Validate the value for using namespace during semantic checks to prevent declaring invalid namespaces (#21162)

src/System.Management.Automation/engine/parser/SemanticChecks.cs

@@ -8,6 +8,7 @@ using System.Linq;
 using System.Reflection;
 using System.Runtime.CompilerServices;
 using System.Text;
+using System.Text.RegularExpressions;
 
 using Microsoft.PowerShell;
 using System.Management.Automation.Security;
@@ -17,7 +18,7 @@ using Microsoft.PowerShell.DesiredStateConfiguration.Internal;
 
 namespace System.Management.Automation.Language
 {
-    internal sealed class SemanticChecks : AstVisitor2, IAstPostVisitHandler
+    internal sealed partial class SemanticChecks : AstVisitor2, IAstPostVisitHandler
     {
         private readonly Parser _parser;
 
@@ -1319,20 +1320,50 @@ namespace System.Management.Automation.Language
 
         public override AstVisitAction VisitUsingStatement(UsingStatementAst usingStatementAst)
         {
-            bool usingKindSupported = usingStatementAst.UsingStatementKind == UsingStatementKind.Namespace ||
-                                      usingStatementAst.UsingStatementKind == UsingStatementKind.Assembly ||
-                                      usingStatementAst.UsingStatementKind == UsingStatementKind.Module;
-            if (!usingKindSupported ||
-                usingStatementAst.Alias != null)
+            UsingStatementKind kind = usingStatementAst.UsingStatementKind;
+            bool usingKindSupported = kind is UsingStatementKind.Namespace or UsingStatementKind.Assembly or UsingStatementKind.Module;
+            if (!usingKindSupported || usingStatementAst.Alias != null)
             {
-                _parser.ReportError(usingStatementAst.Extent,
+                _parser.ReportError(
+                    usingStatementAst.Extent,
                     nameof(ParserStrings.UsingStatementNotSupported),
                     ParserStrings.UsingStatementNotSupported);
             }
 
+            if (kind is UsingStatementKind.Namespace)
+            {
+                Regex nsPattern = NamespacePattern();
+                if (!nsPattern.IsMatch(usingStatementAst.Name.Value))
+                {
+                    _parser.ReportError(
+                        usingStatementAst.Name.Extent,
+                        nameof(ParserStrings.InvalidNamespaceValue),
+                        ParserStrings.InvalidNamespaceValue);
+                }
+            }
+
             return AstVisitAction.Continue;
         }
 
+        /// <summary>
+        /// This regular expression is for validating if a namespace string is valid.
+        ///
+        /// In C#, a legit namespace is defined as `identifier ('.' identifier)*` [see https://learn.microsoft.com/dotnet/csharp/language-reference/language-specification/namespaces#143-namespace-declarations].
+        /// And `identifier` is defined in https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/identifier-names#naming-rules, summarized below:
+        ///   - Identifiers must start with a letter or underscore (_).
+        ///   - Identifiers can contain
+        ///     * Unicode letter characters (categories: Lu, Ll, Lt, Lm, Lo or Nl);
+        ///     * decimal digit characters (category: Nd);
+        ///     * Unicode connecting characters (category: Pc);
+        ///     * Unicode combining characters (categories: Mn, Mc);
+        ///     * Unicode formatting characters (category: Cf).
+        ///
+        /// For details about how Unicode categories are represented in regular expression, see the "Unicode Categories" section in the following article:
+        ///   - https://www.regular-expressions.info/unicode.html
+        /// </summary>
+        [GeneratedRegex(@"^[\p{L}\p{Nl}_][\p{L}\p{Nl}\p{Nd}\p{Pc}\p{Mn}\p{Mc}\p{Cf}_]*(?:\.[\p{L}\p{Nl}_][\p{L}\p{Nl}\p{Nd}\p{Pc}\p{Mn}\p{Mc}\p{Cf}_]*)*$")]
+        private static partial Regex NamespacePattern();
+
         public override AstVisitAction VisitConfigurationDefinition(ConfigurationDefinitionAst configurationDefinitionAst)
         {
             //

src/System.Management.Automation/resources/ParserStrings.resx

@@ -1229,6 +1229,9 @@ ModuleVersion : Version of module to import. If used, ModuleName must represent
   <data name="UsingStatementNotSupported" xml:space="preserve">
     <value>This syntax of the 'using' statement is not supported.</value>
   </data>
+  <data name="InvalidNamespaceValue" xml:space="preserve">
+    <value>The specified namespace in the 'using' statement contains invalid characters.</value>
+  </data>
   <data name="InformationStream" xml:space="preserve">
     <value>information stream</value>
   </data>

test/powershell/Language/Parser/UsingNamespace.Tests.ps1

@@ -128,7 +128,10 @@ Describe "Using Namespace" -Tags "CI" {
 
     ShouldBeParseError "1; using namespace System" UsingMustBeAtStartOfScript 3
     ShouldBeParseError "using namespace Foo = System" UsingStatementNotSupported 0
+    ShouldBeParseError "using namespace ''" InvalidNamespaceValue 16
+    ShouldBeParseError "using namespace [System]" InvalidNamespaceValue 16
+    ShouldBeParseError "using namespace ',System'" InvalidNamespaceValue 16
+    ShouldBeParseError "using namespace ']System'" InvalidNamespaceValue 16
     # TODO: add diagnostic (low pri)
     # ShouldBeParseError "using namespace System; using namespace System" UsingNamespaceAlreadySpecified 24
 }
-