Auto merge of #140748 - m-ou-se:super-format-args3, r=jdonszelmann

 Allow storing `format_args!()` in variable

Fixes https://github.com/rust-lang/rust/issues/92698

Tracking issue for super let: https://github.com/rust-lang/rust/issues/139076

Tracking issue for format_args: https://github.com/rust-lang/rust/issues/99012

This change allows:

```rust
let name = "world";
let f = format_args!("hello {name}!"); // New: Store format_args!() for later!

println!("{f}");
```

This will need an FCP.

This implementation makes use of `super let`, which is unstable and might not exist in the future in its current form. However, it is entirely reasonable to assume future Rust will always have _a_ way of expressing temporary lifetimes like this, since the (stable) `pin!()` macro needs this too. (This was also the motivation for merging https://github.com/rust-lang/rust/pull/139114.)

(This is a second version of https://github.com/rust-lang/rust/pull/139135)

1 files changed, 6 insertions, 6 deletions

diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 718edad0cc6..f297bf9f4cf 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -2289,12 +2289,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
         span: Span,
         elements: &'hir [hir::Expr<'hir>],
     ) -> hir::Expr<'hir> {
-        let addrof = hir::ExprKind::AddrOf(
-            hir::BorrowKind::Ref,
-            hir::Mutability::Not,
-            self.arena.alloc(self.expr(span, hir::ExprKind::Array(elements))),
-        );
-        self.expr(span, addrof)
+        let array = self.arena.alloc(self.expr(span, hir::ExprKind::Array(elements)));
+        self.expr_ref(span, array)
+    }
+
+    pub(super) fn expr_ref(&mut self, span: Span, expr: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> {
+        self.expr(span, hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, expr))
     }
 
     pub(super) fn expr(&mut self, span: Span, kind: hir::ExprKind<'hir>) -> hir::Expr<'hir> {