Swift: add Pattern.getEnclosingPattern()

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

@@ -185,7 +185,7 @@ private predicate switchMatching(SwitchStmt switch, CaseStmt c, AstNode ast) {
   (
     c.getALabel() = ast
     or
-    isSubPattern+(c.getALabel().getPattern(), ast)
+    ast.(Pattern).getEnclosingPattern+() = c.getALabel().getPattern()
   )
 }
 
@@ -216,27 +216,10 @@ predicate catchMatchingPattern(DoCatchStmt s, CaseStmt c, Pattern pattern) {
   exists(CaseLabelItem cli | catchMatching(s, c, cli) |
     cli.getPattern() = pattern
     or
-    isSubPattern+(cli.getPattern(), pattern)
+    pattern.getEnclosingPattern+() = cli.getPattern()
   )
 }
 
-/** Holds if `sub` is a subpattern of `p`. */
-private predicate isSubPattern(Pattern p, Pattern sub) {
-  sub = p.(BindingPattern).getImmediateSubPattern()
-  or
-  sub = p.(EnumElementPattern).getImmediateSubPattern()
-  or
-  sub = p.(IsPattern).getImmediateSubPattern()
-  or
-  sub = p.(OptionalSomePattern).getImmediateSubPattern()
-  or
-  sub = p.(ParenPattern).getImmediateSubPattern()
-  or
-  sub = p.(TuplePattern).getImmediateElement(_)
-  or
-  sub = p.(TypedPattern).getImmediateSubPattern()
-}
-
 /** Gets the value of `e` if it is a constant value, disregarding conversions. */
 private string getExprValue(Expr e) {
   result = e.(IntegerLiteralExpr).getStringValue()

swift/ql/lib/codeql/swift/elements/pattern/NamedPattern.qll

@@ -1,14 +1,5 @@
 private import codeql.swift.generated.pattern.NamedPattern
-private import codeql.swift.elements.pattern.BindingPattern
-private import codeql.swift.elements.pattern.EnumElementPattern
-private import codeql.swift.elements.pattern.IsPattern
-private import codeql.swift.elements.pattern.OptionalSomePattern
-private import codeql.swift.elements.pattern.ParenPattern
-private import codeql.swift.elements.pattern.TuplePattern
-private import codeql.swift.elements.pattern.TypedPattern
 private import codeql.swift.elements.decl.VarDecl
-private import codeql.swift.elements.stmt.LabeledConditionalStmt
-private import codeql.swift.elements.stmt.ConditionElement
 
 class NamedPattern extends Generated::NamedPattern {
   /** Holds if this named pattern has a corresponding `VarDecl` */
@@ -16,25 +7,9 @@ class NamedPattern extends Generated::NamedPattern {
 
   /** Gets the `VarDecl` bound by this named pattern, if any. */
   VarDecl getVarDecl() {
-    isSubPattern*(result.getParentPattern().getFullyUnresolved(), this) and
+    this.getEnclosingPattern*() = result.getParentPattern().getFullyUnresolved() and
     result.getName() = this.getName()
   }
 
   override string toString() { result = this.getName() }
 }
-
-private predicate isSubPattern(Pattern p, Pattern sub) {
-  sub = p.(BindingPattern).getImmediateSubPattern()
-  or
-  sub = p.(EnumElementPattern).getImmediateSubPattern()
-  or
-  sub = p.(IsPattern).getImmediateSubPattern()
-  or
-  sub = p.(OptionalSomePattern).getImmediateSubPattern()
-  or
-  sub = p.(ParenPattern).getImmediateSubPattern()
-  or
-  sub = p.(TuplePattern).getImmediateElement(_)
-  or
-  sub = p.(TypedPattern).getImmediateSubPattern()
-}

swift/ql/lib/codeql/swift/elements/pattern/Pattern.qll

@@ -65,4 +65,32 @@ class Pattern extends Generated::Pattern {
 
   /** Holds if this pattern is matched against an expression. */
   predicate hasMatchingExpr() { exists(this.getMatchingExpr()) }
+
+  /**
+   * Holds if this occurs as a sub-pattern of the result.
+   */
+  Pattern getEnclosingPattern() {
+    this = result.(EnumElementPattern).getImmediateSubPattern()
+    or
+    this = result.(OptionalSomePattern).getImmediateSubPattern()
+    or
+    this = result.(TuplePattern).getImmediateElement(_)
+    or
+    result = this.getIdentityPreservingEnclosingPattern()
+  }
+
+  /**
+   * Holds if this occurs as a sub-pattern of the result
+   * without any intervening destructurings of
+   * complex data structures.
+   */
+  Pattern getIdentityPreservingEnclosingPattern() {
+    this = result.(BindingPattern).getImmediateSubPattern()
+    or
+    this = result.(IsPattern).getImmediateSubPattern()
+    or
+    this = result.(ParenPattern).getImmediateSubPattern()
+    or
+    this = result.(TypedPattern).getImmediateSubPattern()
+  }
 }