Fix const_err with -(-0.0)

src/librustc_mir/transform/const_prop.rs

@@ -405,13 +405,15 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                 }
 
                 let arg = self.eval_operand(arg, source_info)?;
+                let is_release_mode = self.tcx.sess.overflow_checks();
                 let val = self.use_ecx(source_info, |this| {
                     let prim = this.ecx.read_immediate(arg)?;
                     match op {
                         UnOp::Neg => {
-                            // Need to do overflow check here: For actual CTFE, MIR
-                            // generation emits code that does this before calling the op.
-                            if prim.to_bits()? == (1 << (prim.layout.size.bits() - 1)) {
+                            // We don't have to check overflow here when we already
+                            // check it in release mode.
+                            if is_release_mode
+                            && prim.to_bits()? == (1 << (prim.layout.size.bits() - 1)) {
                                 throw_panic!(OverflowNeg)
                             }
                         }
@@ -485,7 +487,9 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                         Scalar::from_bool(overflow).into(),
                     )
                 } else {
-                    if overflow {
+                    // We don't have to check overflow here when we already
+                    // check it in release mode.
+                    if self.tcx.sess.overflow_checks() && overflow {
                         let err = err_panic!(Overflow(op)).into();
                         let _: Option<()> = self.use_ecx(source_info, |_| Err(err));
                         return None;

src/test/ui/consts/const-err2.rs

@@ -13,13 +13,9 @@ fn black_box<T>(_: T) {
 
 fn main() {
     let a = -std::i8::MIN;
-    //~^ ERROR const_err
     let b = 200u8 + 200u8 + 200u8;
-    //~^ ERROR const_err
     let c = 200u8 * 4;
-    //~^ ERROR const_err
     let d = 42u8 - (42u8 + 1);
-    //~^ ERROR const_err
     let _e = [5u8][1];
     //~^ ERROR const_err
     black_box(a);

src/test/ui/consts/const-err2.stderr

@@ -1,38 +1,14 @@
-error: this expression will panic at runtime
-  --> $DIR/const-err2.rs:15:13
+error: index out of bounds: the len is 1 but the index is 1
+  --> $DIR/const-err2.rs:19:14
    |
-LL |     let a = -std::i8::MIN;
-   |             ^^^^^^^^^^^^^ attempt to negate with overflow
+LL |     let _e = [5u8][1];
+   |              ^^^^^^^^
    |
 note: lint level defined here
   --> $DIR/const-err2.rs:8:9
    |
 LL | #![deny(const_err)]
    |         ^^^^^^^^^
 
-error: this expression will panic at runtime
-  --> $DIR/const-err2.rs:17:13
-   |
-LL |     let b = 200u8 + 200u8 + 200u8;
-   |             ^^^^^^^^^^^^^ attempt to add with overflow
-
-error: this expression will panic at runtime
-  --> $DIR/const-err2.rs:19:13
-   |
-LL |     let c = 200u8 * 4;
-   |             ^^^^^^^^^ attempt to multiply with overflow
-
-error: this expression will panic at runtime
-  --> $DIR/const-err2.rs:21:13
-   |
-LL |     let d = 42u8 - (42u8 + 1);
-   |             ^^^^^^^^^^^^^^^^^ attempt to subtract with overflow
-
-error: index out of bounds: the len is 1 but the index is 1
-  --> $DIR/const-err2.rs:23:14
-   |
-LL |     let _e = [5u8][1];
-   |              ^^^^^^^^
-
-error: aborting due to 5 previous errors
+error: aborting due to previous error
 

src/test/ui/consts/const-eval/promoted_errors.rs

@@ -5,7 +5,6 @@
 fn main() {
     println!("{}", 0u32 - 1);
     let _x = 0u32 - 1;
-    //~^ ERROR this expression will panic at runtime [const_err]
     println!("{}", 1/(1-1));
     //~^ ERROR attempt to divide by zero [const_err]
     //~| ERROR reaching this expression at runtime will panic or abort [const_err]

src/test/ui/consts/const-eval/promoted_errors.stderr

@@ -1,62 +1,56 @@
-error: this expression will panic at runtime
-  --> $DIR/promoted_errors.rs:7:14
+error: attempt to divide by zero
+  --> $DIR/promoted_errors.rs:8:20
    |
-LL |     let _x = 0u32 - 1;
-   |              ^^^^^^^^ attempt to subtract with overflow
+LL |     println!("{}", 1/(1-1));
+   |                    ^^^^^^^
    |
 note: lint level defined here
   --> $DIR/promoted_errors.rs:3:9
    |
 LL | #![deny(const_err)]
    |         ^^^^^^^^^
 
-error: attempt to divide by zero
-  --> $DIR/promoted_errors.rs:9:20
-   |
-LL |     println!("{}", 1/(1-1));
-   |                    ^^^^^^^
-
 error: reaching this expression at runtime will panic or abort
-  --> $DIR/promoted_errors.rs:9:20
+  --> $DIR/promoted_errors.rs:8:20
    |
 LL |     println!("{}", 1/(1-1));
    |                    ^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/promoted_errors.rs:12:14
+  --> $DIR/promoted_errors.rs:11:14
    |
 LL |     let _x = 1/(1-1);
    |              ^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/promoted_errors.rs:12:14
+  --> $DIR/promoted_errors.rs:11:14
    |
 LL |     let _x = 1/(1-1);
    |              ^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/promoted_errors.rs:15:20
+  --> $DIR/promoted_errors.rs:14:20
    |
 LL |     println!("{}", 1/(false as u32));
    |                    ^^^^^^^^^^^^^^^^
 
 error: reaching this expression at runtime will panic or abort
-  --> $DIR/promoted_errors.rs:15:20
+  --> $DIR/promoted_errors.rs:14:20
    |
 LL |     println!("{}", 1/(false as u32));
    |                    ^^^^^^^^^^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/promoted_errors.rs:18:14
+  --> $DIR/promoted_errors.rs:17:14
    |
 LL |     let _x = 1/(false as u32);
    |              ^^^^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/promoted_errors.rs:18:14
+  --> $DIR/promoted_errors.rs:17:14
    |
 LL |     let _x = 1/(false as u32);
    |              ^^^^^^^^^^^^^^^^ attempt to divide by zero
 
-error: aborting due to 9 previous errors
+error: aborting due to 8 previous errors
 

src/test/ui/consts/issue-64059.rs

@@ -0,0 +1,5 @@
+// run-pass
+
+fn main() {
+    let _ = -(-0.0);
+}

src/test/ui/issues/issue-8460-const.rs

@@ -6,19 +6,14 @@ use std::thread;
 fn main() {
     assert!(thread::spawn(move|| { isize::MIN / -1; }).join().is_err());
     //~^ ERROR attempt to divide with overflow
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { i8::MIN / -1; }).join().is_err());
     //~^ ERROR attempt to divide with overflow
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { i16::MIN / -1; }).join().is_err());
     //~^ ERROR attempt to divide with overflow
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { i32::MIN / -1; }).join().is_err());
     //~^ ERROR attempt to divide with overflow
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { i64::MIN / -1; }).join().is_err());
     //~^ ERROR attempt to divide with overflow
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
     //~^ ERROR attempt to divide by zero
     //~| ERROR this expression will panic at runtime
@@ -36,19 +31,14 @@ fn main() {
     //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with overflow
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with overflow
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { i16::MIN % -1; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with overflow
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { i32::MIN % -1; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with overflow
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { i64::MIN % -1; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with overflow
-    //~| ERROR this expression will panic at runtime
     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
     //~^ ERROR attempt to calculate the remainder with a divisor of zero
     //~| ERROR this expression will panic at runtime