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Tweak tuple indexing suggestion

This commit is contained in:
Michael Goulet 2023-04-08 21:32:36 +00:00
parent dd2b19539e
commit fbc3457d35
5 changed files with 35 additions and 17 deletions
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29
compiler/rustc_hir_typeck/src/expr.rs
View File

@ -2810,23 +2810,26 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
"cannot index into a value of type `{base_t}`",
);
// Try to give some advice about indexing tuples.
if let ty::Tuple(..) = base_t.kind() {
if let ty::Tuple(types) = base_t.kind() {
let mut needs_note = true;
// If the index is an integer, we can show the actual
// fixed expression:
if let ExprKind::Lit(ref lit) = idx.kind {
if let ast::LitKind::Int(i, ast::LitIntType::Unsuffixed) = lit.node {
let snip = self.tcx.sess.source_map().span_to_snippet(base.span);
if let Ok(snip) = snip {
err.span_suggestion(
expr.span,
"to access tuple elements, use",
format!("{snip}.{i}"),
Applicability::MachineApplicable,
);
needs_note = false;
}
if let ExprKind::Lit(ref lit) = idx.kind
&& let ast::LitKind::Int(i, ast::LitIntType::Unsuffixed) = lit.node
&& i < types.len().try_into().expect("expected tuple index to be < usize length")
{
let snip = self.tcx.sess.source_map().span_to_snippet(base.span);
if let Ok(snip) = snip {
err.span_suggestion(
expr.span,
"to access tuple elements, use",
format!("{snip}.{i}"),
Applicability::MachineApplicable,
);
needs_note = false;
}
} else if let ExprKind::Path(..) = idx.peel_borrows().kind {
err.span_label(idx.span, "cannot access tuple elements at a variable index");
}
if needs_note {
err.help(

4
tests/ui/index_message.rs
View File

@ -1,4 +1,4 @@
fn main() {
let z = ();
let _ = z[0]; //~ ERROR cannot index into a value of type `()`
let z = (10,);
let _ = z[0]; //~ ERROR cannot index into a value of type `({integer},)`
}

2
tests/ui/index_message.stderr
View File

@ -1,4 +1,4 @@
error[E0608]: cannot index into a value of type `()`
error[E0608]: cannot index into a value of type `({integer},)`
--> $DIR/index_message.rs:3:13
|
LL | let _ = z[0];

5
tests/ui/issues/issue-27842.rs
View File

@ -8,4 +8,9 @@ fn main() {
let i = 0_usize;
let _ = tup[i];
//~^ ERROR cannot index into a value of type
// the case where the index is out of bounds
let tup = (10,);
let _ = tup[3];
//~^ ERROR cannot index into a value of type
}

12
tests/ui/issues/issue-27842.stderr
View File

@ -8,10 +8,20 @@ error[E0608]: cannot index into a value of type `({integer}, {integer}, {integer
--> $DIR/issue-27842.rs:9:13
|
LL | let _ = tup[i];
| ^^^^-^
| |
| cannot access tuple elements at a variable index
|
= help: to access tuple elements, use tuple indexing syntax (e.g., `tuple.0`)
error[E0608]: cannot index into a value of type `({integer},)`
--> $DIR/issue-27842.rs:14:13
|
LL | let _ = tup[3];
| ^^^^^^
|
= help: to access tuple elements, use tuple indexing syntax (e.g., `tuple.0`)
error: aborting due to 2 previous errors
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0608`.