Swift: CFG for normal autoclosure exprs

Author: rdmarsh2

swift/ql/lib/codeql/swift/controlflow/internal/ControlFlowElements.qll

@@ -4,7 +4,7 @@ cached
 newtype TControlFlowElement =
   TAstElement(AstNode n) or
   TFuncDeclElement(Function func) { func.hasBody() } or
-  TClosureElement(ExplicitClosureExpr clos) or
+  TClosureElement(ClosureExpr clos) { isNormalAutoClosureOrExplicitClosure(clos) } or
   TPropertyGetterElement(Decl accessor, Expr ref) { isPropertyGetterElement(accessor, ref) } or
   TPropertySetterElement(Accessor accessor, AssignExpr assign) {
     isPropertySetterElement(accessor, assign)
@@ -41,6 +41,13 @@ predicate isPropertyGetterElement(PropertyGetterElement pge, Accessor accessor,
   pge = TPropertyGetterElement(accessor, ref)
 }
 
+predicate isNormalAutoClosureOrExplicitClosure(ClosureExpr clos) {
+  clos instanceof AutoClosureExpr and
+  exists(CallExpr call | call.getAnArgument().getExpr() = clos)
+  or
+  clos instanceof ExplicitClosureExpr
+}
+
 private predicate hasDirectToImplementationSemantics(Expr e) {
   e.(MemberRefExpr).hasDirectToImplementationSemantics()
   or
@@ -195,13 +202,13 @@ class KeyPathElement extends ControlFlowElement, TKeyPathElement {
 }
 
 class ClosureElement extends ControlFlowElement, TClosureElement {
-  ExplicitClosureExpr expr;
+  ClosureExpr expr;
 
   ClosureElement() { this = TClosureElement(expr) }
 
   override Location getLocation() { result = expr.getLocation() }
 
-  ExplicitClosureExpr getAst() { result = expr }
+  ClosureExpr getAst() { result = expr }
 
   override string toString() { result = expr.toString() }
 }

swift/ql/lib/codeql/swift/controlflow/internal/ControlFlowGraphImpl.qll

@@ -67,10 +67,13 @@ module CfgScope {
     final override predicate exit(ControlFlowElement last, Completion c) { last(tree, last, c) }
   }
 
-  private class ClosureExprScope extends Range_ instanceof ExplicitClosureExpr {
+  private class ClosureExprScope extends Range_ instanceof ClosureExpr {
     Exprs::ClosureExprTree tree;
 
-    ClosureExprScope() { tree.getAst() = this }
+    ClosureExprScope() {
+      isNormalAutoClosureOrExplicitClosure(this) and
+      tree.getAst() = this
+    }
 
     final override predicate entry(ControlFlowElement first) { first(tree, first) }
 
@@ -1139,11 +1142,11 @@ module Exprs {
   }
 
   class ClosureExprTree extends StandardPreOrderTree, TClosureElement {
-    ExplicitClosureExpr expr;
+    ClosureExpr expr;
 
     ClosureExprTree() { this = TClosureElement(expr) }
 
-    ExplicitClosureExpr getAst() { result = expr }
+    ClosureExpr getAst() { result = expr }
 
     final override ControlFlowElement getChildElement(int i) {
       result.asAstNode() = expr.getParam(i)

swift/ql/test/library-tests/controlflow/graph/Cfg.expected

@@ -6317,5 +6317,22 @@ cfg.swift:
 #  555| call to usesAutoclosure(_:)
 #-----|  -> exit autoclosureTest() (normal)
 
+#  555| 1
+#-----|  -> return ...
+
+#  555| enter { ... }
+#-----|  -> { ... }
+
+#  555| exit { ... }
+
+#  555| exit { ... } (normal)
+#-----|  -> exit { ... }
+
+#  555| return ...
+#-----|  -> exit { ... } (normal)
+
+#  555| { ... }
+#-----|  -> 1
+
 #  555| { ... }
 #-----|  -> call to usesAutoclosure(_:)

swift/ql/test/library-tests/dataflow/dataflow/DataFlow.expected

@@ -560,6 +560,7 @@ edges
 | test.swift:873:21:873:31 | [...] [Collection element] | test.swift:856:29:856:40 | args [Collection element] |
 | test.swift:873:21:873:31 | [...] [Collection element] | test.swift:873:21:873:31 | [...] [Collection element] |
 | test.swift:873:24:873:31 | call to source() | test.swift:873:21:873:31 | [...] [Collection element] |
+| test.swift:881:19:881:26 | call to source() | test.swift:877:13:877:18 | call to ... |
 nodes
 | file://:0:0:0:0 | .a [x] | semmle.label | .a [x] |
 | file://:0:0:0:0 | .s [x] | semmle.label | .s [x] |
@@ -1164,6 +1165,8 @@ nodes
 | test.swift:873:21:873:31 | [...] [Collection element] | semmle.label | [...] [Collection element] |
 | test.swift:873:21:873:31 | [...] [Collection element] | semmle.label | [...] [Collection element] |
 | test.swift:873:24:873:31 | call to source() | semmle.label | call to source() |
+| test.swift:877:13:877:18 | call to ... | semmle.label | call to ... |
+| test.swift:881:19:881:26 | call to source() | semmle.label | call to source() |
 subpaths
 | test.swift:75:22:75:22 | x | test.swift:65:16:65:28 | arg1 | test.swift:65:1:70:1 | arg2[return] | test.swift:75:32:75:32 | [post] y |
 | test.swift:114:19:114:19 | arg | test.swift:109:9:109:14 | arg | test.swift:110:12:110:12 | arg | test.swift:114:12:114:22 | call to ... |
@@ -1355,3 +1358,4 @@ subpaths
 | test.swift:859:15:859:21 | ...[...] | test.swift:873:24:873:31 | call to source() | test.swift:859:15:859:21 | ...[...] | result |
 | test.swift:860:15:860:21 | ...[...] | test.swift:873:24:873:31 | call to source() | test.swift:860:15:860:21 | ...[...] | result |
 | test.swift:867:15:867:38 | \\...[...] | test.swift:873:24:873:31 | call to source() | test.swift:867:15:867:38 | \\...[...] | result |
+| test.swift:877:13:877:18 | call to ... | test.swift:881:19:881:26 | call to source() | test.swift:877:13:877:18 | call to ... | result |

swift/ql/test/library-tests/dataflow/dataflow/test.swift

@@ -874,7 +874,7 @@ func testVarargsCaller() {
 }
 
 func usesAutoclosure(_ expr: @autoclosure () -> Int) {
-  sink(arg: expr())
+  sink(arg: expr()) // $ flow=881
 }
 
 func autoclosureTest() {