Merge pull request #1392 from calumgrant/cs/cs8/static-using-null

C#: More C# 8 features

change-notes/1.21/analysis-csharp.md

@@ -13,6 +13,10 @@
 * The following C# 8 features are now extracted:
     - Range expressions
     - Recursive patterns
+    - Using declaration statements
+    - `static` modifiers on local functions
+    - Null-coalescing assignment expressions
+
 * The `unmanaged` type parameter constraint is now extracted.
 
 ## Changes to QL libraries
@@ -20,6 +24,7 @@
 * The class `Attribute` has two new predicates: `getConstructorArgument()` and `getNamedArgument()`. The first predicate returns arguments to the underlying constructor call and the latter returns named arguments for initializing fields and properties.
 * The class `TypeParameterConstraints` has a new predicate `hasUnmanagedTypeConstraint()`, indicating that the type parameter has the `unmanaged` constraint.
 * The following QL classes have been added to model C# 8 features:
+    - Class `AssignCoalesceExpr` models null-coalescing assignment, for example `x ??= y`
     - Class `IndexExpr` models from-end index expressions, for example `^1`
     - Class `PatternExpr` is an `Expr` that appears in a pattern. It has the new subclasses `DiscardPatternExpr`, `LabeledPatternExpr`, `RecursivePatternExpr`, `TypeAccessPatternExpr`, `TypePatternExpr`, and `VariablePatternExpr`.
     - Class `PatternMatch` models a pattern being matched. It has the subclasses `Case` and `IsExpr`.
@@ -31,5 +36,6 @@
     - Classes `IsConstantExpr`, `IsTypeExpr` and `IsPatternExpr` are deprecated in favour of `IsExpr`
     - Class `Switch` models both `SwitchExpr` and `SwitchStmt`
     - Class `Case` models both `CaseStmt` and `SwitchCaseExpr`
+    - Class `UsingStmt` models both `UsingBlockStmt` and `UsingDeclStmt`
 
 ## Changes to autobuilder

csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Assignment.cs

@@ -71,6 +71,8 @@ namespace Semmle.Extraction.CSharp.Entities.Expressions
                     return ExprKind.ASSIGN_LSHIFT;
                 case SyntaxKind.GreaterThanGreaterThanEqualsToken:
                     return ExprKind.ASSIGN_RSHIFT;
+                case SyntaxKind.QuestionQuestionEqualsToken:
+                    return ExprKind.ASSIGN_COALESCE;
                 default:
                     cx.ModelError(syntax, "Unrecognised assignment type " + GetKind(cx, syntax));
                     return ExprKind.UNKNOWN;
@@ -142,6 +144,8 @@ namespace Semmle.Extraction.CSharp.Entities.Expressions
                         return ExprKind.SUB;
                     case ExprKind.ASSIGN_XOR:
                         return ExprKind.BIT_XOR;
+                    case ExprKind.ASSIGN_COALESCE:
+                        return ExprKind.NULL_COALESCING;
                     default:
                         cx.ModelError(Syntax, "Couldn't unfold assignment of type " + kind);
                         return ExprKind.UNKNOWN;

csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Factory.cs

@@ -80,6 +80,7 @@ namespace Semmle.Extraction.CSharp.Entities.Expressions
                     case SyntaxKind.RightShiftAssignmentExpression:
                     case SyntaxKind.DivideAssignmentExpression:
                     case SyntaxKind.ModuloAssignmentExpression:
+                    case SyntaxKind.CoalesceAssignmentExpression:
                         return Assignment.Create(info);
 
                     case SyntaxKind.ObjectCreationExpression:

csharp/extractor/Semmle.Extraction.CSharp/Entities/LocalFunction.cs

@@ -1,4 +1,6 @@
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using System.Linq;
 
 namespace Semmle.Extraction.CSharp.Entities
 {
@@ -39,6 +41,18 @@ namespace Semmle.Extraction.CSharp.Entities
         public override void Populate()
         {
             PopulateMethod();
+
+            // There is a "bug" in Roslyn whereby the IMethodSymbol associated with the local function symbol
+            // is always static, so we need to go to the syntax reference of the local function to see whether
+            // the "static" modifier is present.
+            if (symbol.DeclaringSyntaxReferences.SingleOrDefault().GetSyntax() is LocalFunctionStatementSyntax fn)
+            {
+                foreach(var modifier in fn.Modifiers)
+                {
+                    Modifier.HasModifier(Context, this, modifier.Text);
+                }
+            }
+
             var originalDefinition = IsSourceDeclaration ? this : Create(Context, symbol.OriginalDefinition);
             var returnType = Type.Create(Context, symbol.ReturnType);
             Context.Emit(Tuples.local_functions(this, symbol.Name, returnType, originalDefinition));

csharp/extractor/Semmle.Extraction.CSharp/Entities/Statements/LocalDeclaration.cs

@@ -6,8 +6,19 @@ namespace Semmle.Extraction.CSharp.Entities.Statements
 {
     class LocalDeclaration : Statement<LocalDeclarationStatementSyntax>
     {
+        static StmtKind GetKind(LocalDeclarationStatementSyntax declStmt)
+        {
+            if (declStmt.UsingKeyword.RawKind != 0)
+                return StmtKind.USING_DECL;
+
+            if (declStmt.IsConst)
+                return StmtKind.CONST_DECL;
+
+            return StmtKind.VAR_DECL;
+        }
+
         LocalDeclaration(Context cx, LocalDeclarationStatementSyntax declStmt, IStatementParentEntity parent, int child)
-            : base(cx, declStmt, declStmt.IsConst ? StmtKind.CONST_DECL : StmtKind.VAR_DECL, parent, child) { }
+            : base(cx, declStmt, GetKind(declStmt), parent, child) { }
 
         public static LocalDeclaration Create(Context cx, LocalDeclarationStatementSyntax node, IStatementParentEntity parent, int child)
         {

csharp/extractor/Semmle.Extraction.CSharp/Kinds/ExprKind.cs

@@ -112,6 +112,7 @@ namespace Semmle.Extraction.Kinds
         RECURSIVE_PATTERN = 115,
         PROPERTY_PATTERN = 116,
         POSITIONAL_PATTERN = 117,
-        SWITCH_CASE = 118
+        SWITCH_CASE = 118,
+        ASSIGN_COALESCE = 119 
     }
 }

csharp/extractor/Semmle.Extraction.CSharp/Kinds/StmtKind.cs

@@ -34,6 +34,7 @@ namespace Semmle.Extraction.Kinds  // lgtm[cs/similar-file]
         LABEL = 27,
         CATCH = 28,
         CASE = 29,
-        LOCAL_FUNCTION = 30
+        LOCAL_FUNCTION = 30,
+        USING_DECL = 31
     }
 }

csharp/ql/src/semmle/code/csharp/Callable.qll

@@ -903,7 +903,7 @@ class ExplicitConversionOperator extends ConversionOperator {
  * }
  * ```
  */
-class LocalFunction extends Callable, @local_function {
+class LocalFunction extends Callable, Modifiable, @local_function {
   override string getName() { local_functions(this, result, _, _) }
 
   override LocalFunction getSourceDeclaration() { local_functions(this, _, _, result) }

csharp/ql/src/semmle/code/csharp/Stmt.qll

@@ -1115,40 +1115,16 @@ class LockStmt extends Stmt, @lock_stmt {
 }
 
 /**
- * A `using` statement, for example
- *
- * ```
- * using (FileStream f = File.Open("settings.xml")) {
- *   ...
- * }
- * ```
+ * A using block or declaration. Either a using declaration (`UsingDeclStmt`) or
+ * a using block (`UsingBlockStmt`).
  */
 class UsingStmt extends Stmt, @using_stmt {
-  /** Gets the `i`th local variable of this `using` statement. */
-  LocalVariable getVariable(int i) { result = this.getVariableDeclExpr(i).getVariable() }
-
-  /** Gets a local variable of this `using` statement. */
-  LocalVariable getAVariable() { result = this.getVariable(_) }
-
   /** Gets the `i`th local variable declaration of this `using` statement. */
-  LocalVariableDeclExpr getVariableDeclExpr(int i) { result = this.getChild(-i - 1) }
+  LocalVariableDeclExpr getVariableDeclExpr(int i) { none() }
 
   /** Gets a local variable declaration of this `using` statement. */
   LocalVariableDeclExpr getAVariableDeclExpr() { result = this.getVariableDeclExpr(_) }
 
-  /**
-   * Gets the expression directly used by this `using` statement, if any. For
-   * example, `f` on line 2 in
-   *
-   * ```
-   * var f = File.Open("settings.xml");
-   * using (f) {
-   *   ...
-   * }
-   * ```
-   */
-  Expr getExpr() { result = this.getChild(0) }
-
   /**
    * Gets an expression that is used in this `using` statement. Either an
    * expression assigned to a variable, for example `File.Open("settings.xml")`
@@ -1169,14 +1145,69 @@ class UsingStmt extends Stmt, @using_stmt {
    * }
    * ```
    */
-  Expr getAnExpr() {
+  Expr getAnExpr() { none() }
+
+  /**
+   * DEPRECATED: Use UsingBlockStmt.getExpr() instead.
+   * Gets the expression directly used by this `using` statement, if any. For
+   * example, `f` on line 2 in
+   *
+   * ```
+   * var f = File.Open("settings.xml");
+   * using (f) {
+   *   ...
+   * }
+   * ```
+   */
+  deprecated Expr getExpr() { none() }
+
+  /**
+   * DEPRECATED: Use UsingBlockStmt.getBody() instead.
+   * Gets the body of this `using` statement.
+   */
+  deprecated Stmt getBody() { none() }
+}
+
+/**
+ * A `using` block statement, for example
+ *
+ * ```
+ * using (FileStream f = File.Open("settings.xml")) {
+ *   ...
+ * }
+ * ```
+ */
+class UsingBlockStmt extends UsingStmt, @using_block_stmt {
+  /** Gets the `i`th local variable of this `using` statement. */
+  LocalVariable getVariable(int i) { result = this.getVariableDeclExpr(i).getVariable() }
+
+  /** Gets a local variable of this `using` statement. */
+  LocalVariable getAVariable() { result = this.getVariable(_) }
+
+  /** Gets the `i`th local variable declaration of this `using` statement. */
+  override LocalVariableDeclExpr getVariableDeclExpr(int i) { result = this.getChild(-i - 1) }
+
+  /**
+   * Gets the expression directly used by this `using` statement, if any. For
+   * example, `f` on line 2 in
+   *
+   * ```
+   * var f = File.Open("settings.xml");
+   * using (f) {
+   *   ...
+   * }
+   * ```
+   */
+  override Expr getExpr() { result = this.getChild(0) }
+
+  override Expr getAnExpr() {
     result = this.getAVariableDeclExpr().getInitializer()
     or
     result = this.getExpr()
   }
 
   /** Gets the body of this `using` statement. */
-  Stmt getBody() { result.getParent() = this }
+  override Stmt getBody() { result.getParent() = this }
 
   override string toString() { result = "using (...) {...}" }
 }
@@ -1254,6 +1285,29 @@ class LocalConstantDeclStmt extends LocalVariableDeclStmt, @const_decl_stmt {
   override string toString() { result = "const ... ...;" }
 }
 
+/**
+ * A `using` declaration statement, for example
+ *
+ * ```
+ * using FileStream f = File.Open("settings.xml");
+ * ```
+ */
+class UsingDeclStmt extends LocalVariableDeclStmt, UsingStmt, @using_decl_stmt {
+  override string toString() { result = "using ... ...;" }
+
+  override LocalVariableDeclExpr getAVariableDeclExpr() {
+    result = LocalVariableDeclStmt.super.getAVariableDeclExpr()
+  }
+
+  override LocalVariableDeclExpr getVariableDeclExpr(int n) {
+    result = LocalVariableDeclStmt.super.getVariableDeclExpr(n)
+  }
+
+  override Expr getAnExpr() {
+    result = this.getAVariableDeclExpr().getInitializer()
+  }
+}
+
 /**
  * An empty statement, for example line 2 in
  *

csharp/ql/src/semmle/code/csharp/controlflow/ControlFlowGraph.qll

@@ -468,7 +468,7 @@ module ControlFlow {
         override ControlFlowElement getChildElement(int i) {
           not this instanceof GeneralCatchClause and
           not this instanceof FixedStmt and
-          not this instanceof UsingStmt and
+          not this instanceof UsingBlockStmt and
           result = this.getChild(i)
           or
           this = any(GeneralCatchClause gcc | i = 0 and result = gcc.getBlock())
@@ -480,7 +480,7 @@ module ControlFlow {
               i = max(int j | exists(fs.getVariableDeclExpr(j))) + 1
             )
           or
-          this = any(UsingStmt us |
+          this = any(UsingBlockStmt us |
               if exists(us.getExpr())
               then (
                 result = us.getExpr() and

csharp/ql/src/semmle/code/csharp/exprs/Assignment.qll

@@ -230,3 +230,10 @@ class AddEventExpr extends AddOrRemoveEventExpr, @add_event_expr {
 class RemoveEventExpr extends AddOrRemoveEventExpr, @remove_event_expr {
   override string toString() { result = "... -= ..." }
 }
+
+/**
+ * A null-coalescing assignment operation, for example `x ??= y`.
+ */
+class AssignCoalesceExpr extends AssignOperation, @assign_coalesce_expr {
+  override string toString() { result = "... ??= ..." }
+}

csharp/ql/src/semmlecode.csharp.dbscheme

@@ -526,7 +526,7 @@ specific_type_parameter_constraints(
 
 @modifiable = @modifiable_direct | @event_accessor;
 
-@modifiable_direct = @member | @accessor;
+@modifiable_direct = @member | @accessor | @local_function;
 
 modifiers(
   unique int id: @modifier,
@@ -798,7 +798,7 @@ case @stmt.kind of
 | 18 = @checked_stmt
 | 19 = @unchecked_stmt
 | 20 = @lock_stmt
-| 21 = @using_stmt
+| 21 = @using_block_stmt
 | 22 = @var_decl_stmt
 | 23 = @const_decl_stmt
 | 24 = @empty_stmt
@@ -808,11 +808,14 @@ case @stmt.kind of
 | 28 = @catch
 | 29 = @case_stmt
 | 30 = @local_function_stmt
+| 31 = @using_decl_stmt
   ;
 
+@using_stmt = @using_block_stmt | @using_decl_stmt;
+
 @labeled_stmt = @label_stmt | @case;
 
-@decl_stmt = @var_decl_stmt | @const_decl_stmt;
+@decl_stmt = @var_decl_stmt | @const_decl_stmt | @using_decl_stmt;
 
 @cond_stmt = @if_stmt | @switch_stmt;
 
@@ -983,6 +986,7 @@ case @expr.kind of
 | 116 = @property_pattern_expr
 | 117 = @positional_pattern_expr
 | 118 = @switch_case_expr
+| 119 = @assign_coalesce_expr
 ;
 
 @switch = @switch_stmt | @switch_expr;
@@ -995,7 +999,7 @@ case @expr.kind of
               | @string_literal_expr | @null_literal_expr;
 
 @assign_expr = @simple_assign_expr | @assign_op_expr | @local_var_decl_expr;
-@assign_op_expr =  @assign_arith_expr | @assign_bitwise_expr | @assign_event_expr;
+@assign_op_expr =  @assign_arith_expr | @assign_bitwise_expr | @assign_event_expr | @assign_coalesce_expr;
 @assign_event_expr = @add_event_expr | @remove_event_expr;
 
 @assign_arith_expr = @assign_add_expr | @assign_sub_expr | @assign_mul_expr | @assign_div_expr

csharp/ql/src/semmlecode.csharp.dbscheme.stats

@@ -360,10 +360,14 @@
 <v>1854</v>
 </e>
 <e>
-<k>@using_stmt</k>
+<k>@using_block_stmt</k>
 <v>5815</v>
 </e>
 <e>
+<k>@using_decl_stmt</k>
+<v>1000</v>
+</e>
+<e>
 <k>@var_decl_stmt</k>
 <v>243866</v>
 </e>
@@ -688,6 +692,10 @@
 <v>116</v>
 </e>
 <e>
+<k>@assign_coalesce_expr</k>
+<v>116</v>
+</e>
+<e>
 <k>@object_init_expr</k>
 <v>5320</v>
 </e>

csharp/ql/test/library-tests/assignables/AssignableAccess.expected

@@ -104,6 +104,7 @@
 | Assignables.cs:133:15:133:15 | access to local variable x | Assignables.cs:132:13:132:13 | x | read |
 | Assignables.cs:133:15:133:15 | access to local variable x | Assignables.cs:132:13:132:13 | x | write |
 | Assignables.cs:133:29:133:29 | String s | Assignables.cs:133:29:133:29 | s | write |
+| Assignables.cs:138:19:138:19 | access to local variable x | Assignables.cs:138:19:138:19 | x | write |
 | Discards.cs:7:9:7:9 | access to parameter x | Discards.cs:5:30:5:30 | x | write |
 | Discards.cs:20:32:20:32 | Boolean z | Discards.cs:20:32:20:32 | z | write |
 | Discards.cs:25:27:25:30 | access to parameter args | Discards.cs:23:27:23:30 | args | read |

csharp/ql/test/library-tests/assignables/AssignableDefinition.expected

@@ -87,6 +87,7 @@
 | Assignables.cs:132:13:132:13 | x | Assignables.cs:132:13:132:17 | Int32 x = ... | Assignables.cs:132:13:132:13 | access to local variable x | Assignables.cs:132:17:132:17 | 0 | certain |
 | Assignables.cs:132:13:132:13 | x | Assignables.cs:133:15:133:15 | access to local variable x | Assignables.cs:133:15:133:15 | access to local variable x | Assignables.cs:133:15:133:15 | <none> | certain |
 | Assignables.cs:133:29:133:29 | s | Assignables.cs:133:29:133:29 | String s | Assignables.cs:133:29:133:29 | String s | Assignables.cs:133:29:133:29 | <none> | certain |
+| Assignables.cs:138:19:138:19 | x | Assignables.cs:138:19:138:50 | MemoryStream x = ... | Assignables.cs:138:19:138:19 | access to local variable x | Assignables.cs:138:23:138:50 | object creation of type MemoryStream | certain |
 | Discards.cs:5:30:5:30 | x | Discards.cs:5:30:5:30 | x | Discards.cs:5:30:5:30 | <none> | Discards.cs:5:30:5:30 | <none> | certain |
 | Discards.cs:5:30:5:30 | x | Discards.cs:7:9:7:17 | ... = ... | Discards.cs:7:9:7:9 | access to parameter x | Discards.cs:7:13:7:17 | false | certain |
 | Discards.cs:19:14:19:14 | x | Discards.cs:19:9:19:29 | ... = ... | Discards.cs:19:9:19:29 | <none> | Discards.cs:19:9:19:29 | <none> | certain |

csharp/ql/test/library-tests/assignables/AssignableDefinitionNode.expected

@@ -86,6 +86,7 @@
 | Assignables.cs:132:13:132:17 | Int32 x = ... | Assignables.cs:132:13:132:17 | Int32 x = ... |
 | Assignables.cs:133:15:133:15 | access to local variable x | Assignables.cs:133:9:133:30 | delegate call |
 | Assignables.cs:133:29:133:29 | String s | Assignables.cs:133:9:133:30 | delegate call |
+| Assignables.cs:138:19:138:50 | MemoryStream x = ... | Assignables.cs:138:19:138:50 | MemoryStream x = ... |
 | Discards.cs:5:30:5:30 | x | Discards.cs:5:19:5:19 | enter f |
 | Discards.cs:7:9:7:17 | ... = ... | Discards.cs:7:9:7:17 | ... = ... |
 | Discards.cs:13:9:13:20 | ... = ... | Discards.cs:13:9:13:20 | ... = ... |

csharp/ql/test/library-tests/assignables/Assignables.cs

@@ -132,4 +132,11 @@ class Assignables
         var x = 0;
         d(ref x, out string s);
     }
+
+    void UsingDeclarations()
+    {
+        using var x = new System.IO.MemoryStream();
+    }
 }
+
+// semmle-extractor-options: /langversion:8.0

csharp/ql/test/library-tests/assignables/Assignables.expected

@@ -95,6 +95,7 @@
 | Assignables.cs:130:31:130:31 | d |
 | Assignables.cs:132:13:132:13 | x |
 | Assignables.cs:133:29:133:29 | s |
+| Assignables.cs:138:19:138:19 | x |
 | Discards.cs:5:6:5:8 | Item1 |
 | Discards.cs:5:11:5:16 | Item2 |
 | Discards.cs:5:30:5:30 | x |

csharp/ql/test/library-tests/assignables/GetAnAssignedValue.expected

@@ -37,6 +37,7 @@
 | Assignables.cs:125:13:125:13 | s | Assignables.cs:125:17:125:25 | nameof(...) |
 | Assignables.cs:125:13:125:13 | s | Assignables.cs:126:13:126:30 | nameof(...) |
 | Assignables.cs:132:13:132:13 | x | Assignables.cs:132:17:132:17 | 0 |
+| Assignables.cs:138:19:138:19 | x | Assignables.cs:138:23:138:50 | object creation of type MemoryStream |
 | Discards.cs:5:30:5:30 | x | Discards.cs:7:13:7:17 | false |
 | Finally.cs:7:13:7:13 | i | Finally.cs:7:17:7:17 | 0 |
 | Finally.cs:7:13:7:13 | i | Finally.cs:15:17:15:17 | 1 |

csharp/ql/test/library-tests/csharp8/NullCoalescingAssignment.cs

@@ -0,0 +1,10 @@
+using System;
+
+class NullCoalescingAssignment
+{
+    void NullCoalescing()
+    {
+        object o = null;
+        o ??= this;
+    }
+}

csharp/ql/test/library-tests/csharp8/NullCoalescingAssignment.expected

@@ -0,0 +1,4 @@
+nullcoalescing
+| NullCoalescingAssignment.cs:8:9:8:18 | ... ?? ... |
+assignments
+| NullCoalescingAssignment.cs:8:9:8:18 | ... ??= ... | NullCoalescingAssignment.cs:8:9:8:18 | ... = ... |

csharp/ql/test/library-tests/csharp8/NullCoalescingAssignment.ql

@@ -0,0 +1,7 @@
+import csharp
+
+query predicate nullcoalescing(NullCoalescingExpr expr) { any() }
+
+query predicate assignments(AssignCoalesceExpr expr, Expr expanded) {
+  expanded = expr.getExpandedAssignment()
+}

csharp/ql/test/library-tests/csharp8/NullCoalescingControlFlow.expected

@@ -0,0 +1,11 @@
+| NullCoalescingAssignment.cs:5:10:5:23 | enter NullCoalescing | NullCoalescingAssignment.cs:6:5:9:5 | {...} | semmle.label | successor |
+| NullCoalescingAssignment.cs:6:5:9:5 | {...} | NullCoalescingAssignment.cs:7:9:7:24 | ... ...; | semmle.label | successor |
+| NullCoalescingAssignment.cs:7:9:7:24 | ... ...; | NullCoalescingAssignment.cs:7:20:7:23 | null | semmle.label | successor |
+| NullCoalescingAssignment.cs:7:16:7:23 | Object o = ... | NullCoalescingAssignment.cs:8:9:8:19 | ...; | semmle.label | successor |
+| NullCoalescingAssignment.cs:7:20:7:23 | null | NullCoalescingAssignment.cs:7:16:7:23 | Object o = ... | semmle.label | successor |
+| NullCoalescingAssignment.cs:8:9:8:9 | access to local variable o | NullCoalescingAssignment.cs:8:9:8:18 | ... = ... | semmle.label | non-null |
+| NullCoalescingAssignment.cs:8:9:8:9 | access to local variable o | NullCoalescingAssignment.cs:8:15:8:18 | this access | semmle.label | null |
+| NullCoalescingAssignment.cs:8:9:8:18 | ... = ... | NullCoalescingAssignment.cs:5:10:5:23 | exit NullCoalescing | semmle.label | successor |
+| NullCoalescingAssignment.cs:8:9:8:18 | ... ?? ... | NullCoalescingAssignment.cs:8:9:8:9 | access to local variable o | semmle.label | successor |
+| NullCoalescingAssignment.cs:8:9:8:19 | ...; | NullCoalescingAssignment.cs:8:9:8:18 | ... ?? ... | semmle.label | successor |
+| NullCoalescingAssignment.cs:8:15:8:18 | this access | NullCoalescingAssignment.cs:8:9:8:18 | ... = ... | semmle.label | successor |

csharp/ql/test/library-tests/csharp8/NullCoalescingControlFlow.ql

@@ -0,0 +1,10 @@
+import csharp
+import semmle.code.csharp.controlflow.ControlFlowGraph
+
+query predicate edges(ControlFlow::Node node1, ControlFlow::Node node2, string label, string value) {
+  label = "semmle.label" and
+  exists(ControlFlow::SuccessorType t |
+    node2 = node1.getASuccessorByType(t) and value = t.toString()
+  )
+  and node1.getEnclosingCallable().hasName("NullCoalescing")
+}

csharp/ql/test/library-tests/csharp8/StaticLocalFunction.cs

@@ -1,10 +0,0 @@
-using System;
-
-class StaticLocalFunction
-{
-    int F()
-    {
-        static int G(int x) => x;
-        return G(12);
-    }
-}

csharp/ql/test/library-tests/csharp8/StaticLocalFunctions.cs

@@ -0,0 +1,13 @@
+// semmle-extractor-options: /langversion:8.0
+
+using System;
+
+class StaticLocalFunctions
+{
+    int Fn(int x)
+    {
+        static int I(int y) => y;
+        int J(int y) => x+y;
+        return I(x) + J(x);
+    }
+}

csharp/ql/test/library-tests/csharp8/StaticLocalFunctions.expected

@@ -0,0 +1 @@
+| StaticLocalFunctions.cs:9:9:9:33 | I | static |

csharp/ql/test/library-tests/csharp8/StaticLocalFunctions.ql

@@ -0,0 +1,5 @@
+import csharp
+
+from LocalFunction fn, string modifier
+where fn.hasModifier(modifier)
+select fn, modifier

csharp/ql/test/library-tests/csharp8/UsingControlFlow.expected

@@ -0,0 +1,26 @@
+| UsingDeclarations.cs:6:10:6:30 | enter TestUsingDeclarations | UsingDeclarations.cs:7:5:16:5 | {...} | semmle.label | successor |
+| UsingDeclarations.cs:7:5:16:5 | {...} | UsingDeclarations.cs:8:9:8:116 | using ... ...; | semmle.label | successor |
+| UsingDeclarations.cs:8:9:8:116 | using ... ...; | UsingDeclarations.cs:8:49:8:53 | "..." | semmle.label | successor |
+| UsingDeclarations.cs:8:26:8:69 | FileStream file1 = ... | UsingDeclarations.cs:8:95:8:99 | "..." | semmle.label | successor |
+| UsingDeclarations.cs:8:34:8:69 | object creation of type FileStream | UsingDeclarations.cs:8:26:8:69 | FileStream file1 = ... | semmle.label | successor |
+| UsingDeclarations.cs:8:49:8:53 | "..." | UsingDeclarations.cs:8:56:8:68 | access to constant Open | semmle.label | successor |
+| UsingDeclarations.cs:8:56:8:68 | access to constant Open | UsingDeclarations.cs:8:34:8:69 | object creation of type FileStream | semmle.label | successor |
+| UsingDeclarations.cs:8:72:8:115 | FileStream file2 = ... | UsingDeclarations.cs:10:9:12:9 | using (...) {...} | semmle.label | successor |
+| UsingDeclarations.cs:8:80:8:115 | object creation of type FileStream | UsingDeclarations.cs:8:72:8:115 | FileStream file2 = ... | semmle.label | successor |
+| UsingDeclarations.cs:8:95:8:99 | "..." | UsingDeclarations.cs:8:102:8:114 | access to constant Open | semmle.label | successor |
+| UsingDeclarations.cs:8:102:8:114 | access to constant Open | UsingDeclarations.cs:8:80:8:115 | object creation of type FileStream | semmle.label | successor |
+| UsingDeclarations.cs:10:9:12:9 | using (...) {...} | UsingDeclarations.cs:10:49:10:53 | "..." | semmle.label | successor |
+| UsingDeclarations.cs:10:26:10:69 | FileStream file3 = ... | UsingDeclarations.cs:10:95:10:99 | "..." | semmle.label | successor |
+| UsingDeclarations.cs:10:34:10:69 | object creation of type FileStream | UsingDeclarations.cs:10:26:10:69 | FileStream file3 = ... | semmle.label | successor |
+| UsingDeclarations.cs:10:49:10:53 | "..." | UsingDeclarations.cs:10:56:10:68 | access to constant Open | semmle.label | successor |
+| UsingDeclarations.cs:10:56:10:68 | access to constant Open | UsingDeclarations.cs:10:34:10:69 | object creation of type FileStream | semmle.label | successor |
+| UsingDeclarations.cs:10:72:10:115 | FileStream file4 = ... | UsingDeclarations.cs:11:9:12:9 | {...} | semmle.label | successor |
+| UsingDeclarations.cs:10:80:10:115 | object creation of type FileStream | UsingDeclarations.cs:10:72:10:115 | FileStream file4 = ... | semmle.label | successor |
+| UsingDeclarations.cs:10:95:10:99 | "..." | UsingDeclarations.cs:10:102:10:114 | access to constant Open | semmle.label | successor |
+| UsingDeclarations.cs:10:102:10:114 | access to constant Open | UsingDeclarations.cs:10:80:10:115 | object creation of type FileStream | semmle.label | successor |
+| UsingDeclarations.cs:11:9:12:9 | {...} | UsingDeclarations.cs:14:9:15:13 | using (...) {...} | semmle.label | successor |
+| UsingDeclarations.cs:14:9:15:13 | using (...) {...} | UsingDeclarations.cs:14:30:14:34 | "..." | semmle.label | successor |
+| UsingDeclarations.cs:14:15:14:50 | object creation of type FileStream | UsingDeclarations.cs:15:13:15:13 | ; | semmle.label | successor |
+| UsingDeclarations.cs:14:30:14:34 | "..." | UsingDeclarations.cs:14:37:14:49 | access to constant Open | semmle.label | successor |
+| UsingDeclarations.cs:14:37:14:49 | access to constant Open | UsingDeclarations.cs:14:15:14:50 | object creation of type FileStream | semmle.label | successor |
+| UsingDeclarations.cs:15:13:15:13 | ; | UsingDeclarations.cs:6:10:6:30 | exit TestUsingDeclarations | semmle.label | successor |

csharp/ql/test/library-tests/csharp8/UsingControlFlow.ql

@@ -0,0 +1,10 @@
+import csharp
+import semmle.code.csharp.controlflow.ControlFlowGraph
+
+query predicate edges(ControlFlow::Node node1, ControlFlow::Node node2, string label, string value) {
+  label = "semmle.label" and
+  exists(ControlFlow::SuccessorType t |
+    node2 = node1.getASuccessorByType(t) and value = t.toString()
+  )
+  and node1.getEnclosingCallable().hasName("TestUsingDeclarations")
+}

csharp/ql/test/library-tests/csharp8/UsingDeclarations.cs

@@ -0,0 +1,17 @@
+using System;
+using System.IO;
+
+class UsingDeclarations
+{
+    void TestUsingDeclarations()
+    {
+        using FileStream file1 = new FileStream("...", FileMode.Open), file2 = new FileStream("...", FileMode.Open);
+
+        using(FileStream file3 = new FileStream("...", FileMode.Open), file4 = new FileStream("...", FileMode.Open))
+        {
+        }
+
+        using(new FileStream("...", FileMode.Open))
+            ;
+    }
+}

csharp/ql/test/library-tests/csharp8/UsingDeclarations.expected

@@ -0,0 +1,26 @@
+localVars
+| UsingDeclarations.cs:8:26:8:30 | file1 |
+| UsingDeclarations.cs:8:72:8:76 | file2 |
+| UsingDeclarations.cs:10:26:10:30 | file3 |
+| UsingDeclarations.cs:10:72:10:76 | file4 |
+localVariableDeclarations
+| UsingDeclarations.cs:8:9:8:116 | using ... ...; | 0 | UsingDeclarations.cs:8:26:8:69 | FileStream file1 = ... |
+| UsingDeclarations.cs:8:9:8:116 | using ... ...; | 1 | UsingDeclarations.cs:8:72:8:115 | FileStream file2 = ... |
+usingStmts1
+| UsingDeclarations.cs:8:9:8:116 | using ... ...; |
+| UsingDeclarations.cs:10:9:12:9 | using (...) {...} |
+| UsingDeclarations.cs:14:9:15:13 | using (...) {...} |
+usingStmts
+| UsingDeclarations.cs:8:9:8:116 | using ... ...; | 0 | UsingDeclarations.cs:8:26:8:69 | FileStream file1 = ... |
+| UsingDeclarations.cs:8:9:8:116 | using ... ...; | 1 | UsingDeclarations.cs:8:72:8:115 | FileStream file2 = ... |
+| UsingDeclarations.cs:10:9:12:9 | using (...) {...} | 0 | UsingDeclarations.cs:10:26:10:69 | FileStream file3 = ... |
+| UsingDeclarations.cs:10:9:12:9 | using (...) {...} | 1 | UsingDeclarations.cs:10:72:10:115 | FileStream file4 = ... |
+usingDecls
+| UsingDeclarations.cs:8:9:8:116 | using ... ...; | 0 | UsingDeclarations.cs:8:26:8:69 | FileStream file1 = ... |
+| UsingDeclarations.cs:8:9:8:116 | using ... ...; | 1 | UsingDeclarations.cs:8:72:8:115 | FileStream file2 = ... |
+usingExprs
+| UsingDeclarations.cs:8:9:8:116 | using ... ...; | UsingDeclarations.cs:8:34:8:69 | object creation of type FileStream |
+| UsingDeclarations.cs:8:9:8:116 | using ... ...; | UsingDeclarations.cs:8:80:8:115 | object creation of type FileStream |
+| UsingDeclarations.cs:10:9:12:9 | using (...) {...} | UsingDeclarations.cs:10:34:10:69 | object creation of type FileStream |
+| UsingDeclarations.cs:10:9:12:9 | using (...) {...} | UsingDeclarations.cs:10:80:10:115 | object creation of type FileStream |
+| UsingDeclarations.cs:14:9:15:13 | using (...) {...} | UsingDeclarations.cs:14:15:14:50 | object creation of type FileStream |

csharp/ql/test/library-tests/csharp8/UsingDeclarations.ql

@@ -0,0 +1,22 @@
+import csharp
+
+query predicate localVars(LocalVariable decl) {
+  decl.getEnclosingCallable().hasName("TestUsingDeclarations")
+}
+
+query predicate localVariableDeclarations(
+  LocalVariableDeclStmt stmt, int i, LocalVariableDeclExpr decl
+) {
+  decl.getEnclosingCallable().hasName("TestUsingDeclarations") and
+  decl = stmt.getVariableDeclExpr(i)
+}
+
+query predicate usingStmts1(UsingStmt stmt) { any() }
+
+query predicate usingStmts(UsingStmt stmt, int i, LocalVariableDeclExpr decl) {
+  decl = stmt.getVariableDeclExpr(i)
+}
+
+query predicate usingDecls(UsingDeclStmt stmt, int i, Expr e) { e = stmt.getChild(i) }
+
+query predicate usingExprs(UsingStmt stmt, Expr e) { e = stmt.getAnExpr() }

csharp/ql/test/library-tests/statements/Using1.ql

@@ -5,7 +5,7 @@
 import csharp
 
 where
-  forall(UsingStmt s |
+  forall(UsingBlockStmt s |
     exists(s.getAnExpr()) and
     exists(s.getBody())
   )

csharp/ql/test/query-tests/API Abuse/DisposeNotCalledOnException/DisposeNotCalledOnException.cs

@@ -58,6 +58,10 @@ class Test
         SqlConnection c1f = new SqlConnection();
         Throw2(c1f);
         c1f.Dispose();
+
+        // GOOD: using declaration
+        using SqlConnection c2 = new SqlConnection("");
+        c2.Open();
     }
 
     void Throw1(SqlConnection sc)
@@ -71,3 +75,5 @@ class Test
         return sc == null ? throw new Exception() : sc;
     }
 }
+
+// semmle-extractor-options: /langversion:8.0

csharp/ql/test/query-tests/API Abuse/NoDisposeCallOnLocalIDisposable/NoDisposeCallOnLocalIDisposable.cs

@@ -78,6 +78,9 @@ class Test
         // GOOD: Passed to a library. This is only detected in CIL.
         Console.SetOut(new StreamWriter("output.txt"));
 
+        // GOOD: Disposed automatically.
+        using var c2 = new Timer(TimerProc);
+
         return null;
     }
 
@@ -88,3 +91,5 @@ class Test
     {
     }
 }
+
+// semmle-extractor-options: /langversion:8.0

csharp/upgrades/22d4df34563b234c6fc108ccebdffe8ae9b8e49c/upgrade.properties

@@ -0,0 +1,2 @@
+description: Support for null-coalescing assignment, static local functions, and using declarations.
+compatibility: backwards