Rust: Fix multiple CFG successors in range pattern without lower bound

Author: paldepind

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

@@ -612,7 +612,7 @@ module PatternTrees {
       result = rank[i + 1](Pat pat, int j | pat = this.getPat(j) | pat order by j)
     }
 
-    predicate isEmpty() { not any(Pat p) = this.getPat(0) }
+    predicate isEmpty() { not any(Pat p) = this.getPatRanked(0) }
 
     override predicate propagatesAbnormal(AstNode child) { child = this.getPatRanked(_) }
 

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

@@ -716,7 +716,6 @@ edges
 | test.rs:335:9:340:9 | MatchExpr | test.rs:334:31:341:5 | BlockExpr |  |
 | test.rs:335:15:335:16 | 42 | test.rs:336:13:336:15 | RangePat |  |
 | test.rs:336:13:336:15 | RangePat | test.rs:336:15:336:15 | LiteralPat | match |
-| test.rs:336:13:336:15 | RangePat | test.rs:336:20:336:20 | 1 | match |
 | test.rs:336:13:336:15 | RangePat | test.rs:337:13:337:16 | RangePat | no-match |
 | test.rs:336:15:336:15 | LiteralPat | test.rs:336:20:336:20 | 1 | match |
 | test.rs:336:15:336:15 | LiteralPat | test.rs:337:13:337:16 | RangePat | no-match |