Rust: Remove erroneous CFG edge from return to break

Author: paldepind

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

@@ -159,7 +159,7 @@ class BreakExprTree extends PostOrderTree, BreakExpr {
   override predicate last(AstNode last, Completion c) { none() }
 
   override predicate succ(AstNode pred, AstNode succ, Completion c) {
-    last(super.getExpr(), pred, c) and succ = this
+    last(super.getExpr(), pred, c) and completionIsNormal(c) and succ = this
     or
     pred = this and
     c.isValidFor(pred) and

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

@@ -207,12 +207,8 @@ edges
 | test.rs:102:13:102:14 | ExprStmt | test.rs:102:13:102:13 | 1 |  |
 | test.rs:106:5:110:5 | enter break_with_return | test.rs:108:13:108:27 | ExprStmt |  |
 | test.rs:106:5:110:5 | exit break_with_return (normal) | test.rs:106:5:110:5 | exit break_with_return |  |
-| test.rs:106:35:110:5 | BlockExpr | test.rs:106:5:110:5 | exit break_with_return (normal) |  |
-| test.rs:107:9:109:9 | LoopExpr | test.rs:106:35:110:5 | BlockExpr |  |
-| test.rs:108:13:108:26 | BreakExpr | test.rs:107:9:109:9 | LoopExpr | break |
 | test.rs:108:13:108:27 | ExprStmt | test.rs:108:26:108:26 | 1 |  |
 | test.rs:108:19:108:26 | ReturnExpr | test.rs:106:5:110:5 | exit break_with_return (normal) | return |
-| test.rs:108:19:108:26 | ReturnExpr | test.rs:108:13:108:26 | BreakExpr | return |
 | test.rs:108:26:108:26 | 1 | test.rs:108:19:108:26 | ReturnExpr |  |
 | test.rs:113:1:116:1 | enter test_nested_function | test.rs:113:25:113:25 | n |  |
 | test.rs:113:1:116:1 | exit test_nested_function (normal) | test.rs:113:1:116:1 | exit test_nested_function |  |