Adds validation against invalid bracket pairs

* Fixes dotnet#7285

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/Runtime/LoggerMessageDefineAnalyzer.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
@@ -192,6 +193,12 @@ private void AnalyzeFormatArgument(OperationAnalysisContext context, IOperation
                 return;
             }
 
+            if (!IsValidBrackets(text))
+            {
+                context.ReportDiagnostic(formatExpression.CreateDiagnostic(CA2017Rule));
+                return;
+            }
+
             LogValuesFormatter formatter;
             try
             {
@@ -251,6 +258,46 @@ private void AnalyzeFormatArgument(OperationAnalysisContext context, IOperation
             }
         }
 
+        /// <summary>
+        /// Does the text have valid brackets?
+        /// </summary>
+        /// <param name="text">The text to check.</param>
+        /// <returns>When true brackets are valid, false otherwise.</returns>
+        private static bool IsValidBrackets(string text)
+        {
+            var relevantBracketPairs = new Dictionary<char, char>()
+            {
+                {'}', '{'},
+            };
+
+            var stack = new Stack<char>();
+
+            for (var i = 0; i < text.Length; i++)
+            {
+                // If we're on a closing bracket...
+                if (relevantBracketPairs.ContainsKey(text[i]))
+                {
+                    // and nothing in the stack, invalid
+                    if (stack.Count == 0)
+                        return false;
+
+                    // Check the "opening" of this type of bracket from the stack matches expectations
+                    var pop = stack.Pop();
+                    if (relevantBracketPairs[text[i]] != pop)
+                        return false;
+                }
+
+                // If we're on a bracket, push onto stack for tracking
+                if (relevantBracketPairs.ContainsValue(text[i]))
+                {
+                    stack.Push(text[i]);
+                }
+            }
+
+            // Entire text has been evaluated and no issues found
+            return true;
+        }
+
         private static bool FindLogParameters(IMethodSymbol methodSymbol, [NotNullWhen(true)] out IParameterSymbol? message, out IParameterSymbol? arguments)
         {
             message = null;

src/NetAnalyzers/UnitTests/Microsoft.NetCore.Analyzers/Runtime/LoggerMessageDefineTests.cs

@@ -107,6 +107,24 @@ public async Task CA2017IsProducedForDefineMessageTypeParameterMismatchAsync(str
             await TriggerCodeAsync(expression);
         }
 
+
+        /// <summary>
+        /// <para>
+        /// https://github.com/dotnet/roslyn-analyzers/issues/7285
+        /// </para>
+        /// <para>
+        /// Unmatched brackets cause runtime exceptions in a message template, should flag CA2017
+        /// </para>
+        /// </summary>
+        [Theory]
+        [InlineData(@"LoggerMessage.DefineScope<int>({|CA2017:""{One}}""|});")]
+        [InlineData(@"LoggerMessage.DefineScope<int>({|CA2017:""{{One}""|});")]
+        [InlineData(@"LoggerMessage.DefineScope<int>({|CA2017:""}{One}""|});")]
+        public async Task Fix7285_CA2017(string format)
+        {
+            await TriggerCodeAsync(format);
+        }
+
         [Theory]
         [InlineData("LogTrace", @"""This is a test {Message}""")]
         [InlineData("LogDebug", @"""This is a test {Message}""")]