C#: Deprecate Ssa::ImplicitEntryDefinition.

Author: aschackmull

csharp/ql/lib/semmle/code/csharp/dataflow/SSA.qll

@@ -539,11 +539,13 @@ module Ssa {
   }
 
   /**
+   * DEPRECATED: Use `SsaParameterInit` or `SsaImplicitEntryDefinition` instead.
+   *
    * An SSA definition representing the implicit initialization of a variable
    * at the beginning of a callable. Either a parameter, a local scope variable
    * captured by the callable, or a field or property accessed inside the callable.
    */
-  class ImplicitEntryDefinition extends ImplicitDefinition {
+  deprecated class ImplicitEntryDefinition extends ImplicitDefinition {
     ImplicitEntryDefinition() {
       exists(BasicBlock bb, SourceVariable v |
         this.definesAt(v, bb, -1) and
@@ -564,7 +566,9 @@ module Ssa {
   }
 
   pragma[nomagic]
-  private predicate implicitEntryDef(ImplicitEntryDefinition def, SourceVariable v, Callable c) {
+  deprecated private predicate implicitEntryDef(
+    ImplicitEntryDefinition def, SourceVariable v, Callable c
+  ) {
     v = def.getSourceVariable() and
     c = def.getCallable()
   }

csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll

@@ -1415,7 +1415,7 @@ private module ParameterNodes {
   }
 
   /** An implicit entry definition for a captured variable. */
-  class SsaCapturedEntryDefinition extends Ssa::ImplicitEntryDefinition {
+  deprecated class SsaCapturedEntryDefinition extends Ssa::ImplicitEntryDefinition {
     private LocalScopeVariable v;
 
     SsaCapturedEntryDefinition() { this.getSourceVariable().getAssignable() = v }
@@ -1996,9 +1996,6 @@ private class FieldOrPropertyRead extends FieldOrPropertyAccess, AssignableRead
     exists(SsaDefinition def, Ssa::ImplicitDefinition idef |
       def.getARead() = this and
       idef = def.getAnUltimateDefinition()
-    |
-      idef instanceof Ssa::ImplicitEntryDefinition or
-      idef instanceof Ssa::ImplicitCallDefinition
     )
   }
 }