rust-clippy/clippy_lints/src/panic.rs

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use rustc::hir::*;
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use rustc::lint::*;
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use syntax::ast::LitKind;
use utils::{is_direct_expn_of, match_def_path, resolve_node, paths, span_lint};
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/// **What it does:** Checks for missing parameters in `panic!`.
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///
/// **Why is this bad?** Contrary to the `format!` family of macros, there are
/// two forms of `panic!`: if there are no parameters given, the first argument
/// is not a format string and used literally. So while `format!("{}")` will
/// fail to compile, `panic!("{}")` will not.
///
/// **Known problems:** Should you want to use curly brackets in `panic!`
/// without any parameter, this lint will warn.
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///
/// **Example:**
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/// ```rust
/// panic!("This `panic!` is probably missing a parameter there: {}");
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/// ```
declare_lint! {
pub PANIC_PARAMS,
Warn,
"missing parameters in `panic!` calls"
}
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#[allow(missing_copy_implementations)]
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pub struct Pass;
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impl LintPass for Pass {
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fn get_lints(&self) -> LintArray {
lint_array!(PANIC_PARAMS)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
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if_let_chain! {[
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let ExprBlock(ref block) = expr.node,
let Some(ref ex) = block.expr,
let ExprCall(ref fun, ref params) = ex.node,
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params.len() == 2,
let ExprPath(ref qpath) = fun.node,
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match_def_path(cx.tcx, resolve_node(cx, qpath, fun.id).def_id(), &paths::BEGIN_PANIC),
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let ExprLit(ref lit) = params[0].node,
is_direct_expn_of(cx, params[0].span, "panic").is_some(),
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let LitKind::Str(ref string, _) = lit.node,
let Some(par) = string.as_str().find('{'),
string.as_str()[par..].contains('}')
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], {
span_lint(cx, PANIC_PARAMS, params[0].span,
"you probably are missing some parameter in your format string");
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}}
}
}