C#: Fix CFG by removing unnecessary edge.

Author: calumgrant

csharp/ql/src/semmle/code/csharp/controlflow/ControlFlowGraph.qll

@@ -947,12 +947,6 @@ module ControlFlow {
               result = cs.getCondition() and
               c = specificBoolean(false)
             )
-            or
-            // Last statement exits with any non-break completion
-            exists(int last | last = max(int i | exists(ss.getStmt(i))) |
-              result = ss.getStmt(last) and
-              c = TRec(TLastRecNonBreakCompletion())
-            )
           )
         or
         cfe = any(SwitchExpr se |

csharp/ql/test/library-tests/controlflow/graph/Consistency.expected

@@ -4,3 +4,4 @@ breakInvariant2
 breakInvariant3
 breakInvariant4
 breakInvariant5
+multipleSuccessors

csharp/ql/test/library-tests/controlflow/graph/Consistency.ql

@@ -94,3 +94,10 @@ query predicate breakInvariant5(
   not (split.hasSuccessor(pred, succ, c) and split = predSplits.getASplit()) and
   not (split.hasEntry(pred, succ, c) and not split = predSplits.getASplit())
 }
+
+query predicate multipleSuccessors(
+  ControlFlow::Node node, SuccessorType t, ControlFlow::Node successor
+) {
+  strictcount(node.getASuccessorByType(t)) > 1 and
+  successor = node.getASuccessorByType(t)
+}

csharp/ql/test/library-tests/controlflow/graph/Dominance.expected

@@ -5124,7 +5124,6 @@ postDominance
 | Switch.cs:131:48:131:51 | null | Switch.cs:131:43:131:43 | _ |
 | Switch.cs:134:9:134:11 | exit M13 | Switch.cs:138:22:138:31 | return ...; |
 | Switch.cs:134:9:134:11 | exit M13 | Switch.cs:139:21:139:29 | return ...; |
-| Switch.cs:134:9:134:11 | exit M13 | Switch.cs:140:18:140:18 | 2 |
 | Switch.cs:134:9:134:11 | exit M13 | Switch.cs:140:21:140:29 | return ...; |
 | Switch.cs:135:5:142:5 | {...} | Switch.cs:134:9:134:11 | enter M13 |
 | Switch.cs:136:9:141:9 | switch (...) {...} | Switch.cs:135:5:142:5 | {...} |
@@ -5139,7 +5138,6 @@ postDominance
 | Switch.cs:140:21:140:29 | return ...; | Switch.cs:140:28:140:28 | 2 |
 | Switch.cs:144:9:144:11 | exit M14 | Switch.cs:148:21:148:29 | return ...; |
 | Switch.cs:144:9:144:11 | exit M14 | Switch.cs:149:22:149:31 | return ...; |
-| Switch.cs:144:9:144:11 | exit M14 | Switch.cs:150:18:150:18 | 2 |
 | Switch.cs:144:9:144:11 | exit M14 | Switch.cs:150:21:150:29 | return ...; |
 | Switch.cs:145:5:152:5 | {...} | Switch.cs:144:9:144:11 | enter M14 |
 | Switch.cs:146:9:151:9 | switch (...) {...} | Switch.cs:145:5:152:5 | {...} |

csharp/ql/test/library-tests/controlflow/graph/ExitElement.expected

@@ -2435,11 +2435,9 @@
 | Switch.cs:131:56:131:66 | call to method ToString | Switch.cs:131:56:131:66 | call to method ToString | normal |
 | Switch.cs:135:5:142:5 | {...} | Switch.cs:138:22:138:31 | return ...; | return |
 | Switch.cs:135:5:142:5 | {...} | Switch.cs:139:21:139:29 | return ...; | return |
-| Switch.cs:135:5:142:5 | {...} | Switch.cs:140:18:140:18 | 2 | no-match |
 | Switch.cs:135:5:142:5 | {...} | Switch.cs:140:21:140:29 | return ...; | return |
 | Switch.cs:136:9:141:9 | switch (...) {...} | Switch.cs:138:22:138:31 | return ...; | return |
 | Switch.cs:136:9:141:9 | switch (...) {...} | Switch.cs:139:21:139:29 | return ...; | return |
-| Switch.cs:136:9:141:9 | switch (...) {...} | Switch.cs:140:18:140:18 | 2 | no-match |
 | Switch.cs:136:9:141:9 | switch (...) {...} | Switch.cs:140:21:140:29 | return ...; | return |
 | Switch.cs:136:17:136:17 | access to parameter i | Switch.cs:136:17:136:17 | access to parameter i | normal |
 | Switch.cs:138:13:138:20 | default: | Switch.cs:138:22:138:31 | return ...; | return |
@@ -2460,11 +2458,9 @@
 | Switch.cs:140:28:140:28 | 2 | Switch.cs:140:28:140:28 | 2 | normal |
 | Switch.cs:145:5:152:5 | {...} | Switch.cs:148:21:148:29 | return ...; | return |
 | Switch.cs:145:5:152:5 | {...} | Switch.cs:149:22:149:31 | return ...; | return |
-| Switch.cs:145:5:152:5 | {...} | Switch.cs:150:18:150:18 | 2 | no-match |
 | Switch.cs:145:5:152:5 | {...} | Switch.cs:150:21:150:29 | return ...; | return |
 | Switch.cs:146:9:151:9 | switch (...) {...} | Switch.cs:148:21:148:29 | return ...; | return |
 | Switch.cs:146:9:151:9 | switch (...) {...} | Switch.cs:149:22:149:31 | return ...; | return |
-| Switch.cs:146:9:151:9 | switch (...) {...} | Switch.cs:150:18:150:18 | 2 | no-match |
 | Switch.cs:146:9:151:9 | switch (...) {...} | Switch.cs:150:21:150:29 | return ...; | return |
 | Switch.cs:146:17:146:17 | access to parameter i | Switch.cs:146:17:146:17 | access to parameter i | normal |
 | Switch.cs:148:13:148:19 | case ...: | Switch.cs:148:18:148:18 | 1 | no-match |

csharp/ql/test/library-tests/controlflow/graph/NodeGraph.expected

@@ -2550,7 +2550,6 @@
 | Switch.cs:139:21:139:29 | return ...; | Switch.cs:134:9:134:11 | exit M13 | semmle.label | return |
 | Switch.cs:139:28:139:28 | 1 | Switch.cs:139:21:139:29 | return ...; | semmle.label | successor |
 | Switch.cs:140:13:140:19 | case ...: | Switch.cs:140:18:140:18 | 2 | semmle.label | successor |
-| Switch.cs:140:18:140:18 | 2 | Switch.cs:134:9:134:11 | exit M13 | semmle.label | no-match |
 | Switch.cs:140:18:140:18 | 2 | Switch.cs:138:13:138:20 | default: | semmle.label | no-match |
 | Switch.cs:140:18:140:18 | 2 | Switch.cs:140:28:140:28 | 2 | semmle.label | match |
 | Switch.cs:140:21:140:29 | return ...; | Switch.cs:134:9:134:11 | exit M13 | semmle.label | return |
@@ -2569,7 +2568,6 @@
 | Switch.cs:149:29:149:30 | -... | Switch.cs:149:22:149:31 | return ...; | semmle.label | successor |
 | Switch.cs:149:30:149:30 | 1 | Switch.cs:149:29:149:30 | -... | semmle.label | successor |
 | Switch.cs:150:13:150:19 | case ...: | Switch.cs:150:18:150:18 | 2 | semmle.label | successor |
-| Switch.cs:150:18:150:18 | 2 | Switch.cs:144:9:144:11 | exit M14 | semmle.label | no-match |
 | Switch.cs:150:18:150:18 | 2 | Switch.cs:149:13:149:20 | default: | semmle.label | no-match |
 | Switch.cs:150:18:150:18 | 2 | Switch.cs:150:28:150:28 | 2 | semmle.label | match |
 | Switch.cs:150:21:150:29 | return ...; | Switch.cs:144:9:144:11 | exit M14 | semmle.label | return |