Auto merge of rust-lang#9464 - lukaslueg:issue9463, r=dswij

Don't panic on invalid shift while constfolding

Instead of panicking on invalid shifts while folding constants we simply give up. Fixes rust-lang#9463

Notice the "attempt to shift right by `1316134912_u32`", which seems weird. AFAICS it comes from rustc itself.

changelog: none

Author: bors

clippy_utils/src/consts.rs

@@ -501,8 +501,8 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
                         BinOpKind::Mul => l.checked_mul(r).map(zext),
                         BinOpKind::Div if r != 0 => l.checked_div(r).map(zext),
                         BinOpKind::Rem if r != 0 => l.checked_rem(r).map(zext),
-                        BinOpKind::Shr => l.checked_shr(r.try_into().expect("invalid shift")).map(zext),
-                        BinOpKind::Shl => l.checked_shl(r.try_into().expect("invalid shift")).map(zext),
+                        BinOpKind::Shr => l.checked_shr(r.try_into().ok()?).map(zext),
+                        BinOpKind::Shl => l.checked_shl(r.try_into().ok()?).map(zext),
                         BinOpKind::BitXor => Some(zext(l ^ r)),
                         BinOpKind::BitOr => Some(zext(l | r)),
                         BinOpKind::BitAnd => Some(zext(l & r)),
@@ -521,8 +521,8 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
                     BinOpKind::Mul => l.checked_mul(r).map(Constant::Int),
                     BinOpKind::Div => l.checked_div(r).map(Constant::Int),
                     BinOpKind::Rem => l.checked_rem(r).map(Constant::Int),
-                    BinOpKind::Shr => l.checked_shr(r.try_into().expect("shift too large")).map(Constant::Int),
-                    BinOpKind::Shl => l.checked_shl(r.try_into().expect("shift too large")).map(Constant::Int),
+                    BinOpKind::Shr => l.checked_shr(r.try_into().ok()?).map(Constant::Int),
+                    BinOpKind::Shl => l.checked_shl(r.try_into().ok()?).map(Constant::Int),
                     BinOpKind::BitXor => Some(Constant::Int(l ^ r)),
                     BinOpKind::BitOr => Some(Constant::Int(l | r)),
                     BinOpKind::BitAnd => Some(Constant::Int(l & r)),

tests/ui/crashes/ice-9463.rs

@@ -0,0 +1,5 @@
+#![deny(arithmetic_overflow, const_err)]
+fn main() {
+    let _x = -1_i32 >> -1;
+    let _y = 1u32 >> 10000000000000u32;
+}

tests/ui/crashes/ice-9463.stderr

@@ -0,0 +1,29 @@
+error: this arithmetic operation will overflow
+  --> $DIR/ice-9463.rs:3:14
+   |
+LL |     let _x = -1_i32 >> -1;
+   |              ^^^^^^^^^^^^ attempt to shift right by `-1_i32`, which would overflow
+   |
+note: the lint level is defined here
+  --> $DIR/ice-9463.rs:1:9
+   |
+LL | #![deny(arithmetic_overflow, const_err)]
+   |         ^^^^^^^^^^^^^^^^^^^
+
+error: this arithmetic operation will overflow
+  --> $DIR/ice-9463.rs:4:14
+   |
+LL |     let _y = 1u32 >> 10000000000000u32;
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^ attempt to shift right by `1316134912_u32`, which would overflow
+
+error: literal out of range for `u32`
+  --> $DIR/ice-9463.rs:4:22
+   |
+LL |     let _y = 1u32 >> 10000000000000u32;
+   |                      ^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[deny(overflowing_literals)]` on by default
+   = note: the literal `10000000000000u32` does not fit into the type `u32` whose range is `0..=4294967295`
+
+error: aborting due to 3 previous errors
+