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Merge pull request #390 from Manishearth/precedence

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improved precedence messages (fixes #389)
This commit is contained in:
Manish Goregaokar 2015-10-13 17:33:23 +05:30
commit a90a4540e9
1 changed files with 26 additions and 8 deletions
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34
src/precedence.rs
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@ -1,7 +1,9 @@
use rustc::lint::*; use rustc::lint::*;
use syntax::codemap::Spanned; use syntax::codemap::Spanned;
use syntax::ast::*; use syntax::ast::*;
use utils::span_lint; use syntax::ast_util::binop_to_string;
use utils::{span_lint, snippet};
declare_lint!(pub PRECEDENCE, Warn, declare_lint!(pub PRECEDENCE, Warn,
"catches operations where precedence may be unclear. See the wiki for a \ "catches operations where precedence may be unclear. See the wiki for a \
@ -19,10 +21,24 @@ fn get_lints(&self) -> LintArray {
impl EarlyLintPass for Precedence { impl EarlyLintPass for Precedence {
fn check_expr(&mut self, cx: &EarlyContext, expr: &Expr) { fn check_expr(&mut self, cx: &EarlyContext, expr: &Expr) {
if let ExprBinary(Spanned { node: op, ..}, ref left, ref right) = expr.node { if let ExprBinary(Spanned { node: op, ..}, ref left, ref right) = expr.node {
if is_bit_op(op) && (is_arith_expr(left) || is_arith_expr(right)) { if !is_bit_op(op) { return; }
span_lint(cx, PRECEDENCE, expr.span, match (is_arith_expr(left), is_arith_expr(right)) {
"operator precedence can trip the unwary. Consider adding parentheses \ (true, true) => span_lint(cx, PRECEDENCE, expr.span,
to the subexpression"); &format!("operator precedence can trip the unwary. \
Consider parenthesizing your expression:\
`({}) {} ({})`", snippet(cx, left.span, ".."),
binop_to_string(op), snippet(cx, right.span, ".."))),
(true, false) => span_lint(cx, PRECEDENCE, expr.span,
&format!("operator precedence can trip the unwary. \
Consider parenthesizing your expression:\
`({}) {} {}`", snippet(cx, left.span, ".."),
binop_to_string(op), snippet(cx, right.span, ".."))),
(false, true) => span_lint(cx, PRECEDENCE, expr.span,
&format!("operator precedence can trip the unwary. \
Consider parenthesizing your expression:\
`{} {} ({})`", snippet(cx, left.span, ".."),
binop_to_string(op), snippet(cx, right.span, ".."))),
_ => (),
} }
} }
@ -32,9 +48,11 @@ fn check_expr(&mut self, cx: &EarlyContext, expr: &Expr) {
if let ExprLit(ref lit) = slf.node { if let ExprLit(ref lit) = slf.node {
match lit.node { match lit.node {
LitInt(..) | LitFloat(..) | LitFloatUnsuffixed(..) => LitInt(..) | LitFloat(..) | LitFloatUnsuffixed(..) =>
span_lint(cx, PRECEDENCE, expr.span, span_lint(cx, PRECEDENCE, expr.span, &format!(
"unary minus has lower precedence than method call. Consider \ "unary minus has lower precedence than \
adding parentheses to clarify your intent"), method call. Consider adding parentheses \
to clarify your intent: -({})",
snippet(cx, rhs.span, ".."))),
_ => () _ => ()
} }
} }