C#: Handle discard variable declarations in switch expressions

hvitved · hvitved · commit 741380e97e1a · 2019-05-28T16:57:37.000+02:00
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/IsPattern.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/IsPattern.cs
@@ -18,13 +18,20 @@ public static Expression CreatePattern(this Context cx, PatternSyntax syntax, IE
                 case DeclarationPatternSyntax declPattern:
                     // Creates a single local variable declaration.
                     {
-                        if (declPattern.Designation is VariableDesignationSyntax designation && cx.Model(syntax).GetDeclaredSymbol(designation) is ILocalSymbol symbol)
+                        if (declPattern.Designation is VariableDesignationSyntax designation)
                         {
-                            var type = Type.Create(cx, symbol.Type);
-
-                            return VariableDeclaration.Create(cx, symbol, type, cx.Create(syntax.GetLocation()), cx.Create(designation.GetLocation()), false, parent, child);
+                            if (cx.Model(syntax).GetDeclaredSymbol(designation) is ILocalSymbol symbol)
+                            {
+                                var type = Type.Create(cx, symbol.Type);
+                                return VariableDeclaration.Create(cx, symbol, type, declPattern.Type, cx.Create(syntax.GetLocation()), cx.Create(designation.GetLocation()), false, parent, child);
+                            }
+                            if (designation is DiscardDesignationSyntax)
+                            {
+                                return Expressions.TypeAccess.Create(cx, declPattern.Type, parent, child);
+                            }
+                            throw new InternalError(designation, "Designation pattern not handled");
                         }
-                        throw new InternalError(syntax, "Is pattern not handled");
+                        throw new InternalError(declPattern, "Declaration pattern not handled");
                     }
 
                 case RecursivePatternSyntax recPattern:
@@ -40,7 +47,7 @@ public static Expression CreatePattern(this Context cx, PatternSyntax syntax, IE
                             {
                                 var type = Type.Create(cx, symbol.Type);
 
-                                return VariableDeclaration.Create(cx, symbol, type, cx.Create(syntax.GetLocation()), cx.Create(varDesignation.GetLocation()), false, parent, child);
+                                return VariableDeclaration.Create(cx, symbol, type, null, cx.Create(syntax.GetLocation()), cx.Create(varDesignation.GetLocation()), false, parent, child);
                             }
                             else
                             {
@@ -54,7 +61,7 @@ public static Expression CreatePattern(this Context cx, PatternSyntax syntax, IE
                     return new Discard(cx, dp, parent, child);
 
                 default:
-                    throw new InternalError(syntax, "Is pattern not handled");
+                    throw new InternalError(syntax, "Pattern not handled");
             }
         }
     }
@@ -108,7 +115,7 @@ public RecursivePattern(Context cx, RecursivePatternSyntax syntax, IExpressionPa
             {
                 var type = Type.Create(cx, symbol.Type);
 
-                VariableDeclaration.Create(cx, symbol, type, cx.Create(syntax.GetLocation()), cx.Create(designation.GetLocation()), false, this, 0);
+                VariableDeclaration.Create(cx, symbol, type, null, cx.Create(syntax.GetLocation()), cx.Create(designation.GetLocation()), false, this, 0);
             }
 
             if (syntax.PositionalPatternClause is PositionalPatternClauseSyntax posPc)
@@ -135,7 +142,7 @@ private void PopulatePattern(PatternSyntax pattern, TypeSyntax optionalType, Syn
             if (!(designation is null) && cx.Model(pattern).GetDeclaredSymbol(designation) is ILocalSymbol symbol)
             {
                 var type = Type.Create(cx, symbol.Type);
-                VariableDeclaration.Create(cx, symbol, type, cx.Create(pattern.GetLocation()), cx.Create(designation.GetLocation()), isVar, this, 2);
+                VariableDeclaration.Create(cx, symbol, type, optionalType, cx.Create(pattern.GetLocation()), cx.Create(designation.GetLocation()), isVar, this, 1);
             }
             else if (!isVar)
                 Expressions.TypeAccess.Create(cx, optionalType, this, 1);
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Query.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Query.cs
@@ -66,19 +66,21 @@ protected Expression DeclareRangeVariable(Context cx, IExpressionParentEntity pa
                 Extraction.Entities.Location nameLoc;
 
                 Type declType;
+                TypeSyntax declTypeSyntax = null;
                 if (getElement)
                 {
                     var from = node as FromClauseSyntax;
-                    declType = from != null && from.Type != null
-                         ? Type.Create(cx, cx.GetType(from.Type))
-                         : type.ElementType;
+                    (declType, declTypeSyntax) = from != null && from.Type != null
+                         ? (Type.Create(cx, cx.GetType(from.Type)), from.Type)
+                         : (type.ElementType, null);
                 }
                 else
                     declType = type;
 
                 var decl = VariableDeclaration.Create(cx,
                     variableSymbol,
                     declType,
+                    declTypeSyntax,
                     cx.Create(node.GetLocation()),
                     nameLoc = cx.Create(name.GetLocation()),
                     true,
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Switch.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Switch.cs
@@ -18,7 +18,7 @@ protected override void Populate()
         {
             SwitchedExpr = Expression.Create(cx, Syntax.GoverningExpression, this, -1);
             int child = 0;
-            foreach(var arm in Syntax.Arms)
+            foreach (var arm in Syntax.Arms)
             {
                 new SwitchCase(cx, arm, this, child++);
             }
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/VariableDeclaration.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/VariableDeclaration.cs
@@ -11,10 +11,15 @@ class VariableDeclaration : Expression
     {
         VariableDeclaration(IExpressionInfo info) : base(info) { }
 
-        public static VariableDeclaration Create(Context cx, ISymbol symbol, Type type, Extraction.Entities.Location exprLocation, Extraction.Entities.Location declLocation, bool isVar, IExpressionParentEntity parent, int child)
+        public static VariableDeclaration Create(Context cx, ISymbol symbol, Type type, TypeSyntax mention, Extraction.Entities.Location exprLocation, Extraction.Entities.Location declLocation, bool isVar, IExpressionParentEntity parent, int child)
         {
             var ret = new VariableDeclaration(new ExpressionInfo(cx, type, exprLocation, ExprKind.LOCAL_VAR_DECL, parent, child, false, null));
-            cx.Try(null, null, () => LocalVariable.Create(cx, symbol, ret, isVar, declLocation));
+            cx.Try(null, null, () =>
+            {
+                LocalVariable.Create(cx, symbol, ret, isVar, declLocation);
+                if (mention != null)
+                    TypeMention.Create(cx, mention, parent, type);
+            });
             return ret;
         }
 
@@ -65,7 +70,7 @@ public static Expression CreateParenthesized(Context cx, VarPatternSyntax varPat
             {
                 var child0 = 0;
                 foreach (var variable in designation.Variables)
-                    switch(variable)
+                    switch (variable)
                     {
                         case ParenthesizedVariableDesignationSyntax paren:
                             CreateParenthesized(cx, varPattern, paren, tuple, child0++);
@@ -97,7 +102,7 @@ public static Expression CreateParenthesized(Context cx, VarPatternSyntax varPat
 
         static Expression Create(Context cx, DeclarationExpressionSyntax node, VariableDesignationSyntax designation, IExpressionParentEntity parent, int child)
         {
-            switch(designation)
+            switch (designation)
             {
                 case SingleVariableDesignationSyntax single:
                     return CreateSingle(cx, node, single, parent, child);
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Statements/Case.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Statements/Case.cs
@@ -76,7 +76,7 @@ private void PopulatePattern(PatternSyntax pattern, TypeSyntax optionalType, Var
                     if (cx.Model(pattern).GetDeclaredSymbol(designation) is ILocalSymbol symbol)
                     {
                         var type = Type.Create(cx, symbol.Type);
-                        Expressions.VariableDeclaration.Create(cx, symbol, type, cx.Create(pattern.GetLocation()), cx.Create(designation.GetLocation()), isVar, this, 0);
+                        Expressions.VariableDeclaration.Create(cx, symbol, type, optionalType, cx.Create(pattern.GetLocation()), cx.Create(designation.GetLocation()), isVar, this, 0);
                     }
                     break;
                 case DiscardDesignationSyntax discard:
diff --git a/csharp/extractor/Semmle.Extraction.CSharp/Entities/Statements/ForEach.cs b/csharp/extractor/Semmle.Extraction.CSharp/Entities/Statements/ForEach.cs
@@ -27,8 +27,9 @@ protected override void Populate()
             var location = cx.Create(Stmt.Identifier.GetLocation());
 
             if (typeSymbol.Name != "_")
-                Expressions.VariableDeclaration.Create(cx, typeSymbol, type, location, location, Stmt.Type.IsVar, this, 0);
-            TypeMention.Create(cx, Stmt.Type, this, type);
+                Expressions.VariableDeclaration.Create(cx, typeSymbol, type, Stmt.Type, location, location, Stmt.Type.IsVar, this, 0);
+            else
+                TypeMention.Create(cx, Stmt.Type, this, type);
 
             Statement.Create(cx, Stmt.Statement, this, 2);
         }
diff --git a/csharp/ql/test/library-tests/controlflow/graph/EntryElement.expected b/csharp/ql/test/library-tests/controlflow/graph/EntryElement.expected
@@ -1241,11 +1241,9 @@
 | Switch.cs:46:17:46:17 | access to parameter o | Switch.cs:46:17:46:17 | access to parameter o |
 | Switch.cs:48:13:48:23 | case ...: | Switch.cs:48:13:48:23 | case ...: |
 | Switch.cs:48:18:48:20 | access to type Int32 | Switch.cs:48:18:48:20 | access to type Int32 |
-| Switch.cs:48:22:48:22 | _ | Switch.cs:48:22:48:22 | _ |
 | Switch.cs:49:17:49:22 | break; | Switch.cs:49:17:49:22 | break; |
 | Switch.cs:50:13:50:39 | case ...: | Switch.cs:50:13:50:39 | case ...: |
 | Switch.cs:50:18:50:21 | access to type Boolean | Switch.cs:50:18:50:21 | access to type Boolean |
-| Switch.cs:50:23:50:23 | _ | Switch.cs:50:23:50:23 | _ |
 | Switch.cs:50:30:50:30 | access to parameter o | Switch.cs:50:30:50:30 | access to parameter o |
 | Switch.cs:50:30:50:38 | ... != ... | Switch.cs:50:30:50:30 | access to parameter o |
 | Switch.cs:50:35:50:38 | null | Switch.cs:50:35:50:38 | null |
@@ -1267,7 +1265,6 @@
 | Switch.cs:68:25:68:25 | access to parameter s | Switch.cs:68:25:68:25 | access to parameter s |
 | Switch.cs:70:13:70:24 | case ...: | Switch.cs:70:13:70:24 | case ...: |
 | Switch.cs:70:18:70:20 | access to type Int32 | Switch.cs:70:18:70:20 | access to type Int32 |
-| Switch.cs:70:22:70:22 | _ | Switch.cs:70:22:70:22 | _ |
 | Switch.cs:71:15:71:20 | break; | Switch.cs:71:15:71:20 | break; |
 | Switch.cs:72:13:72:21 | case ...: | Switch.cs:72:13:72:21 | case ...: |
 | Switch.cs:72:18:72:19 | "" | Switch.cs:72:18:72:19 | "" |
@@ -1295,7 +1292,6 @@
 | Switch.cs:93:17:93:17 | access to parameter o | Switch.cs:93:17:93:17 | access to parameter o |
 | Switch.cs:95:13:95:24 | case ...: | Switch.cs:95:13:95:24 | case ...: |
 | Switch.cs:95:18:95:20 | access to type Int32 | Switch.cs:95:18:95:20 | access to type Int32 |
-| Switch.cs:95:22:95:22 | _ | Switch.cs:95:22:95:22 | _ |
 | Switch.cs:96:15:96:26 | return ...; | Switch.cs:96:22:96:25 | true |
 | Switch.cs:96:22:96:25 | true | Switch.cs:96:22:96:25 | true |
 | Switch.cs:98:9:98:21 | return ...; | Switch.cs:98:16:98:20 | false |
diff --git a/csharp/ql/test/library-tests/controlflow/graph/ExitElement.expected b/csharp/ql/test/library-tests/controlflow/graph/ExitElement.expected
@@ -1588,14 +1588,12 @@
 | Switch.cs:48:13:48:23 | case ...: | Switch.cs:49:17:49:22 | break; | break |
 | Switch.cs:48:18:48:20 | access to type Int32 | Switch.cs:48:18:48:20 | access to type Int32 | match |
 | Switch.cs:48:18:48:20 | access to type Int32 | Switch.cs:48:18:48:20 | access to type Int32 | no-match |
-| Switch.cs:48:22:48:22 | _ | Switch.cs:48:22:48:22 | _ | normal |
 | Switch.cs:49:17:49:22 | break; | Switch.cs:49:17:49:22 | break; | break |
 | Switch.cs:50:13:50:39 | case ...: | Switch.cs:50:18:50:21 | access to type Boolean | no-match |
 | Switch.cs:50:13:50:39 | case ...: | Switch.cs:50:30:50:38 | ... != ... | false/false |
 | Switch.cs:50:13:50:39 | case ...: | Switch.cs:51:17:51:22 | break; | break |
 | Switch.cs:50:18:50:21 | access to type Boolean | Switch.cs:50:18:50:21 | access to type Boolean | match |
 | Switch.cs:50:18:50:21 | access to type Boolean | Switch.cs:50:18:50:21 | access to type Boolean | no-match |
-| Switch.cs:50:23:50:23 | _ | Switch.cs:50:23:50:23 | _ | normal |
 | Switch.cs:50:30:50:30 | access to parameter o | Switch.cs:50:30:50:30 | access to parameter o | normal |
 | Switch.cs:50:30:50:38 | ... != ... | Switch.cs:50:30:50:38 | ... != ... | false/false |
 | Switch.cs:50:30:50:38 | ... != ... | Switch.cs:50:30:50:38 | ... != ... | true/true |
@@ -1626,7 +1624,6 @@
 | Switch.cs:70:13:70:24 | case ...: | Switch.cs:70:18:70:20 | access to type Int32 | no-match |
 | Switch.cs:70:13:70:24 | case ...: | Switch.cs:71:15:71:20 | break; | break |
 | Switch.cs:70:18:70:20 | access to type Int32 | Switch.cs:70:18:70:20 | access to type Int32 | no-match |
-| Switch.cs:70:22:70:22 | _ | Switch.cs:70:22:70:22 | _ | normal |
 | Switch.cs:71:15:71:20 | break; | Switch.cs:71:15:71:20 | break; | break |
 | Switch.cs:72:13:72:21 | case ...: | Switch.cs:72:18:72:19 | "" | no-match |
 | Switch.cs:72:13:72:21 | case ...: | Switch.cs:73:15:73:20 | break; | break |
@@ -1672,7 +1669,6 @@
 | Switch.cs:95:13:95:24 | case ...: | Switch.cs:96:15:96:26 | return ...; | return |
 | Switch.cs:95:18:95:20 | access to type Int32 | Switch.cs:95:18:95:20 | access to type Int32 | match |
 | Switch.cs:95:18:95:20 | access to type Int32 | Switch.cs:95:18:95:20 | access to type Int32 | no-match |
-| Switch.cs:95:22:95:22 | _ | Switch.cs:95:22:95:22 | _ | normal |
 | Switch.cs:96:15:96:26 | return ...; | Switch.cs:96:15:96:26 | return ...; | return |
 | Switch.cs:96:22:96:25 | true | Switch.cs:96:22:96:25 | true | normal |
 | Switch.cs:98:9:98:21 | return ...; | Switch.cs:98:9:98:21 | return ...; | return |
diff --git a/csharp/ql/test/library-tests/csharp7/Discards.expected b/csharp/ql/test/library-tests/csharp7/Discards.expected
@@ -6,4 +6,3 @@
 | CSharp7.cs:224:17:224:17 | _ | Double |
 | CSharp7.cs:224:28:224:28 | _ | Boolean |
 | CSharp7.cs:225:10:225:10 | _ | Int32 |
-| CSharp7.cs:267:25:267:25 | _ | null |
diff --git a/csharp/ql/test/library-tests/csharp8/patterns.cs b/csharp/ql/test/library-tests/csharp8/patterns.cs
@@ -137,7 +137,9 @@ void Expressions2(object o)
             {
                 1 => throw new ArgumentException(),
                 2 => 3,
-                object y when y is {} => 4
+                object y when y is {} => 4,
+                string _ => 5,
+                MyStruct { X: 10 } _ => 6
             };
         }
         catch(InvalidOperationException ex)
diff --git a/csharp/ql/test/library-tests/csharp8/patterns.expected b/csharp/ql/test/library-tests/csharp8/patterns.expected
@@ -3,7 +3,7 @@ switchExprs
 | patterns.cs:108:24:112:9 | ... switch { ... } | patterns.cs:108:24:108:31 | (..., ...) |
 | patterns.cs:115:20:120:9 | ... switch { ... } | patterns.cs:115:20:115:27 | (..., ...) |
 | patterns.cs:126:17:132:9 | ... switch { ... } | patterns.cs:126:17:126:17 | access to local variable s |
-| patterns.cs:136:17:141:13 | ... switch { ... } | patterns.cs:136:17:136:17 | access to parameter o |
+| patterns.cs:136:17:143:13 | ... switch { ... } | patterns.cs:136:17:136:17 | access to parameter o |
 switchExprCases
 | patterns.cs:101:13:101:40 | ... => ... | patterns.cs:101:13:101:17 | Int32 y | patterns.cs:101:34:101:40 | "large" |
 | patterns.cs:102:13:102:24 | ... => ... | patterns.cs:102:13:102:13 | _ | patterns.cs:102:18:102:24 | "small" |
@@ -19,6 +19,8 @@ switchExprCases
 | patterns.cs:138:17:138:50 | ... => ... | patterns.cs:138:17:138:17 | 1 | patterns.cs:138:22:138:50 | throw ... |
 | patterns.cs:139:17:139:22 | ... => ... | patterns.cs:139:17:139:17 | 2 | patterns.cs:139:22:139:22 | 3 |
 | patterns.cs:140:17:140:42 | ... => ... | patterns.cs:140:17:140:24 | Object y | patterns.cs:140:42:140:42 | 4 |
+| patterns.cs:141:17:141:29 | ... => ... | patterns.cs:141:17:141:22 | access to type String | patterns.cs:141:29:141:29 | 5 |
+| patterns.cs:142:17:142:41 | ... => ... | patterns.cs:142:17:142:36 | { ... } | patterns.cs:142:41:142:41 | 6 |
 switchFilters
 | patterns.cs:101:13:101:40 | ... => ... | patterns.cs:101:24:101:29 | ... > ... |
 | patterns.cs:128:13:128:49 | ... => ... | patterns.cs:128:40:128:44 | ... > ... |
@@ -39,6 +41,7 @@ propertyPatterns
 | patterns.cs:128:22:128:33 | { ... } |
 | patterns.cs:129:22:129:30 | { ... } |
 | patterns.cs:140:36:140:37 | { ... } |
+| patterns.cs:142:26:142:34 | { ... } |
 propertyPatternChild
 | patterns.cs:13:27:13:38 | { ... } | 0 | patterns.cs:13:32:13:36 | Int32 x |
 | patterns.cs:22:27:22:53 | { ... } | 0 | patterns.cs:22:31:22:32 | 12 |
@@ -54,6 +57,7 @@ propertyPatternChild
 | patterns.cs:70:27:70:35 | { ... } | 0 | patterns.cs:70:32:70:33 | 10 |
 | patterns.cs:128:22:128:33 | { ... } | 0 | patterns.cs:128:27:128:31 | Int32 x |
 | patterns.cs:129:22:129:30 | { ... } | 0 | patterns.cs:129:27:129:28 | 10 |
+| patterns.cs:142:26:142:34 | { ... } | 0 | patterns.cs:142:31:142:32 | 10 |
 positionalPatterns
 | patterns.cs:57:18:57:23 | ( ... ) | patterns.cs:57:18:57:23 | { ... } | 0 | patterns.cs:57:19:57:19 | 1 |
 | patterns.cs:57:18:57:23 | ( ... ) | patterns.cs:57:18:57:23 | { ... } | 1 | patterns.cs:57:22:57:22 | 2 |
@@ -145,6 +149,7 @@ recursivePatterns
 | patterns.cs:129:13:129:33 | { ... } |
 | patterns.cs:130:13:130:18 | { ... } |
 | patterns.cs:140:36:140:37 | { ... } |
+| patterns.cs:142:17:142:36 | { ... } |
 discards
 | patterns.cs:27:51:27:51 | _ |
 | patterns.cs:94:22:94:22 | _ |
@@ -181,3 +186,4 @@ labeledPatternExpr
 | patterns.cs:70:32:70:33 | 10 | X |
 | patterns.cs:128:27:128:31 | Int32 x | X |
 | patterns.cs:129:27:129:28 | 10 | X |
+| patterns.cs:142:31:142:32 | 10 | X |
diff --git a/csharp/ql/test/library-tests/csharp8/switchexprcontrolflow.expected b/csharp/ql/test/library-tests/csharp8/switchexprcontrolflow.expected

Original file line number	Diff line number	Diff line change
`@@ -18,13 +18,20 @@ public static Expression CreatePattern(this Context cx, PatternSyntax syntax, IE`
`18`	`18`	`case DeclarationPatternSyntax declPattern:`
`19`	`19`	`// Creates a single local variable declaration.`
`20`	`20`	`{`
`21`		`- if (declPattern.Designation is VariableDesignationSyntax designation && cx.Model(syntax).GetDeclaredSymbol(designation) is ILocalSymbol symbol)`
	`21`	`+ if (declPattern.Designation is VariableDesignationSyntax designation)`
`22`	`22`	`{`
`23`		`- var type = Type.Create(cx, symbol.Type);`
`24`		`-`
`25`		`- return VariableDeclaration.Create(cx, symbol, type, cx.Create(syntax.GetLocation()), cx.Create(designation.GetLocation()), false, parent, child);`
	`23`	`+ if (cx.Model(syntax).GetDeclaredSymbol(designation) is ILocalSymbol symbol)`
	`24`	`+ {`
	`25`	`+ var type = Type.Create(cx, symbol.Type);`
	`26`	`+ return VariableDeclaration.Create(cx, symbol, type, declPattern.Type, cx.Create(syntax.GetLocation()), cx.Create(designation.GetLocation()), false, parent, child);`
	`27`	`+ }`
	`28`	`+ if (designation is DiscardDesignationSyntax)`
	`29`	`+ {`
	`30`	`+ return Expressions.TypeAccess.Create(cx, declPattern.Type, parent, child);`
	`31`	`+ }`
	`32`	`+ throw new InternalError(designation, "Designation pattern not handled");`
`26`	`33`	`}`
`27`		`- throw new InternalError(syntax, "Is pattern not handled");`
	`34`	`+ throw new InternalError(declPattern, "Declaration pattern not handled");`
`28`	`35`	`}`
`29`	`36`
`30`	`37`	`case RecursivePatternSyntax recPattern:`
`@@ -40,7 +47,7 @@ public static Expression CreatePattern(this Context cx, PatternSyntax syntax, IE`
`40`	`47`	`{`
`41`	`48`	`var type = Type.Create(cx, symbol.Type);`
`42`	`49`
`43`		`- return VariableDeclaration.Create(cx, symbol, type, cx.Create(syntax.GetLocation()), cx.Create(varDesignation.GetLocation()), false, parent, child);`
	`50`	`+ return VariableDeclaration.Create(cx, symbol, type, null, cx.Create(syntax.GetLocation()), cx.Create(varDesignation.GetLocation()), false, parent, child);`
`44`	`51`	`}`
`45`	`52`	`else`
`46`	`53`	`{`
`@@ -54,7 +61,7 @@ public static Expression CreatePattern(this Context cx, PatternSyntax syntax, IE`
`54`	`61`	`return new Discard(cx, dp, parent, child);`
`55`	`62`
`56`	`63`	`default:`
`57`		`- throw new InternalError(syntax, "Is pattern not handled");`
	`64`	`+ throw new InternalError(syntax, "Pattern not handled");`
`58`	`65`	`}`
`59`	`66`	`}`
`60`	`67`	`}`
`@@ -108,7 +115,7 @@ public RecursivePattern(Context cx, RecursivePatternSyntax syntax, IExpressionPa`
`108`	`115`	`{`
`109`	`116`	`var type = Type.Create(cx, symbol.Type);`
`110`	`117`
`111`		`- VariableDeclaration.Create(cx, symbol, type, cx.Create(syntax.GetLocation()), cx.Create(designation.GetLocation()), false, this, 0);`
	`118`	`+ VariableDeclaration.Create(cx, symbol, type, null, cx.Create(syntax.GetLocation()), cx.Create(designation.GetLocation()), false, this, 0);`
`112`	`119`	`}`
`113`	`120`
`114`	`121`	`if (syntax.PositionalPatternClause is PositionalPatternClauseSyntax posPc)`
`@@ -135,7 +142,7 @@ private void PopulatePattern(PatternSyntax pattern, TypeSyntax optionalType, Syn`
`135`	`142`	`if (!(designation is null) && cx.Model(pattern).GetDeclaredSymbol(designation) is ILocalSymbol symbol)`
`136`	`143`	`{`
`137`	`144`	`var type = Type.Create(cx, symbol.Type);`
`138`		`- VariableDeclaration.Create(cx, symbol, type, cx.Create(pattern.GetLocation()), cx.Create(designation.GetLocation()), isVar, this, 2);`
	`145`	`+ VariableDeclaration.Create(cx, symbol, type, optionalType, cx.Create(pattern.GetLocation()), cx.Create(designation.GetLocation()), isVar, this, 1);`
`139`	`146`	`}`
`140`	`147`	`else if (!isVar)`
`141`	`148`	`Expressions.TypeAccess.Create(cx, optionalType, this, 1);`
Original file line number	Diff line number	Diff line change
`@@ -18,7 +18,7 @@ protected override void Populate()`
`18`	`18`	`{`
`19`	`19`	`SwitchedExpr = Expression.Create(cx, Syntax.GoverningExpression, this, -1);`
`20`	`20`	`int child = 0;`
`21`		`- foreach(var arm in Syntax.Arms)`
	`21`	`+ foreach (var arm in Syntax.Arms)`
`22`	`22`	`{`
`23`	`23`	`new SwitchCase(cx, arm, this, child++);`
`24`	`24`	`}`
Original file line number	Diff line number	Diff line change
`@@ -11,10 +11,15 @@ class VariableDeclaration : Expression`
`11`	`11`	`{`
`12`	`12`	`VariableDeclaration(IExpressionInfo info) : base(info) { }`
`13`	`13`
`14`		`- public static VariableDeclaration Create(Context cx, ISymbol symbol, Type type, Extraction.Entities.Location exprLocation, Extraction.Entities.Location declLocation, bool isVar, IExpressionParentEntity parent, int child)`
	`14`	`+ public static VariableDeclaration Create(Context cx, ISymbol symbol, Type type, TypeSyntax mention, Extraction.Entities.Location exprLocation, Extraction.Entities.Location declLocation, bool isVar, IExpressionParentEntity parent, int child)`
`15`	`15`	`{`
`16`	`16`	`var ret = new VariableDeclaration(new ExpressionInfo(cx, type, exprLocation, ExprKind.LOCAL_VAR_DECL, parent, child, false, null));`
`17`		`- cx.Try(null, null, () => LocalVariable.Create(cx, symbol, ret, isVar, declLocation));`
	`17`	`+ cx.Try(null, null, () =>`
	`18`	`+ {`
	`19`	`+ LocalVariable.Create(cx, symbol, ret, isVar, declLocation);`
	`20`	`+ if (mention != null)`
	`21`	`+ TypeMention.Create(cx, mention, parent, type);`
	`22`	`+ });`
`18`	`23`	`return ret;`
`19`	`24`	`}`
`20`	`25`
`@@ -65,7 +70,7 @@ public static Expression CreateParenthesized(Context cx, VarPatternSyntax varPat`
`65`	`70`	`{`
`66`	`71`	`var child0 = 0;`
`67`	`72`	`foreach (var variable in designation.Variables)`
`68`		`- switch(variable)`
	`73`	`+ switch (variable)`
`69`	`74`	`{`
`70`	`75`	`case ParenthesizedVariableDesignationSyntax paren:`
`71`	`76`	`CreateParenthesized(cx, varPattern, paren, tuple, child0++);`
`@@ -97,7 +102,7 @@ public static Expression CreateParenthesized(Context cx, VarPatternSyntax varPat`
`97`	`102`
`98`	`103`	`static Expression Create(Context cx, DeclarationExpressionSyntax node, VariableDesignationSyntax designation, IExpressionParentEntity parent, int child)`
`99`	`104`	`{`
`100`		`- switch(designation)`
	`105`	`+ switch (designation)`
`101`	`106`	`{`
`102`	`107`	`case SingleVariableDesignationSyntax single:`
`103`	`108`	`return CreateSingle(cx, node, single, parent, child);`
Original file line number	Diff line number	Diff line change
`@@ -76,7 +76,7 @@ private void PopulatePattern(PatternSyntax pattern, TypeSyntax optionalType, Var`
`76`	`76`	`if (cx.Model(pattern).GetDeclaredSymbol(designation) is ILocalSymbol symbol)`
`77`	`77`	`{`
`78`	`78`	`var type = Type.Create(cx, symbol.Type);`
`79`		`- Expressions.VariableDeclaration.Create(cx, symbol, type, cx.Create(pattern.GetLocation()), cx.Create(designation.GetLocation()), isVar, this, 0);`
	`79`	`+ Expressions.VariableDeclaration.Create(cx, symbol, type, optionalType, cx.Create(pattern.GetLocation()), cx.Create(designation.GetLocation()), isVar, this, 0);`
`80`	`80`	`}`
`81`	`81`	`break;`
`82`	`82`	`case DiscardDesignationSyntax discard:`
Original file line number	Diff line number	Diff line change
`@@ -137,7 +137,9 @@ void Expressions2(object o)`
`137`	`137`	`{`
`138`	`138`	`1 => throw new ArgumentException(),`
`139`	`139`	`2 => 3,`
`140`		`- object y when y is {} => 4`
	`140`	`+ object y when y is {} => 4,`
	`141`	`+ string _ => 5,`
	`142`	`+ MyStruct { X: 10 } _ => 6`
`141`	`143`	`};`
`142`	`144`	`}`
`143`	`145`	`catch(InvalidOperationException ex)`