Fix S1854 FP: Value used in catch or when should LiveIn for all try blocks

analyzers/its/expected/Ember-MM/S2259-EmberAPI.json

@@ -36,6 +36,24 @@
       "Uri": "https://github.com/SonarSource/sonar-dotnet/blob/master/analyzers/its/Projects/Ember-MM/EmberAPI/clsAPIDatabase.vb#L280",
       "Location": "Line 280 Position 61-73"
     },
+    {
+      "Id": "S2259",
+      "Message": "\u0027inList\u0027 is Nothing on at least one execution path.",
+      "Uri": "https://github.com/SonarSource/sonar-dotnet/blob/master/analyzers/its/Projects/Ember-MM/EmberAPI/clsAPIScanner.vb#L1022",
+      "Location": "Line 1022 Position 60-66"
+    },
+    {
+      "Id": "S2259",
+      "Message": "\u0027dList\u0027 is Nothing on at least one execution path.",
+      "Uri": "https://github.com/SonarSource/sonar-dotnet/blob/master/analyzers/its/Projects/Ember-MM/EmberAPI/clsAPIScanner.vb#L926",
+      "Location": "Line 926 Position 52-57"
+    },
+    {
+      "Id": "S2259",
+      "Message": "\u0027inList\u0027 is Nothing on at least one execution path.",
+      "Uri": "https://github.com/SonarSource/sonar-dotnet/blob/master/analyzers/its/Projects/Ember-MM/EmberAPI/clsAPIScanner.vb#L995",
+      "Location": "Line 995 Position 56-62"
+    },
     {
       "Id": "S2259",
       "Message": "\u0027movieName\u0027 is Nothing on at least one execution path.",

analyzers/src/SonarAnalyzer.CFG/LiveVariableAnalysis/RoslynLiveVariableAnalysis.cs

@@ -93,18 +93,25 @@ private void BuildBranches(BasicBlock block)
             var catchesAll = false;
             foreach (var catchOrFilterRegion in block.Successors.SelectMany(CatchOrFilterRegions))
             {
-                AddBranch(block, Cfg.Blocks[catchOrFilterRegion.FirstBlockOrdinal]);
+                var catchOrFilterBlock = Cfg.Blocks[catchOrFilterRegion.FirstBlockOrdinal];
+                AddBranch(block, catchOrFilterBlock);
+                AddPredecessorsOutsideRegion(catchOrFilterBlock);
                 catchesAll = catchesAll || (catchOrFilterRegion.Kind == ControlFlowRegionKind.Catch && IsCatchAllType(catchOrFilterRegion.ExceptionType));
             }
             if (!catchesAll && block.EnclosingRegion(ControlFlowRegionKind.TryAndFinally)?.NestedRegion(ControlFlowRegionKind.Finally) is { } finallyRegion)
             {
                 var finallyBlock = Cfg.Blocks[finallyRegion.FirstBlockOrdinal];
                 AddBranch(block, finallyBlock);
-                // We assume that this block can throw in its first operation. Therefore predecessors outside this tryRegion need to be redirected to finally
-                foreach (var predecessor in block.Predecessors.Where(x => x.Source.Ordinal < tryRegion.FirstBlockOrdinal || x.Source.Ordinal > tryRegion.LastBlockOrdinal))
-                {
-                    AddBranch(predecessor.Source, finallyBlock);
-                }
+                AddPredecessorsOutsideRegion(finallyBlock);
+            }
+        }
+
+        void AddPredecessorsOutsideRegion(BasicBlock destination)
+        {
+            // We assume that current block can throw in its first operation. Therefore predecessors outside this tryRegion need to be redirected to catch/filter/finally
+            foreach (var predecessor in block.Predecessors.Where(x => x.Source.Ordinal < tryRegion.FirstBlockOrdinal || x.Source.Ordinal > tryRegion.LastBlockOrdinal))
+            {
+                AddBranch(predecessor.Source, destination);
             }
         }
     }

analyzers/tests/SonarAnalyzer.Test/LiveVariableAnalysis/RoslynLiveVariableAnalysisTest.TryCatchFinally.cs

@@ -538,12 +538,38 @@ public void Catch_AssignedInTry_LiveOut()
             """;
         var context = CreateContextCS(code);
         context.ValidateEntry();
-        context.Validate("Method(0);"/*Should be:, LiveOut("variable")*/);
+        context.Validate("Method(0);", LiveOut("variable"));
         context.Validate("Method(1);", LiveOut("variable"));
         context.Validate("Method(variable);", LiveIn("variable"));
         context.Validate("Method(2);");
     }
 
+    [TestMethod]
+    public void Catch_When_AssignedInTry_LiveOut()
+    {
+        var code = """
+            int variable = 42;
+            Method(0);
+            try
+            {
+                Method(1);  // Can throw
+                variable = 0;
+            }
+            catch when(variable == 0)
+            {
+                Method(2);
+            }
+            Method(3);
+            """;
+        var context = CreateContextCS(code);
+        context.ValidateEntry();
+        context.Validate("Method(0);", LiveOut("variable"));
+        context.Validate("Method(1);", LiveOut("variable"));
+        context.Validate("variable == 0", LiveIn("variable"));
+        context.Validate("Method(2);");
+        context.Validate("Method(3);");
+    }
+
     [TestMethod]
     public void Catch_Loop_Propagates_LiveIn()
     {

analyzers/tests/SonarAnalyzer.Test/TestCases/DeadStores.RoslynCfg.cs

@@ -1436,7 +1436,7 @@ public void UsedInFinally_NestedInLambda()
             {
             }
         }
-        
+
         public void UsedInFinally_Throw()
         {
             var value = 42; // Compliant 

analyzers/tests/SonarAnalyzer.Test/TestCases/SymbolicExecution/Roslyn/ConditionEvaluatesToConstant.cs

@@ -4166,9 +4166,9 @@ void Method()
                 exception = e;
             }
         }
-        if (exception != null)  // FN!
+        if (exception != null)              // Noncompliant
         {
-            Console.WriteLine(exception);
+            Console.WriteLine(exception);   // Secondary
         }
         Console.WriteLine(success);
     }