Fix #518

src/attrs.rs

@@ -6,7 +6,7 @@ use reexport::*;
 use syntax::codemap::Span;
 use syntax::attr::*;
 use syntax::ast::{Attribute, MetaList, MetaWord};
-use utils::{in_macro, match_path, span_lint};
+use utils::{in_macro, match_path, span_lint, BEGIN_UNWIND};
 
 /// **What it does:** This lint warns on items annotated with `#[inline(always)]`, unless the annotated function is empty or simply panics.
 ///
@@ -94,7 +94,7 @@ fn is_relevant_expr(expr: &Expr) -> bool {
         ExprRet(None) | ExprBreak(_) => false,
         ExprCall(ref path_expr, _) => {
             if let ExprPath(_, ref path) = path_expr.node {
-                !match_path(path, &["std", "rt", "begin_unwind"])
+                !match_path(path, &BEGIN_UNWIND)
             } else { true }
         }
         _ => true

src/lib.rs

@@ -67,6 +67,7 @@ pub mod cyclomatic_complexity;
 pub mod escape;
 pub mod misc_early;
 pub mod array_indexing;
+pub mod panic;
 
 mod reexport {
     pub use syntax::ast::{Name, NodeId};
@@ -123,6 +124,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
     reg.register_early_lint_pass(box misc_early::MiscEarly);
     reg.register_late_lint_pass(box misc::UsedUnderscoreBinding);
     reg.register_late_lint_pass(box array_indexing::ArrayIndexing);
+    reg.register_late_lint_pass(box panic::PanicPass);
 
     reg.register_lint_group("clippy_pedantic", vec![
         methods::OPTION_UNWRAP_USED,
@@ -198,6 +200,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
         needless_update::NEEDLESS_UPDATE,
         no_effect::NO_EFFECT,
         open_options::NONSENSICAL_OPEN_OPTIONS,
+        panic::PANIC_PARAMS,
         precedence::PRECEDENCE,
         ptr_arg::PTR_ARG,
         ranges::RANGE_STEP_BY_ZERO,

src/panic.rs

@@ -0,0 +1,42 @@
+use rustc::lint::*;
+use rustc_front::hir::*;
+use syntax::ast::Lit_::LitStr;
+
+use utils::{span_lint, in_external_macro, match_path, BEGIN_UNWIND};
+
+/// **What it does:** Warn about missing parameters in `panic!`.
+///
+/// **Known problems:** Should you want to use curly brackets in `panic!` without any parameter,
+/// this lint will warn.
+///
+/// **Example:**
+/// ```
+/// panic!("This panic! is probably missing a parameter there: {}");
+/// ```
+declare_lint!(pub PANIC_PARAMS, Warn, "missing parameters in `panic!`");
+
+#[allow(missing_copy_implementations)]
+pub struct PanicPass;
+
+impl LintPass for PanicPass {
+    fn get_lints(&self) -> LintArray {
+        lint_array!(PANIC_PARAMS)
+    }
+}
+
+impl LateLintPass for PanicPass {
+    fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
+        if_let_chain! {[
+            in_external_macro(cx, expr.span),
+            let ExprCall(ref fun, ref params) = expr.node,
+            params.len() == 2,
+            let ExprPath(None, ref path) = fun.node,
+            match_path(path, &BEGIN_UNWIND),
+            let ExprLit(ref lit) = params[0].node,
+            let LitStr(ref string, _) = lit.node,
+            string.contains('{')
+        ], {
+            span_lint(cx, PANIC_PARAMS, expr.span, "You probably are missing some parameter in your `panic!` call");
+        }}
+    }
+}

src/utils.rs

@@ -21,6 +21,7 @@ pub const LL_PATH:     [&'static str; 3] = ["collections", "linked_list", "Linke
 pub const OPEN_OPTIONS_PATH: [&'static str; 3] = ["std", "fs", "OpenOptions"];
 pub const MUTEX_PATH:  [&'static str; 4] = ["std", "sync", "mutex", "Mutex"];
 pub const CLONE_PATH:  [&'static str; 2] = ["Clone", "clone"];
+pub const BEGIN_UNWIND:[&'static str; 3] = ["std", "rt", "begin_unwind"];
 
 /// Produce a nested chain of if-lets and ifs from the patterns:
 ///