Auto merge of #7471 - flip1995:ice-7410, r=giraffate

Fix ICE in redundant_pattern_matching

Fixes #7410

changelog: Fix ICE in `redundant_pattern_matching` in `no_std` crates.

Author: bors

clippy_utils/src/ty.rs

@@ -257,10 +257,12 @@ pub fn is_type_diagnostic_item(cx: &LateContext<'_>, ty: Ty<'_>, diag_item: Symb
     }
 }
 
-/// Checks if the type is equal to a lang item
+/// Checks if the type is equal to a lang item.
+///
+/// Returns `false` if the `LangItem` is not defined.
 pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangItem) -> bool {
     match ty.kind() {
-        ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).unwrap() == adt.did,
+        ty::Adt(adt, _) => cx.tcx.lang_items().require(lang_item).map_or(false, |li| li == adt.did),
         _ => false,
     }
 }

tests/ui/crashes/ice-7410.rs

@@ -0,0 +1,31 @@
+// compile-flags: -Clink-arg=-nostartfiles
+// ignore-macos
+// ignore-windows
+
+#![feature(lang_items, start, libc)]
+#![no_std]
+#![allow(clippy::redundant_pattern_matching)]
+
+use core::panic::PanicInfo;
+
+struct S;
+
+impl Drop for S {
+    fn drop(&mut self) {}
+}
+
+#[start]
+fn main(argc: isize, argv: *const *const u8) -> isize {
+    if let Some(_) = Some(S) {
+    } else {
+    }
+    0
+}
+
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+    loop {}
+}
+
+#[lang = "eh_personality"]
+extern "C" fn eh_personality() {}