fix logic in IncrementVisitor

There used to be a logical bug where IncrementVisitor would
completely stop checking an expression/block after seeing a continue
statement. This led to issues such as #10058 where a variable incremented
(or otherwise modified) after any continue statement could still be
considered incremented only once.

The solution is to continue scanning the expression after seeing a
`continue` statement, but increment self.depth so that the Visitor
thinks that the rest of the loop is within a conditional.

Author: ericwu17

clippy_lints/src/loops/utils.rs

@@ -95,7 +95,7 @@ impl<'a, 'tcx> Visitor<'tcx> for IncrementVisitor<'a, 'tcx> {
             walk_expr(self, expr);
             self.depth -= 1;
         } else if let ExprKind::Continue(_) = expr.kind {
-            self.done = true;
+            self.depth += 1;
         } else {
             walk_expr(self, expr);
         }

tests/ui/explicit_counter_loop.rs

@@ -189,3 +189,33 @@ mod issue_7920 {
         }
     }
 }
+
+mod issue_10058 {
+    pub fn test() {
+        // should not lint since we are increasing counter potentially more than once in the loop
+        let values = [0, 1, 0, 1, 1, 1, 0, 1, 0, 1];
+        let mut counter = 0;
+        for value in values {
+            counter += 1;
+
+            if value == 0 {
+                continue;
+            }
+
+            counter += 1;
+        }
+    }
+
+    pub fn test2() {
+        // should not lint since we are increasing counter potentially more than once in the loop
+        let values = [0, 1, 0, 1, 1, 1, 0, 1, 0, 1];
+        let mut counter = 0;
+        for value in values {
+            counter += 1;
+
+            if value != 0 {
+                counter += 1;
+            }
+        }
+    }
+}