C#: Rename CollectionExpr to EnumerableCollectionExpr.

csharp/ql/lib/semmle/code/csharp/controlflow/Guards.qll

@@ -480,12 +480,17 @@ class DereferenceableExpr extends Expr {
   }
 }
 
+/**
+ * DEPRECATED: Use `EnumerableCollectionExpr` instead.
+ */
+deprecated class CollectionExpr = EnumerableCollectionExpr;
+
 /**
  * An expression that evaluates to a collection. That is, an expression whose
  * (transitive, reflexive) base type is `IEnumerable`.
  */
-class CollectionExpr extends Expr {
-  CollectionExpr() {
+class EnumerableCollectionExpr extends Expr {
+  EnumerableCollectionExpr() {
     this.getType().(ValueOrRefType).getABaseType*() instanceof SystemCollectionsIEnumerableInterface
   }
 
@@ -1431,7 +1436,7 @@ module Internal {
           or
           val.branch(_, _, e)
           or
-          e instanceof CollectionExpr and
+          e instanceof EnumerableCollectionExpr and
           val = TEmptyCollectionValue(_)
         ) and
         not e = any(ExprStmt es).getExpr() and
@@ -1570,7 +1575,9 @@ module Internal {
           (g1 != g2 or v1 != v2)
         )
         or
-        exists(boolean isEmpty | g1 = g2.(CollectionExpr).getAnEmptinessCheck(v1, isEmpty) |
+        exists(boolean isEmpty |
+          g1 = g2.(EnumerableCollectionExpr).getAnEmptinessCheck(v1, isEmpty)
+        |
           v2 =
             any(EmptyCollectionValue ecv | if ecv.isEmpty() then isEmpty = true else isEmpty = false) and
           g1 != g2

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

@@ -1162,7 +1162,8 @@ module LoopSplitting {
 
   /** Holds if `ce` is guarded by a (non-)empty check, as specified by `v`. */
   private predicate emptinessGuarded(
-    Guards::Guard g, Guards::CollectionExpr ce, Guards::AbstractValues::EmptyCollectionValue v
+    Guards::Guard g, Guards::EnumerableCollectionExpr ce,
+    Guards::AbstractValues::EmptyCollectionValue v
   ) {
     exists(PreBasicBlock bb | Guards::Internal::preControls(g, bb, v) |
       PreSsa::adjacentReadPairSameVar(g, ce) and

csharp/ql/test/library-tests/controlflow/guards/Collections.ql

@@ -2,7 +2,7 @@ import csharp
 private import semmle.code.csharp.controlflow.Guards
 
 query predicate emptinessCheck(
-  Expr check, CollectionExpr collection, AbstractValue v, boolean isEmpty
+  Expr check, EnumerableCollectionExpr collection, AbstractValue v, boolean isEmpty
 ) {
   check = collection.getAnEmptinessCheck(v, isEmpty)
 }