Better messages than a throw
[mono.git] / mcs / mcs / statement.cs
old mode 100755 (executable)
new mode 100644 (file)
index 7a48a21..608de2a
@@ -3,7 +3,7 @@
 //
 // Author:
 //   Miguel de Icaza (miguel@ximian.com)
-//   Martin Baulig (martin@gnome.org)
+//   Martin Baulig (martin@ximian.com)
 //
 // (C) 2001, 2002, 2003 Ximian, Inc.
 // (C) 2003, 2004 Novell, Inc.
@@ -46,16 +46,14 @@ namespace Mono.CSharp {
                        // in unreachable code, for instance.
                        //
 
+                       if (warn && (RootContext.WarningLevel >= 2))
+                               Report.Warning (162, loc, "Unreachable code detected");
+
                        ec.StartFlowBranching (FlowBranching.BranchingType.Block, loc);
                        bool ok = Resolve (ec);
                        ec.KillFlowBranching ();
 
-                       if (!ok)
-                               return false;
-
-                       if (warn && (RootContext.WarningLevel >= 2))
-                               Report.Warning (162, loc, "Unreachable code detected");
-                       return true;
+                       return ok;
                }
                
                protected void CheckObsolete (Type type)
@@ -148,6 +146,11 @@ namespace Mono.CSharp {
                                return false;
                        }
 
+                       Assign ass = expr as Assign;
+                       if (ass != null && ass.Source is Constant) {
+                               Report.Warning (665, 3, loc, "Assignment in conditional expression is always constant; did you mean to use == instead of = ?");
+                       }
+
                        //
                        // Dead code elimination
                        //
@@ -527,7 +530,8 @@ namespace Mono.CSharp {
 
                public override bool Resolve (EmitContext ec)
                {
-                       expr = expr.ResolveStatement (ec);
+                       if (expr != null)
+                               expr = expr.ResolveStatement (ec);
                        return expr != null;
                }
                
@@ -576,6 +580,12 @@ namespace Mono.CSharp {
                                        return false;
                                }
 
+                               if (ec.InIterator) {
+                                       Report.Error (1622, loc, "Cannot return a value from iterators. Use the yield return " +
+                                               "statement to return a value, or yield break to end the iteration");
+                                       return false;
+                               }
+
                                Expr = Expr.Resolve (ec);
                                if (Expr == null)
                                        return false;
@@ -643,6 +653,7 @@ namespace Mono.CSharp {
                                label.AddUsageVector (ec.CurrentBranching.CurrentUsageVector);
 
                        ec.CurrentBranching.CurrentUsageVector.Goto ();
+                       label.AddReference ();
 
                        return true;
                }
@@ -672,6 +683,7 @@ namespace Mono.CSharp {
                bool defined;
                bool referenced;
                Label label;
+               ILGenerator ig;
 
                FlowBranching.UsageVector vectors;
                
@@ -684,6 +696,7 @@ namespace Mono.CSharp {
                {
                        if (defined)
                                return label;
+                       ig = ec.ig;
                        label = ec.ig.DefineLabel ();
                        defined = true;
 
@@ -713,16 +726,23 @@ namespace Mono.CSharp {
                {
                        ec.CurrentBranching.Label (vectors);
 
-                       referenced = true;
-
                        return true;
                }
 
                protected override void DoEmit (EmitContext ec)
                {
+                       if (ig != null && ig != ec.ig) {
+                               Report.Error (1632, "Control cannot leave body of anonymous method");
+                               return;
+                       }
                        LabelTarget (ec);
                        ec.ig.MarkLabel (label);
                }
+
+               public void AddReference ()
+               {
+                       referenced = true;
+               }
        }
        
 
@@ -822,7 +842,6 @@ namespace Mono.CSharp {
 
                public override bool Resolve (EmitContext ec)
                {
-                       bool in_catch = ec.CurrentBranching.InCatch ();
                        ec.CurrentBranching.CurrentUsageVector.Throw ();
 
                        if (expr != null){
@@ -833,7 +852,7 @@ namespace Mono.CSharp {
                                ExprClass eclass = expr.eclass;
 
                                if (!(eclass == ExprClass.Variable || eclass == ExprClass.PropertyAccess ||
-                                     eclass == ExprClass.Value || eclass == ExprClass.IndexerAccess)) {
+                                       eclass == ExprClass.Value || eclass == ExprClass.IndexerAccess)) {
                                        expr.Error_UnexpectedKind ("value, variable, property or indexer access ", loc);
                                        return false;
                                }
@@ -841,20 +860,25 @@ namespace Mono.CSharp {
                                Type t = expr.Type;
                                
                                if ((t != TypeManager.exception_type) &&
-                                   !t.IsSubclassOf (TypeManager.exception_type) &&
-                                   !(expr is NullLiteral)) {
+                                       !t.IsSubclassOf (TypeManager.exception_type) &&
+                                       !(expr is NullLiteral)) {
                                        Error (155,
-                                              "The type caught or thrown must be derived " +
-                                              "from System.Exception");
+                                               "The type caught or thrown must be derived " +
+                                               "from System.Exception");
                                        return false;
                                }
-                       } else if (!in_catch) {
-                               Error (156,
-                                      "A throw statement with no argument is only " +
-                                      "allowed in a catch clause");
+                               return true;
+                       }
+
+                       if (ec.CurrentBranching.InFinally (true)) {
+                               Error (724, "A throw statement with no argument is only allowed in a catch clause nested inside of the innermost catch clause");
                                return false;
                        }
 
+                       if (!ec.CurrentBranching.InCatch ()) {
+                               Error (156, "A throw statement with no argument is only allowed in a catch clause");
+                               return false;
+                       }
                        return true;
                }
                        
@@ -1420,12 +1444,12 @@ namespace Mono.CSharp {
                // </summary>
                public LocalInfo ThisVariable {
                        get {
-                               if (this_variable != null)
-                                       return this_variable;
-                               else if (Parent != null)
-                                       return Parent.ThisVariable;
-                               else
-                                       return null;
+                               for (Block b = this; b != null; b = b.Parent) {
+                                       if (b.this_variable != null)
+                                               return b.this_variable;
+                               }
+                               
+                               return null;
                        }
                }
 
@@ -1747,8 +1771,6 @@ namespace Mono.CSharp {
                /// </remarks>
                public void ResolveMeta (ToplevelBlock toplevel, EmitContext ec, InternalParameters ip)
                {
-                       ILGenerator ig = ec.ig;
-
                        bool old_unsafe = ec.InUnsafe;
 
                        // If some parent block was unsafe, we remain unsafe even if this block
@@ -1936,7 +1958,7 @@ namespace Mono.CSharp {
 
                        Report.Debug (4, "RESOLVE BLOCK", StartLocation, ec.CurrentBranching);
 
-                       bool unreachable = false;
+                       bool unreachable = unreachable_shown;
 
                        int statement_count = statements.Count;
                        for (int ix = 0; ix < statement_count; ix++){
@@ -1954,8 +1976,10 @@ namespace Mono.CSharp {
                                        else
                                                s.loc = Location.Null;
 
-                                       statements [ix] = EmptyStatement.Value;
-                                       continue;
+                                       if (ok && !(s is Block)) {
+                                               statements [ix] = EmptyStatement.Value;
+                                               continue;
+                                       }
                                }
 
                                if (s.Resolve (ec) == false) {
@@ -2012,7 +2036,18 @@ namespace Mono.CSharp {
                public override bool ResolveUnreachable (EmitContext ec, bool warn)
                {
                        unreachable_shown = true;
-                       return base.ResolveUnreachable (ec, warn);
+
+                       if (warn && (RootContext.WarningLevel >= 2))
+                               Report.Warning (162, loc, "Unreachable code detected");
+
+                       if (Implicit)
+                               return Resolve (ec);
+
+                       ec.StartFlowBranching (FlowBranching.BranchingType.Block, loc);
+                       bool ok = Resolve (ec);
+                       ec.KillFlowBranching ();
+
+                       return ok;
                }
                
                protected override void DoEmit (EmitContext ec)
@@ -2023,7 +2058,7 @@ namespace Mono.CSharp {
                                // Check whether we are the last statement in a
                                // top-level block.
 
-                               if ((Parent == null) && (ix+1 == num_statements))
+                               if (((Parent == null) || Implicit) && (ix+1 == num_statements) && !(s is Block))
                                        ec.IsLastStatement = true;
                                else
                                        ec.IsLastStatement = false;
@@ -2043,7 +2078,7 @@ namespace Mono.CSharp {
 
                        if (emit_debug_info) {
                                if (is_lexical_block)
-                                       ec.ig.BeginScope ();
+                                       ec.BeginScope ();
 
                                if (variables != null) {
                                        foreach (DictionaryEntry de in variables) {
@@ -2063,7 +2098,7 @@ namespace Mono.CSharp {
                        ec.Mark (EndLocation, true); 
 
                        if (emit_debug_info && is_lexical_block)
-                               ec.ig.EndScope ();
+                               ec.EndScope ();
 
                        ec.CurrentBlock = prev_block;
                }
@@ -2117,8 +2152,6 @@ namespace Mono.CSharp {
 
                static int did = 0;
                
-               int my_id = did++;
-
                        
                public void RegisterCaptureContext (CaptureContext cc)
                {
@@ -2347,12 +2380,12 @@ namespace Mono.CSharp {
 
                        if (allowed_types == null){
                                allowed_types = new Type [] {
+                                       TypeManager.int32_type,
+                                       TypeManager.uint32_type,
                                        TypeManager.sbyte_type,
                                        TypeManager.byte_type,
                                        TypeManager.short_type,
                                        TypeManager.ushort_type,
-                                       TypeManager.int32_type,
-                                       TypeManager.uint32_type,
                                        TypeManager.int64_type,
                                        TypeManager.uint64_type,
                                        TypeManager.char_type,
@@ -2375,13 +2408,26 @@ namespace Mono.CSharp {
                                if (e == null)
                                        continue;
 
+                               //
+                               // Ignore over-worked ImplicitUserConversions that do
+                               // an implicit conversion in addition to the user conversion.
+                               // 
+                               if (e is UserCast){
+                                       UserCast ue = e as UserCast;
+
+                                       if (ue.Source != Expr)
+                                               e = null;
+                               }
+                               
                                if (converted != null){
-                                       Report.Error (-12, loc, "More than one conversion to an integral " +
-                                                     " type exists for type `" +
-                                                     TypeManager.CSharpName (Expr.Type)+"'");
+                                       Report.ExtraInformation (
+                                               loc,
+                                               String.Format ("reason: more than one conversion to an integral type exist for type {0}",
+                                                              TypeManager.CSharpName (Expr.Type)));
                                        return null;
-                               } else
+                               } else {
                                        converted = e;
+                               }
                        }
                        return converted;
                }
@@ -3273,15 +3319,81 @@ namespace Mono.CSharp {
                ArrayList declarators;
                Statement statement;
                Type expr_type;
-               FixedData[] data;
+               Emitter[] data;
                bool has_ret;
 
-               struct FixedData {
-                       public bool is_object;
-                       public LocalInfo vi;
-                       public Expression expr;
-                       public Expression converted;
-               }                       
+               abstract class Emitter
+               {
+                       protected LocalInfo vi;
+                       protected Expression converted;
+
+                       protected Emitter (Expression expr, LocalInfo li)
+                       {
+                               converted = expr;
+                               vi = li;
+                       }
+
+                       public abstract void Emit (EmitContext ec);
+                       public abstract void EmitExit (ILGenerator ig);
+               }
+
+               class ExpressionEmitter: Emitter {
+                       public ExpressionEmitter (Expression converted, LocalInfo li) :
+                               base (converted, li)
+                       {
+                       }
+
+                       public override void Emit (EmitContext ec) {
+                               //
+                               // Store pointer in pinned location
+                               //
+                               converted.Emit (ec);
+                               ec.ig.Emit (OpCodes.Stloc, vi.LocalBuilder);
+                       }
+
+                       public override void EmitExit (ILGenerator ig)
+                       {
+                               ig.Emit (OpCodes.Ldc_I4_0);
+                               ig.Emit (OpCodes.Conv_U);
+                               ig.Emit (OpCodes.Stloc, vi.LocalBuilder);
+                       }
+               }
+
+               class StringEmitter: Emitter {
+                       LocalBuilder pinned_string;
+                       Location loc;
+
+                       public StringEmitter (Expression expr, LocalInfo li, Location loc):
+                               base (expr, li)
+                       {
+                               this.loc = loc;
+                       }
+
+                       public override void Emit (EmitContext ec)
+                       {
+                               ILGenerator ig = ec.ig;
+                               pinned_string = TypeManager.DeclareLocalPinned (ig, TypeManager.string_type);
+                                       
+                               converted.Emit (ec);
+                               ig.Emit (OpCodes.Stloc, pinned_string);
+
+                               Expression sptr = new StringPtr (pinned_string, loc);
+                               converted = Convert.ImplicitConversionRequired (
+                                       ec, sptr, vi.VariableType, loc);
+                                       
+                               if (converted == null)
+                                       return;
+
+                               converted.Emit (ec);
+                               ig.Emit (OpCodes.Stloc, vi.LocalBuilder);
+                       }
+
+                       public override void EmitExit(ILGenerator ig)
+                       {
+                               ig.Emit (OpCodes.Ldnull);
+                               ig.Emit (OpCodes.Stloc, pinned_string);
+                       }
+               }
 
                public Fixed (Expression type, ArrayList decls, Statement stmt, Location l)
                {
@@ -3311,7 +3423,7 @@ namespace Mono.CSharp {
                                return false;
                        }
                        
-                       data = new FixedData [declarators.Count];
+                       data = new Emitter [declarators.Count];
 
                        if (!expr_type.IsPointer){
                                Report.Error (209, loc, "Variables in a fixed statement must be pointers");
@@ -3368,10 +3480,7 @@ namespace Mono.CSharp {
                                        if (!TypeManager.VerifyUnManaged (child.Type, loc))
                                                return false;
 
-                                       data [i].is_object = true;
-                                       data [i].expr = e;
-                                       data [i].converted = null;
-                                       data [i].vi = vi;
+                                       data [i] = new ExpressionEmitter (e, vi);
                                        i++;
 
                                        continue;
@@ -3399,17 +3508,14 @@ namespace Mono.CSharp {
                                        // and T* is implicitly convertible to the
                                        // pointer type given in the fixed statement.
                                        //
-                                       ArrayPtr array_ptr = new ArrayPtr (e, loc);
+                                       ArrayPtr array_ptr = new ArrayPtr (e, array_type, loc);
                                        
                                        Expression converted = Convert.ImplicitConversionRequired (
                                                ec, array_ptr, vi.VariableType, loc);
                                        if (converted == null)
                                                return false;
 
-                                       data [i].is_object = false;
-                                       data [i].expr = e;
-                                       data [i].converted = converted;
-                                       data [i].vi = vi;
+                                       data [i] = new ExpressionEmitter (converted, vi);
                                        i++;
 
                                        continue;
@@ -3419,14 +3525,30 @@ namespace Mono.CSharp {
                                // Case 3: string
                                //
                                if (e.Type == TypeManager.string_type){
-                                       data [i].is_object = false;
-                                       data [i].expr = e;
-                                       data [i].converted = null;
-                                       data [i].vi = vi;
+                                       data [i] = new StringEmitter (e, vi, loc);
                                        i++;
                                        continue;
                                }
 
+                               // Case 4: fixed buffer
+                               FieldExpr fe = e as FieldExpr;
+                               if (fe != null) {
+                                       IFixedBuffer ff = AttributeTester.GetFixedBuffer (fe.FieldInfo);
+                                       if (ff != null) {
+                                               Expression fixed_buffer_ptr = new FixedBufferPtr (fe, ff.ElementType, loc);
+                                       
+                                               Expression converted = Convert.ImplicitConversionRequired (
+                                                       ec, fixed_buffer_ptr, vi.VariableType, loc);
+                                               if (converted == null)
+                                                       return false;
+
+                                               data [i] = new ExpressionEmitter (converted, vi);
+                                               i++;
+
+                                               continue;
+                                       }
+                               }
+
                                //
                                // For other cases, flag a `this is already fixed expression'
                                //
@@ -3456,60 +3578,8 @@ namespace Mono.CSharp {
                
                protected override void DoEmit (EmitContext ec)
                {
-                       ILGenerator ig = ec.ig;
-
-                       LocalBuilder [] clear_list = new LocalBuilder [data.Length];
-                       
                        for (int i = 0; i < data.Length; i++) {
-                               LocalInfo vi = data [i].vi;
-
-                               //
-                               // Case 1: & object.
-                               //
-                               if (data [i].is_object) {
-                                       //
-                                       // Store pointer in pinned location
-                                       //
-                                       data [i].expr.Emit (ec);
-                                       ig.Emit (OpCodes.Stloc, vi.LocalBuilder);
-                                       clear_list [i] = vi.LocalBuilder;
-                                       continue;
-                               }
-
-                               //
-                               // Case 2: Array
-                               //
-                               if (data [i].expr.Type.IsArray){
-                                       //
-                                       // Store pointer in pinned location
-                                       //
-                                       data [i].converted.Emit (ec);
-                                       
-                                       ig.Emit (OpCodes.Stloc, vi.LocalBuilder);
-                                       clear_list [i] = vi.LocalBuilder;
-                                       continue;
-                               }
-
-                               //
-                               // Case 3: string
-                               //
-                               if (data [i].expr.Type == TypeManager.string_type){
-                                       LocalBuilder pinned_string = TypeManager.DeclareLocalPinned (ig, TypeManager.string_type);
-                                       clear_list [i] = pinned_string;
-                                       
-                                       data [i].expr.Emit (ec);
-                                       ig.Emit (OpCodes.Stloc, pinned_string);
-
-                                       Expression sptr = new StringPtr (pinned_string, loc);
-                                       Expression converted = Convert.ImplicitConversionRequired (
-                                               ec, sptr, vi.VariableType, loc);
-                                       
-                                       if (converted == null)
-                                               continue;
-
-                                       converted.Emit (ec);
-                                       ig.Emit (OpCodes.Stloc, vi.LocalBuilder);
-                               }
+                               data [i].Emit (ec);
                        }
 
                        statement.Emit (ec);
@@ -3517,18 +3587,13 @@ namespace Mono.CSharp {
                        if (has_ret)
                                return;
 
+                       ILGenerator ig = ec.ig;
+
                        //
                        // Clear the pinned variable
                        //
                        for (int i = 0; i < data.Length; i++) {
-                               if (data [i].is_object || data [i].expr.Type.IsArray) {
-                                       ig.Emit (OpCodes.Ldc_I4_0);
-                                       ig.Emit (OpCodes.Conv_U);
-                                       ig.Emit (OpCodes.Stloc, clear_list [i]);
-                               } else if (data [i].expr.Type == TypeManager.string_type){
-                                       ig.Emit (OpCodes.Ldnull);
-                                       ig.Emit (OpCodes.Stloc, clear_list [i]);
-                               }
+                               data [i].EmitExit (ig);
                        }
                }
        }
@@ -3871,7 +3936,7 @@ namespace Mono.CSharp {
                        ILGenerator ig = ec.ig;
 
                        int i = assign.Length;
-                       foreach (DictionaryEntry e in var_list){
+                       for (int ii = 0; ii < var_list.Count; ++ii){
                                Expression var = resolved_vars [--i];
                                Label skip = ig.DefineLabel ();
 
@@ -3945,12 +4010,39 @@ namespace Mono.CSharp {
                void EmitExpressionFinally (EmitContext ec)
                {
                        ILGenerator ig = ec.ig;
-                       Label skip = ig.DefineLabel ();
-                       ig.Emit (OpCodes.Ldloc, local_copy);
-                       ig.Emit (OpCodes.Brfalse, skip);
-                       ig.Emit (OpCodes.Ldloc, local_copy);
-                       ig.Emit (OpCodes.Callvirt, TypeManager.void_dispose_void);
-                       ig.MarkLabel (skip);
+                       if (!local_copy.LocalType.IsValueType) {
+                               Label skip = ig.DefineLabel ();
+                               ig.Emit (OpCodes.Ldloc, local_copy);
+                               ig.Emit (OpCodes.Brfalse, skip);
+                               ig.Emit (OpCodes.Ldloc, local_copy);
+                               ig.Emit (OpCodes.Callvirt, TypeManager.void_dispose_void);
+                               ig.MarkLabel (skip);
+                       } else {
+                               Expression ml = Expression.MemberLookup(ec, TypeManager.idisposable_type, local_copy.LocalType, "Dispose", Mono.CSharp.Location.Null);
+
+                               if (!(ml is MethodGroupExpr)) {
+                                       ig.Emit (OpCodes.Ldloc, local_copy);
+                                       ig.Emit (OpCodes.Box, local_copy.LocalType);
+                                       ig.Emit (OpCodes.Callvirt, TypeManager.void_dispose_void);
+                               } else {
+                                       MethodInfo mi = null;
+
+                                       foreach (MethodInfo mk in ((MethodGroupExpr) ml).Methods) {
+                                               if (TypeManager.GetArgumentTypes (mk).Length == 0) {
+                                                       mi = mk;
+                                                       break;
+                                               }
+                                       }
+
+                                       if (mi == null) {
+                                               Report.Error(-100, Mono.CSharp.Location.Null, "Internal error: No Dispose method which takes 0 parameters.");
+                                               return;
+                                       }
+
+                                       ig.Emit (OpCodes.Ldloca, local_copy);
+                                       ig.Emit (OpCodes.Call, mi);
+                               }
+                       }
                }
                
                public override bool Resolve (EmitContext ec)
@@ -4045,6 +4137,11 @@ namespace Mono.CSharp {
                        if (expr == null)
                                return false;
 
+                       if (expr is NullLiteral) {
+                               Report.Error (186, expr.Location, "Use of null is not valid in this context");
+                               return false;
+                       }
+
                        TypeExpr texpr = type.ResolveAsTypeTerminal (ec, false);
                        if (texpr == null)
                                return false;
@@ -4246,7 +4343,6 @@ namespace Mono.CSharp {
                                        return false;
                        }
                        ForeachHelperMethods hm = (ForeachHelperMethods) criteria;
-                       EmitContext ec = hm.ec;
 
                        // Check whether GetEnumerator is public
                        if ((mi.Attributes & MethodAttributes.Public) != MethodAttributes.Public)
@@ -4463,7 +4559,8 @@ namespace Mono.CSharp {
                        ig.Emit (OpCodes.Brfalse, end_try);
 
                        if (ec.InIterator)
-                               enumerator.EmitThis (ig);
+                               ig.Emit (OpCodes.Ldarg_0);
+                       
                        enumerator.EmitCall (ig, hm.get_current);
 
                        if (ec.InIterator){
@@ -4560,7 +4657,7 @@ namespace Mono.CSharp {
                                ig.MarkLabel (loop);
 
                                if (ec.InIterator)
-                                       ec.EmitThis ();
+                                       ig.Emit (OpCodes.Ldarg_0);
                                
                                copy.EmitThis (ig);
                                copy.EmitLoad (ig);
@@ -4629,7 +4726,8 @@ namespace Mono.CSharp {
                                }
 
                                if (ec.InIterator)
-                                       ec.EmitThis ();
+                                       ig.Emit (OpCodes.Ldarg_0);
+                               
                                copy.EmitThis (ig);
                                copy.EmitLoad (ig);
                                for (dim = 0; dim < rank; dim++){