diff options
Diffstat (limited to 'compiler/rustc_ast_lowering/src/format.rs')
| -rw-r--r-- | compiler/rustc_ast_lowering/src/format.rs | 59 |
1 files changed, 41 insertions, 18 deletions
diff --git a/compiler/rustc_ast_lowering/src/format.rs b/compiler/rustc_ast_lowering/src/format.rs index c41bdc440..afcf8b15c 100644 --- a/compiler/rustc_ast_lowering/src/format.rs +++ b/compiler/rustc_ast_lowering/src/format.rs @@ -186,7 +186,7 @@ enum ArgumentType { /// Generates: /// /// ```text -/// <core::fmt::ArgumentV1>::new_…(arg) +/// <core::fmt::Argument>::new_…(arg) /// ``` fn make_argument<'hir>( ctx: &mut LoweringContext<'_, 'hir>, @@ -220,19 +220,19 @@ fn make_argument<'hir>( /// Generates: /// /// ```text -/// <core::fmt::rt::v1::Count>::Is(…) +/// <core::fmt::rt::Count>::Is(…) /// ``` /// /// or /// /// ```text -/// <core::fmt::rt::v1::Count>::Param(…) +/// <core::fmt::rt::Count>::Param(…) /// ``` /// /// or /// /// ```text -/// <core::fmt::rt::v1::Count>::Implied +/// <core::fmt::rt::Count>::Implied /// ``` fn make_count<'hir>( ctx: &mut LoweringContext<'_, 'hir>, @@ -278,13 +278,13 @@ fn make_count<'hir>( /// Generates /// /// ```text -/// <core::fmt::rt::v1::Argument::new( +/// <core::fmt::rt::Placeholder::new( /// …usize, // position /// '…', // fill -/// <core::fmt::rt::v1::Alignment>::…, // alignment +/// <core::fmt::rt::Alignment>::…, // alignment /// …u32, // flags -/// <core::fmt::rt::v1::Count::…>, // width -/// <core::fmt::rt::v1::Count::…>, // precision +/// <core::fmt::rt::Count::…>, // width +/// <core::fmt::rt::Count::…>, // precision /// ) /// ``` fn make_format_spec<'hir>( @@ -327,7 +327,7 @@ fn make_format_spec<'hir>( None => sym::Unknown, }, ); - // This needs to match `FlagV1` in library/core/src/fmt/mod.rs. + // This needs to match `Flag` in library/core/src/fmt/rt.rs. let flags: u32 = ((sign == Some(FormatSign::Plus)) as u32) | ((sign == Some(FormatSign::Minus)) as u32) << 1 | (alternate as u32) << 2 @@ -438,7 +438,7 @@ fn expand_format_args<'hir>( // If the args array contains exactly all the original arguments once, // in order, we can use a simple array instead of a `match` construction. // However, if there's a yield point in any argument except the first one, - // we don't do this, because an ArgumentV1 cannot be kept across yield points. + // we don't do this, because an Argument cannot be kept across yield points. // // This is an optimization, speeding up compilation about 1-2% in some cases. // See https://github.com/rust-lang/rust/pull/106770#issuecomment-1380790609 @@ -446,12 +446,35 @@ fn expand_format_args<'hir>( && argmap.iter().enumerate().all(|(i, (&(j, _), _))| i == j) && arguments.iter().skip(1).all(|arg| !may_contain_yield_point(&arg.expr)); - let args = if use_simple_array { + let args = if arguments.is_empty() { + // Generate: + // &<core::fmt::Argument>::none() + // + // Note: + // `none()` just returns `[]`. We use `none()` rather than `[]` to limit the lifetime. + // + // This makes sure that this still fails to compile, even when the argument is inlined: + // + // ``` + // let f = format_args!("{}", "a"); + // println!("{f}"); // error E0716 + // ``` + // + // Cases where keeping the object around is allowed, such as `format_args!("a")`, + // are handled above by the `allow_const` case. + let none_fn = ctx.arena.alloc(ctx.expr_lang_item_type_relative( + macsp, + hir::LangItem::FormatArgument, + sym::none, + )); + let none = ctx.expr_call(macsp, none_fn, &[]); + ctx.expr(macsp, hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, none)) + } else if use_simple_array { // Generate: // &[ - // <core::fmt::ArgumentV1>::new_display(&arg0), - // <core::fmt::ArgumentV1>::new_lower_hex(&arg1), - // <core::fmt::ArgumentV1>::new_debug(&arg2), + // <core::fmt::Argument>::new_display(&arg0), + // <core::fmt::Argument>::new_lower_hex(&arg1), + // <core::fmt::Argument>::new_debug(&arg2), // … // ] let elements: Vec<_> = arguments @@ -477,9 +500,9 @@ fn expand_format_args<'hir>( // Generate: // &match (&arg0, &arg1, &…) { // args => [ - // <core::fmt::ArgumentV1>::new_display(args.0), - // <core::fmt::ArgumentV1>::new_lower_hex(args.1), - // <core::fmt::ArgumentV1>::new_debug(args.0), + // <core::fmt::Argument>::new_display(args.0), + // <core::fmt::Argument>::new_lower_hex(args.1), + // <core::fmt::Argument>::new_debug(args.0), // … // ] // } @@ -583,7 +606,7 @@ fn may_contain_yield_point(e: &ast::Expr) -> bool { impl Visitor<'_> for MayContainYieldPoint { fn visit_expr(&mut self, e: &ast::Expr) { - if let ast::ExprKind::Await(_) | ast::ExprKind::Yield(_) = e.kind { + if let ast::ExprKind::Await(_, _) | ast::ExprKind::Yield(_) = e.kind { self.0 = true; } else { visit::walk_expr(self, e); |