fix todo item check, remove unimplemented

Author: digama0

clippy_lints/src/loops/never_loop.rs

@@ -7,7 +7,7 @@ use clippy_utils::source::snippet;
 use rustc_errors::Applicability;
 use rustc_hir::{Block, Destination, Expr, ExprKind, HirId, InlineAsmOperand, Pat, Stmt, StmtKind};
 use rustc_lint::LateContext;
-use rustc_span::Span;
+use rustc_span::{sym, Span};
 use std::iter::{once, Iterator};
 
 pub(super) fn check<'tcx>(
@@ -273,7 +273,7 @@ fn never_loop_expr<'tcx>(
     });
     if  let NeverLoopResult::Diverging = result &&
         let Some(macro_call) = root_macro_call_first_node(cx, expr) &&
-        let "todo" | "unimplemented" = cx.tcx.item_name(macro_call.def_id).as_str()
+        let Some(sym::todo_macro) = cx.tcx.get_diagnostic_name(macro_call.def_id)
     {
         // We return MayContinueMainLoop here because we treat `todo!()` and
         // `unimplemented!()` macros as potentially containing any code,

tests/ui/never_loop.rs

@@ -391,7 +391,7 @@ pub fn test32() {
         panic!("oh no");
     }
     loop {
-        // no error
+        //~^ ERROR: this loop never actually loops
         unimplemented!("not yet");
     }
     loop {

tests/ui/never_loop.stderr

@@ -170,5 +170,14 @@ LL | |         panic!("oh no");
 LL | |     }
    | |_____^
 
-error: aborting due to 15 previous errors
+error: this loop never actually loops
+  --> $DIR/never_loop.rs:393:5
+   |
+LL | /     loop {
+LL | |
+LL | |         unimplemented!("not yet");
+LL | |     }
+   | |_____^
+
+error: aborting due to 16 previous errors