Merge pull request github#5623 from hvitved/csharp/enclosing

C#: Compute enclosing callable as a transitive closure

Author: hvitved

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

@@ -138,6 +138,54 @@ private module Cached {
         )
     else expr_parent(child, i, parent)
   }
+
+  private Expr getAChildExpr(ExprOrStmtParent parent) {
+    result = parent.getAChildExpr() or
+    result = parent.(AssignOperation).getExpandedAssignment()
+  }
+
+  private ControlFlowElement getAChild(ExprOrStmtParent parent) {
+    result = getAChildExpr(parent)
+    or
+    result = parent.getAChildStmt()
+  }
+
+  pragma[inline]
+  private ControlFlowElement enclosingStart(ControlFlowElement cfe) {
+    result = cfe
+    or
+    getAChild(result).(AnonymousFunctionExpr) = cfe
+  }
+
+  private predicate parent(ControlFlowElement child, ExprOrStmtParent parent) {
+    child = getAChild(parent) and
+    not child instanceof Callable
+  }
+
+  /** Holds if the enclosing body of `cfe` is `body`. */
+  cached
+  predicate enclosingBody(ControlFlowElement cfe, ControlFlowElement body) {
+    body = any(Callable c).getBody() and
+    parent*(enclosingStart(cfe), body)
+  }
+
+  /** Holds if the enclosing callable of `cfe` is `c`. */
+  cached
+  predicate enclosingCallable(ControlFlowElement cfe, Callable c) {
+    enclosingBody(cfe, c.getBody())
+    or
+    parent*(enclosingStart(cfe), c.(Constructor).getInitializer())
+  }
+
+  /** Holds if the enclosing statement of expression `e` is `s`. */
+  cached
+  predicate enclosingStmt(Expr e, Stmt s) {
+    // Compute the enclosing statement for an expression. Note that this need
+    // not exist, since expressions can occur in contexts where they have no
+    // enclosing statement (examples include field initialisers, both inline
+    // and explicit on constructor definitions, and annotation arguments).
+    getAChildExpr+(s) = e
+  }
 }
 
 import Cached

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

@@ -8,7 +8,7 @@ import Element
 import Location
 import Member
 import exprs.Expr
-private import semmle.code.csharp.Enclosing::Internal
+private import semmle.code.csharp.ExprOrStmtParent
 private import semmle.code.csharp.frameworks.System
 private import TypeRef
 

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

@@ -20,7 +20,7 @@ import semmle.code.csharp.Location
 import semmle.code.csharp.Stmt
 import semmle.code.csharp.Type
 private import dotnet
-private import semmle.code.csharp.Enclosing::Internal
+private import semmle.code.csharp.ExprOrStmtParent
 private import semmle.code.csharp.frameworks.System
 private import semmle.code.csharp.TypeRef
 
@@ -55,7 +55,7 @@ class Expr extends DotNet::Expr, ControlFlowElement, @expr {
   final Stmt getEnclosingStmt() { enclosingStmt(this, result) }
 
   /** Gets the enclosing callable of this expression, if any. */
-  override Callable getEnclosingCallable() { exprEnclosingCallable(this, result) }
+  override Callable getEnclosingCallable() { enclosingCallable(this, result) }
 
   /**
    * Holds if this expression is generated by the compiler and does not appear