Swift: fix IfConfigDecl in QL libraries

This fixes `IfConfigDecl` for both the AST printer and control flow
libraries.

It turns out that the active lements of an `IfConfigDecl` are already
listed in the enclosing scope (like a `BraceStmt`), so they should not
be listed as children, and `IfConfigDecl` can be jsut a leaf in the
control flow.

Author: redsun82

csharp/ql/lib/semmle/code/csharp/controlflow/internal/ControlFlowGraphImplShared.qll

@@ -52,7 +52,7 @@ predicate last(ControlFlowTree cft, ControlFlowElement last, Completion c) {
  */
 pragma[nomagic]
 predicate succ(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
-  any(ControlFlowTree cft).succ(pred, succ, c)
+  exists(ControlFlowTree cft | cft.succ(pred, succ, c))
 }
 
 /** An element that is executed in pre-order. */

ruby/ql/lib/codeql/ruby/controlflow/internal/ControlFlowGraphImplShared.qll

@@ -52,7 +52,7 @@ predicate last(ControlFlowTree cft, ControlFlowElement last, Completion c) {
  */
 pragma[nomagic]
 predicate succ(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
-  any(ControlFlowTree cft).succ(pred, succ, c)
+  exists(ControlFlowTree cft | cft.succ(pred, succ, c))
 }
 
 /** An element that is executed in pre-order. */

swift/codegen/schema.yml

@@ -303,8 +303,7 @@ EnumCaseDecl:
 
 IfConfigDecl:
   _extends: Decl
-  _children:
-    active_elements: AstNode*
+  active_elements: AstNode*
 
 ImportDecl:
   _extends: Decl

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

@@ -1002,6 +1002,15 @@ module Decls {
       i = ast.getNumberOfParams()
     }
   }
+
+  /**
+   * The control-flow of an #if block.
+   * The active elements are already listed in the containing scope, so we can just flow through
+   * this as a leaf.
+   */
+  class IfConfigDeclTree extends AstLeafTree {
+    override IfConfigDecl ast;
+  }
 }
 
 module Exprs {

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

@@ -52,7 +52,7 @@ predicate last(ControlFlowTree cft, ControlFlowElement last, Completion c) {
  */
 pragma[nomagic]
 predicate succ(ControlFlowElement pred, ControlFlowElement succ, Completion c) {
-  any(ControlFlowTree cft).succ(pred, succ, c)
+  exists(ControlFlowTree cft | cft.succ(pred, succ, c))
 }
 
 /** An element that is executed in pre-order. */

swift/ql/lib/codeql/swift/generated/ParentChild.qll

@@ -1760,18 +1760,14 @@ private module Impl {
   private Element getImmediateChildOfIfConfigDecl(
     IfConfigDecl e, int index, string partialPredicateCall
   ) {
-    exists(int b, int bDecl, int n, int nActiveElement |
+    exists(int b, int bDecl, int n |
       b = 0 and
       bDecl = b + 1 + max(int i | i = -1 or exists(getImmediateChildOfDecl(e, i, _)) | i) and
       n = bDecl and
-      nActiveElement = n + 1 + max(int i | i = -1 or exists(e.getImmediateActiveElement(i)) | i) and
       (
         none()
         or
         result = getImmediateChildOfDecl(e, index - b, partialPredicateCall)
-        or
-        result = e.getImmediateActiveElement(index - n) and
-        partialPredicateCall = "ActiveElement(" + (index - n).toString() + ")"
       )
     )
   }

swift/ql/test/extractor-tests/declarations/all.expected

@@ -263,3 +263,7 @@
 | declarations.swift:155:1:155:28 | var ... = ... |
 | declarations.swift:155:1:155:28 | { ... } |
 | declarations.swift:155:5:155:5 | d |
+| declarations.swift:157:1:180:1 | ifConfig() |
+| declarations.swift:158:3:166:3 | #if ... |
+| declarations.swift:168:3:171:3 | #if ... |
+| declarations.swift:173:3:179:3 | #if ... |

swift/ql/test/extractor-tests/declarations/declarations.swift

@@ -153,3 +153,28 @@ class Derived : Baz {}
 
 // multiple conversions
 var d: Baz? = Derived() as Baz
+
+func ifConfig() {
+  #if FOO
+  1
+  2
+  3
+  #else
+  4
+  5
+  6
+  #endif
+
+  #if BAR
+  7
+  8
+  #endif
+
+  #if true
+  9
+  10
+  #else
+  11
+  12
+  #endif
+}

swift/ql/test/library-tests/ast/PrintAst.expected

@@ -706,6 +706,17 @@ declarations.swift:
 #  155|         getTypeRepr(): [TypeRepr] Baz?
 #  155| [ConcreteVarDecl] d
 #  155|     Type = Baz?
+#  157| [ConcreteFuncDecl] ifConfig()
+#  157|     InterfaceType = () -> ()
+#  157|   getBody(): [BraceStmt] { ... }
+#  158|     getElement(0): [IfConfigDecl] #if ...
+#  163|     getElement(1): [IntegerLiteralExpr] 4
+#  164|     getElement(2): [IntegerLiteralExpr] 5
+#  165|     getElement(3): [IntegerLiteralExpr] 6
+#  168|     getElement(4): [IfConfigDecl] #if ...
+#  173|     getElement(5): [IfConfigDecl] #if ...
+#  174|     getElement(6): [IntegerLiteralExpr] 9
+#  175|     getElement(7): [IntegerLiteralExpr] 10
 expressions.swift:
 #    1| [TopLevelCodeDecl] { ... }
 #    1|   getBody(): [BraceStmt] { ... }

swift/ql/test/library-tests/ast/declarations.swift

@@ -153,3 +153,28 @@ class Derived : Baz {}
 
 // multiple conversions
 var d: Baz? = Derived() as Baz
+
+func ifConfig() {
+  #if FOO
+  1
+  2
+  3
+  #else
+  4
+  5
+  6
+  #endif
+
+  #if BAR
+  7
+  8
+  #endif
+
+  #if true
+  9
+  10
+  #else
+  11
+  12
+  #endif
+}