Merge pull request #1611 from ian-semmle/lambda

C++: Follow changes to how lambdas are extracted

cpp/ql/src/semmle/code/cpp/exprs/Lambda.qll

@@ -24,7 +24,7 @@ class LambdaExpression extends Expr, @lambdaexpr {
    * Gets the nth implicitly or explicitly captured value of this lambda expression.
    */
   LambdaCapture getCapture(int index) {
-    lambda_capture(result, underlyingElement(this), index, _, _, _)
+    lambda_capture(result, underlyingElement(this), index, _, _, _, _)
   }
 
   /**
@@ -64,7 +64,7 @@ class LambdaExpression extends Expr, @lambdaexpr {
    * Gets the initializer that initializes the captured variables in the closure, if any.
    * A lambda that does not capture any variables will not have an initializer.
    */
-  Expr getInitializer() {
+  ClassAggregateLiteral getInitializer() {
     result = getChild(0)
   }
 }
@@ -109,7 +109,7 @@ class LambdaCapture extends @lambdacapture {
    * Holds if this capture was made implicitly.
    */
   predicate isImplicit() {
-    lambda_capture(this, _, _, _, true, _)
+    lambda_capture(this, _, _, _, _, true, _)
   }
 
   /**
@@ -122,7 +122,7 @@ class LambdaCapture extends @lambdacapture {
    *                                is actually "*this" being captured rather than "this".]
    */
   predicate isCapturedByReference() {
-    lambda_capture(this, _, _, true, _, _)
+    lambda_capture(this, _, _, _, true, _, _)
   }
 
   /**
@@ -134,16 +134,14 @@ class LambdaCapture extends @lambdacapture {
    * expression which accesses the captured variable.
    */
   Location getLocation() {
-    lambda_capture(this, _, _, _, _, result)
+    lambda_capture(this, _, _, _, _, _, result)
   }
 
   /**
    * Gets the field of the lambda expression's closure type which is used to store this capture.
    */
   MemberVariable getField() {
-    exists(LambdaExpression lambda, int index | this = lambda.getCapture(index) |
-      result = lambda.getType().(Closure).getCanonicalMember(index)
-    )
+    lambda_capture(this, _, _, result, _, _, _)
   }
 
   /**
@@ -154,9 +152,8 @@ class LambdaCapture extends @lambdacapture {
    * For by-value captures of non-primitive types, this will be a call to a copy constructor.
    */
   Expr getInitializer() {
-    exists(LambdaExpression lambda, int index | this = lambda.getCapture(index) |
-      result = lambda.getChild(0)     // Call to the constructor of the closure type.
-                     .getChild(index) // The appropriate argument to the constructor.
+    exists(LambdaExpression lambda | this = lambda.getCapture(_) |
+      result = lambda.getInitializer().getFieldExpr(this.getField())
     )
   }
 }

cpp/ql/src/semmlecode.cpp.dbscheme

@@ -1579,6 +1579,7 @@ lambda_capture(
     unique int id: @lambdacapture,
     int lambda: @lambdaexpr ref,
     int index: int ref,
+    int field: @membervariable ref,
     boolean captured_by_reference: boolean ref,
     boolean is_implicit: boolean ref,
     int location: @location_default ref

cpp/ql/test/library-tests/lambdas/captures/captures.expected

@@ -1,6 +1,6 @@
-| captures.cpp:3:6:3:6 | x | explicit | 1 |
-| captures.cpp:3:9:3:12 | (captured this) | explicit | 2 |
-| captures.cpp:10:7:10:7 | (captured this) | implicit | 1 |
-| captures.cpp:10:9:10:9 | x | implicit | 2 |
-| captures.cpp:15:6:15:6 | x | explicit | 1 |
-| end_pos.cpp:9:17:9:18 | ii | explicit | 1 |
+| captures.cpp:3:6:3:6 | x | explicit | 0 |
+| captures.cpp:3:9:3:12 | (captured this) | explicit | 1 |
+| captures.cpp:10:7:10:7 | (captured this) | implicit | 0 |
+| captures.cpp:10:9:10:9 | x | implicit | 1 |
+| captures.cpp:15:6:15:6 | x | explicit | 0 |
+| end_pos.cpp:9:17:9:18 | ii | explicit | 0 |

cpp/upgrades/814fae599505510ff15102f4c72600586734770a/lambda_capture.ql

@@ -0,0 +1,15 @@
+
+class LambdaCapture extends @lambdacapture { string toString() { none() } }
+class Lambda extends @lambdaexpr { string toString() { none() } }
+class Field extends @membervariable { string toString() { none() } }
+class Location extends @location_default { string toString() { none() } }
+class Type extends @usertype { string toString() { none() } }
+
+from LambdaCapture lc, Lambda l, int i, Field f,
+     boolean captured_by_reference, boolean is_implicit,
+     Location loc, Type t
+where lambda_capture(lc, l, i, captured_by_reference, is_implicit, loc)
+  and expr_types(l, t, _)
+  and member(t, i, f)
+select lc, l, i, f, captured_by_reference, is_implicit, loc
+

cpp/upgrades/814fae599505510ff15102f4c72600586734770a/upgrade.properties

@@ -0,0 +1,4 @@
+description: Add field to lambda_capture
+compatibility: backwards
+lambda_capture.rel: run lambda_capture.qlo
+