Rust: Conditional completion of match arm expression should now flow to next arm

Author: paldepind

rust/ql/lib/codeql/rust/controlflow/internal/ControlFlowGraphImpl.qll

@@ -507,9 +507,12 @@ class MatchExprTree extends PostOrderTree instanceof MatchExpr {
     first(super.getArm(0).getPat(), succ) and
     completionIsNormal(c)
     or
-    // Edge from a failed match/guard in one arm to the beginning of the next arm.
+    // Edge from a failed pattern or guard in one arm to the beginning of the next arm.
     exists(int i |
-      last(super.getArm(i), pred, c) and
+      (
+        last(super.getArm(i).getPat(), pred, c) or
+        last(super.getArm(i).getGuard().getCondition(), pred, c)
+      ) and
       first(super.getArm(i + 1), succ) and
       c.(ConditionalCompletion).failed()
     )

rust/ql/test/library-tests/controlflow/Cfg.expected

@@ -661,7 +661,6 @@ edges
 | test.rs:297:18:297:18 | a | test.rs:297:24:297:24 | a | match |
 | test.rs:297:24:297:24 | a | test.rs:296:10:299:9 | [boolean(false)] MatchExpr | false |
 | test.rs:297:24:297:24 | a | test.rs:296:10:299:9 | [boolean(true)] MatchExpr | true |
-| test.rs:297:24:297:24 | a | test.rs:298:13:298:13 | WildcardPat | false |
 | test.rs:298:13:298:13 | WildcardPat | test.rs:298:18:298:22 | false | match |
 | test.rs:298:18:298:22 | false | test.rs:296:10:299:9 | [boolean(false)] MatchExpr | false |
 | test.rs:299:15:299:18 | cond | test.rs:296:9:299:18 | ... && ... |  |