Auto merge of rust-lang#139473 - Kobzol:rollup-ycksn9b, r=Kobzol

Rollup of 5 pull requests

Successful merges:

 - rust-lang#138314 (fix usage of `autodiff` macro with inner functions)
 - rust-lang#139426 (Make the UnifyKey and UnifyValue imports non-nightly)
 - rust-lang#139431 (Remove LLVM 18 inline ASM span fallback)
 - rust-lang#139456 (style guide: add let-chain rules)
 - rust-lang#139467 (More trivial tweaks)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

Diff for: Cargo.lock

@@ -4589,6 +4589,7 @@ version = "0.0.0"
 dependencies = [
  "bitflags",
  "derive-where",
+ "ena",
  "indexmap",
  "rustc-hash 1.1.0",
  "rustc_ast_ir",

Diff for: compiler/rustc_builtin_macros/src/autodiff.rs

@@ -17,7 +17,7 @@ mod llvm_enzyme {
     use rustc_ast::visit::AssocCtxt::*;
     use rustc_ast::{
         self as ast, AssocItemKind, BindingMode, ExprKind, FnRetTy, FnSig, Generics, ItemKind,
-        MetaItemInner, PatKind, QSelf, TyKind,
+        MetaItemInner, PatKind, QSelf, TyKind, Visibility,
     };
     use rustc_expand::base::{Annotatable, ExtCtxt};
     use rustc_span::{Ident, Span, Symbol, kw, sym};
@@ -72,6 +72,16 @@ mod llvm_enzyme {
         }
     }
 
+    // Get information about the function the macro is applied to
+    fn extract_item_info(iitem: &P<ast::Item>) -> Option<(Visibility, FnSig, Ident)> {
+        match &iitem.kind {
+            ItemKind::Fn(box ast::Fn { sig, ident, .. }) => {
+                Some((iitem.vis.clone(), sig.clone(), ident.clone()))
+            }
+            _ => None,
+        }
+    }
+
     pub(crate) fn from_ast(
         ecx: &mut ExtCtxt<'_>,
         meta_item: &ThinVec<MetaItemInner>,
@@ -199,32 +209,26 @@ mod llvm_enzyme {
             return vec![item];
         }
         let dcx = ecx.sess.dcx();
-        // first get the annotable item:
-        let (primal, sig, is_impl): (Ident, FnSig, bool) = match &item {
-            Annotatable::Item(iitem) => {
-                let (ident, sig) = match &iitem.kind {
-                    ItemKind::Fn(box ast::Fn { ident, sig, .. }) => (ident, sig),
-                    _ => {
-                        dcx.emit_err(errors::AutoDiffInvalidApplication { span: item.span() });
-                        return vec![item];
-                    }
-                };
-                (*ident, sig.clone(), false)
-            }
+
+        // first get information about the annotable item:
+        let Some((vis, sig, primal)) = (match &item {
+            Annotatable::Item(iitem) => extract_item_info(iitem),
+            Annotatable::Stmt(stmt) => match &stmt.kind {
+                ast::StmtKind::Item(iitem) => extract_item_info(iitem),
+                _ => None,
+            },
             Annotatable::AssocItem(assoc_item, Impl { of_trait: false }) => {
-                let (ident, sig) = match &assoc_item.kind {
-                    ast::AssocItemKind::Fn(box ast::Fn { ident, sig, .. }) => (ident, sig),
-                    _ => {
-                        dcx.emit_err(errors::AutoDiffInvalidApplication { span: item.span() });
-                        return vec![item];
+                match &assoc_item.kind {
+                    ast::AssocItemKind::Fn(box ast::Fn { sig, ident, .. }) => {
+                        Some((assoc_item.vis.clone(), sig.clone(), ident.clone()))
                     }
-                };
-                (*ident, sig.clone(), true)
-            }
-            _ => {
-                dcx.emit_err(errors::AutoDiffInvalidApplication { span: item.span() });
-                return vec![item];
+                    _ => None,
+                }
             }
+            _ => None,
+        }) else {
+            dcx.emit_err(errors::AutoDiffInvalidApplication { span: item.span() });
+            return vec![item];
         };
 
         let meta_item_vec: ThinVec<MetaItemInner> = match meta_item.kind {
@@ -238,15 +242,6 @@ mod llvm_enzyme {
         let has_ret = has_ret(&sig.decl.output);
         let sig_span = ecx.with_call_site_ctxt(sig.span);
 
-        let vis = match &item {
-            Annotatable::Item(iitem) => iitem.vis.clone(),
-            Annotatable::AssocItem(assoc_item, _) => assoc_item.vis.clone(),
-            _ => {
-                dcx.emit_err(errors::AutoDiffInvalidApplication { span: item.span() });
-                return vec![item];
-            }
-        };
-
         // create TokenStream from vec elemtents:
         // meta_item doesn't have a .tokens field
         let mut ts: Vec<TokenTree> = vec![];
@@ -379,6 +374,22 @@ mod llvm_enzyme {
                 }
                 Annotatable::AssocItem(assoc_item.clone(), i)
             }
+            Annotatable::Stmt(ref mut stmt) => {
+                match stmt.kind {
+                    ast::StmtKind::Item(ref mut iitem) => {
+                        if !iitem.attrs.iter().any(|a| same_attribute(&a.kind, &attr.kind)) {
+                            iitem.attrs.push(attr);
+                        }
+                        if !iitem.attrs.iter().any(|a| same_attribute(&a.kind, &inline_never.kind))
+                        {
+                            iitem.attrs.push(inline_never.clone());
+                        }
+                    }
+                    _ => unreachable!("stmt kind checked previously"),
+                };
+
+                Annotatable::Stmt(stmt.clone())
+            }
             _ => {
                 unreachable!("annotatable kind checked previously")
             }
@@ -389,22 +400,40 @@ mod llvm_enzyme {
             delim: rustc_ast::token::Delimiter::Parenthesis,
             tokens: ts,
         });
+
         let d_attr = outer_normal_attr(&rustc_ad_attr, new_id, span);
-        let d_annotatable = if is_impl {
-            let assoc_item: AssocItemKind = ast::AssocItemKind::Fn(asdf);
-            let d_fn = P(ast::AssocItem {
-                attrs: thin_vec![d_attr, inline_never],
-                id: ast::DUMMY_NODE_ID,
-                span,
-                vis,
-                kind: assoc_item,
-                tokens: None,
-            });
-            Annotatable::AssocItem(d_fn, Impl { of_trait: false })
-        } else {
-            let mut d_fn = ecx.item(span, thin_vec![d_attr, inline_never], ItemKind::Fn(asdf));
-            d_fn.vis = vis;
-            Annotatable::Item(d_fn)
+        let d_annotatable = match &item {
+            Annotatable::AssocItem(_, _) => {
+                let assoc_item: AssocItemKind = ast::AssocItemKind::Fn(asdf);
+                let d_fn = P(ast::AssocItem {
+                    attrs: thin_vec![d_attr, inline_never],
+                    id: ast::DUMMY_NODE_ID,
+                    span,
+                    vis,
+                    kind: assoc_item,
+                    tokens: None,
+                });
+                Annotatable::AssocItem(d_fn, Impl { of_trait: false })
+            }
+            Annotatable::Item(_) => {
+                let mut d_fn = ecx.item(span, thin_vec![d_attr, inline_never], ItemKind::Fn(asdf));
+                d_fn.vis = vis;
+
+                Annotatable::Item(d_fn)
+            }
+            Annotatable::Stmt(_) => {
+                let mut d_fn = ecx.item(span, thin_vec![d_attr, inline_never], ItemKind::Fn(asdf));
+                d_fn.vis = vis;
+
+                Annotatable::Stmt(P(ast::Stmt {
+                    id: ast::DUMMY_NODE_ID,
+                    kind: ast::StmtKind::Item(d_fn),
+                    span,
+                }))
+            }
+            _ => {
+                unreachable!("item kind checked previously")
+            }
         };
 
         return vec![orig_annotatable, d_annotatable];

Diff for: compiler/rustc_codegen_llvm/src/back/write.rs

@@ -439,12 +439,9 @@ fn report_inline_asm(
     let span = if cookie == 0 || matches!(cgcx.lto, Lto::Fat | Lto::Thin) {
         SpanData::default()
     } else {
-        let lo = BytePos::from_u32(cookie as u32);
-        let hi = BytePos::from_u32((cookie >> 32) as u32);
         SpanData {
-            lo,
-            // LLVM version < 19 silently truncates the cookie to 32 bits in some situations.
-            hi: if hi.to_u32() != 0 { hi } else { lo },
+            lo: BytePos::from_u32(cookie as u32),
+            hi: BytePos::from_u32((cookie >> 32) as u32),
             ctxt: SyntaxContext::root(),
             parent: None,
         }

Diff for: compiler/rustc_hir_analysis/src/check/region.rs

@@ -446,14 +446,11 @@ fn resolve_expr<'tcx>(
         // Mark this expr's scope and all parent scopes as containing `yield`.
         let mut scope = Scope { local_id: expr.hir_id.local_id, data: ScopeData::Node };
         loop {
-            let span = match expr.kind {
-                hir::ExprKind::Yield(expr, hir::YieldSource::Await { .. }) => {
-                    expr.span.shrink_to_hi().to(expr.span)
-                }
-                _ => expr.span,
+            let data = YieldData {
+                span: expr.span,
+                expr_and_pat_count: visitor.expr_and_pat_count,
+                source: *source,
             };
-            let data =
-                YieldData { span, expr_and_pat_count: visitor.expr_and_pat_count, source: *source };
             match visitor.scope_tree.yield_in_scope.get_mut(&scope) {
                 Some(yields) => yields.push(data),
                 None => {

Diff for: compiler/rustc_hir_typeck/src/demand.rs

@@ -865,10 +865,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // `&'name Ty` -> `&'name mut Ty` or `&Ty` -> `&mut Ty`
                 vec![(
                     ty_ref.1.ty.span.shrink_to_lo(),
-                    format!(
-                        "{}mut ",
-                        if ty_ref.0.ident.span.lo() == ty_ref.0.ident.span.hi() { "" } else { " " },
-                    ),
+                    format!("{}mut ", if ty_ref.0.ident.span.is_empty() { "" } else { " " },),
                 )]
             };
             sugg.extend([

Diff for: compiler/rustc_passes/src/liveness.rs

@@ -1655,7 +1655,7 @@ impl<'tcx> Liveness<'_, 'tcx> {
                 // `&'name Ty` -> `&'name mut Ty` or `&Ty` -> `&mut Ty`
                 Some(mut_ty.ty.span.shrink_to_lo())
             };
-            let pre = if lt.ident.span.lo() == lt.ident.span.hi() { "" } else { " " };
+            let pre = if lt.ident.span.is_empty() { "" } else { " " };
             Some(errors::UnusedAssignSuggestion {
                 ty_span,
                 pre,

Diff for: compiler/rustc_type_ir/Cargo.toml

@@ -7,6 +7,7 @@ edition = "2024"
 # tidy-alphabetical-start
 bitflags = "2.4.1"
 derive-where = "1.2.7"
+ena = "0.14.3"
 indexmap = "2.0.0"
 rustc-hash = "1.1.0"
 rustc_ast_ir = { path = "../rustc_ast_ir", default-features = false }

Diff for: compiler/rustc_type_ir/src/data_structures/mod.rs

@@ -1,5 +1,6 @@
 use std::hash::BuildHasherDefault;
 
+pub use ena::unify::{NoError, UnifyKey, UnifyValue};
 use rustc_hash::FxHasher;
 pub use rustc_hash::{FxHashMap as HashMap, FxHashSet as HashSet};
 

Diff for: compiler/rustc_type_ir/src/ty_kind.rs

@@ -6,9 +6,8 @@ use rustc_ast_ir::Mutability;
 #[cfg(feature = "nightly")]
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 #[cfg(feature = "nightly")]
-use rustc_data_structures::unify::{NoError, UnifyKey, UnifyValue};
-#[cfg(feature = "nightly")]
 use rustc_macros::{Decodable_NoContext, Encodable_NoContext, HashStable_NoContext};
+use rustc_type_ir::data_structures::{NoError, UnifyKey, UnifyValue};
 use rustc_type_ir_macros::{Lift_Generic, TypeFoldable_Generic, TypeVisitable_Generic};
 
 use self::TyKind::*;
@@ -796,7 +795,6 @@ pub enum InferTy {
 
 /// Raw `TyVid` are used as the unification key for `sub_relations`;
 /// they carry no values.
-#[cfg(feature = "nightly")]
 impl UnifyKey for TyVid {
     type Value = ();
     #[inline]
@@ -812,7 +810,6 @@ impl UnifyKey for TyVid {
     }
 }
 
-#[cfg(feature = "nightly")]
 impl UnifyValue for IntVarValue {
     type Error = NoError;
 
@@ -832,7 +829,6 @@ impl UnifyValue for IntVarValue {
     }
 }
 
-#[cfg(feature = "nightly")]
 impl UnifyKey for IntVid {
     type Value = IntVarValue;
     #[inline] // make this function eligible for inlining - it is quite hot.
@@ -848,7 +844,6 @@ impl UnifyKey for IntVid {
     }
 }
 
-#[cfg(feature = "nightly")]
 impl UnifyValue for FloatVarValue {
     type Error = NoError;
 
@@ -866,7 +861,6 @@ impl UnifyValue for FloatVarValue {
     }
 }
 
-#[cfg(feature = "nightly")]
 impl UnifyKey for FloatVid {
     type Value = FloatVarValue;
     #[inline]

Diff for: src/doc/style-guide/src/expressions.md

@@ -521,8 +521,11 @@ self.pre_comment.as_ref().map_or(
 
 ## Control flow expressions
 
-This section covers `if`, `if let`, `loop`, `while`, `while let`, and `for`
-expressions.
+This section covers `for` and `loop` expressions, as well as `if` and `while`
+expressions with their sub-expression variants. This includes those with a
+single `let` sub-expression (i.e. `if let` and `while let`)
+as well as "let-chains": those with one or more `let` sub-expressions and
+one or more bool-type conditions (i.e.  `if a && let Some(b) = c`).
 
 Put the keyword, any initial clauses, and the opening brace of the block all on
 a single line, if they fit. Apply the usual rules for [block
@@ -548,10 +551,11 @@ if let ... {
 }
 ```
 
-If the control line needs to be broken, prefer to break before the `=` in `*
-let` expressions and before `in` in a `for` expression; block-indent the
-following line. If the control line is broken for any reason, put the opening
-brace on its own line, not indented. Examples:
+If the control line needs to be broken, then prefer breaking after the `=` for any
+`let` sub-expression in an `if` or `while` expression that does not fit,
+and before `in` in a `for` expression; the following line should be block indented.
+If the control line is broken for any reason, then the opening brace should be on its
+own line and not indented. Examples:
 
 ```rust
 while let Some(foo)
@@ -572,6 +576,68 @@ if a_long_expression
 {
     ...
 }
+
+if let Some(a) = b
+    && another_long_expression
+    && a_third_long_expression
+{
+    // ...
+}
+
+if let Some(relatively_long_thing)
+    = a_long_expression
+    && another_long_expression
+    && a_third_long_expression
+{
+    // ...
+}
+
+if some_expr
+    && another_long_expression
+    && let Some(relatively_long_thing) =
+        a_long_long_long_long_long_long_really_reallllllllllyyyyyyy_long_expression
+    && a_third_long_expression
+{
+    // ...
+}
+```
+
+A let-chain control line is allowed to be formatted on a single line provided
+it only consists of two clauses, with the first, left-hand side operand being a literal or an
+`ident` (which can optionally be preceded by any number of unary prefix operators),
+and the second, right-hand side operand being a single-line `let` clause. Otherwise,
+the control line must be broken and formatted according to the above rules. For example:
+
+```rust
+if a && let Some(b) = foo() {
+    // ...
+}
+
+if true && let Some(b) = foo() {
+    // ...
+}
+
+let operator = if !from_hir_call && let Some(p) = parent {
+    // ...
+};
+
+if let Some(b) = foo()
+    && a
+{
+    // ..
+}
+
+if foo()
+    && let Some(b) = bar
+{
+    // ...
+}
+
+if gen_pos != GenericArgPosition::Type
+    && let Some(b) = gen_args.bindings.first()
+{
+    // ..
+}
 ```
 
 Where the initial clause spans multiple lines and ends with one or more closing