69bded2493
This commit adds justifications to error messages for conflicting borrows of union fields. Where previously an error message would say ``cannot borrow `u.b` as mutable..``, it now says ``cannot borrow `u` (via `u.b`) as mutable..``.
99 lines
2.7 KiB
Rust
99 lines
2.7 KiB
Rust
// ignore-tidy-linelength
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#[derive(Clone, Copy)]
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union U {
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a: u8,
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b: u64,
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}
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fn main() {
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unsafe {
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let mut u = U { b: 0 };
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// Imm borrow, same field
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{
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let ra = &u.a;
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let ra2 = &u.a; // OK
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drop(ra);
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}
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{
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let ra = &u.a;
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let a = u.a; // OK
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drop(ra);
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}
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{
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let ra = &u.a;
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let rma = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
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drop(ra);
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}
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{
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let ra = &u.a;
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u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
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drop(ra);
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}
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// Imm borrow, other field
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{
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let ra = &u.a;
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let rb = &u.b; // OK
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drop(ra);
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}
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{
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let ra = &u.a;
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let b = u.b; // OK
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drop(ra);
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}
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{
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let ra = &u.a;
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let rmb = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable because `u` is also borrowed as immutable (via `u.a`)
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drop(ra);
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}
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{
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let ra = &u.a;
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u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
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drop(ra);
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}
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// Mut borrow, same field
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{
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let rma = &mut u.a;
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let ra = &u.a; //~ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
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drop(rma);
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}
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{
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let ra = &mut u.a;
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let a = u.a; //~ ERROR cannot use `u.a` because it was mutably borrowed
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drop(ra);
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}
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{
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let rma = &mut u.a;
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let rma2 = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable more than once at a time
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drop(rma);
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}
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{
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let rma = &mut u.a;
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u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
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drop(rma);
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}
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// Mut borrow, other field
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{
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let rma = &mut u.a;
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let rb = &u.b; //~ ERROR cannot borrow `u` (via `u.b`) as immutable because `u` is also borrowed as mutable (via `u.a`)
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drop(rma);
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}
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{
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let ra = &mut u.a;
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let b = u.b; //~ ERROR cannot use `u.b` because it was mutably borrowed
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drop(ra);
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}
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{
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let rma = &mut u.a;
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let rmb2 = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable more than once at a time
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drop(rma);
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}
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{
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let rma = &mut u.a;
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u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
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drop(rma);
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}
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}
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}
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