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Suggest using an inclusive range for an overflowing endpoint

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This commit is contained in:
varkor 2019-04-27 12:44:51 +01:00
parent 2cefd9987b
commit 5ec2f5e87e
1 changed files with 61 additions and 15 deletions
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76
src/librustc_lint/types.rs
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@ -1,6 +1,7 @@
#![allow(non_snake_case)]
use rustc::hir::Node;
use rustc::hir::{ExprKind, Node};
use rustc::hir::lowering::is_range_literal;
use rustc::ty::subst::SubstsRef;
use rustc::ty::{self, AdtKind, ParamEnv, Ty, TyCtxt};
use rustc::ty::layout::{self, IntegerExt, LayoutOf, VariantIdx};
@ -129,21 +130,66 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeLimits {
if lit_val < min || lit_val > max {
let parent_id = cx.tcx.hir().get_parent_node_by_hir_id(e.hir_id);
if let Node::Expr(parent_expr) = cx.tcx.hir().get_by_hir_id(parent_id) {
if let hir::ExprKind::Cast(..) = parent_expr.node {
if let ty::Char = cx.tables.expr_ty(parent_expr).sty {
let mut err = cx.struct_span_lint(
OVERFLOWING_LITERALS,
parent_expr.span,
"only u8 can be cast into char");
err.span_suggestion(
parent_expr.span,
&"use a char literal instead",
format!("'\\u{{{:X}}}'", lit_val),
Applicability::MachineApplicable
);
err.emit();
return
match parent_expr.node {
hir::ExprKind::Cast(..) => {
if let ty::Char = cx.tables.expr_ty(parent_expr).sty {
let mut err = cx.struct_span_lint(
OVERFLOWING_LITERALS,
parent_expr.span,
"only u8 can be cast into char",
);
err.span_suggestion(
parent_expr.span,
&"use a char literal instead",
format!("'\\u{{{:X}}}'", lit_val),
Applicability::MachineApplicable,
);
err.emit();
return;
}
}
hir::ExprKind::Struct(..)
if is_range_literal(cx.sess(), parent_expr) => {
// We only want to handle exclusive (`..`) ranges,
// which are represented as `ExprKind::Struct`.
if let ExprKind::Struct(_, eps, _) = &parent_expr.node {
debug_assert_eq!(eps.len(), 2);
// We can suggest using an inclusive range
// (`..=`) instead only if it is the `end` that is
// overflowing and only by 1.
if eps[1].expr.hir_id == e.hir_id
&& lit_val - 1 == max
{
let mut err = cx.struct_span_lint(
OVERFLOWING_LITERALS,
parent_expr.span,
&format!(
"range endpoint is out of range \
for {:?}",
t,
),
);
if let Ok(start) = cx.sess().source_map()
.span_to_snippet(eps[0].span)
{
let suggestion = format!(
"{}..={}",
start,
lit_val - 1,
);
err.span_suggestion(
parent_expr.span,
&"use an inclusive range instead",
suggestion,
Applicability::MachineApplicable,
);
err.emit();
return;
}
}
}
}
_ => {}
}
}
if let Some(repr_str) = get_bin_hex_repr(cx, lit) {