Auto merge of rust-lang#11106 - syvb:literal_unwrap_ice, r=dswij

[`unnecessary_literal_unwrap`]: Fix ICE on None.unwrap_or_default()

Fixes rust-lang#11099
Fixes rust-lang#11064

I'm running into rust-lang#11099 (cc `@y21)` on my Rust codebase. Clippy ICEs on this code when evaluating the `unnecessary_literal_unwrap` lint:
```rust
fn main() {
    let val1: u8 = None.unwrap_or_default();
}
```

This fixes that ICE and adds an message specifically for that case:

```
error: used `unwrap_or_default()` on `None` value
  --> $DIR/unnecessary_literal_unwrap.rs:26:5
   |
LL |     None::<String>.unwrap_or_default();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove the `None` and `unwrap_or_default()`: `String::default()`
```

This PR also fixes the same ICE with `None.unwrap_or_else` (by giving the generic error message for the lint in that case).

changelog: Fix ICE in `unnecessary_literal_unwrap` on `None.unwrap_or_default()`

Author: bors

src/tools/clippy/clippy_lints/src/methods/unnecessary_literal_unwrap.rs

@@ -2,6 +2,8 @@ use clippy_utils::{diagnostics::span_lint_and_then, is_res_lang_ctor, last_path_
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_lint::LateContext;
+use rustc_middle::ty;
+use rustc_middle::ty::print::with_forced_trimmed_paths;
 
 use super::UNNECESSARY_LITERAL_UNWRAP;
 
@@ -21,6 +23,7 @@ fn get_ty_from_args<'a>(args: Option<&'a [hir::GenericArg<'a>]>, index: usize) -
     }
 }
 
+#[expect(clippy::too_many_lines)]
 pub(super) fn check(
     cx: &LateContext<'_>,
     expr: &hir::Expr<'_>,
@@ -62,6 +65,34 @@ pub(super) fn check(
                 (expr.span.with_hi(args[0].span.lo()), "panic!(".to_string()),
                 (expr.span.with_lo(args[0].span.hi()), ")".to_string()),
             ]),
+            ("None", "unwrap_or_default", _) => {
+                let ty = cx.typeck_results().expr_ty(expr);
+                let default_ty_string = if let ty::Adt(def, ..) = ty.kind() {
+                    with_forced_trimmed_paths!(format!("{}", cx.tcx.def_path_str(def.did())))
+                } else {
+                    "Default".to_string()
+                };
+                Some(vec![(expr.span, format!("{default_ty_string}::default()"))])
+            },
+            ("None", "unwrap_or", _) => Some(vec![
+                (expr.span.with_hi(args[0].span.lo()), String::new()),
+                (expr.span.with_lo(args[0].span.hi()), String::new()),
+            ]),
+            ("None", "unwrap_or_else", _) => match args[0].kind {
+                hir::ExprKind::Closure(hir::Closure {
+                    fn_decl:
+                        hir::FnDecl {
+                            output: hir::FnRetTy::DefaultReturn(span) | hir::FnRetTy::Return(hir::Ty { span, .. }),
+                            ..
+                        },
+                    ..
+                }) => Some(vec![
+                    (expr.span.with_hi(span.hi()), String::new()),
+                    (expr.span.with_lo(args[0].span.hi()), String::new()),
+                ]),
+                _ => None,
+            },
+            _ if call_args.is_empty() => None,
             (_, _, Some(_)) => None,
             ("Ok", "unwrap_err", None) | ("Err", "unwrap", None) => Some(vec![
                 (

src/tools/clippy/tests/ui/unnecessary_literal_unwrap.fixed

@@ -16,12 +16,23 @@ fn unwrap_option_some() {
     1;
 }
 
+#[rustfmt::skip] // force rustfmt not to remove braces in `|| { 234 }`
 fn unwrap_option_none() {
     let _val = panic!();
     let _val = panic!("this always happens");
+    let _val: String = String::default();
+    let _val: u16 = 234;
+    let _val: u16 = 234;
+    let _val: u16 = { 234 };
+    let _val: u16 =  { 234 };
 
     panic!();
     panic!("this always happens");
+    String::default();
+    234;
+    234;
+    { 234 };
+     { 234 };
 }
 
 fn unwrap_result_ok() {

src/tools/clippy/tests/ui/unnecessary_literal_unwrap.rs

@@ -16,12 +16,23 @@ fn unwrap_option_some() {
     Some(1).expect("this never happens");
 }
 
+#[rustfmt::skip] // force rustfmt not to remove braces in `|| { 234 }`
 fn unwrap_option_none() {
     let _val = None::<()>.unwrap();
     let _val = None::<()>.expect("this always happens");
+    let _val: String = None.unwrap_or_default();
+    let _val: u16 = None.unwrap_or(234);
+    let _val: u16 = None.unwrap_or_else(|| 234);
+    let _val: u16 = None.unwrap_or_else(|| { 234 });
+    let _val: u16 = None.unwrap_or_else(|| -> u16 { 234 });
 
     None::<()>.unwrap();
     None::<()>.expect("this always happens");
+    None::<String>.unwrap_or_default();
+    None::<u16>.unwrap_or(234);
+    None::<u16>.unwrap_or_else(|| 234);
+    None::<u16>.unwrap_or_else(|| { 234 });
+    None::<u16>.unwrap_or_else(|| -> u16 { 234 });
 }
 
 fn unwrap_result_ok() {