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tweak "make mut" spans when assigning to locals

This commit is contained in:
Ezra Shaw 2023-04-19 18:22:03 +12:00 committed by Ezra Shaw
parent 3320f2fab6
commit fd8aa5ec7d
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GPG Key ID: 5156CF5845150B0D
12 changed files with 46 additions and 41 deletions
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56
compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
View File

@ -1202,36 +1202,42 @@ fn suggest_ampmut<'tcx>(
opt_assignment_rhs_span: Option<Span>,
opt_ty_info: Option<Span>,
) -> (bool, Span, String) {
// if there is a RHS and it starts with a `&` from it, then check if it is
// mutable, and if not, put suggest putting `mut ` to make it mutable.
// we don't have to worry about lifetime annotations here because they are
// not valid when taking a reference. For example, the following is not valid Rust:
//
// let x: &i32 = &'a 5;
// ^^ lifetime annotation not allowed
//
if let Some(assignment_rhs_span) = opt_assignment_rhs_span
&& let Ok(src) = tcx.sess.source_map().span_to_snippet(assignment_rhs_span)
&& let Some(stripped) = src.strip_prefix('&')
{
let is_mutbl = |ty: &str| -> bool {
if let Some(rest) = ty.strip_prefix("mut") {
match rest.chars().next() {
// e.g. `&mut x`
Some(c) if c.is_whitespace() => true,
// e.g. `&mut(x)`
Some('(') => true,
// e.g. `&mut{x}`
Some('{') => true,
// e.g. `&mutablevar`
_ => false,
}
} else {
false
let is_mut = if let Some(rest) = stripped.trim_start().strip_prefix("mut") {
match rest.chars().next() {
// e.g. `&mut x`
Some(c) if c.is_whitespace() => true,
// e.g. `&mut(x)`
Some('(') => true,
// e.g. `&mut{x}`
Some('{') => true,
// e.g. `&mutablevar`
_ => false,
}
} else {
false
};
if let (true, Some(ws_pos)) = (src.starts_with("&'"), src.find(char::is_whitespace)) {
let lt_name = &src[1..ws_pos];
let ty = src[ws_pos..].trim_start();
if !is_mutbl(ty) {
return (true, assignment_rhs_span, format!("&{lt_name} mut {ty}"));
}
} else if let Some(stripped) = src.strip_prefix('&') {
let stripped = stripped.trim_start();
if !is_mutbl(stripped) {
return (true, assignment_rhs_span, format!("&mut {stripped}"));
}
// if the reference is already mutable then there is nothing we can do
// here.
if !is_mut {
let span = assignment_rhs_span;
// shrink the span to just after the `&` in `&variable`
let span = span.with_lo(span.lo() + BytePos(1)).shrink_to_lo();
// FIXME(Ezrashaw): returning is bad because we still might want to
// update the annotated type, see #106857.
return (true, span, "mut ".to_owned());
}
}

2
tests/ui/array-slice-vec/slice-mut-2.stderr
View File

@ -7,7 +7,7 @@ LL | let _ = &mut x[2..4];
help: consider changing this to be a mutable reference
|
LL | let x: &[isize] = &mut [1, 2, 3, 4, 5];
| ~~~~~~~~~~~~~~~~~~~~
| +++
error: aborting due to previous error

4
tests/ui/borrowck/borrow-raw-address-of-deref-mutability.stderr
View File

@ -7,7 +7,7 @@ LL | let q = &raw mut *x;
help: consider changing this to be a mutable reference
|
LL | let x = &mut 0;
| ~~~~~~
| +++
error[E0596]: cannot borrow `*x` as mutable, as it is behind a `*const` pointer
--> $DIR/borrow-raw-address-of-deref-mutability.rs:14:13
@ -18,7 +18,7 @@ LL | let q = &raw mut *x;
help: consider changing this to be a mutable pointer
|
LL | let x = &mut 0 as *const i32;
| ~~~~~~
| +++
error: aborting due to 2 previous errors

6
tests/ui/borrowck/borrowck-access-permissions.stderr
View File

@ -35,7 +35,7 @@ LL | let _y1 = &mut *ref_x;
help: consider changing this to be a mutable reference
|
LL | let ref_x = &mut x;
| ~~~~~~
| +++
error[E0596]: cannot borrow `*ptr_x` as mutable, as it is behind a `*const` pointer
--> $DIR/borrowck-access-permissions.rs:39:23
@ -46,7 +46,7 @@ LL | let _y1 = &mut *ptr_x;
help: consider changing this to be a mutable pointer
|
LL | let ptr_x : *const _ = &mut x;
| ~~~~~~
| +++
error[E0596]: cannot borrow `*foo_ref.f` as mutable, as it is behind a `&` reference
--> $DIR/borrowck-access-permissions.rs:48:18
@ -57,7 +57,7 @@ LL | let _y = &mut *foo_ref.f;
help: consider changing this to be a mutable reference
|
LL | let foo_ref = &mut foo;
| ~~~~~~~~
| +++
error: aborting due to 6 previous errors

2
tests/ui/borrowck/borrowck-issue-14498.stderr
View File

@ -7,7 +7,7 @@ LL | ***p = 2;
help: consider changing this to be a mutable reference
|
LL | let p = &mut y;
| ~~~~~~
| +++
error[E0506]: cannot assign to `**y` because it is borrowed
--> $DIR/borrowck-issue-14498.rs:25:5

2
tests/ui/borrowck/issue-85765.stderr
View File

@ -18,7 +18,7 @@ LL | *r = 0;
help: consider changing this to be a mutable reference
|
LL | let r = &mut mutvar;
| ~~~~~~~~~~~
| +++
error[E0594]: cannot assign to `*x`, which is behind a `&` reference
--> $DIR/issue-85765.rs:19:5

2
tests/ui/closures/2229_closure_analysis/diagnostics/mut_ref.stderr
View File

@ -10,7 +10,7 @@ LL | **ref_mref_x = y;
help: consider changing this to be a mutable reference
|
LL | let ref_mref_x = &mut mref_x;
| ~~~~~~~~~~~
| +++
error[E0596]: cannot borrow `**mref_ref_x` as mutable, as it is behind a `&` reference
--> $DIR/mut_ref.rs:26:13

2
tests/ui/did_you_mean/issue-40823.stderr
View File

@ -7,7 +7,7 @@ LL | buf.iter_mut();
help: consider changing this to be a mutable reference
|
LL | let mut buf = &mut [1, 2, 3, 4];
| ~~~~~~~~~~~~~~~~~
| +++
error: aborting due to previous error

2
tests/ui/error-codes/E0389.stderr
View File

@ -7,7 +7,7 @@ LL | fancy_ref.num = 6;
help: consider changing this to be a mutable reference
|
LL | let fancy_ref = &mut (&mut fancy);
| ~~~~~~~~~~~~~~~~~
| +++
error: aborting due to previous error

1
tests/ui/issues/issue-51515.rs
View File

@ -1,7 +1,6 @@
fn main() {
let foo = &16;
//~^ HELP consider changing this to be a mutable reference
//~| SUGGESTION &mut 16
*foo = 32;
//~^ ERROR cannot assign to `*foo`, which is behind a `&` reference
let bar = foo;

6
tests/ui/issues/issue-51515.stderr
View File

@ -1,5 +1,5 @@
error[E0594]: cannot assign to `*foo`, which is behind a `&` reference
--> $DIR/issue-51515.rs:5:5
--> $DIR/issue-51515.rs:4:5
|
LL | *foo = 32;
| ^^^^^^^^^ `foo` is a `&` reference, so the data it refers to cannot be written
@ -7,10 +7,10 @@ LL | *foo = 32;
help: consider changing this to be a mutable reference
|
LL | let foo = &mut 16;
| ~~~~~~~
| +++
error[E0594]: cannot assign to `*bar`, which is behind a `&` reference
--> $DIR/issue-51515.rs:9:5
--> $DIR/issue-51515.rs:8:5
|
LL | *bar = 64;
| ^^^^^^^^^ `bar` is a `&` reference, so the data it refers to cannot be written

2
tests/ui/nll/issue-47388.stderr
View File

@ -7,7 +7,7 @@ LL | fancy_ref.num = 6;
help: consider changing this to be a mutable reference
|
LL | let fancy_ref = &mut (&mut fancy);
| ~~~~~~~~~~~~~~~~~
| +++
error: aborting due to previous error