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Added new 'float_cmp' lint (see issue #46)

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This commit is contained in:
llogiq 2015-05-06 10:01:49 +02:00
parent ae05d5fee2
commit ac151bb1f0
5 changed files with 87 additions and 11 deletions
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3
src/lib.rs
View file

@ -34,6 +34,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
reg.register_lint_pass(box ptr_arg::PtrArg as LintPassObject);
reg.register_lint_pass(box needless_bool::NeedlessBool as LintPassObject);
reg.register_lint_pass(box approx_const::ApproxConstant as LintPassObject);
reg.register_lint_pass(box misc::FloatCmp as LintPassObject);
reg.register_lint_group("clippy", vec![types::BOX_VEC, types::LINKEDLIST,
misc::SINGLE_MATCH, misc::STR_TO_STRING,
@ -41,6 +42,6 @@ pub fn plugin_registrar(reg: &mut Registry) {
bit_mask::BAD_BIT_MASK, ptr_arg::PTR_ARG,
needless_bool::NEEDLESS_BOOL,
approx_const::APPROX_CONSTANT,
misc::CMP_NAN
misc::CMP_NAN, misc::FLOAT_CMP,
]);
}

50
src/misc.rs
View file

@ -1,14 +1,22 @@
use syntax::ptr::P;
use syntax::ast;
use syntax::ast::*;
use syntax::ast_util::is_comparison_binop;
use syntax::ast_util::{is_comparison_binop, binop_to_string};
use syntax::visit::{FnKind};
use rustc::lint::{Context, LintPass, LintArray, Lint, Level};
use rustc::middle::ty::{self, expr_ty, ty_str, ty_ptr, ty_rptr};
use rustc::middle::ty::{self, expr_ty, ty_str, ty_ptr, ty_rptr, ty_float};
use syntax::codemap::Span;
use types::span_note_and_lint;
fn walk_ty<'t>(ty: ty::Ty<'t>) -> ty::Ty<'t> {
match ty.sty {
ty_ptr(ref tm) | ty_rptr(_, ref tm) => walk_ty(tm.ty),
_ => ty
}
}
/// Handles uncategorized lints
/// Currently handles linting of if-let-able matches
#[allow(missing_copy_implementations)]
@ -71,13 +79,6 @@ impl LintPass for StrToStringPass {
}
fn is_str(cx: &Context, expr: &ast::Expr) -> bool {
fn walk_ty<'t>(ty: ty::Ty<'t>) -> ty::Ty<'t> {
//println!("{}: -> {}", depth, ty);
match ty.sty {
ty_ptr(ref tm) | ty_rptr(_, ref tm) => walk_ty(tm.ty),
_ => ty
}
}
match walk_ty(expr_ty(cx.tcx, expr)).sty {
ty_str => true,
_ => false
@ -110,7 +111,7 @@ impl LintPass for TopLevelRefPass {
}
}
declare_lint!(pub CMP_NAN, Allow, "Deny comparisons to std::f32::NAN or std::f64::NAN");
declare_lint!(pub CMP_NAN, Deny, "Deny comparisons to std::f32::NAN or std::f64::NAN");
#[derive(Copy,Clone)]
pub struct CmpNan;
@ -139,3 +140,32 @@ fn check_nan(cx: &Context, path: &Path, span: Span) {
cx.span_lint(CMP_NAN, span, "Doomed comparison with NAN, use std::{f32,f64}::is_nan instead");
});
}
declare_lint!(pub FLOAT_CMP, Warn,
"Warn on ==/!= comparison of floaty values");
#[derive(Copy,Clone)]
pub struct FloatCmp;
impl LintPass for FloatCmp {
fn get_lints(&self) -> LintArray {
lint_array!(FLOAT_CMP)
}
fn check_expr(&mut self, cx: &Context, expr: &Expr) {
if let ExprBinary(ref cmp, ref left, ref right) = expr.node {
let op = cmp.node;
if (op == BiEq || op == BiNe) && (is_float(cx, left) || is_float(cx, right)) {
let map = cx.sess().codemap();
cx.span_lint(FLOAT_CMP, expr.span, &format!(
"{}-Comparison of f32 or f64 detected. You may want to change this to 'abs({} - {}) < epsilon' for some suitable value of epsilon",
binop_to_string(op), &*map.span_to_snippet(left.span).unwrap_or("..".to_string()),
&*map.span_to_snippet(right.span).unwrap_or("..".to_string())));
}
}
}
}
fn is_float(cx: &Context, expr: &Expr) -> bool {
if let ty_float(_) = walk_ty(expr_ty(cx.tcx, expr)).sty { true } else { false }
}