MIR borrowck: print lvalues in error messages in the same way that the AST borrowck #44985
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r? @pnkfelix (rust_highfive has picked a reviewer for you, use r? to override) |
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I'd like some feedback on this PR. I can't think of any example that trigger the messages marked |
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@zilbuz I'm about to hit the sack, but if you use the following input code, I think you should see some examples of some of the cases you are wondering about: #![feature(slice_patterns)]
fn main() {
#[derive(Debug)]
enum E<X> { A(X), B { x: X } }
#[derive(Debug)]
struct S<'a, X: 'a, Y>{ x: &'a [X], y: (Y, Y), };
let e = E::A(3);
match e {
E::A(ref ax) => println!("e.ax: {:?}", ax),
E::B { x: ref bx } => println!("e.bx: {:?}", bx),
}
let s = S { x: &[1, 2, 3,], y: (999, 998) };
match s {
S {
x: &[ref x0, ref xn..],
y: (ref y0, ref y1)
} => {
println!("s.x0: {:?} s.xn: {:?}", x0, xn);
println!("s.y0: {:?}, s.y1: {:?}", y0, y1);
}
_ => panic!("other case"),
}
} |
aidanhs
added
the
S-waiting-on-review
… AST borrowck - Print fields with `.name` rather than `.<num>` - Autoderef values if followed by a field or an index
…type that is neither Adt nor tuple
…reported lvalue for constant index Previously the constant index was reported as `[x of y]` or `[-x of y]` where `x` was the offset and `y` the minimum length of the slice. The minus sign wasn't in the right case since for `&[_, x, .., _, _]`, the error reported was `[-1 of 4]`, and for `&[_, _, .., x, _]`, the error reported was `[2 of 4]`. This commit fixes the sign so that the indexes 1 and -2 are reported, and remove the ` of y` part of the message to make it more succinct.
….]` to match the AST borrowck output
…variable hasn't a name
zilbuz
changed the title
| // Static and field from struct | ||
| unsafe { | ||
| let _x = sfoo.x(); | ||
| sfoo.x; //[mir]~ ERROR cannot use `sfoo.x` because it was mutably borrowed (Mir) |
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oh interesting...
(I think this represents a bug in MIR-borrowck. But fixing that is orthogonal to this PR in any case.)
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(likewise for all the other cases below that are paths based off of static variables)
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📌 Commit e32e81c has been approved by |
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⌛ Testing commit e32e81c with merge fd85391dbaf891fda53943b00e97cd609d3186c2... |
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💔 Test failed - status-travis |
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@bors retry
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MIR borrowck: print lvalues in error messages in the same way that the AST borrowck Fix #44974 - Print fields with `.name` rather than `.<num>` - Autoderef values if followed by a field or an index - Output `[..]` when borrowing inside a slice
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☀️ Test successful - status-appveyor, status-travis |
Fix #44974
.namerather than.<num>[..]when borrowing inside a slice