Auto merge of #149853 - matthiaskrgr:rollup-m2rkwqr, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #148052 (Stabilize `const_mul_add`)
 - #149386 (Display funding link in the github overview)
 - #149489 (Experimentally add *heterogeneous* `try` blocks)
 - #149764 (Make `--print=backend-has-zstd` work by default on any backend)
 - #149838 (Build auxiliary in pretty tests)
 - #149839 (Use `PointeeSized` bound for `TrivialClone` impls)
 - #149846 (Statically require links to an issue or the edition guide for all FCWs)

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

Author: bors

.github/FUNDING.yml

@@ -0,0 +1 @@
+custom: ["rust-lang.org/funding"]

compiler/rustc_ast/src/ast.rs

@@ -1819,8 +1819,14 @@ pub enum ExprKind {
     /// A use expression (`x.use`). Span is of use keyword.
     Use(Box<Expr>, Span),
 
-    /// A try block (`try { ... }`).
-    TryBlock(Box<Block>),
+    /// A try block (`try { ... }`), if the type is `None`, or
+    /// A try block (`try bikeshed Ty { ... }`) if the type is `Some`.
+    ///
+    /// Note that `try bikeshed` is a *deliberately ridiculous* placeholder
+    /// syntax to avoid deciding what keyword or symbol should go there.
+    /// It's that way for experimentation only; an RFC to decide the final
+    /// semantics and syntax would be needed to put it on stabilization-track.
+    TryBlock(Box<Block>, Option<Box<Ty>>),
 
     /// An assignment (`a = foo()`).
     /// The `Span` argument is the span of the `=` token.

compiler/rustc_ast/src/visit.rs

@@ -1048,8 +1048,8 @@ macro_rules! common_visitor_and_walkers {
                     visit_visitable!($($mut)? vis, kind),
                 ExprKind::Try(subexpression) =>
                     visit_visitable!($($mut)? vis, subexpression),
-                ExprKind::TryBlock(body) =>
-                    visit_visitable!($($mut)? vis, body),
+                ExprKind::TryBlock(body, optional_type) =>
+                    visit_visitable!($($mut)? vis, body, optional_type),
                 ExprKind::Lit(token) =>
                     visit_visitable!($($mut)? vis, token),
                 ExprKind::IncludedBytes(bytes) =>

compiler/rustc_ast_lowering/src/expr.rs

@@ -1,3 +1,4 @@
+use std::mem;
 use std::ops::ControlFlow;
 use std::sync::Arc;
 
@@ -27,7 +28,9 @@ use super::{
     GenericArgsMode, ImplTraitContext, LoweringContext, ParamMode, ResolverAstLoweringExt,
 };
 use crate::errors::{InvalidLegacyConstGenericArg, UseConstGenericArg, YieldInClosure};
-use crate::{AllowReturnTypeNotation, FnDeclKind, ImplTraitPosition, fluent_generated};
+use crate::{
+    AllowReturnTypeNotation, FnDeclKind, ImplTraitPosition, TryBlockScope, fluent_generated,
+};
 
 struct WillCreateDefIdsVisitor {}
 
@@ -199,7 +202,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         )
                     })
                 }
-                ExprKind::TryBlock(body) => self.lower_expr_try_block(body),
+                ExprKind::TryBlock(body, opt_ty) => {
+                    self.lower_expr_try_block(body, opt_ty.as_deref())
+                }
                 ExprKind::Match(expr, arms, kind) => hir::ExprKind::Match(
                     self.lower_expr(expr),
                     self.arena.alloc_from_iter(arms.iter().map(|x| self.lower_arm(x))),
@@ -562,9 +567,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
     /// Desugar `try { <stmts>; <expr> }` into `{ <stmts>; ::std::ops::Try::from_output(<expr>) }`,
     /// `try { <stmts>; }` into `{ <stmts>; ::std::ops::Try::from_output(()) }`
     /// and save the block id to use it as a break target for desugaring of the `?` operator.
-    fn lower_expr_try_block(&mut self, body: &Block) -> hir::ExprKind<'hir> {
+    fn lower_expr_try_block(&mut self, body: &Block, opt_ty: Option<&Ty>) -> hir::ExprKind<'hir> {
         let body_hir_id = self.lower_node_id(body.id);
-        self.with_catch_scope(body_hir_id, |this| {
+        let new_scope = if opt_ty.is_some() {
+            TryBlockScope::Heterogeneous(body_hir_id)
+        } else {
+            TryBlockScope::Homogeneous(body_hir_id)
+        };
+        let whole_block = self.with_try_block_scope(new_scope, |this| {
             let mut block = this.lower_block_noalloc(body_hir_id, body, true);
 
             // Final expression of the block (if present) or `()` with span at the end of block
@@ -598,8 +608,16 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 ok_wrapped_span,
             ));
 
-            hir::ExprKind::Block(this.arena.alloc(block), None)
-        })
+            this.arena.alloc(block)
+        });
+
+        if let Some(ty) = opt_ty {
+            let ty = self.lower_ty(ty, ImplTraitContext::Disallowed(ImplTraitPosition::Path));
+            let block_expr = self.arena.alloc(self.expr_block(whole_block));
+            hir::ExprKind::Type(block_expr, ty)
+        } else {
+            hir::ExprKind::Block(whole_block, None)
+        }
     }
 
     fn wrap_in_try_constructor(
@@ -1617,10 +1635,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn with_catch_scope<T>(&mut self, catch_id: hir::HirId, f: impl FnOnce(&mut Self) -> T) -> T {
-        let old_scope = self.catch_scope.replace(catch_id);
+    fn with_try_block_scope<T>(
+        &mut self,
+        scope: TryBlockScope,
+        f: impl FnOnce(&mut Self) -> T,
+    ) -> T {
+        let old_scope = mem::replace(&mut self.try_block_scope, scope);
         let result = f(self);
-        self.catch_scope = old_scope;
+        self.try_block_scope = old_scope;
         result
     }
 
@@ -1978,18 +2000,25 @@ impl<'hir> LoweringContext<'_, 'hir> {
             let residual_ident = Ident::with_dummy_span(sym::residual);
             let (residual_local, residual_local_nid) = self.pat_ident(try_span, residual_ident);
             let residual_expr = self.expr_ident_mut(try_span, residual_ident, residual_local_nid);
+
+            let (constructor_item, target_id) = match self.try_block_scope {
+                TryBlockScope::Function => {
+                    (hir::LangItem::TryTraitFromResidual, Err(hir::LoopIdError::OutsideLoopScope))
+                }
+                TryBlockScope::Homogeneous(block_id) => {
+                    (hir::LangItem::ResidualIntoTryType, Ok(block_id))
+                }
+                TryBlockScope::Heterogeneous(block_id) => {
+                    (hir::LangItem::TryTraitFromResidual, Ok(block_id))
+                }
+            };
             let from_residual_expr = self.wrap_in_try_constructor(
-                if self.catch_scope.is_some() {
-                    hir::LangItem::ResidualIntoTryType
-                } else {
-                    hir::LangItem::TryTraitFromResidual
-                },
+                constructor_item,
                 try_span,
                 self.arena.alloc(residual_expr),
                 unstable_span,
             );
-            let ret_expr = if let Some(catch_id) = self.catch_scope {
-                let target_id = Ok(catch_id);
+            let ret_expr = if target_id.is_ok() {
                 self.arena.alloc(self.expr(
                     try_span,
                     hir::ExprKind::Break(
@@ -2044,11 +2073,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
             yeeted_span,
         );
 
-        if let Some(catch_id) = self.catch_scope {
-            let target_id = Ok(catch_id);
-            hir::ExprKind::Break(hir::Destination { label: None, target_id }, Some(from_yeet_expr))
-        } else {
-            self.checked_return(Some(from_yeet_expr))
+        match self.try_block_scope {
+            TryBlockScope::Homogeneous(block_id) | TryBlockScope::Heterogeneous(block_id) => {
+                hir::ExprKind::Break(
+                    hir::Destination { label: None, target_id: Ok(block_id) },
+                    Some(from_yeet_expr),
+                )
+            }
+            TryBlockScope::Function => self.checked_return(Some(from_yeet_expr)),
         }
     }
 

compiler/rustc_ast_lowering/src/lib.rs

@@ -35,6 +35,7 @@
 #![feature(if_let_guard)]
 // tidy-alphabetical-end
 
+use std::mem;
 use std::sync::Arc;
 
 use rustc_ast::node_id::NodeMap;
@@ -117,7 +118,7 @@ struct LoweringContext<'a, 'hir> {
     /// outside of an `async fn`.
     current_item: Option<Span>,
 
-    catch_scope: Option<HirId>,
+    try_block_scope: TryBlockScope,
     loop_scope: Option<HirId>,
     is_in_loop_condition: bool,
     is_in_dyn_type: bool,
@@ -173,7 +174,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             trait_map: Default::default(),
 
             // Lowering state.
-            catch_scope: None,
+            try_block_scope: TryBlockScope::Function,
             loop_scope: None,
             is_in_loop_condition: false,
             is_in_dyn_type: false,
@@ -416,6 +417,18 @@ enum AstOwner<'a> {
     ForeignItem(&'a ast::ForeignItem),
 }
 
+#[derive(Copy, Clone, Debug)]
+enum TryBlockScope {
+    /// There isn't a `try` block, so a `?` will use `return`.
+    Function,
+    /// We're inside a `try { … }` block, so a `?` will block-break
+    /// from that block using a type depending only on the argument.
+    Homogeneous(HirId),
+    /// We're inside a `try as _ { … }` block, so a `?` will block-break
+    /// from that block using the type specified.
+    Heterogeneous(HirId),
+}
+
 fn index_crate<'a>(
     node_id_to_def_id: &NodeMap<LocalDefId>,
     krate: &'a Crate,
@@ -936,10 +949,10 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
         let old_contract = self.contract_ensures.take();
 
-        let catch_scope = self.catch_scope.take();
+        let try_block_scope = mem::replace(&mut self.try_block_scope, TryBlockScope::Function);
         let loop_scope = self.loop_scope.take();
         let ret = f(self);
-        self.catch_scope = catch_scope;
+        self.try_block_scope = try_block_scope;
         self.loop_scope = loop_scope;
 
         self.contract_ensures = old_contract;

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -334,9 +334,17 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
 
     fn visit_expr(&mut self, e: &'a ast::Expr) {
         match e.kind {
-            ast::ExprKind::TryBlock(_) => {
+            ast::ExprKind::TryBlock(_, None) => {
                 gate!(&self, try_blocks, e.span, "`try` expression is experimental");
             }
+            ast::ExprKind::TryBlock(_, Some(_)) => {
+                gate!(
+                    &self,
+                    try_blocks_heterogeneous,
+                    e.span,
+                    "`try bikeshed` expression is experimental"
+                );
+            }
             ast::ExprKind::Lit(token::Lit {
                 kind: token::LitKind::Float | token::LitKind::Integer,
                 suffix,

compiler/rustc_ast_pretty/src/pprust/state/expr.rs

@@ -818,10 +818,15 @@ impl<'a> State<'a> {
                 );
                 self.word("?")
             }
-            ast::ExprKind::TryBlock(blk) => {
+            ast::ExprKind::TryBlock(blk, opt_ty) => {
                 let cb = self.cbox(0);
                 let ib = self.ibox(0);
                 self.word_nbsp("try");
+                if let Some(ty) = opt_ty {
+                    self.word_nbsp("bikeshed");
+                    self.print_type(ty);
+                    self.space();
+                }
                 self.print_block_with_attrs(blk, attrs, cb, ib)
             }
             ast::ExprKind::UnsafeBinderCast(kind, expr, ty) => {

compiler/rustc_builtin_macros/src/assert/context.rs

@@ -315,7 +315,7 @@ impl<'cx, 'a> Context<'cx, 'a> {
             | ExprKind::Path(_, _)
             | ExprKind::Ret(_)
             | ExprKind::Try(_)
-            | ExprKind::TryBlock(_)
+            | ExprKind::TryBlock(_, _)
             | ExprKind::Type(_, _)
             | ExprKind::Underscore
             | ExprKind::While(_, _, _)

compiler/rustc_codegen_cranelift/src/lib.rs

@@ -47,7 +47,7 @@ use rustc_codegen_ssa::{CodegenResults, TargetConfig};
 use rustc_log::tracing::info;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_session::Session;
-use rustc_session::config::{OutputFilenames, PrintKind, PrintRequest};
+use rustc_session::config::OutputFilenames;
 use rustc_span::{Symbol, sym};
 use rustc_target::spec::{Abi, Arch, Env, Os};
 
@@ -160,16 +160,6 @@ impl CodegenBackend for CraneliftCodegenBackend {
         }
     }
 
-    fn print(&self, req: &PrintRequest, out: &mut String, _sess: &Session) {
-        match req.kind {
-            // FIXME have a default impl that returns false
-            PrintKind::BackendHasZstd => {
-                out.push_str("false\n");
-            }
-            _ => {}
-        }
-    }
-
     fn target_config(&self, sess: &Session) -> TargetConfig {
         // FIXME return the actually used target features. this is necessary for #[cfg(target_feature)]
         let target_features = match sess.target.arch {

compiler/rustc_codegen_llvm/src/lib.rs

@@ -257,10 +257,6 @@ impl CodegenBackend for LlvmCodegenBackend {
                 }
                 writeln!(out).unwrap();
             }
-            PrintKind::BackendHasZstd => {
-                let has_zstd = llvm::LLVMRustLLVMHasZstdCompression();
-                writeln!(out, "{has_zstd}").unwrap();
-            }
             PrintKind::CodeModels => {
                 writeln!(out, "Available code models:").unwrap();
                 for name in &["tiny", "small", "kernel", "medium", "large"] {
@@ -314,6 +310,10 @@ impl CodegenBackend for LlvmCodegenBackend {
         llvm_util::print_version();
     }
 
+    fn has_zstd(&self) -> bool {
+        llvm::LLVMRustLLVMHasZstdCompression()
+    }
+
     fn target_config(&self, sess: &Session) -> TargetConfig {
         target_config(sess)
     }