) - Html - \n\n
-                TagHelper - (35:2,0 [647] MinimizedTagHelpers.cshtml) - p - TagMode.StartTagAndEndTag
+                TagHelper - (35:2,0 [762] MinimizedTagHelpers.cshtml) - p - TagMode.StartTagAndEndTag
                     DefaultTagHelperBody - 
                         HtmlContent - (64:2,29 [34] MinimizedTagHelpers.cshtml)
                             IntermediateToken - (64:2,29 [6] MinimizedTagHelpers.cshtml) - Html - \n    
@@ -84,8 +85,24 @@ Document -
                                 HtmlContent - (667:16,40 [5] MinimizedTagHelpers.cshtml)
                                     IntermediateToken - (667:16,40 [5] MinimizedTagHelpers.cshtml) - Html - world
                             DefaultTagHelperExecute - 
-                        HtmlContent - (676:16,49 [2] MinimizedTagHelpers.cshtml)
+                        HtmlContent - (676:16,49 [6] MinimizedTagHelpers.cshtml)
-                            IntermediateToken - (676:16,49 [2] MinimizedTagHelpers.cshtml) - Html - \n
+                            IntermediateToken - (676:16,49 [6] MinimizedTagHelpers.cshtml) - Html - \n    
+                        TagHelper - (682:17,4 [41] MinimizedTagHelpers.cshtml) - div - TagMode.StartTagAndEndTag
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            DefaultTagHelperProperty -  - boundbool - bool DivTagHelper.BoundBoolProp - HtmlAttributeValueStyle.Minimized
+                            DefaultTagHelperProperty -  - booldict-prefix-key - System.Collections.Generic.IDictionary<string, bool> DivTagHelper.BoolDictProp - HtmlAttributeValueStyle.Minimized
+                            DefaultTagHelperExecute - 
+                        HtmlContent - (723:17,45 [6] MinimizedTagHelpers.cshtml)
+                            IntermediateToken - (723:17,45 [6] MinimizedTagHelpers.cshtml) - Html - \n    
+                        TagHelper - (729:18,4 [62] MinimizedTagHelpers.cshtml) - div - TagMode.StartTagAndEndTag
+                            DefaultTagHelperBody - 
+                                HtmlContent - (734:18,9 [51] MinimizedTagHelpers.cshtml)
+                                    IntermediateToken - (734:18,9 [51] MinimizedTagHelpers.cshtml) - Html - Tag helper with unmatched bound boolean attributes.
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            DefaultTagHelperExecute - 
+                        HtmlContent - (791:18,66 [2] MinimizedTagHelpers.cshtml)
+                            IntermediateToken - (791:18,66 [2] MinimizedTagHelpers.cshtml) - Html - \n
                     DefaultTagHelperCreate -  - TestNamespace.CatchAllTagHelper
                     DefaultTagHelperHtmlAttribute -  - catchall-unbound-required - HtmlAttributeValueStyle.Minimized
                     DefaultTagHelperExecute - 

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/MinimizedTagHelpers_DesignTime.mappings.txt

@@ -1,5 +1,5 @@
 Source Location: (14:0,14 [17] TestFiles/IntegrationTests/CodeGenerationIntegrationTest/MinimizedTagHelpers.cshtml)
 |"*, TestAssembly"|
-Generated Location: (603:12,37 [17] )
+Generated Location: (657:13,37 [17] )
 |"*, TestAssembly"|
 

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/MinimizedTagHelpers_Runtime.codegen.cs

@@ -1,4 +1,4 @@
-#pragma checksum "TestFiles/IntegrationTests/CodeGenerationIntegrationTest/MinimizedTagHelpers.cshtml" "{ff1816ec-aa5e-4d10-87f7-6f4963833460}" "cc93b363a32adf077cc406265e403db466e4ae7d"
+#pragma checksum "TestFiles/IntegrationTests/CodeGenerationIntegrationTest/MinimizedTagHelpers.cshtml" "{ff1816ec-aa5e-4d10-87f7-6f4963833460}" "ab8c9a5af38d07138a55ae82942b4a97fe3c9025"
 // <auto-generated/>
 #pragma warning disable 1591
 namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
@@ -33,6 +33,7 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
         }
         private global::TestNamespace.CatchAllTagHelper __TestNamespace_CatchAllTagHelper;
         private global::TestNamespace.InputTagHelper __TestNamespace_InputTagHelper;
+        private global::DivTagHelper __DivTagHelper;
         #pragma warning disable 1998
         public async System.Threading.Tasks.Task ExecuteAsync()
         {
@@ -128,6 +129,41 @@ namespace Microsoft.AspNetCore.Razor.Language.IntegrationTests.TestFiles
                 }
                 Write(__tagHelperExecutionContext.Output);
                 __tagHelperExecutionContext = __tagHelperScopeManager.End();
+                WriteLiteral("\r\n    ");
+                __tagHelperExecutionContext = __tagHelperScopeManager.Begin("div", global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode.StartTagAndEndTag, "test", async() => {
+                }
+                );
+                __DivTagHelper = CreateTagHelper<global::DivTagHelper>();
+                __tagHelperExecutionContext.Add(__DivTagHelper);
+                __DivTagHelper.BoundBoolProp = true;
+                __tagHelperExecutionContext.AddTagHelperAttribute("boundbool", __DivTagHelper.BoundBoolProp, global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.Minimized);
+                if (__DivTagHelper.BoolDictProp == null)
+                {
+                    throw new InvalidOperationException(InvalidTagHelperIndexerAssignment("booldict-prefix-key", "DivTagHelper", "BoolDictProp"));
+                }
+                __DivTagHelper.BoolDictProp["key"] = true;
+                __tagHelperExecutionContext.AddTagHelperAttribute("booldict-prefix-key", __DivTagHelper.BoolDictProp["key"], global::Microsoft.AspNetCore.Razor.TagHelpers.HtmlAttributeValueStyle.Minimized);
+                await __tagHelperRunner.RunAsync(__tagHelperExecutionContext);
+                if (!__tagHelperExecutionContext.Output.IsContentModified)
+                {
+                    await __tagHelperExecutionContext.SetOutputContentAsync();
+                }
+                Write(__tagHelperExecutionContext.Output);
+                __tagHelperExecutionContext = __tagHelperScopeManager.End();
+                WriteLiteral("\r\n    ");
+                __tagHelperExecutionContext = __tagHelperScopeManager.Begin("div", global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode.StartTagAndEndTag, "test", async() => {
+                    WriteLiteral("Tag helper with unmatched bound boolean attributes.");
+                }
+                );
+                __DivTagHelper = CreateTagHelper<global::DivTagHelper>();
+                __tagHelperExecutionContext.Add(__DivTagHelper);
+                await __tagHelperRunner.RunAsync(__tagHelperExecutionContext);
+                if (!__tagHelperExecutionContext.Output.IsContentModified)
+                {
+                    await __tagHelperExecutionContext.SetOutputContentAsync();
+                }
+                Write(__tagHelperExecutionContext.Output);
+                __tagHelperExecutionContext = __tagHelperScopeManager.End();
                 WriteLiteral("\r\n");
             }
             );

test/Microsoft.AspNetCore.Razor.Language.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/MinimizedTagHelpers_Runtime.ir.txt

@@ -11,10 +11,11 @@ Document -
             DefaultTagHelperRuntime - 
             FieldDeclaration -  - private - global::TestNamespace.CatchAllTagHelper - __TestNamespace_CatchAllTagHelper
             FieldDeclaration -  - private - global::TestNamespace.InputTagHelper - __TestNamespace_InputTagHelper
+            FieldDeclaration -  - private - global::DivTagHelper - __DivTagHelper
             MethodDeclaration -  - public async - System.Threading.Tasks.Task - ExecuteAsync
                 HtmlContent - (33:1,0 [2] MinimizedTagHelpers.cshtml)
                     IntermediateToken - (33:1,0 [2] MinimizedTagHelpers.cshtml) - Html - \n
-                TagHelper - (35:2,0 [647] MinimizedTagHelpers.cshtml) - p - TagMode.StartTagAndEndTag
+                TagHelper - (35:2,0 [762] MinimizedTagHelpers.cshtml) - p - TagMode.StartTagAndEndTag
                     DefaultTagHelperBody - 
                         HtmlContent - (64:2,29 [34] MinimizedTagHelpers.cshtml)
                             IntermediateToken - (64:2,29 [6] MinimizedTagHelpers.cshtml) - Html - \n    
@@ -63,8 +64,24 @@ Document -
                             DefaultTagHelperHtmlAttribute -  - catchall-unbound-required - HtmlAttributeValueStyle.Minimized
                             PreallocatedTagHelperProperty - (667:16,40 [5] MinimizedTagHelpers.cshtml) - __tagHelperAttribute_6 - input-bound-required-string - BoundRequiredString
                             DefaultTagHelperExecute - 
-                        HtmlContent - (676:16,49 [2] MinimizedTagHelpers.cshtml)
+                        HtmlContent - (676:16,49 [6] MinimizedTagHelpers.cshtml)
-                            IntermediateToken - (676:16,49 [2] MinimizedTagHelpers.cshtml) - Html - \n
+                            IntermediateToken - (676:16,49 [6] MinimizedTagHelpers.cshtml) - Html - \n    
+                        TagHelper - (682:17,4 [41] MinimizedTagHelpers.cshtml) - div - TagMode.StartTagAndEndTag
+                            DefaultTagHelperBody - 
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            DefaultTagHelperProperty -  - boundbool - bool DivTagHelper.BoundBoolProp - HtmlAttributeValueStyle.Minimized
+                            DefaultTagHelperProperty -  - booldict-prefix-key - System.Collections.Generic.IDictionary<string, bool> DivTagHelper.BoolDictProp - HtmlAttributeValueStyle.Minimized
+                            DefaultTagHelperExecute - 
+                        HtmlContent - (723:17,45 [6] MinimizedTagHelpers.cshtml)
+                            IntermediateToken - (723:17,45 [6] MinimizedTagHelpers.cshtml) - Html - \n    
+                        TagHelper - (729:18,4 [62] MinimizedTagHelpers.cshtml) - div - TagMode.StartTagAndEndTag
+                            DefaultTagHelperBody - 
+                                HtmlContent - (734:18,9 [51] MinimizedTagHelpers.cshtml)
+                                    IntermediateToken - (734:18,9 [51] MinimizedTagHelpers.cshtml) - Html - Tag helper with unmatched bound boolean attributes.
+                            DefaultTagHelperCreate -  - DivTagHelper
+                            DefaultTagHelperExecute - 
+                        HtmlContent - (791:18,66 [2] MinimizedTagHelpers.cshtml)
+                            IntermediateToken - (791:18,66 [2] MinimizedTagHelpers.cshtml) - Html - \n
                     DefaultTagHelperCreate -  - TestNamespace.CatchAllTagHelper
                     DefaultTagHelperHtmlAttribute -  - catchall-unbound-required - HtmlAttributeValueStyle.Minimized
                     DefaultTagHelperExecute -