Exceptions cleanup (#1862)

Src/IronPython/Runtime/Exceptions/PythonExceptions.cs

@@ -719,7 +719,7 @@ internal static BaseException CreateBaseExceptionForRaise(CodeContext/*!*/ conte
         /// <summary>
         /// Given a CLR exception returns the Python exception which most closely maps to the CLR exception.
         /// </summary>
-        public static object ToPython(System.Exception/*!*/ clrException) {
+        public static BaseException ToPython(System.Exception/*!*/ clrException) {
             var res = clrException.GetPythonException();
             if (res is null) {
                 // explicit extra conversions that need a special transformation

Src/IronPython/Runtime/Exceptions/SystemExitException.cs

@@ -2,8 +2,11 @@
 // The .NET Foundation licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
 using System;
 using System.Runtime.Serialization;
+
 using IronPython.Modules;
 using IronPython.Runtime.Operations;
 using IronPython.Runtime.Types;
@@ -15,15 +18,19 @@ namespace IronPython.Runtime.Exceptions {
     [Serializable]
     public sealed class SystemExitException : Exception {
         public SystemExitException() : base() { }
+
         public SystemExitException(string msg)
             : base(msg) {
         }
+
         public SystemExitException(string message, Exception innerException)
             : base(message, innerException) {
         }
+
 #if FEATURE_SERIALIZATION
         private SystemExitException(SerializationInfo info, StreamingContext context) : base(info, context) { }
 #endif
+
         /// <summary>
         /// Result of sys.exit(n)
         /// </summary>
@@ -36,30 +43,26 @@ private SystemExitException(SerializationInfo info, StreamingContext context) :
         /// int_value if the script exited using "sys.exit(int_value)"
         /// 1 otherwise
         /// </returns>
-        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1007:UseGenericsWhereAppropriate")]
         [PythonHidden]
-        public int GetExitCode(out object otherCode) {
+        public int GetExitCode(out object? otherCode) {
             otherCode = null;
-            object pyObj = PythonExceptions.ToPython(this);
+            var pyObj = PythonExceptions.ToPython(this);
 
-            object args;
-            PythonTuple t;
-
-            if (!PythonOps.TryGetBoundAttr(pyObj, "args", out args) ||
-                (t = args as PythonTuple) == null ||
-                t.__len__() == 0) {
-                return 0;
-            } else if (Builtin.isinstance(t[0], TypeCache.Int32)) {
-                return Converter.ConvertToInt32(t[0]);
-            } else if (Builtin.isinstance(t[0], TypeCache.BigInteger)) {
-                var b = Converter.ConvertToBigInteger(t[0]);
-                if (b > int.MaxValue || b < int.MinValue) {
-                    return -1;
+            if (PythonOps.TryGetBoundAttr(pyObj, "code", out object? code)) {
+                if (code is null) {
+                    return 0;
+                } else if (Builtin.isinstance(code, TypeCache.Int32)) {
+                    return Converter.ConvertToInt32(code);
+                } else if (Builtin.isinstance(code, TypeCache.BigInteger)) {
+                    var b = Converter.ConvertToBigInteger(code);
+                    if (b > int.MaxValue || b < int.MinValue) {
+                        return -1;
+                    }
+                    return (int)b;
+                } else {
+                    otherCode = code;
                 }
-                return (int)b;
             }
-
-            otherCode = t[0];
             return 1;
         }
     }

Src/IronPython/Runtime/Exceptions/TraceBack.cs

@@ -8,18 +8,15 @@
 using System.Runtime.CompilerServices;
 using System.Text;
 
-using Microsoft.Scripting;
-using Microsoft.Scripting.Runtime;
-
 using IronPython.Runtime.Operations;
 
-[module: System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", Scope = "member", Target = "IronPython.Runtime.Exceptions.TraceBackFrame..ctor(System.Object,System.Object,System.Object)", MessageId = "0#globals")]
-[module: System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", Scope = "member", Target = "IronPython.Runtime.Exceptions.TraceBackFrame.Globals", MessageId = "Globals")]
+using Microsoft.Scripting;
+using Microsoft.Scripting.Runtime;
 
 namespace IronPython.Runtime.Exceptions {
     [PythonType("traceback")]
     [Serializable]
-    public class TraceBack {
+    public sealed class TraceBack {
         private readonly TraceBack _next;
         private readonly TraceBackFrame _frame;
         private int _line;
@@ -79,7 +76,7 @@ internal string Extract() {
     [PythonType("frame")]
     [DebuggerDisplay("Code = {f_code.co_name}, Line = {f_lineno}")]
     [Serializable]
-    public class TraceBackFrame {
+    public sealed class TraceBackFrame {
         private readonly PythonTracebackListener _traceAdapter;
         private TracebackDelegate _trace;
         private object _traceObject;
@@ -118,11 +115,11 @@ internal TraceBackFrame(PythonTracebackListener traceAdapter, FunctionCode code,
 
         [SpecialName, PropertyMethod]
         public object Getf_trace() {
-                if (_traceAdapter != null) {
-                    return _traceObject;
-                } else {
-                    return null;
-                }
+            if (_traceAdapter != null) {
+                return _traceObject;
+            } else {
+                return null;
+            }
         }
 
         [SpecialName, PropertyMethod]
@@ -230,7 +227,7 @@ private void SetLineNumber(int newLineNum) {
 
             Dictionary<int, bool> currentLoopIds = null;
             bool inForLoopOrFinally = loopAndFinallyLocations != null && loopAndFinallyLocations.TryGetValue(_lineNo, out currentLoopIds);
-            
+
             int originalNewLine = newLineNum;
 
             if (newLineNum < funcCode.Span.Start.Line) {
@@ -246,7 +243,7 @@ private void SetLineNumber(int newLineNum) {
                 // Check if we're jumping onto a handler
                 bool handlerIsFinally;
                 if (handlerLocations != null && handlerLocations.TryGetValue(newLineNum, out handlerIsFinally)) {
-                    throw PythonOps.ValueError("can't jump to 'except' line");                    
+                    throw PythonOps.ValueError("can't jump to 'except' line");
                 }
 
                 // Check if we're jumping into a for-loop

Src/IronPython/Runtime/Operations/PythonOps.cs

@@ -2457,20 +2457,9 @@ public static PythonTuple GetExceptionInfo(CodeContext/*!*/ context) {
                 return PythonTuple.MakeTuple(null, null, null);
             }
 
-            PythonContext pc = context.LanguageContext;
-
-            object pyExcep = PythonExceptions.ToPython(ex);
-            TraceBack? tb = CreateTraceBack(pc, ex);
-
-            object excType;
-            if (pyExcep is IPythonObject pyObj) {
-                // class is always the Python type for new-style types (this is also the common case)
-                excType = pyObj.PythonType;
-            } else {
-                excType = PythonOps.GetBoundAttr(context, pyExcep, "__class__");
-            }
-
-            return PythonTuple.MakeTuple(excType, pyExcep, tb);
+            var pyExcep = PythonExceptions.ToPython(ex);
+            TraceBack? tb = CreateTraceBack(context.LanguageContext, ex);
+            return PythonTuple.MakeTuple(((IPythonObject)pyExcep).PythonType, pyExcep, tb);
         }
 
         /// <summary>

Src/IronPython/Runtime/PythonContext.cs

@@ -1332,7 +1332,7 @@ public override string FormatException(Exception exception) {
 
             StringBuilder result = new StringBuilder();
 
-            object pythonEx = PythonExceptions.ToPython(exception);
+            var pythonEx = PythonExceptions.ToPython(exception);
 
             if (exception.InnerException != null) {
                 if (exception.InnerException.GetPythonException() is PythonExceptions.BaseException pythonInnerException) {
@@ -1438,28 +1438,24 @@ private static string FormatCLSException(Exception e) {
             return result.ToString();
         }
 
-        internal static string FormatPythonException(object pythonException) {
+        internal static string FormatPythonException(PythonExceptions.BaseException pythonException) {
             string result = "";
 
             // dump the python exception.
             if (pythonException != null) {
-                if (pythonException is string str) {
-                    result += str;
-                } else {
-                    result += GetPythonExceptionClassName(pythonException);
+                result += GetPythonExceptionClassName(pythonException);
 
-                    string excepStr = PythonOps.ToString(pythonException);
+                string excepStr = PythonOps.ToString(pythonException);
 
-                    if (!string.IsNullOrEmpty(excepStr)) {
-                        result += ": " + excepStr;
-                    }
+                if (!string.IsNullOrEmpty(excepStr)) {
+                    result += ": " + excepStr;
                 }
             }
 
             return result;
         }
 
-        private static string GetPythonExceptionClassName(object pythonException) {
+        private static string GetPythonExceptionClassName(PythonExceptions.BaseException pythonException) {
             string className = string.Empty;
             if (PythonOps.TryGetBoundAttr(pythonException, "__class__", out object val)) {
                 if (PythonOps.TryGetBoundAttr(val, "__name__", out val)) {
@@ -1644,9 +1640,8 @@ public override CompilerOptions GetCompilerOptions()
         }
 
         public override void GetExceptionMessage(Exception exception, out string message, out string typeName) {
-            object pythonEx = PythonExceptions.ToPython(exception);
-
-            message = FormatPythonException(PythonExceptions.ToPython(exception));
+            var pythonEx = PythonExceptions.ToPython(exception);
+            message = FormatPythonException(pythonEx);
             typeName = GetPythonExceptionClassName(pythonEx);
         }