Auto merge of #71201 - Dylan-DPC:rollup-23202uf, r=Dylan-DPC

Rollup of 5 pull requests

Successful merges:

 - #70566 (Don't bail out before linting in generic contexts.)
 - #71141 (Provide better compiler output when using `?` on `Option` in fn returning `Result` and vice-versa)
 - #71149 (remove an impossible branch from check_consts)
 - #71179 (fix more clippy warnings)
 - #71191 (Clean up E0520 explanation)

Failed merges:

r? @ghost

7 files changed, 174 insertions, 110 deletions

diff --git a/src/test/ui/lint/lint-exceeding-bitshifts.noopt.stderr b/src/test/ui/lint/lint-exceeding-bitshifts.noopt.stderr
index ce9b02b6d82..a2fb5ad8b8b 100644
--- a/src/test/ui/lint/lint-exceeding-bitshifts.noopt.stderr
+++ b/src/test/ui/lint/lint-exceeding-bitshifts.noopt.stderr
@@ -1,146 +1,152 @@
-error: this arithmetic operation will overflow
-  --> $DIR/lint-exceeding-bitshifts.rs:22:13
+warning: this arithmetic operation will overflow
+  --> $DIR/lint-exceeding-bitshifts.rs:18:20
    |
-LL |     let _ = x << 42;
-   |             ^^^^^^^ attempt to shift left with overflow
+LL |     const N: i32 = T::N << 42;
+   |                    ^^^^^^^^^^ attempt to shift left with overflow
    |
 note: the lint level is defined here
   --> $DIR/lint-exceeding-bitshifts.rs:9:9
    |
-LL | #![deny(arithmetic_overflow, const_err)]
+LL | #![warn(arithmetic_overflow, const_err)]
    |         ^^^^^^^^^^^^^^^^^^^
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
+  --> $DIR/lint-exceeding-bitshifts.rs:22:13
+   |
+LL |     let _ = x << 42;
+   |             ^^^^^^^ attempt to shift left with overflow
+
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:27:15
    |
 LL |       let n = 1u8 << 8;
    |               ^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:29:15
    |
 LL |       let n = 1u16 << 16;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:31:15
    |
 LL |       let n = 1u32 << 32;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:33:15
    |
 LL |       let n = 1u64 << 64;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:35:15
    |
 LL |       let n = 1i8 << 8;
    |               ^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:37:15
    |
 LL |       let n = 1i16 << 16;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:39:15
    |
 LL |       let n = 1i32 << 32;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:41:15
    |
 LL |       let n = 1i64 << 64;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:44:15
    |
 LL |       let n = 1u8 >> 8;
    |               ^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:46:15
    |
 LL |       let n = 1u16 >> 16;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:48:15
    |
 LL |       let n = 1u32 >> 32;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:50:15
    |
 LL |       let n = 1u64 >> 64;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:52:15
    |
 LL |       let n = 1i8 >> 8;
    |               ^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:54:15
    |
 LL |       let n = 1i16 >> 16;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:56:15
    |
 LL |       let n = 1i32 >> 32;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:58:15
    |
 LL |       let n = 1i64 >> 64;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:62:15
    |
 LL |       let n = n << 8;
    |               ^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:64:15
    |
 LL |       let n = 1u8 << -8;
    |               ^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:69:15
    |
 LL |       let n = 1u8 << (4+4);
    |               ^^^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:71:15
    |
 LL |       let n = 1i64 >> [64][0];
    |               ^^^^^^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:77:15
    |
 LL |       let n = 1_isize << BITS;
    |               ^^^^^^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:78:15
    |
 LL |       let n = 1_usize << BITS;
    |               ^^^^^^^^^^^^^^^ attempt to shift left with overflow
 
-error: aborting due to 23 previous errors
+warning: 24 warnings emitted
 
diff --git a/src/test/ui/lint/lint-exceeding-bitshifts.opt.stderr b/src/test/ui/lint/lint-exceeding-bitshifts.opt.stderr
index ce9b02b6d82..a2fb5ad8b8b 100644
--- a/src/test/ui/lint/lint-exceeding-bitshifts.opt.stderr
+++ b/src/test/ui/lint/lint-exceeding-bitshifts.opt.stderr
@@ -1,146 +1,152 @@
-error: this arithmetic operation will overflow
-  --> $DIR/lint-exceeding-bitshifts.rs:22:13
+warning: this arithmetic operation will overflow
+  --> $DIR/lint-exceeding-bitshifts.rs:18:20
    |
-LL |     let _ = x << 42;
-   |             ^^^^^^^ attempt to shift left with overflow
+LL |     const N: i32 = T::N << 42;
+   |                    ^^^^^^^^^^ attempt to shift left with overflow
    |
 note: the lint level is defined here
   --> $DIR/lint-exceeding-bitshifts.rs:9:9
    |
-LL | #![deny(arithmetic_overflow, const_err)]
+LL | #![warn(arithmetic_overflow, const_err)]
    |         ^^^^^^^^^^^^^^^^^^^
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
+  --> $DIR/lint-exceeding-bitshifts.rs:22:13
+   |
+LL |     let _ = x << 42;
+   |             ^^^^^^^ attempt to shift left with overflow
+
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:27:15
    |
 LL |       let n = 1u8 << 8;
    |               ^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:29:15
    |
 LL |       let n = 1u16 << 16;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:31:15
    |
 LL |       let n = 1u32 << 32;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:33:15
    |
 LL |       let n = 1u64 << 64;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:35:15
    |
 LL |       let n = 1i8 << 8;
    |               ^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:37:15
    |
 LL |       let n = 1i16 << 16;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:39:15
    |
 LL |       let n = 1i32 << 32;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:41:15
    |
 LL |       let n = 1i64 << 64;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:44:15
    |
 LL |       let n = 1u8 >> 8;
    |               ^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:46:15
    |
 LL |       let n = 1u16 >> 16;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:48:15
    |
 LL |       let n = 1u32 >> 32;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:50:15
    |
 LL |       let n = 1u64 >> 64;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:52:15
    |
 LL |       let n = 1i8 >> 8;
    |               ^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:54:15
    |
 LL |       let n = 1i16 >> 16;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:56:15
    |
 LL |       let n = 1i32 >> 32;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:58:15
    |
 LL |       let n = 1i64 >> 64;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:62:15
    |
 LL |       let n = n << 8;
    |               ^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:64:15
    |
 LL |       let n = 1u8 << -8;
    |               ^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:69:15
    |
 LL |       let n = 1u8 << (4+4);
    |               ^^^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:71:15
    |
 LL |       let n = 1i64 >> [64][0];
    |               ^^^^^^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:77:15
    |
 LL |       let n = 1_isize << BITS;
    |               ^^^^^^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:78:15
    |
 LL |       let n = 1_usize << BITS;
    |               ^^^^^^^^^^^^^^^ attempt to shift left with overflow
 
-error: aborting due to 23 previous errors
+warning: 24 warnings emitted
 
diff --git a/src/test/ui/lint/lint-exceeding-bitshifts.opt_with_overflow_checks.stderr b/src/test/ui/lint/lint-exceeding-bitshifts.opt_with_overflow_checks.stderr
index ce9b02b6d82..a2fb5ad8b8b 100644
--- a/src/test/ui/lint/lint-exceeding-bitshifts.opt_with_overflow_checks.stderr
+++ b/src/test/ui/lint/lint-exceeding-bitshifts.opt_with_overflow_checks.stderr
@@ -1,146 +1,152 @@
-error: this arithmetic operation will overflow
-  --> $DIR/lint-exceeding-bitshifts.rs:22:13
+warning: this arithmetic operation will overflow
+  --> $DIR/lint-exceeding-bitshifts.rs:18:20
    |
-LL |     let _ = x << 42;
-   |             ^^^^^^^ attempt to shift left with overflow
+LL |     const N: i32 = T::N << 42;
+   |                    ^^^^^^^^^^ attempt to shift left with overflow
    |
 note: the lint level is defined here
   --> $DIR/lint-exceeding-bitshifts.rs:9:9
    |
-LL | #![deny(arithmetic_overflow, const_err)]
+LL | #![warn(arithmetic_overflow, const_err)]
    |         ^^^^^^^^^^^^^^^^^^^
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
+  --> $DIR/lint-exceeding-bitshifts.rs:22:13
+   |
+LL |     let _ = x << 42;
+   |             ^^^^^^^ attempt to shift left with overflow
+
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:27:15
    |
 LL |       let n = 1u8 << 8;
    |               ^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:29:15
    |
 LL |       let n = 1u16 << 16;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:31:15
    |
 LL |       let n = 1u32 << 32;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:33:15
    |
 LL |       let n = 1u64 << 64;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:35:15
    |
 LL |       let n = 1i8 << 8;
    |               ^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:37:15
    |
 LL |       let n = 1i16 << 16;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:39:15
    |
 LL |       let n = 1i32 << 32;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:41:15
    |
 LL |       let n = 1i64 << 64;
    |               ^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:44:15
    |
 LL |       let n = 1u8 >> 8;
    |               ^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:46:15
    |
 LL |       let n = 1u16 >> 16;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:48:15
    |
 LL |       let n = 1u32 >> 32;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:50:15
    |
 LL |       let n = 1u64 >> 64;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:52:15
    |
 LL |       let n = 1i8 >> 8;
    |               ^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:54:15
    |
 LL |       let n = 1i16 >> 16;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:56:15
    |
 LL |       let n = 1i32 >> 32;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:58:15
    |
 LL |       let n = 1i64 >> 64;
    |               ^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:62:15
    |
 LL |       let n = n << 8;
    |               ^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:64:15
    |
 LL |       let n = 1u8 << -8;
    |               ^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:69:15
    |
 LL |       let n = 1u8 << (4+4);
    |               ^^^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:71:15
    |
 LL |       let n = 1i64 >> [64][0];
    |               ^^^^^^^^^^^^^^^ attempt to shift right with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:77:15
    |
 LL |       let n = 1_isize << BITS;
    |               ^^^^^^^^^^^^^^^ attempt to shift left with overflow
 
-error: this arithmetic operation will overflow
+warning: this arithmetic operation will overflow
   --> $DIR/lint-exceeding-bitshifts.rs:78:15
    |
 LL |       let n = 1_usize << BITS;
    |               ^^^^^^^^^^^^^^^ attempt to shift left with overflow
 
-error: aborting due to 23 previous errors
+warning: 24 warnings emitted
 
diff --git a/src/test/ui/lint/lint-exceeding-bitshifts.rs b/src/test/ui/lint/lint-exceeding-bitshifts.rs
index 7deee5320a8..5d0cfd3ab78 100644
--- a/src/test/ui/lint/lint-exceeding-bitshifts.rs
+++ b/src/test/ui/lint/lint-exceeding-bitshifts.rs
@@ -3,10 +3,10 @@
 //[opt]compile-flags: -O
 //[opt_with_overflow_checks]compile-flags: -C overflow-checks=on -O
 
-// build-fail
+// build-pass
 
 #![crate_type="lib"]
-#![deny(arithmetic_overflow, const_err)]
+#![warn(arithmetic_overflow, const_err)]
 #![allow(unused_variables)]
 #![allow(dead_code)]
 
@@ -15,65 +15,65 @@ pub trait Foo {
 }
 
 impl<T: Foo> Foo for Vec<T> {
-    const N: i32 = T::N << 42; // FIXME this should warn
+    const N: i32 = T::N << 42; //~ WARN: arithmetic operation will overflow
 }
 
 pub fn foo(x: i32) {
-    let _ = x << 42; //~ ERROR: arithmetic operation will overflow
+    let _ = x << 42; //~ WARN: arithmetic operation will overflow
 }
 
 pub fn main() {
       let n = 1u8 << 7;
-      let n = 1u8 << 8;   //~ ERROR: arithmetic operation will overflow
+      let n = 1u8 << 8;   //~ WARN: arithmetic operation will overflow
       let n = 1u16 << 15;
-      let n = 1u16 << 16; //~ ERROR: arithmetic operation will overflow
+      let n = 1u16 << 16; //~ WARN: arithmetic operation will overflow
       let n = 1u32 << 31;
-      let n = 1u32 << 32; //~ ERROR: arithmetic operation will overflow
+      let n = 1u32 << 32; //~ WARN: arithmetic operation will overflow
       let n = 1u64 << 63;
-      let n = 1u64 << 64; //~ ERROR: arithmetic operation will overflow
+      let n = 1u64 << 64; //~ WARN: arithmetic operation will overflow
       let n = 1i8 << 7;
-      let n = 1i8 << 8;   //~ ERROR: arithmetic operation will overflow
+      let n = 1i8 << 8;   //~ WARN: arithmetic operation will overflow
       let n = 1i16 << 15;
-      let n = 1i16 << 16; //~ ERROR: arithmetic operation will overflow
+      let n = 1i16 << 16; //~ WARN: arithmetic operation will overflow
       let n = 1i32 << 31;
-      let n = 1i32 << 32; //~ ERROR: arithmetic operation will overflow
+      let n = 1i32 << 32; //~ WARN: arithmetic operation will overflow
       let n = 1i64 << 63;
-      let n = 1i64 << 64; //~ ERROR: arithmetic operation will overflow
+      let n = 1i64 << 64; //~ WARN: arithmetic operation will overflow
 
       let n = 1u8 >> 7;
-      let n = 1u8 >> 8;   //~ ERROR: arithmetic operation will overflow
+      let n = 1u8 >> 8;   //~ WARN: arithmetic operation will overflow
       let n = 1u16 >> 15;
-      let n = 1u16 >> 16; //~ ERROR: arithmetic operation will overflow
+      let n = 1u16 >> 16; //~ WARN: arithmetic operation will overflow
       let n = 1u32 >> 31;
-      let n = 1u32 >> 32; //~ ERROR: arithmetic operation will overflow
+      let n = 1u32 >> 32; //~ WARN: arithmetic operation will overflow
       let n = 1u64 >> 63;
-      let n = 1u64 >> 64; //~ ERROR: arithmetic operation will overflow
+      let n = 1u64 >> 64; //~ WARN: arithmetic operation will overflow
       let n = 1i8 >> 7;
-      let n = 1i8 >> 8;   //~ ERROR: arithmetic operation will overflow
+      let n = 1i8 >> 8;   //~ WARN: arithmetic operation will overflow
       let n = 1i16 >> 15;
-      let n = 1i16 >> 16; //~ ERROR: arithmetic operation will overflow
+      let n = 1i16 >> 16; //~ WARN: arithmetic operation will overflow
       let n = 1i32 >> 31;
-      let n = 1i32 >> 32; //~ ERROR: arithmetic operation will overflow
+      let n = 1i32 >> 32; //~ WARN: arithmetic operation will overflow
       let n = 1i64 >> 63;
-      let n = 1i64 >> 64; //~ ERROR: arithmetic operation will overflow
+      let n = 1i64 >> 64; //~ WARN: arithmetic operation will overflow
 
       let n = 1u8;
       let n = n << 7;
-      let n = n << 8; //~ ERROR: arithmetic operation will overflow
+      let n = n << 8; //~ WARN: arithmetic operation will overflow
 
-      let n = 1u8 << -8; //~ ERROR: arithmetic operation will overflow
+      let n = 1u8 << -8; //~ WARN: arithmetic operation will overflow
 
       let n = 1i8<<(1isize+-1);
 
       let n = 1u8 << (4+3);
-      let n = 1u8 << (4+4); //~ ERROR: arithmetic operation will overflow
+      let n = 1u8 << (4+4); //~ WARN: arithmetic operation will overflow
       let n = 1i64 >> [63][0];
-      let n = 1i64 >> [64][0]; //~ ERROR: arithmetic operation will overflow
+      let n = 1i64 >> [64][0]; //~ WARN: arithmetic operation will overflow
 
       #[cfg(target_pointer_width = "32")]
       const BITS: usize = 32;
       #[cfg(target_pointer_width = "64")]
       const BITS: usize = 64;
-      let n = 1_isize << BITS; //~ ERROR: arithmetic operation will overflow
-      let n = 1_usize << BITS; //~ ERROR: arithmetic operation will overflow
+      let n = 1_isize << BITS; //~ WARN: arithmetic operation will overflow
+      let n = 1_usize << BITS; //~ WARN: arithmetic operation will overflow
 }
diff --git a/src/test/ui/option-to-result.rs b/src/test/ui/option-to-result.rs
new file mode 100644
index 00000000000..00e8b5244c5
--- /dev/null
+++ b/src/test/ui/option-to-result.rs
@@ -0,0 +1,13 @@
+fn main(){ }
+
+fn test_result() -> Result<(),()> {
+    let a:Option<()> = Some(());
+    a?;//~ ERROR `?` couldn't convert the error
+    Ok(())
+}
+
+fn test_option() -> Option<i32>{
+    let a:Result<i32, i32> = Ok(5);
+    a?;//~ ERROR `?` couldn't convert the error
+    Some(5)
+}
diff --git a/src/test/ui/option-to-result.stderr b/src/test/ui/option-to-result.stderr
new file mode 100644
index 00000000000..f673ef7fc1e
--- /dev/null
+++ b/src/test/ui/option-to-result.stderr
@@ -0,0 +1,29 @@
+error[E0277]: `?` couldn't convert the error to `()`
+  --> $DIR/option-to-result.rs:5:6
+   |
+LL |     a?;
+   |      ^ the trait `std::convert::From<std::option::NoneError>` is not implemented for `()`
+   |
+   = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
+   = note: required by `std::convert::From::from`
+help: consider converting the `Option<T>` into a `Result<T, _>` using `Option::ok_or` or `Option::ok_or_else`
+   |
+LL |     a.ok_or_else(|| /* error value */)?;
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0277]: `?` couldn't convert the error to `std::option::NoneError`
+  --> $DIR/option-to-result.rs:11:6
+   |
+LL |     a?;
+   |      ^ the trait `std::convert::From<i32>` is not implemented for `std::option::NoneError`
+   |
+   = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
+   = note: required by `std::convert::From::from`
+help: consider converting the `Result<T, _>` into an `Option<T>` using `Result::ok`
+   |
+LL |     a.ok()?;
+   |      ^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/try-on-option.stderr b/src/test/ui/try-on-option.stderr
index 07615b52a48..7a4bb75967b 100644
--- a/src/test/ui/try-on-option.stderr
+++ b/src/test/ui/try-on-option.stderr
@@ -6,6 +6,10 @@ LL |     x?;
    |
    = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
    = note: required by `std::convert::From::from`
+help: consider converting the `Option<T>` into a `Result<T, _>` using `Option::ok_or` or `Option::ok_or_else`
+   |
+LL |     x.ok_or_else(|| /* error value */)?;
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `std::ops::Try`)
   --> $DIR/try-on-option.rs:13:5