Fix span issue on implicit_saturating_sub

Fixes rust-lang#13524

clippy_lints/src/implicit_saturating_sub.rs

@@ -107,9 +107,7 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitSaturatingSub {
         }) = higher::If::hir(expr)
             && let ExprKind::Binary(ref cond_op, cond_left, cond_right) = cond.kind
         {
-            check_manual_check(
-                cx, expr, cond_op, cond_left, cond_right, if_block, else_block, &self.msrv,
-            );
+            check_manual_check(cx, cond_op, cond_left, cond_right, if_block, else_block, &self.msrv);
         }
     }
 
@@ -119,7 +117,6 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitSaturatingSub {
 #[allow(clippy::too_many_arguments)]
 fn check_manual_check<'tcx>(
     cx: &LateContext<'tcx>,
-    expr: &Expr<'tcx>,
     condition: &BinOp,
     left_hand: &Expr<'tcx>,
     right_hand: &Expr<'tcx>,
@@ -130,26 +127,12 @@ fn check_manual_check<'tcx>(
     let ty = cx.typeck_results().expr_ty(left_hand);
     if ty.is_numeric() && !ty.is_signed() {
         match condition.node {
-            BinOpKind::Gt | BinOpKind::Ge => check_gt(
-                cx,
-                condition.span,
-                expr.span,
-                left_hand,
-                right_hand,
-                if_block,
-                else_block,
-                msrv,
-            ),
-            BinOpKind::Lt | BinOpKind::Le => check_gt(
-                cx,
-                condition.span,
-                expr.span,
-                right_hand,
-                left_hand,
-                if_block,
-                else_block,
-                msrv,
-            ),
+            BinOpKind::Gt | BinOpKind::Ge => {
+                check_gt(cx, condition.span, left_hand, right_hand, if_block, else_block, msrv);
+            },
+            BinOpKind::Lt | BinOpKind::Le => {
+                check_gt(cx, condition.span, right_hand, left_hand, if_block, else_block, msrv);
+            },
             _ => {},
         }
     }
@@ -159,7 +142,6 @@ fn check_manual_check<'tcx>(
 fn check_gt(
     cx: &LateContext<'_>,
     condition_span: Span,
-    expr_span: Span,
     big_var: &Expr<'_>,
     little_var: &Expr<'_>,
     if_block: &Expr<'_>,
@@ -169,16 +151,7 @@ fn check_gt(
     if let Some(big_var) = Var::new(big_var)
         && let Some(little_var) = Var::new(little_var)
     {
-        check_subtraction(
-            cx,
-            condition_span,
-            expr_span,
-            big_var,
-            little_var,
-            if_block,
-            else_block,
-            msrv,
-        );
+        check_subtraction(cx, condition_span, big_var, little_var, if_block, else_block, msrv);
     }
 }
 
@@ -200,7 +173,6 @@ impl Var {
 fn check_subtraction(
     cx: &LateContext<'_>,
     condition_span: Span,
-    expr_span: Span,
     big_var: Var,
     little_var: Var,
     if_block: &Expr<'_>,
@@ -217,16 +189,7 @@ fn check_subtraction(
         }
         // If the subtraction is done in the `else` block, then we need to also revert the two
         // variables as it means that the check was reverted too.
-        check_subtraction(
-            cx,
-            condition_span,
-            expr_span,
-            little_var,
-            big_var,
-            else_block,
-            if_block,
-            msrv,
-        );
+        check_subtraction(cx, condition_span, little_var, big_var, else_block, if_block, msrv);
         return;
     }
     if is_integer_literal(else_block, 0)
@@ -245,7 +208,7 @@ fn check_subtraction(
                 span_lint_and_sugg(
                     cx,
                     IMPLICIT_SATURATING_SUB,
-                    expr_span,
+                    else_block.span,
                     "manual arithmetic check found",
                     "replace it with",
                     format!("{big_var_snippet}.saturating_sub({little_var_snippet})"),

tests/ui/implicit_saturating_sub.fixed

@@ -222,3 +222,14 @@ fn main() {
         a - b
     };
 }
+
+// https://github.com/rust-lang/rust-clippy/issues/13524
+fn regression_13524(a: usize, b: usize, c: bool) -> usize {
+    if c {
+        123
+    } else if a >= b {
+        b.saturating_sub(a)
+    } else {
+        b - a
+    }
+}

tests/ui/implicit_saturating_sub.rs

@@ -268,3 +268,14 @@ fn main() {
         a - b
     };
 }
+
+// https://github.com/rust-lang/rust-clippy/issues/13524
+fn regression_13524(a: usize, b: usize, c: bool) -> usize {
+    if c {
+        123
+    } else if a >= b {
+        0
+    } else {
+        b - a
+    }
+}

tests/ui/implicit_saturating_sub.stderr

@@ -185,5 +185,11 @@ LL | |         i_64 -= 1;
 LL | |     }
    | |_____^ help: try: `i_64 = i_64.saturating_sub(1);`
 
-error: aborting due to 23 previous errors
+error: manual arithmetic check found
+  --> tests/ui/implicit_saturating_sub.rs:277:9
+   |
+LL |         0
+   |         ^ help: replace it with: `b.saturating_sub(a)`
+
+error: aborting due to 24 previous errors
 

tests/ui/manual_arithmetic_check.fixed

@@ -6,14 +6,14 @@ fn main() {
     let b = 13u32;
     let c = 8u32;
 
-    let result = a.saturating_sub(b);
+    let result = if a > b { a - b } else { a.saturating_sub(b) };
     //~^ ERROR: manual arithmetic check found
-    let result = a.saturating_sub(b);
+    let result = if b < a { a - b } else { a.saturating_sub(b) };
     //~^ ERROR: manual arithmetic check found
 
-    let result = a.saturating_sub(b);
+    let result = if a < b { a.saturating_sub(b) } else { a - b };
     //~^ ERROR: manual arithmetic check found
-    let result = a.saturating_sub(b);
+    let result = if b > a { a.saturating_sub(b) } else { a - b };
     //~^ ERROR: manual arithmetic check found
 
     // Should not warn!

tests/ui/manual_arithmetic_check.stderr

@@ -1,29 +1,29 @@
 error: manual arithmetic check found
-  --> tests/ui/manual_arithmetic_check.rs:9:18
+  --> tests/ui/manual_arithmetic_check.rs:9:44
    |
 LL |     let result = if a > b { a - b } else { 0 };
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `a.saturating_sub(b)`
+   |                                            ^ help: replace it with: `a.saturating_sub(b)`
    |
    = note: `-D clippy::implicit-saturating-sub` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::implicit_saturating_sub)]`
 
 error: manual arithmetic check found
-  --> tests/ui/manual_arithmetic_check.rs:11:18
+  --> tests/ui/manual_arithmetic_check.rs:11:44
    |
 LL |     let result = if b < a { a - b } else { 0 };
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `a.saturating_sub(b)`
+   |                                            ^ help: replace it with: `a.saturating_sub(b)`
 
 error: manual arithmetic check found
-  --> tests/ui/manual_arithmetic_check.rs:14:18
+  --> tests/ui/manual_arithmetic_check.rs:14:29
    |
 LL |     let result = if a < b { 0 } else { a - b };
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `a.saturating_sub(b)`
+   |                             ^ help: replace it with: `a.saturating_sub(b)`
 
 error: manual arithmetic check found
-  --> tests/ui/manual_arithmetic_check.rs:16:18
+  --> tests/ui/manual_arithmetic_check.rs:16:29
    |
 LL |     let result = if b > a { 0 } else { a - b };
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `a.saturating_sub(b)`
+   |                             ^ help: replace it with: `a.saturating_sub(b)`
 
 error: aborting due to 4 previous errors