Fix int_ty_to_nbits

Thanks @oli-obk for the detailed instructions.
Fixes #1957.
This commit is contained in:
Malo Jaffré 2017-08-23 22:18:04 +02:00
parent 7715f00592
commit d6e4e0639e

View file

@ -3,7 +3,7 @@ use rustc::hir;
use rustc::hir::*;
use rustc::hir::intravisit::{FnKind, Visitor, walk_ty, NestedVisitorMap};
use rustc::lint::*;
use rustc::ty::{self, Ty};
use rustc::ty::{self, Ty, TyCtxt};
use rustc::ty::subst::Substs;
use std::cmp::Ordering;
use syntax::ast::{IntTy, UintTy, FloatTy};
@ -479,17 +479,25 @@ declare_lint! {
/// Returns the size in bits of an integral type.
/// Will return 0 if the type is not an int or uint variant
fn int_ty_to_nbits(typ: Ty) -> usize {
let n = match typ.sty {
ty::TyInt(i) => 4 << (i as usize),
ty::TyUint(u) => 4 << (u as usize),
fn int_ty_to_nbits(typ: Ty, tcx: TyCtxt) -> u64 {
match typ.sty {
ty::TyInt(i) => match i {
IntTy::Is => tcx.data_layout.pointer_size.bits(),
IntTy::I8 => 8,
IntTy::I16 => 16,
IntTy::I32 => 32,
IntTy::I64 => 64,
IntTy::I128 => 128,
},
ty::TyUint(i) => match i {
UintTy::Us => tcx.data_layout.pointer_size.bits(),
UintTy::U8 => 8,
UintTy::U16 => 16,
UintTy::U32 => 32,
UintTy::U64 => 64,
UintTy::U128 => 128,
},
_ => 0,
};
// n == 4 is the usize/isize case
if n == 4 {
::std::mem::size_of::<usize>() * 8
} else {
n
}
}
@ -510,7 +518,7 @@ fn span_precision_loss_lint(cx: &LateContext, expr: &Expr, cast_from: Ty, cast_t
} else if is_isize_or_usize(cast_from) {
"32 or 64".to_owned()
} else {
int_ty_to_nbits(cast_from).to_string()
int_ty_to_nbits(cast_from, cx.tcx).to_string()
};
span_lint(
cx,
@ -542,7 +550,8 @@ fn check_truncation_and_wrapping(cx: &LateContext, expr: &Expr, cast_from: Ty, c
let arch_64_suffix = " on targets with 64-bit wide pointers";
let arch_32_suffix = " on targets with 32-bit wide pointers";
let cast_unsigned_to_signed = !cast_from.is_signed() && cast_to.is_signed();
let (from_nbits, to_nbits) = (int_ty_to_nbits(cast_from), int_ty_to_nbits(cast_to));
let from_nbits = int_ty_to_nbits(cast_from, cx.tcx);
let to_nbits = int_ty_to_nbits(cast_to, cx.tcx);
let (span_truncation, suffix_truncation, span_wrap, suffix_wrap) =
match (is_isize_or_usize(cast_from), is_isize_or_usize(cast_to)) {
(true, true) | (false, false) => {
@ -650,7 +659,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CastPass {
if cast_from.is_numeric() && cast_to.is_numeric() && !in_external_macro(cx, expr.span) {
match (cast_from.is_integral(), cast_to.is_integral()) {
(true, false) => {
let from_nbits = int_ty_to_nbits(cast_from);
let from_nbits = int_ty_to_nbits(cast_from, cx.tcx);
let to_nbits = if let ty::TyFloat(FloatTy::F32) = cast_to.sty {
32
} else {