58 lines
1.6 KiB
Rust
58 lines
1.6 KiB
Rust
use rustc::declare_lint_pass;
|
|
use rustc::lint::{in_external_macro, EarlyContext, EarlyLintPass, LintArray, LintContext, LintPass};
|
|
use rustc_session::declare_tool_lint;
|
|
use syntax::ast::*;
|
|
|
|
use crate::utils::span_help_and_lint;
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for usage of `as` conversions.
|
|
///
|
|
/// **Why is this bad?** `as` conversions will perform many kinds of
|
|
/// conversions, including silently lossy conversions and dangerous coercions.
|
|
/// There are cases when it makes sense to use `as`, so the lint is
|
|
/// Allow by default.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust,ignore
|
|
/// let a: u32;
|
|
/// ...
|
|
/// f(a as u16);
|
|
/// ```
|
|
///
|
|
/// Usually better represents the semantics you expect:
|
|
/// ```rust,ignore
|
|
/// f(a.try_into()?);
|
|
/// ```
|
|
/// or
|
|
/// ```rust,ignore
|
|
/// f(a.try_into().expect("Unexpected u16 overflow in f"));
|
|
/// ```
|
|
///
|
|
pub AS_CONVERSIONS,
|
|
restriction,
|
|
"using a potentially dangerous silent `as` conversion"
|
|
}
|
|
|
|
declare_lint_pass!(AsConversions => [AS_CONVERSIONS]);
|
|
|
|
impl EarlyLintPass for AsConversions {
|
|
fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
|
|
if in_external_macro(cx.sess(), expr.span) {
|
|
return;
|
|
}
|
|
|
|
if let ExprKind::Cast(_, _) = expr.kind {
|
|
span_help_and_lint(
|
|
cx,
|
|
AS_CONVERSIONS,
|
|
expr.span,
|
|
"using a potentially dangerous silent `as` conversion",
|
|
"consider using a safe wrapper for this conversion",
|
|
);
|
|
}
|
|
}
|
|
}
|