Added lint for checking iXX::min_value()

Author: pmk21

clippy_lints/src/implicit_saturating_sub.rs

@@ -100,6 +100,17 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ImplicitSaturatingSub {
                             return;
                         }
                     },
+                    ExprKind::Call(ref func, _) => {
+                        if let ExprKind::Path(ref cond_right_path) = func.kind {
+                            if match_qpath(cond_right_path, &["i8", "min_value"]) || match_qpath(cond_right_path, &["i16", "min_value"]) || match_qpath(cond_right_path, &["i32", "min_value"]) || match_qpath(cond_right_path, &["i64", "min_value"]) {
+                                print_lint_and_sugg(cx, &var_name, expr);
+                            } else {
+                                return;
+                            }
+                        } else {
+                            return;
+                        }
+                    },
                     _ => (),
                 }
             }

tests/ui/implicit_saturating_sub.rs

@@ -97,6 +97,11 @@ fn main() {
         i_8 -= 1;
     }
 
+    // Lint
+    if i_8 > i8::min_value() {
+        i_8 -= 1;
+    }
+
     let endi_16: i16 = 45;
     let starti_16: i16 = 44;
 
@@ -107,6 +112,11 @@ fn main() {
         i_16 -= 1;
     }
 
+    // Lint
+    if i_16 > i16::min_value() {
+        i_16 -= 1;
+    }
+
     let endi_32: i32 = 45;
     let starti_32: i32 = 44;
 
@@ -117,6 +127,11 @@ fn main() {
         i_32 -= 1;
     }
 
+    // Lint
+    if i_32 > i32::min_value() {
+        i_32 -= 1;
+    }
+
     let endi_64: i64 = 45;
     let starti_64: i64 = 44;
 
@@ -126,4 +141,9 @@ fn main() {
     if i_64 > i64::MIN {
         i_64 -= 1;
     }
+
+    // Lint
+    if i_64 > i64::min_value() {
+        i_64 -= 1;
+    }
 }

tests/ui/implicit_saturating_sub.stderr

@@ -57,7 +57,15 @@ LL | |     }
    | |_____^ help: try: `i_8 = i_8.saturating_sub(1);`
 
 error: Implicitly performing saturating subtraction
-  --> $DIR/implicit_saturating_sub.rs:106:5
+  --> $DIR/implicit_saturating_sub.rs:101:5
+   |
+LL | /     if i_8 > i8::min_value() {
+LL | |         i_8 -= 1;
+LL | |     }
+   | |_____^ help: try: `i_8 = i_8.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+  --> $DIR/implicit_saturating_sub.rs:111:5
    |
 LL | /     if i_16 > i16::MIN {
 LL | |         i_16 -= 1;
@@ -67,18 +75,42 @@ LL | |     }
 error: Implicitly performing saturating subtraction
   --> $DIR/implicit_saturating_sub.rs:116:5
    |
+LL | /     if i_16 > i16::min_value() {
+LL | |         i_16 -= 1;
+LL | |     }
+   | |_____^ help: try: `i_16 = i_16.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+  --> $DIR/implicit_saturating_sub.rs:126:5
+   |
 LL | /     if i_32 > i32::MIN {
 LL | |         i_32 -= 1;
 LL | |     }
    | |_____^ help: try: `i_32 = i_32.saturating_sub(1);`
 
 error: Implicitly performing saturating subtraction
-  --> $DIR/implicit_saturating_sub.rs:126:5
+  --> $DIR/implicit_saturating_sub.rs:131:5
+   |
+LL | /     if i_32 > i32::min_value() {
+LL | |         i_32 -= 1;
+LL | |     }
+   | |_____^ help: try: `i_32 = i_32.saturating_sub(1);`
+
+error: Implicitly performing saturating subtraction
+  --> $DIR/implicit_saturating_sub.rs:141:5
    |
 LL | /     if i_64 > i64::MIN {
 LL | |         i_64 -= 1;
 LL | |     }
    | |_____^ help: try: `i_64 = i_64.saturating_sub(1);`
 
-error: aborting due to 10 previous errors
+error: Implicitly performing saturating subtraction
+  --> $DIR/implicit_saturating_sub.rs:146:5
+   |
+LL | /     if i_64 > i64::min_value() {
+LL | |         i_64 -= 1;
+LL | |     }
+   | |_____^ help: try: `i_64 = i_64.saturating_sub(1);`
+
+error: aborting due to 14 previous errors