C#: Do not calculate field-based SSA for enums

Author: hvitved

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

@@ -108,7 +108,11 @@ private module SourceVariableImpl {
    */
   predicate isPlainFieldOrPropAccess(FieldOrPropAccess fpa, FieldOrProp fp, Callable c) {
     fieldOrPropAccessInCallable(fpa, fp, c) and
-    (ownFieldOrPropAccess(fpa) or fp.isStatic())
+    (
+      ownFieldOrPropAccess(fpa)
+      or
+      fp.isStatic() and not fp instanceof EnumConstant
+    )
   }
 
   /**

csharp/ql/test/library-tests/dataflow/ssa/ReadAdjacentRead.expected

@@ -19,7 +19,6 @@
 | DefUse.cs:144:22:144:22 | x | DefUse.cs:146:17:146:17 | access to local variable x | DefUse.cs:147:17:147:17 | access to local variable x |
 | DefUse.cs:152:9:152:14 | Field4 | DefUse.cs:156:13:156:18 | access to field Field4 | DefUse.cs:157:13:157:18 | access to field Field4 |
 | DefUse.cs:152:9:152:14 | Field4 | DefUse.cs:162:13:162:18 | access to field Field4 | DefUse.cs:163:13:163:18 | access to field Field4 |
-| Enum.cs:3:5:3:5 | A | Enum.cs:11:18:11:20 | access to constant A | Enum.cs:12:18:12:20 | access to constant A |
 | Example.cs:4:9:4:13 | Field | Example.cs:14:13:14:22 | access to field Field | Example.cs:15:13:15:22 | access to field Field |
 | Example.cs:6:23:6:23 | i | Example.cs:8:22:8:22 | access to parameter i | Example.cs:10:13:10:13 | access to parameter i |
 | Example.cs:6:23:6:23 | i | Example.cs:10:13:10:13 | access to parameter i | Example.cs:11:26:11:26 | access to parameter i |

csharp/ql/test/library-tests/dataflow/ssa/SsaDef.expected

@@ -94,7 +94,6 @@
 | DefUse.cs:184:9:184:14 | this.Field5 | DefUse.cs:184:9:184:18 | SSA def(this.Field5) |
 | DefUse.cs:184:9:184:14 | this.Field5 | DefUse.cs:191:9:191:11 | SSA call def(this.Field5) |
 | DefUse.cs:188:13:188:18 | this.Field5 | DefUse.cs:188:13:188:22 | SSA def(this.Field5) |
-| Enum.cs:11:18:11:20 | E.A | Enum.cs:8:10:8:10 | SSA entry def(E.A) |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:8:9:8:22 | SSA def(this.Field) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:11:13:11:30 | SSA def(this.Field) |

csharp/ql/test/library-tests/dataflow/ssa/SsaDefElement.expected

@@ -89,7 +89,6 @@
 | DefUse.cs:186:9:190:9 | SSA def(a) | DefUse.cs:186:9:190:9 | ... = ... |
 | DefUse.cs:188:13:188:22 | SSA def(this.Field5) | DefUse.cs:188:13:188:22 | ... = ... |
 | DefUse.cs:191:9:191:11 | SSA call def(this.Field5) | DefUse.cs:191:9:191:11 | delegate call |
-| Enum.cs:8:10:8:10 | SSA entry def(E.A) | Enum.cs:8:10:8:10 | M |
 | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:6:23:6:23 | i |
 | Example.cs:8:9:8:22 | SSA def(this.Field) | Example.cs:8:9:8:22 | ... = ... |
 | Example.cs:11:13:11:30 | SSA def(this.Field) | Example.cs:11:13:11:30 | ... = ... |

csharp/ql/test/library-tests/dataflow/ssa/SsaDefLastRead.expected

@@ -83,7 +83,6 @@
 | DefUse.cs:184:9:184:14 | this.Field5 | DefUse.cs:184:9:184:18 | SSA def(this.Field5) | DefUse.cs:185:13:185:18 | access to field Field5 |
 | DefUse.cs:184:9:184:14 | this.Field5 | DefUse.cs:191:9:191:11 | SSA call def(this.Field5) | DefUse.cs:192:13:192:18 | access to field Field5 |
 | DefUse.cs:188:13:188:18 | this.Field5 | DefUse.cs:188:13:188:22 | SSA def(this.Field5) | DefUse.cs:189:17:189:22 | access to field Field5 |
-| Enum.cs:11:18:11:20 | E.A | Enum.cs:8:10:8:10 | SSA entry def(E.A) | Enum.cs:12:18:12:20 | access to constant A |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:11:26:11:26 | access to parameter i |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:12:18:12:18 | access to parameter i |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:8:9:8:22 | SSA def(this.Field) | Example.cs:9:13:9:22 | access to field Field |

csharp/ql/test/library-tests/dataflow/ssa/SsaRead.expected

@@ -100,8 +100,6 @@
 | DefUse.cs:184:9:184:14 | this.Field5 | DefUse.cs:184:9:184:18 | SSA def(this.Field5) | DefUse.cs:185:13:185:18 | access to field Field5 |
 | DefUse.cs:184:9:184:14 | this.Field5 | DefUse.cs:191:9:191:11 | SSA call def(this.Field5) | DefUse.cs:192:13:192:18 | access to field Field5 |
 | DefUse.cs:188:13:188:18 | this.Field5 | DefUse.cs:188:13:188:22 | SSA def(this.Field5) | DefUse.cs:189:17:189:22 | access to field Field5 |
-| Enum.cs:11:18:11:20 | E.A | Enum.cs:8:10:8:10 | SSA entry def(E.A) | Enum.cs:11:18:11:20 | access to constant A |
-| Enum.cs:11:18:11:20 | E.A | Enum.cs:8:10:8:10 | SSA entry def(E.A) | Enum.cs:12:18:12:20 | access to constant A |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:8:22:8:22 | access to parameter i |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:10:13:10:13 | access to parameter i |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:11:26:11:26 | access to parameter i |

csharp/ql/test/library-tests/dataflow/ssa/SsaUltimateDef.expected

@@ -100,7 +100,6 @@
 | DefUse.cs:184:9:184:14 | this.Field5 | DefUse.cs:191:9:191:11 | SSA call def(this.Field5) | DefUse.cs:184:9:184:18 | SSA def(this.Field5) |
 | DefUse.cs:184:9:184:14 | this.Field5 | DefUse.cs:191:9:191:11 | SSA call def(this.Field5) | DefUse.cs:191:9:191:11 | SSA call def(this.Field5) |
 | DefUse.cs:188:13:188:18 | this.Field5 | DefUse.cs:188:13:188:22 | SSA def(this.Field5) | DefUse.cs:188:13:188:22 | SSA def(this.Field5) |
-| Enum.cs:11:18:11:20 | E.A | Enum.cs:8:10:8:10 | SSA entry def(E.A) | Enum.cs:8:10:8:10 | SSA entry def(E.A) |
 | Example.cs:6:23:6:23 | i | Example.cs:6:23:6:23 | SSA param(i) | Example.cs:6:23:6:23 | SSA param(i) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:8:9:8:22 | SSA def(this.Field) | Example.cs:8:9:8:22 | SSA def(this.Field) |
 | Example.cs:8:9:8:18 | this.Field | Example.cs:11:13:11:30 | SSA def(this.Field) | Example.cs:11:13:11:30 | SSA def(this.Field) |