Expand exception logic

WoofWare.PawPrint.Test/TestPureCases.fs

@@ -193,6 +193,24 @@ module TestPureCases =
                 NativeImpls = MockEnv.make ()
                 LocalVariablesOfMain = [ CliType.Numeric (CliNumericType.Int32 10) ] |> Some
             }
+            {
+                FileName = "ExceptionWithNestedHandlers.cs"
+                ExpectedReturnCode = 10112
+                NativeImpls = NativeImpls.PassThru ()
+                LocalVariablesOfMain =
+                    [ 10112 ]
+                    |> List.map (fun i -> CliType.Numeric (CliNumericType.Int32 i))
+                    |> Some
+            }
+            {
+                FileName = "ExceptionWithTypeMatching.cs"
+                ExpectedReturnCode = 10112
+                NativeImpls = NativeImpls.PassThru ()
+                LocalVariablesOfMain =
+                    [ 10112 ]
+                    |> List.map (fun i -> CliType.Numeric (CliNumericType.Int32 i))
+                    |> Some
+            }
             {
                 FileName = "Floats.cs"
                 ExpectedReturnCode = 0

WoofWare.PawPrint.Test/WoofWare.PawPrint.Test.fsproj

@@ -26,6 +26,8 @@
     <EmbeddedResource Include="sourcesPure\Ldelema.cs" />
     <EmbeddedResource Include="sourcesPure\ExceptionWithNoOpCatch.cs" />
     <EmbeddedResource Include="sourcesPure\ExceptionWithNoOpFinally.cs" />
+    <EmbeddedResource Include="sourcesPure\ExceptionWithNestedHandlers.cs" />
+    <EmbeddedResource Include="sourcesPure\ExceptionWithTypeMatching.cs" />
     <EmbeddedResource Include="sourcesPure\TryCatchWithThrowInBody.cs" />
     <EmbeddedResource Include="sourcesPure\ComplexTryCatch.cs" />
     <EmbeddedResource Include="sourcesPure\TriangleNumber.cs" />

WoofWare.PawPrint.Test/sourcesPure/ExceptionWithNestedHandlers.cs

@@ -0,0 +1,47 @@
+using System;
+
+namespace HelloWorld
+{
+    class Program {
+        static int Test_NestedHandlers()
+        {
+            int x = 0;
+            try
+            {
+                try
+                {
+                    x = 1;
+                    throw new InvalidOperationException();
+                }
+                catch (InvalidOperationException)
+                {
+                    x = 2;
+                    throw new ArgumentException(); // Re-throw different exception
+                }
+                finally
+                {
+                    x += 10; // Inner finally
+                }
+            }
+            catch (ArgumentException)
+            {
+                x += 100; // Outer catch
+            }
+            catch (Exception)
+            {
+                x += 1000; // This should NOT execute
+            }
+            finally
+            {
+                x += 10000; // Outer finally
+            }
+
+            return x; // Expected: 10112 (1 -> 2 -> 12 -> 112 -> 10112)
+        }
+
+        static int Main(string[] args)
+        {
+            return Test_NestedHandlers();
+        }
+    }
+}

WoofWare.PawPrint.Test/sourcesPure/ExceptionWithTypeMatching.cs

@@ -0,0 +1,41 @@
+using System;
+
+namespace HelloWorld
+{
+    class Program {
+        static int Test_TypeMatching()
+        {
+            int x = 0;
+            try
+            {
+                try
+                {
+                    x = 1;
+                    throw new ArgumentNullException();  // Derives from ArgumentException
+                }
+                catch (InvalidOperationException)
+                {
+                    x = 999;  // Should NOT execute
+                }
+                catch (ArgumentException)  // This should catch ArgumentNullException
+                {
+                    x = 2;
+                }
+                catch (Exception)
+                {
+                    x = 888;  // Should NOT execute (more general handler)
+                }
+            }
+            catch (Exception)
+            {
+                x = 777;  // Should NOT execute (outer handler)
+            }
+            return x;  // Expected: 2
+        }
+
+        static int Main(string[] args)
+        {
+            return Test_TypeMatching();
+        }
+    }
+}

WoofWare.PawPrint/Exceptions.fs

@@ -1,32 +1,29 @@
 namespace WoofWare.PawPrint
 
-open System
 open System.Collections.Immutable
 
 /// Represents a location in the code where an exception occurred
-type ExceptionStackFrame<'typeGen, 'methodGen, 'methodVar
-    when 'typeGen : comparison and 'typeGen :> IComparable<'typeGen>> =
+type ExceptionStackFrame =
     {
-        Method : WoofWare.PawPrint.MethodInfo<'typeGen, 'methodGen, 'methodVar>
+        Method : WoofWare.PawPrint.MethodInfo<TypeDefn, TypeDefn>
         /// The number of bytes into the IL of the method we were in
         IlOffset : int
     }
 
 /// Represents a CLI exception being propagated
-type CliException<'typeGen, 'methodGen, 'methodVar when 'typeGen : comparison and 'typeGen :> IComparable<'typeGen>> =
+type CliException =
     {
         /// The exception object allocated on the heap
         ExceptionObject : ManagedHeapAddress
         /// Stack trace built during unwinding
-        StackTrace : ExceptionStackFrame<'typeGen, 'methodGen, 'methodVar> list
+        StackTrace : ExceptionStackFrame list
     }
 
 /// Represents what to do after executing a finally/filter block
-type ExceptionContinuation<'typeGen, 'methodGen, 'methodVar
-    when 'typeGen : comparison and 'typeGen :> IComparable<'typeGen>> =
+type ExceptionContinuation =
     | ResumeAfterFinally of targetPC : int
-    | PropagatingException of exn : CliException<'typeGen, 'methodGen, 'methodVar>
-    | ResumeAfterFilter of handlerPC : int * exn : CliException<'typeGen, 'methodGen, 'methodVar>
+    | PropagatingException of exn : CliException
+    | ResumeAfterFilter of handlerPC : int * exn : CliException
 
 /// Helper functions for exception handling
 [<RequireQualifiedAccess>]
@@ -47,7 +44,7 @@ module ExceptionHandling =
     let findExceptionHandler
         (currentPC : int)
         (exceptionTypeCrate : TypeInfoCrate)
-        (method : WoofWare.PawPrint.MethodInfo<'typeGen, 'methodGeneric, 'methodVar>)
+        (method : WoofWare.PawPrint.MethodInfo<TypeDefn, 'methodGeneric>)
         (assemblies : ImmutableDictionary<string, DumpedAssembly>)
         : (WoofWare.PawPrint.ExceptionRegion * bool) option // handler, isFinally
         =
@@ -56,6 +53,7 @@ module ExceptionHandling =
         | Some instructions ->
 
         // Find all handlers that cover the current PC
+        let handlers =
             instructions.ExceptionRegions
             |> Seq.choose (fun region ->
                 match region with
@@ -63,7 +61,7 @@ module ExceptionHandling =
                     if currentPC >= offset.TryOffset && currentPC < offset.TryOffset + offset.TryLength then
                         // Check if exception type matches
                         if isExceptionAssignableTo exceptionTypeCrate typeToken assemblies then
-                        Some (region, false)
+                            Some (region, false, offset.TryOffset, offset.TryLength)
                         else
                             None
                     else
@@ -73,29 +71,50 @@ module ExceptionHandling =
                         failwith "TODO: filter needs to be evaluated"
                     else
                         None
+                | ExceptionRegion.Finally offset ->
+                    // Don't return finally blocks here - they're handled separately
+                    None
+                | ExceptionRegion.Fault offset ->
+                    // Fault blocks are only executed when propagating exceptions
+                    None
+            )
+            |> Seq.toList
+
+        // If multiple catch handlers, return the innermost one (highest TryOffset)
+        match handlers with
+        | [] ->
+            // No catch/filter handler found, check for finally/fault blocks
+            // that need to run while propagating
+            instructions.ExceptionRegions
+            |> Seq.choose (fun region ->
+                match region with
                 | ExceptionRegion.Finally offset ->
                     if currentPC >= offset.TryOffset && currentPC < offset.TryOffset + offset.TryLength then
-                    Some (region, true)
+                        Some (region, true, offset.TryOffset, offset.TryLength)
                     else
                         None
                 | ExceptionRegion.Fault offset ->
                     if currentPC >= offset.TryOffset && currentPC < offset.TryOffset + offset.TryLength then
-                    Some (region, true)
+                        Some (region, true, offset.TryOffset, offset.TryLength)
                     else
                         None
+                | _ -> None
             )
-        |> Seq.toList
-        |> fun x ->
-            match x with
-            | [] -> None
-            | [ x ] -> Some x
-            | _ -> failwith "multiple exception regions"
+            |> Seq.sortByDescending (fun (_, _, tryOffset, _) -> tryOffset)
+            |> Seq.tryHead
+            |> Option.map (fun (region, isFinally, _, _) -> (region, isFinally))
+        | handlers ->
+            // Return the innermost handler (highest TryOffset, or smallest TryLength for same offset)
+            handlers
+            |> List.sortBy (fun (_, _, tryOffset, tryLength) -> (-tryOffset, tryLength))
+            |> List.head
+            |> fun (region, isFinally, _, _) -> Some (region, isFinally)
 
     /// Find finally blocks that need to run when leaving a try region
     let findFinallyBlocksToRun
         (currentPC : int)
         (targetPC : int)
-        (method : WoofWare.PawPrint.MethodInfo<'typeGeneric, 'methodGeneric, 'methodVar>)
+        (method : WoofWare.PawPrint.MethodInfo<TypeDefn, 'methodGeneric>)
         : ExceptionOffset list
         =
         match method.Instructions with
@@ -125,7 +144,7 @@ module ExceptionHandling =
     /// Get the active exception regions at a given offset
     let getActiveRegionsAtOffset
         (offset : int)
-        (method : WoofWare.PawPrint.MethodInfo<'a, 'b, 'c>)
+        (method : WoofWare.PawPrint.MethodInfo<TypeDefn, 'methodGeneric>)
         : WoofWare.PawPrint.ExceptionRegion list
         =
         match method.Instructions with