Fix overflow_check

9 files changed, 170 insertions, 56 deletions

diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs
index b43323687cd..091e68cd066 100644
--- a/src/librustc_mir/transform/const_prop.rs
+++ b/src/librustc_mir/transform/const_prop.rs
@@ -405,14 +405,14 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                 }
 
                 let arg = self.eval_operand(arg, source_info)?;
-                let is_release_mode = self.tcx.sess.overflow_checks();
+                let oflo_check = self.tcx.sess.overflow_checks();
                 let val = self.use_ecx(source_info, |this| {
                     let prim = this.ecx.read_immediate(arg)?;
                     match op {
                         UnOp::Neg => {
-                            // We don't have to check overflow here when we already
-                            // check it in release mode.
-                            if is_release_mode
+                            // We check overflow in debug mode already
+                            // so should only check in release mode.
+                            if !oflo_check
                             && prim.to_bits()? == (1 << (prim.layout.size.bits() - 1)) {
                                 throw_panic!(OverflowNeg)
                             }
@@ -487,9 +487,9 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                         Scalar::from_bool(overflow).into(),
                     )
                 } else {
-                    // We don't have to check overflow here when we already
-                    // check it in release mode.
-                    if self.tcx.sess.overflow_checks() && overflow {
+                    // We check overflow in debug mode already
+                    // so should only check 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;
diff --git a/src/test/ui/consts/const-err2.rs b/src/test/ui/consts/const-err2.rs
index 6da6addf60a..a5f685a159b 100644
--- a/src/test/ui/consts/const-err2.rs
+++ b/src/test/ui/consts/const-err2.rs
@@ -13,9 +13,13 @@ 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);
diff --git a/src/test/ui/consts/const-err2.stderr b/src/test/ui/consts/const-err2.stderr
index 30855fd215f..659c3afc618 100644
--- a/src/test/ui/consts/const-err2.stderr
+++ b/src/test/ui/consts/const-err2.stderr
@@ -1,8 +1,8 @@
-error: index out of bounds: the len is 1 but the index is 1
-  --> $DIR/const-err2.rs:19:14
+error: this expression will panic at runtime
+  --> $DIR/const-err2.rs:15:13
    |
-LL |     let _e = [5u8][1];
-   |              ^^^^^^^^
+LL |     let a = -std::i8::MIN;
+   |             ^^^^^^^^^^^^^ attempt to negate with overflow
    |
 note: lint level defined here
   --> $DIR/const-err2.rs:8:9
@@ -10,5 +10,29 @@ note: lint level defined here
 LL | #![deny(const_err)]
    |         ^^^^^^^^^
 
-error: aborting due to previous error
+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
 
diff --git a/src/test/ui/consts/const-eval/promoted_errors.rs b/src/test/ui/consts/const-eval/promoted_errors.rs
index a9a7a66fe61..cd989731452 100644
--- a/src/test/ui/consts/const-eval/promoted_errors.rs
+++ b/src/test/ui/consts/const-eval/promoted_errors.rs
@@ -5,6 +5,7 @@
 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]
diff --git a/src/test/ui/consts/const-eval/promoted_errors.stderr b/src/test/ui/consts/const-eval/promoted_errors.stderr
index 3940fa13d78..40d5c73e866 100644
--- a/src/test/ui/consts/const-eval/promoted_errors.stderr
+++ b/src/test/ui/consts/const-eval/promoted_errors.stderr
@@ -1,8 +1,8 @@
-error: attempt to divide by zero
-  --> $DIR/promoted_errors.rs:8:20
+error: this expression will panic at runtime
+  --> $DIR/promoted_errors.rs:7:14
    |
-LL |     println!("{}", 1/(1-1));
-   |                    ^^^^^^^
+LL |     let _x = 0u32 - 1;
+   |              ^^^^^^^^ attempt to subtract with overflow
    |
 note: lint level defined here
   --> $DIR/promoted_errors.rs:3:9
@@ -10,47 +10,53 @@ note: lint level defined here
 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:8:20
+  --> $DIR/promoted_errors.rs:9:20
    |
 LL |     println!("{}", 1/(1-1));
    |                    ^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/promoted_errors.rs:11:14
+  --> $DIR/promoted_errors.rs:12:14
    |
 LL |     let _x = 1/(1-1);
    |              ^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/promoted_errors.rs:11:14
+  --> $DIR/promoted_errors.rs:12:14
    |
 LL |     let _x = 1/(1-1);
    |              ^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/promoted_errors.rs:14:20
+  --> $DIR/promoted_errors.rs:15:20
    |
 LL |     println!("{}", 1/(false as u32));
    |                    ^^^^^^^^^^^^^^^^
 
 error: reaching this expression at runtime will panic or abort
-  --> $DIR/promoted_errors.rs:14:20
+  --> $DIR/promoted_errors.rs:15:20
    |
 LL |     println!("{}", 1/(false as u32));
    |                    ^^^^^^^^^^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/promoted_errors.rs:17:14
+  --> $DIR/promoted_errors.rs:18:14
    |
 LL |     let _x = 1/(false as u32);
    |              ^^^^^^^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/promoted_errors.rs:17:14
+  --> $DIR/promoted_errors.rs:18:14
    |
 LL |     let _x = 1/(false as u32);
    |              ^^^^^^^^^^^^^^^^ attempt to divide by zero
 
-error: aborting due to 8 previous errors
+error: aborting due to 9 previous errors
 
diff --git a/src/test/ui/consts/issue-64059.rs b/src/test/ui/consts/issue-64059.rs
index c4c895fef66..30b8744cb7f 100644
--- a/src/test/ui/consts/issue-64059.rs
+++ b/src/test/ui/consts/issue-64059.rs
@@ -1,5 +1,4 @@
-// run-pass
-
 fn main() {
     let _ = -(-0.0);
+    //~^ ERROR: this expression will panic at runtime
 }
diff --git a/src/test/ui/consts/issue-64059.stderr b/src/test/ui/consts/issue-64059.stderr
new file mode 100644
index 00000000000..6f27653421b
--- /dev/null
+++ b/src/test/ui/consts/issue-64059.stderr
@@ -0,0 +1,10 @@
+error: this expression will panic at runtime
+  --> $DIR/issue-64059.rs:2:13
+   |
+LL |     let _ = -(-0.0);
+   |             ^^^^^^^ attempt to negate with overflow
+   |
+   = note: `#[deny(const_err)]` on by default
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/issues/issue-8460-const.rs b/src/test/ui/issues/issue-8460-const.rs
index 6a5b98fa9b1..611d280f774 100644
--- a/src/test/ui/issues/issue-8460-const.rs
+++ b/src/test/ui/issues/issue-8460-const.rs
@@ -6,14 +6,19 @@ 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
@@ -31,14 +36,19 @@ 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
diff --git a/src/test/ui/issues/issue-8460-const.stderr b/src/test/ui/issues/issue-8460-const.stderr
index b9fbf0bdaa6..31b1da4f804 100644
--- a/src/test/ui/issues/issue-8460-const.stderr
+++ b/src/test/ui/issues/issue-8460-const.stderr
@@ -10,179 +10,239 @@ note: lint level defined here
 LL | #![deny(const_err)]
    |         ^^^^^^^^^
 
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const.rs:7:36
+   |
+LL |     assert!(thread::spawn(move|| { isize::MIN / -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^^^ attempt to divide with overflow
+
 error: attempt to divide with overflow
-  --> $DIR/issue-8460-const.rs:9:36
+  --> $DIR/issue-8460-const.rs:10:36
    |
 LL |     assert!(thread::spawn(move|| { i8::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^
 
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const.rs:10:36
+   |
+LL |     assert!(thread::spawn(move|| { i8::MIN / -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^ attempt to divide with overflow
+
 error: attempt to divide with overflow
-  --> $DIR/issue-8460-const.rs:11:36
+  --> $DIR/issue-8460-const.rs:13:36
    |
 LL |     assert!(thread::spawn(move|| { i16::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
-error: attempt to divide with overflow
+error: this expression will panic at runtime
   --> $DIR/issue-8460-const.rs:13:36
    |
+LL |     assert!(thread::spawn(move|| { i16::MIN / -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^ attempt to divide with overflow
+
+error: attempt to divide with overflow
+  --> $DIR/issue-8460-const.rs:16:36
+   |
 LL |     assert!(thread::spawn(move|| { i32::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const.rs:16:36
+   |
+LL |     assert!(thread::spawn(move|| { i32::MIN / -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^ attempt to divide with overflow
+
 error: attempt to divide with overflow
-  --> $DIR/issue-8460-const.rs:15:36
+  --> $DIR/issue-8460-const.rs:19:36
    |
 LL |     assert!(thread::spawn(move|| { i64::MIN / -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const.rs:19:36
+   |
+LL |     assert!(thread::spawn(move|| { i64::MIN / -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^ attempt to divide with overflow
+
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:17:36
+  --> $DIR/issue-8460-const.rs:22:36
    |
 LL |     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
    |                                    ^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:17:36
+  --> $DIR/issue-8460-const.rs:22:36
    |
 LL |     assert!(thread::spawn(move|| { 1isize / 0; }).join().is_err());
    |                                    ^^^^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:20:36
+  --> $DIR/issue-8460-const.rs:25:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
    |                                    ^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:20:36
+  --> $DIR/issue-8460-const.rs:25:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 / 0; }).join().is_err());
    |                                    ^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:23:36
+  --> $DIR/issue-8460-const.rs:28:36
    |
 LL |     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:23:36
+  --> $DIR/issue-8460-const.rs:28:36
    |
 LL |     assert!(thread::spawn(move|| { 1i16 / 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:26:36
+  --> $DIR/issue-8460-const.rs:31:36
    |
 LL |     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:26:36
+  --> $DIR/issue-8460-const.rs:31:36
    |
 LL |     assert!(thread::spawn(move|| { 1i32 / 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to divide by zero
 
 error: attempt to divide by zero
-  --> $DIR/issue-8460-const.rs:29:36
+  --> $DIR/issue-8460-const.rs:34:36
    |
 LL |     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:29:36
+  --> $DIR/issue-8460-const.rs:34:36
    |
 LL |     assert!(thread::spawn(move|| { 1i64 / 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to divide by zero
 
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:32:36
+  --> $DIR/issue-8460-const.rs:37:36
    |
 LL |     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^^^
 
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const.rs:37:36
+   |
+LL |     assert!(thread::spawn(move|| { isize::MIN % -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
+
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:34:36
+  --> $DIR/issue-8460-const.rs:40:36
    |
 LL |     assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^
 
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const.rs:40:36
+   |
+LL |     assert!(thread::spawn(move|| { i8::MIN % -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^ attempt to calculate the remainder with overflow
+
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:36:36
+  --> $DIR/issue-8460-const.rs:43:36
    |
 LL |     assert!(thread::spawn(move|| { i16::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const.rs:43:36
+   |
+LL |     assert!(thread::spawn(move|| { i16::MIN % -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
+
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:38:36
+  --> $DIR/issue-8460-const.rs:46:36
    |
 LL |     assert!(thread::spawn(move|| { i32::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const.rs:46:36
+   |
+LL |     assert!(thread::spawn(move|| { i32::MIN % -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
+
 error: attempt to calculate the remainder with overflow
-  --> $DIR/issue-8460-const.rs:40:36
+  --> $DIR/issue-8460-const.rs:49:36
    |
 LL |     assert!(thread::spawn(move|| { i64::MIN % -1; }).join().is_err());
    |                                    ^^^^^^^^^^^^^
 
+error: this expression will panic at runtime
+  --> $DIR/issue-8460-const.rs:49:36
+   |
+LL |     assert!(thread::spawn(move|| { i64::MIN % -1; }).join().is_err());
+   |                                    ^^^^^^^^^^^^^ attempt to calculate the remainder with overflow
+
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:42:36
+  --> $DIR/issue-8460-const.rs:52:36
    |
 LL |     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
    |                                    ^^^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:42:36
+  --> $DIR/issue-8460-const.rs:52:36
    |
 LL |     assert!(thread::spawn(move|| { 1isize % 0; }).join().is_err());
    |                                    ^^^^^^^^^^ attempt to calculate the remainder with a divisor of zero
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:45:36
+  --> $DIR/issue-8460-const.rs:55:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
    |                                    ^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:45:36
+  --> $DIR/issue-8460-const.rs:55:36
    |
 LL |     assert!(thread::spawn(move|| { 1i8 % 0; }).join().is_err());
    |                                    ^^^^^^^ attempt to calculate the remainder with a divisor of zero
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:48:36
+  --> $DIR/issue-8460-const.rs:58:36
    |
 LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:48:36
+  --> $DIR/issue-8460-const.rs:58:36
    |
 LL |     assert!(thread::spawn(move|| { 1i16 % 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:51:36
+  --> $DIR/issue-8460-const.rs:61:36
    |
 LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:51:36
+  --> $DIR/issue-8460-const.rs:61:36
    |
 LL |     assert!(thread::spawn(move|| { 1i32 % 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
 
 error: attempt to calculate the remainder with a divisor of zero
-  --> $DIR/issue-8460-const.rs:54:36
+  --> $DIR/issue-8460-const.rs:64:36
    |
 LL |     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
    |                                    ^^^^^^^^
 
 error: this expression will panic at runtime
-  --> $DIR/issue-8460-const.rs:54:36
+  --> $DIR/issue-8460-const.rs:64:36
    |
 LL |     assert!(thread::spawn(move|| { 1i64 % 0; }).join().is_err());
    |                                    ^^^^^^^^ attempt to calculate the remainder with a divisor of zero
 
-error: aborting due to 30 previous errors
+error: aborting due to 40 previous errors