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Suggest to change numeric literal instead of casting #54273

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Merged
merged 6 commits into from
Sep 18, 2018
Merged

Suggest to change numeric literal instead of casting #54273

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1984079
lint to change numeric literal instead of into
csmoe Sep 16, 2018
0ff0669
replace old literal in expr
csmoe Sep 16, 2018
17a28f7
add test for numeric literal cast
csmoe Sep 16, 2018
d31a2a0
trim type numeric literal suffix
csmoe Sep 16, 2018
9d6c4f0
merge into/literal suggestion for DRY
csmoe Sep 17, 2018
2fb6585
add test for float/integer
csmoe Sep 17, 2018
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90 changes: 72 additions & 18 deletions src/librustc_typeck/check/demand.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -419,6 +419,21 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
if needs_paren { "(" } else { "" },
src,
if needs_paren { ")" } else { "" });
let suffix_suggestion = format!(
"{}{}{}{}",
if needs_paren { "(" } else { "" },
src.trim_right_matches(&checked_ty.to_string()),
expected_ty,
if needs_paren { ")" } else { "" },
);

let is_suffixed = |expr: &hir::Expr| {
if let hir::ExprKind::Lit(lit) = &expr.node {
lit.node.is_suffixed()
} else {
false
}
};

match (&expected_ty.sty, &checked_ty.sty) {
(&ty::Int(ref exp), &ty::Int(ref found)) => {
Expand All @@ -444,12 +459,25 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
}
}
_ => {
err.span_suggestion_with_applicability(
expr.span,
&format!("{}, which {}", msg, will_sign_extend),
into_suggestion,
Applicability::MachineApplicable
);
if is_suffixed(expr) {
err.span_suggestion_with_applicability(
expr.span,
&format!(
"change the type of the numeric literal from `{}` to `{}`",
checked_ty,
expected_ty,
),
suffix_suggestion,
Applicability::MaybeIncorrect,
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I feel these might count as MachineApplicable...

);
} else {
err.span_suggestion_with_applicability(
expr.span,
&format!("{}, which {}", msg, will_sign_extend),
into_suggestion,
Applicability::MachineApplicable
);
}
}
}
true
Expand Down Expand Up @@ -477,12 +505,25 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
}
}
_ => {
err.span_suggestion_with_applicability(
expr.span,
&format!("{}, which {}", msg, will_zero_extend),
into_suggestion,
Applicability::MachineApplicable
);
if is_suffixed(expr) {
err.span_suggestion_with_applicability(
expr.span,
&format!(
"change the type of the numeric literal from `{}` to `{}`",
checked_ty,
expected_ty,
),
suffix_suggestion,
Applicability::MaybeIncorrect,
);
} else {
err.span_suggestion_with_applicability(
expr.span,
&format!("{}, which {}", msg, will_zero_extend),
into_suggestion,
Applicability::MachineApplicable
);
}
}
}
true
Expand Down Expand Up @@ -583,12 +624,25 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
}
(&ty::Float(ref exp), &ty::Float(ref found)) => {
if found.bit_width() < exp.bit_width() {
err.span_suggestion_with_applicability(
expr.span,
&format!("{} in a lossless way", msg),
into_suggestion,
Applicability::MachineApplicable
);
if is_suffixed(expr) {
err.span_suggestion_with_applicability(
expr.span,
&format!(
"change the type of the numeric literal from `{}` to `{}`",
checked_ty,
expected_ty,
),
suffix_suggestion,
Applicability::MaybeIncorrect,
);
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I feel there's a bit of duplication on these, would it make sense to have is_suffixed (with a more accurate name) take mut err, checked_ty and expected_ty, and if it would return true now it would also apply the suggestion, and here you just call it as if !is_sufficed(expr) { with the following block (as each one of these has slightly different wording).

} else {
err.span_suggestion_with_applicability(
expr.span,
&format!("{} in a lossless way", msg),
into_suggestion,
Applicability::MachineApplicable
);
}
} else if can_cast {
err.span_suggestion_with_applicability(
expr.span,
Expand Down
15 changes: 15 additions & 0 deletions src/test/ui/mismatched_types/numeric-literal-cast.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

fn foo(_: u16) {}
fn main() {
foo(8u8);
}
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Can you add a test for floats too?


13 changes: 13 additions & 0 deletions src/test/ui/mismatched_types/numeric-literal-cast.stderr
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Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
error[E0308]: mismatched types
--> $DIR/numeric-literal-cast.rs:13:9
|
LL | foo(8u8);
| ^^^ expected u16, found u8
help: change the type of the numeric literal from `u8` to `u16`
|
LL | foo(8u16);
| ^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.