Rollup merge of rust-lang#134661 - dtolnay:prefixattr, r=fmease

Reduce precedence of expressions that have an outer attr

Previously, `-Zunpretty=expanded` would expand this program as follows:

```rust
#![feature(stmt_expr_attributes)]

macro_rules! repro {
    ($e:expr) => {
        #[allow(deprecated)] $e
    };
}

#[derive(Default)]
struct Thing {
    #[deprecated]
    field: i32,
}

fn main() {
    let thing = Thing::default();
    let _ = repro!(thing).field;
}
```

```rs
#![feature(prelude_import)]
#![feature(stmt_expr_attributes)]
#[prelude_import]
use std::prelude::rust_2021::*;
#[macro_use]
extern crate std;

struct Thing {
    #[deprecated]
    field: i32,
}

#[automatically_derived]
impl ::core::default::Default for Thing {
    #[inline]
    fn default() -> Thing {
        Thing { field: ::core::default::Default::default() }
    }
}

fn main() {
    let thing = Thing::default();
    let _ = #[allow(deprecated)] thing.field;
}
```

This is not the correct expansion. The correct output would have `(#[allow(deprecated)] thing).field` with the attribute applying only to `thing`, not to `thing.field`.

Author: fmease

clippy_lints/src/casts/unnecessary_cast.rs

@@ -185,7 +185,7 @@ pub(super) fn check<'tcx>(
             Node::Expr(parent) if is_borrow_expr(cx, parent) && !is_in_allowed_macro(cx, parent) => {
                 MaybeParenOrBlock::Block
             },
-            Node::Expr(parent) if cast_expr.precedence() < parent.precedence() => MaybeParenOrBlock::Paren,
+            Node::Expr(parent) if cx.precedence(cast_expr) < cx.precedence(parent) => MaybeParenOrBlock::Paren,
             _ => MaybeParenOrBlock::Nothing,
         };
 

clippy_lints/src/dereference.rs

@@ -972,7 +972,7 @@ fn report<'tcx>(
                 "&"
             };
 
-            let expr_str = if !expr_is_macro_call && is_ufcs && expr.precedence() < ExprPrecedence::Prefix {
+            let expr_str = if !expr_is_macro_call && is_ufcs && cx.precedence(expr) < ExprPrecedence::Prefix {
                 Cow::Owned(format!("({expr_str})"))
             } else {
                 expr_str
@@ -1015,10 +1015,10 @@ fn report<'tcx>(
                         Node::Expr(e) => match e.kind {
                             ExprKind::Call(callee, _) if callee.hir_id != data.first_expr.hir_id => false,
                             ExprKind::Call(..) => {
-                                expr.precedence() < ExprPrecedence::Unambiguous
+                                cx.precedence(expr) < ExprPrecedence::Unambiguous
                                     || matches!(expr.kind, ExprKind::Field(..))
                             },
-                            _ => expr.precedence() < e.precedence(),
+                            _ => cx.precedence(expr) < cx.precedence(e),
                         },
                         _ => false,
                     };
@@ -1066,7 +1066,7 @@ fn report<'tcx>(
                         Mutability::Not => "&",
                         Mutability::Mut => "&mut ",
                     };
-                    (prefix, expr.precedence() < ExprPrecedence::Prefix)
+                    (prefix, cx.precedence(expr) < ExprPrecedence::Prefix)
                 },
                 None if !ty.is_ref() && data.adjusted_ty.is_ref() => ("&", false),
                 _ => ("", false),
@@ -1172,7 +1172,7 @@ impl<'tcx> Dereferencing<'tcx> {
                 },
                 Some(parent) if !parent.span.from_expansion() => {
                     // Double reference might be needed at this point.
-                    if parent.precedence() == ExprPrecedence::Unambiguous {
+                    if cx.precedence(parent) == ExprPrecedence::Unambiguous {
                         // Parentheses would be needed here, don't lint.
                         *outer_pat = None;
                     } else {

clippy_lints/src/loops/single_element_loop.rs

@@ -84,7 +84,7 @@ pub(super) fn check<'tcx>(
         if !prefix.is_empty()
             && (
                 // Precedence of internal expression is less than or equal to precedence of `&expr`.
-                arg_expression.precedence() <= ExprPrecedence::Prefix || is_range_literal(arg_expression)
+                cx.precedence(arg_expression) <= ExprPrecedence::Prefix || is_range_literal(arg_expression)
             )
         {
             arg_snip = format!("({arg_snip})").into();

clippy_lints/src/matches/manual_utils.rs

@@ -117,7 +117,7 @@ where
     // it's being passed by value.
     let scrutinee = peel_hir_expr_refs(scrutinee).0;
     let (scrutinee_str, _) = snippet_with_context(cx, scrutinee.span, expr_ctxt, "..", &mut app);
-    let scrutinee_str = if scrutinee.span.eq_ctxt(expr.span) && scrutinee.precedence() < ExprPrecedence::Unambiguous {
+    let scrutinee_str = if scrutinee.span.eq_ctxt(expr.span) && cx.precedence(scrutinee) < ExprPrecedence::Unambiguous {
         format!("({scrutinee_str})")
     } else {
         scrutinee_str.into()

clippy_lints/src/neg_multiply.rs

@@ -64,7 +64,7 @@ fn check_mul(cx: &LateContext<'_>, span: Span, lit: &Expr<'_>, exp: &Expr<'_>) {
     {
         let mut applicability = Applicability::MachineApplicable;
         let (snip, from_macro) = snippet_with_context(cx, exp.span, span.ctxt(), "..", &mut applicability);
-        let suggestion = if !from_macro && exp.precedence() < ExprPrecedence::Prefix && !has_enclosing_paren(&snip) {
+        let suggestion = if !from_macro && cx.precedence(exp) < ExprPrecedence::Prefix && !has_enclosing_paren(&snip) {
             format!("-({snip})")
         } else {
             format!("-{snip}")

clippy_lints/src/redundant_slicing.rs

@@ -86,7 +86,7 @@ impl<'tcx> LateLintPass<'tcx> for RedundantSlicing {
             let (indexed_ty, indexed_ref_count) = peel_middle_ty_refs(cx.typeck_results().expr_ty(indexed));
             let parent_expr = get_parent_expr(cx, expr);
             let needs_parens_for_prefix =
-                parent_expr.is_some_and(|parent| parent.precedence() > ExprPrecedence::Prefix);
+                parent_expr.is_some_and(|parent| cx.precedence(parent) > ExprPrecedence::Prefix);
 
             if expr_ty == indexed_ty {
                 if expr_ref_count > indexed_ref_count {

clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs

@@ -44,7 +44,7 @@ pub(super) fn check<'tcx>(
     };
 
     if let Node::Expr(parent) = cx.tcx.parent_hir_node(e.hir_id)
-        && parent.precedence() > ExprPrecedence::Cast
+        && cx.precedence(parent) > ExprPrecedence::Cast
     {
         sugg = format!("({sugg})");
     }