Merge pull request #415 from birkenfeld/fix_409

Fix reverse_range_loop not taking sign into account (fixes #409)
This commit is contained in:
Georg Brandl 2015-10-26 08:07:24 +01:00
commit 3fe6ca9def
3 changed files with 71 additions and 3 deletions

64
src/consts.rs Normal file → Executable file
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@ -6,10 +6,12 @@ use rustc::middle::def::PathResolution;
use rustc::middle::def::Def::*;
use rustc_front::hir::*;
use syntax::ptr::P;
use std::char;
use std::cmp::PartialOrd;
use std::cmp::Ordering::{self, Greater, Less, Equal};
use std::rc::Rc;
use std::ops::Deref;
use std::fmt;
use self::Constant::*;
use self::FloatWidth::*;
@ -21,6 +23,7 @@ use syntax::ast::{UintTy, FloatTy, StrStyle};
use syntax::ast::UintTy::*;
use syntax::ast::FloatTy::*;
use syntax::ast::Sign::{self, Plus, Minus};
use syntax::ast_util;
#[derive(PartialEq, Eq, Debug, Copy, Clone)]
@ -159,6 +162,67 @@ impl PartialOrd for Constant {
}
}
fn format_byte(fmt: &mut fmt::Formatter, b: u8) -> fmt::Result {
if b == b'\\' {
write!(fmt, "\\\\")
} else if 0x20 <= b && b <= 0x7e {
write!(fmt, "{}", char::from_u32(b as u32).expect("all u8 are valid char"))
} else if b == 0x0a {
write!(fmt, "\\n")
} else if b == 0x0d {
write!(fmt, "\\r")
} else {
write!(fmt, "\\x{:02x}", b)
}
}
impl fmt::Display for Constant {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match *self {
ConstantStr(ref s, _) => write!(fmt, "{:?}", s),
ConstantByte(ref b) =>
write!(fmt, "b'").and_then(|_| format_byte(fmt, *b))
.and_then(|_| write!(fmt, "'")),
ConstantBinary(ref bs) => {
try!(write!(fmt, "b\""));
for b in bs.iter() {
try!(format_byte(fmt, *b));
}
write!(fmt, "\"")
}
ConstantChar(ref c) => write!(fmt, "'{}'", c),
ConstantInt(ref i, ref ity) => {
let (sign, suffix) = match *ity {
LitIntType::SignedIntLit(ref sity, ref sign) =>
(if let Sign::Minus = *sign { "-" } else { "" },
ast_util::int_ty_to_string(*sity, None)),
LitIntType::UnsignedIntLit(ref uity) =>
("", ast_util::uint_ty_to_string(*uity, None)),
LitIntType::UnsuffixedIntLit(ref sign) =>
(if let Sign::Minus = *sign { "-" } else { "" },
"".into()),
};
write!(fmt, "{}{}{}", sign, i, suffix)
}
ConstantFloat(ref s, ref fw) => {
let suffix = match *fw {
FloatWidth::Fw32 => "f32",
FloatWidth::Fw64 => "f64",
FloatWidth::FwAny => "",
};
write!(fmt, "{}{}", s, suffix)
}
ConstantBool(ref b) => write!(fmt, "{}", b),
ConstantRepeat(ref c, ref n) => write!(fmt, "[{}; {}]", c, n),
ConstantVec(ref v) => write!(fmt, "[{}]",
v.iter().map(|i| format!("{}", i))
.collect::<Vec<_>>().join(", ")),
ConstantTuple(ref t) => write!(fmt, "({})",
t.iter().map(|i| format!("{}", i))
.collect::<Vec<_>>().join(", ")),
}
}
}
fn lit_to_constant(lit: &Lit_) -> Constant {

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@ -88,8 +88,8 @@ impl LateLintPass for LoopsPass {
// if this for loop is iterating over a two-sided range...
if let ExprRange(Some(ref start_expr), Some(ref stop_expr)) = arg.node {
// ...and both sides are compile-time constant integers...
if let Some(Constant::ConstantInt(start_idx, _)) = constant_simple(start_expr) {
if let Some(Constant::ConstantInt(stop_idx, _)) = constant_simple(stop_expr) {
if let Some(start_idx @ Constant::ConstantInt(..)) = constant_simple(start_expr) {
if let Some(stop_idx @ Constant::ConstantInt(..)) = constant_simple(stop_expr) {
// ...and the start index is greater than the stop index,
// this loop will never run. This is often confusing for developers
// who think that this will iterate from the larger value to the

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@ -46,6 +46,10 @@ fn main() {
println!("{}", i);
}
for i in -10..0 { // not an error
println!("{}", i);
}
for i in (10..0).rev() { // not an error, this is an established idiom for looping backwards on a range
println!("{}", i);
}