[pylint] Correct ordering of arguments in fix for if-stmt-min-max…

… (`PLR1730`) (#16080)

The PR addresses the issue #16040 .

---

The logic used into the rule is the following:

Suppose to have an expression of the form 

```python
if a cmp b:
    c = d
```
where `a`,` b`, `c` and `d` are Python obj and `cmp` one of `<`, `>`,
`<=`, `>=`.

Then:

- `if a=c and b=d`
    
    - if `<=` fix with `a = max(b, a)`
    - if `>=`  fix with `a = min(b, a)`
    - if `>` fix with `a = min(a, b)`
    - if `<` fix with `a = max(a, b)`

- `if a=d and b=c`

    - if `<=` fix with `b = min(a, b)`
    - if `>=`  fix with `b = max(a, b)`
    - if `>` fix with `b = max(b, a)`
    - if `<` fix with `b = min(b, a)`
 
- do nothing, i.e., we cannot fix this case.

---

In total we have 8 different and possible cases.

```

| Case  | Expression       | Fix           |
|-------|------------------|---------------|
| 1     | if a >= b: a = b | a = min(b, a) |
| 2     | if a <= b: a = b | a = max(b, a) |
| 3     | if a <= b: b = a | b = min(a, b) |
| 4     | if a >= b: b = a | b = max(a, b) |
| 5     | if a > b: a = b  | a = min(a, b) |
| 6     | if a < b: a = b  | a = max(a, b) |
| 7     | if a < b: b = a  | b = min(b, a) |
| 8     | if a > b: b = a  | b = max(b, a) |
```

I added them in the tests. 

Please double-check that I didn't make any mistakes. It's quite easy to
mix up > and <.

---------

Co-authored-by: Micha Reiser <micha@reiser.io>

crates/ruff_linter/resources/test/fixtures/pylint/if_stmt_min_max.py

@@ -1,39 +1,98 @@
 # pylint: disable=missing-docstring, invalid-name, too-few-public-methods, redefined-outer-name
 
+
+# the rule take care of the following cases:
+#
+# | Case  | Expression       | Fix           |
+# |-------|------------------|---------------|
+# | 1     | if a >= b: a = b | a = min(b, a) |
+# | 2     | if a <= b: a = b | a = max(b, a) |
+# | 3     | if a <= b: b = a | b = min(a, b) |
+# | 4     | if a >= b: b = a | b = max(a, b) |
+# | 5     | if a > b: a = b  | a = min(a, b) |
+# | 6     | if a < b: a = b  | a = max(a, b) |
+# | 7     | if a < b: b = a  | b = min(b, a) |
+# | 8     | if a > b: b = a  | b = max(b, a) |
+
+# the 8 base cases
+a, b = [], []
+
+# case 1: a = min(b, a)
+if a >= b:
+    a = b
+
+# case 2: a = max(b, a)
+if a <= b:
+    a = b
+
+# case 3: b = min(a, b)
+if a <= b:
+    b = a
+
+# case 4: b = max(a, b)
+if a >= b:
+    b = a
+
+# case 5: a = min(a, b)
+if a > b:
+    a = b
+
+# case 6: a = max(a, b)
+if a < b:
+    a = b
+
+# case 7: b = min(b, a)
+if a < b:
+    b = a
+
+# case 8: b = max(b, a)
+if a > b:
+    b = a
+
+
+# test cases with assigned variables and primitives
 value = 10
 value2 = 0
 value3 = 3
 
-# Positive
-if value < 10:  # [max-instead-of-if]
+# base case 6: value = max(value, 10)
+if value < 10:
     value = 10
 
-if value <= 10:  # [max-instead-of-if]
+# base case 2: value = max(10, value)
+if value <= 10:
     value = 10
 
-if value < value2:  # [max-instead-of-if]
+# base case 6: value = max(value, value2)
+if value < value2:
     value = value2
 
-if value > 10:  # [min-instead-of-if]
+# base case 5: value = min(value, 10)
+if value > 10:
     value = 10
 
-if value >= 10:  # [min-instead-of-if]
+# base case 1: value = min(10, value)
+if value >= 10:
     value = 10
 
-if value > value2:  # [min-instead-of-if]
+# base case 5: value = min(value, value2)
+if value > value2:
     value = value2
 
 
+# cases with calls
 class A:
     def __init__(self):
         self.value = 13
 
 
 A1 = A()
-if A1.value < 10:  # [max-instead-of-if]
+
+
+if A1.value < 10:
     A1.value = 10
 
-if A1.value > 10:  # [min-instead-of-if]
+if A1.value > 10:
     A1.value = 10
 
 
@@ -159,3 +218,22 @@ def foo(self, value) -> None:
             self._min = value
         if self._max >= value:
             self._max = value
+
+
+counter = {"a": 0, "b": 0}
+
+# base case 2: counter["a"] = max(counter["b"], counter["a"])
+if counter["a"] <= counter["b"]:
+    counter["a"] = counter["b"]
+
+# case 3: counter["b"] = min(counter["a"], counter["b"])
+if counter["a"] <= counter["b"]:
+    counter["b"] = counter["a"]
+
+# case 5: counter["a"] = min(counter["a"], counter["b"])
+if counter["a"] > counter["b"]:
+    counter["b"] = counter["a"]
+
+# case 8: counter["a"] = max(counter["b"], counter["a"])
+if counter["a"] > counter["b"]:
+    counter["b"] = counter["a"]

crates/ruff_linter/src/rules/pylint/rules/if_stmt_min_max.rs

@@ -106,47 +106,44 @@ pub(crate) fn if_stmt_min_max(checker: &Checker, stmt_if: &ast::StmtIf) {
     let [op] = &**ops else {
         return;
     };
-
     let [right] = &**comparators else {
         return;
     };
 
-    let left_cmp = ComparableExpr::from(left);
-    let body_target_cmp = ComparableExpr::from(body_target);
-    let right_cmp = ComparableExpr::from(right);
-    let body_value_cmp = ComparableExpr::from(body_value);
-
-    let left_is_target = left_cmp == body_target_cmp;
-    let right_is_target = right_cmp == body_target_cmp;
-    let left_is_value = left_cmp == body_value_cmp;
-    let right_is_value = right_cmp == body_value_cmp;
-
-    let min_max = match (
-        left_is_target,
-        right_is_target,
-        left_is_value,
-        right_is_value,
-    ) {
-        (true, false, false, true) => match op {
-            CmpOp::Lt | CmpOp::LtE => MinMax::Max,
-            CmpOp::Gt | CmpOp::GtE => MinMax::Min,
+    // extract helpful info from expression of the form
+    // `if cmp_left op cmp_right: target = assignment_value`
+    let cmp_left = ComparableExpr::from(left);
+    let cmp_right = ComparableExpr::from(right);
+    let target = ComparableExpr::from(body_target);
+    let assignment_value = ComparableExpr::from(body_value);
+
+    // Ex): if a < b: a = b
+    let (min_max, flip_args) = if cmp_left == target && cmp_right == assignment_value {
+        match op {
+            CmpOp::Lt => (MinMax::Max, false),
+            CmpOp::LtE => (MinMax::Max, true),
+            CmpOp::Gt => (MinMax::Min, false),
+            CmpOp::GtE => (MinMax::Min, true),
             _ => return,
-        },
-        (false, true, true, false) => match op {
-            CmpOp::Lt | CmpOp::LtE => MinMax::Min,
-            CmpOp::Gt | CmpOp::GtE => MinMax::Max,
+        }
+    }
+    // Ex): `if a < b: b = a`
+    else if cmp_left == assignment_value && cmp_right == target {
+        match op {
+            CmpOp::Lt => (MinMax::Min, true),
+            CmpOp::LtE => (MinMax::Min, false),
+            CmpOp::Gt => (MinMax::Max, true),
+            CmpOp::GtE => (MinMax::Max, false),
             _ => return,
-        },
-        _ => return,
+        }
+    } else {
+        return;
     };
 
-    // Determine whether to use `min()` or `max()`, and make sure that the first
-    // arg of the `min()` or `max()` method is equal to the target of the comparison.
-    // This is to be consistent with the Python implementation of the methods `min()` and `max()`.
-    let (arg1, arg2) = if left_is_target {
-        (&**left, right)
-    } else {
+    let (arg1, arg2) = if flip_args {
         (right, &**left)
+    } else {
+        (&**left, right)
     };
 
     let replacement = format!(