Merge pull request #6935 from mavasani/Issue6929

Avoid 'Collection was modified' InvalidOperationException

Author: mavasani

src/Utilities/FlowAnalysis/FlowAnalysis/Framework/DataFlow/AnalysisEntityBasedPredicateAnalysisData.cs

@@ -6,6 +6,7 @@
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using Analyzer.Utilities.PooledObjects;
 
 namespace Microsoft.CodeAnalysis.FlowAnalysis.DataFlow
 {
@@ -170,6 +171,11 @@ private void ClearOverlappingAnalysisDataForIndexedEntity(AnalysisEntity analysi
                 return;
             }
 
+            // Collect all the overlapping indexed entities whose value needs to be updated into a builder.
+            // Ensure that we perform these state updates after the foreach loop to avoid modifying the
+            // underlying CoreAnalysisData within the loop.
+            // See https://github.com/dotnet/roslyn-analyzers/issues/6929 for more details.
+            using var builder = ArrayBuilder<(AnalysisEntity, TValue)>.GetInstance(CoreAnalysisData.Count);
             foreach (var entity in CoreAnalysisData.Keys)
             {
                 if (entity.Indices.Length != analysisEntity.Indices.Length ||
@@ -197,10 +203,15 @@ private void ClearOverlappingAnalysisDataForIndexedEntity(AnalysisEntity analysi
                     var mergedValue = ValueDomain.Merge(value, existingValue);
                     if (!existingValue!.Equals(mergedValue))
                     {
-                        SetAbstractValue(entity, mergedValue);
+                        builder.Add((entity, mergedValue));
                     }
                 }
             }
+
+            foreach (var (entity, newValue) in builder.AsEnumerable())
+            {
+                SetAbstractValue(entity, newValue);
+            }
         }
 
         protected override void Dispose(bool disposing)