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Merged
merged 3 commits into from
Sep 21, 2018
Merged

Suggest array indexing when tuple indexing on an array #54292

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30556d5
Suggest array indexing when tuple indexing on an array.
memoryruins Sep 17, 2018
dff1bc1
Set diagnostic applicability based on array length
memoryruins Sep 18, 2018
73fdc81
Use expr's span
memoryruins Sep 18, 2018
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24 changes: 18 additions & 6 deletions src/librustc_typeck/check/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3344,12 +3344,24 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
}
};
}
ty::Array(ty, _) if ty.is_numeric() => {
let base = self.tcx.hir.node_to_pretty_string(base.id);
let msg = format!("attempting to use tuple indexing on an array; try");
let suggestion = format!("{}[{}]", base, field);
err.span_suggestion(field.span, &msg, suggestion);
},
ty::Array(_, len) => {
if let (Some(len), Ok(user_index)) = (
len.assert_usize(self.tcx),
field.as_str().parse::<u64>()
) {
let base = self.tcx.hir.node_to_pretty_string(base.id);
let help = "instead of using tuple indexing, use array indexing";
let suggestion = format!("{}[{}]", base, field);
let applicability = if len < user_index {
Applicability::MachineApplicable
} else {
Applicability::MaybeIncorrect
};
err.span_suggestion_with_applicability(
field.span, help, suggestion, applicability
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You probably want to use expr.span here instead of field.span.

);
}
}
ty::RawPtr(..) => {
let base = self.tcx.hir.node_to_pretty_string(base.id);
let msg = format!("`{}` is a native pointer; try dereferencing it", base);
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2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-53712.rs
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Expand Up @@ -4,6 +4,6 @@ fn main() {
let arr = [10, 20, 30, 40, 50];
arr.0;
//~^ ERROR no field `0` on type `[{integer}; 5]` [E0609]
//~| HELP attempting to use tuple indexing on an array; try
//~| HELP instead of using tuple indexing, use array indexing
//~| SUGGESTION arr[0]
}
2 changes: 1 addition & 1 deletion src/test/ui/issues/issue-53712.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0609]: no field `0` on type `[{integer}; 5]`
--> $DIR/issue-53712.rs:5:9
|
LL | arr.0;
| ^ help: attempting to use tuple indexing on an array; try: `arr[0]`
| ^ help: instead of using tuple indexing, use array indexing: `arr[0]`
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I just realized that the suggestion span is slightly incorrect. The suggestion span should cover the entire expression, otherwise when applying the suggestion with rustfix, for example, you'd end up with the following code

    arr.arr[0];

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Ah, right you are!


error: aborting due to previous error

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