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Cleaned up formatting and fixed bug in rev_binop
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-105
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‎src/rustc/middle/lint.rs

+119-105
Original file line numberDiff line numberDiff line change
@@ -54,7 +54,7 @@ enum lint {
5454
deprecated_pattern,
5555
non_camel_case_types,
5656
structural_records,
57-
type_limits,
57+
type_limits,
5858

5959
managed_heap_memory,
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owned_heap_memory,
@@ -187,10 +187,10 @@ fn get_lint_dict() -> lint_dict {
187187
desc: ~"allow legacy modes",
188188
default: forbid}),
189189

190-
(~"type_limits",
191-
@{lint: type_limits,
192-
desc: ~"comparisons made useless by limits of the types involved",
193-
default: warn})
190+
(~"type_limits",
191+
@{lint: type_limits,
192+
desc: ~"comparisons made useless by limits of the types involved",
193+
default: warn})
194194

195195
/* FIXME(#3266)--make liveness warnings lintable
196196
(~"unused_variable",
@@ -403,7 +403,7 @@ fn check_item(i: @ast::item, cx: ty::ctxt) {
403403
check_item_heap(cx, i);
404404
check_item_structural_records(cx, i);
405405
check_item_deprecated_modes(cx, i);
406-
check_item_type_limits(cx, i);
406+
check_item_type_limits(cx, i);
407407
}
408408

409409
// Take a visitor, and modify it so that it will not proceed past subitems.
@@ -438,105 +438,119 @@ fn check_item_while_true(cx: ty::ctxt, it: @ast::item) {
438438
}
439439

440440
fn check_item_type_limits(cx: ty::ctxt, it: @ast::item) {
441-
pure fn is_valid<T: cmp::Ord>(binop: ast::binop, v: T, min: T, max: T) -> bool {
442-
match binop {
443-
ast::lt => v <= max,
444-
ast::le => v < max,
445-
ast::gt => v >= min,
446-
ast::ge => v > min,
447-
ast::eq | ast::ne => v >= min && v <= max,
448-
_ => fail
449-
}
450-
}
451-
452-
pure fn rev_binop(binop: ast::binop) -> ast::binop {
453-
match binop {
454-
ast::lt => ast::ge,
455-
ast::le => ast::gt,
456-
ast::gt => ast::le,
457-
ast::ge => ast::lt,
458-
_ => binop
459-
}
460-
}
461-
462-
fn check_limits(cx: ty::ctxt, binop: ast::binop, l: &ast::expr,
463-
r: &ast::expr) -> bool {
464-
let (lit, expr, swap) = match (l.node, r.node) {
465-
(ast::expr_lit(_), _) => (l, r, true),
466-
(_, ast::expr_lit(_)) => (r, l, false),
467-
_ => return true
468-
};
469-
// Normalize the binop so that the literal is always on the RHS in
470-
// the comparison
471-
let norm_binop = if (swap) {
472-
rev_binop(binop)
473-
} else {
474-
binop
475-
};
476-
match ty::get(ty::expr_ty(cx, @*expr)).sty {
477-
ty::ty_int(int_ty) => {
478-
let (min, max): (i64, i64) = match int_ty {
479-
ast::ty_i => (int::min_value as i64, int::max_value as i64),
480-
ast::ty_char => (u32::min_value as i64, u32::max_value as i64),
481-
ast::ty_i8 => (i8::min_value as i64, i8::max_value as i64),
482-
ast::ty_i16 => (i16::min_value as i64, i16::max_value as i64),
483-
ast::ty_i32 => (i32::min_value as i64, i32::max_value as i64),
484-
ast::ty_i64 => (i64::min_value, i64::max_value)
485-
};
486-
let lit_val: i64 = match lit.node {
487-
ast::expr_lit(@li) => match li.node {
488-
ast::lit_int(v, _) => v,
489-
ast::lit_uint(v, _) => v as i64,
490-
ast::lit_int_unsuffixed(v) => v,
491-
_ => return true
492-
},
493-
_ => fail
494-
};
495-
is_valid(norm_binop, lit_val, min, max)
496-
}
497-
ty::ty_uint(uint_ty) => {
498-
let (min, max): (u64, u64) = match uint_ty {
499-
ast::ty_u => (uint::min_value as u64, uint::max_value as u64),
500-
ast::ty_u8 => (u8::min_value as u64, u8::max_value as u64),
501-
ast::ty_u16 => (u16::min_value as u64, u16::max_value as u64),
502-
ast::ty_u32 => (u32::min_value as u64, u32::max_value as u64),
503-
ast::ty_u64 => (u64::min_value, u64::max_value)
504-
};
505-
let lit_val: u64 = match lit.node {
506-
ast::expr_lit(@li) => match li.node {
507-
ast::lit_int(v, _) => v as u64,
508-
ast::lit_uint(v, _) => v,
509-
ast::lit_int_unsuffixed(v) => v as u64,
510-
_ => return true
511-
},
512-
_ => fail
513-
};
514-
is_valid(norm_binop, lit_val, min, max)
515-
}
516-
_ => true
517-
}
518-
}
519-
520-
let visit = item_stopping_visitor(visit::mk_simple_visitor(@{
521-
visit_expr: fn@(e: @ast::expr) {
522-
match e.node {
523-
ast::expr_binary(binop, @l, @r) => {
524-
match binop {
525-
ast::eq | ast::lt | ast::le | ast::ne | ast::ge | ast::gt => {
526-
if !check_limits(cx, binop, &l, &r) {
527-
cx.sess.span_lint(type_limits, e.id, it.id, e.span,
528-
~"comparison is useless due to type limits");
529-
}
530-
}
531-
_ => ()
532-
}
533-
}
534-
_ => ()
535-
}
536-
},
537-
.. *visit::default_simple_visitor()
538-
}));
539-
visit::visit_item(it, (), visit);
441+
pure fn is_valid<T: cmp::Ord>(binop: ast::binop, v: T,
442+
min: T, max: T) -> bool {
443+
match binop {
444+
ast::lt => v <= max,
445+
ast::le => v < max,
446+
ast::gt => v >= min,
447+
ast::ge => v > min,
448+
ast::eq | ast::ne => v >= min && v <= max,
449+
_ => fail
450+
}
451+
}
452+
453+
pure fn rev_binop(binop: ast::binop) -> ast::binop {
454+
match binop {
455+
ast::lt => ast::gt,
456+
ast::le => ast::ge,
457+
ast::gt => ast::lt,
458+
ast::ge => ast::le,
459+
_ => binop
460+
}
461+
}
462+
463+
pure fn int_ty_range(int_ty: ast::int_ty) -> (i64, i64) {
464+
match int_ty {
465+
ast::ty_i => (int::min_value as i64, int::max_value as i64),
466+
ast::ty_char => (u32::min_value as i64, u32::max_value as i64),
467+
ast::ty_i8 => (i8::min_value as i64, i8::max_value as i64),
468+
ast::ty_i16 => (i16::min_value as i64, i16::max_value as i64),
469+
ast::ty_i32 => (i32::min_value as i64, i32::max_value as i64),
470+
ast::ty_i64 => (i64::min_value, i64::max_value)
471+
}
472+
}
473+
474+
pure fn uint_ty_range(uint_ty: ast::uint_ty) -> (u64, u64) {
475+
match uint_ty {
476+
ast::ty_u => (uint::min_value as u64, uint::max_value as u64),
477+
ast::ty_u8 => (u8::min_value as u64, u8::max_value as u64),
478+
ast::ty_u16 => (u16::min_value as u64, u16::max_value as u64),
479+
ast::ty_u32 => (u32::min_value as u64, u32::max_value as u64),
480+
ast::ty_u64 => (u64::min_value, u64::max_value)
481+
}
482+
}
483+
484+
fn check_limits(cx: ty::ctxt, binop: ast::binop, l: &ast::expr,
485+
r: &ast::expr) -> bool {
486+
let (lit, expr, swap) = match (l.node, r.node) {
487+
(ast::expr_lit(_), _) => (l, r, true),
488+
(_, ast::expr_lit(_)) => (r, l, false),
489+
_ => return true
490+
};
491+
// Normalize the binop so that the literal is always on the RHS in
492+
// the comparison
493+
let norm_binop = if (swap) {
494+
rev_binop(binop)
495+
} else {
496+
binop
497+
};
498+
match ty::get(ty::expr_ty(cx, @*expr)).sty {
499+
ty::ty_int(int_ty) => {
500+
let (min, max) = int_ty_range(int_ty);
501+
let lit_val: i64 = match lit.node {
502+
ast::expr_lit(@li) => match li.node {
503+
ast::lit_int(v, _) => v,
504+
ast::lit_uint(v, _) => v as i64,
505+
ast::lit_int_unsuffixed(v) => v,
506+
_ => return true
507+
},
508+
_ => fail
509+
};
510+
is_valid(norm_binop, lit_val, min, max)
511+
}
512+
ty::ty_uint(uint_ty) => {
513+
let (min, max): (u64, u64) = uint_ty_range(uint_ty);
514+
let lit_val: u64 = match lit.node {
515+
ast::expr_lit(@li) => match li.node {
516+
ast::lit_int(v, _) => v as u64,
517+
ast::lit_uint(v, _) => v,
518+
ast::lit_int_unsuffixed(v) => v as u64,
519+
_ => return true
520+
},
521+
_ => fail
522+
};
523+
is_valid(norm_binop, lit_val, min, max)
524+
}
525+
_ => true
526+
}
527+
}
528+
529+
pure fn is_comparison(binop: ast::binop) -> bool {
530+
match binop {
531+
ast::eq | ast::lt | ast::le |
532+
ast::ne | ast::ge | ast::gt => true,
533+
_ => false
534+
}
535+
}
536+
537+
let visit = item_stopping_visitor(visit::mk_simple_visitor(@{
538+
visit_expr: fn@(e: @ast::expr) {
539+
match e.node {
540+
ast::expr_binary(binop, @l, @r) => {
541+
if is_comparison(binop)
542+
&& !check_limits(cx, binop, &l, &r) {
543+
cx.sess.span_lint(
544+
type_limits, e.id, it.id, e.span,
545+
~"comparison is useless due to type limits");
546+
}
547+
}
548+
_ => ()
549+
}
550+
},
551+
.. *visit::default_simple_visitor()
552+
}));
553+
visit::visit_item(it, (), visit);
540554
}
541555

542556
fn check_item_structural_records(cx: ty::ctxt, it: @ast::item) {

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