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| 1 | +use crate::errors; |
| 2 | +use crate::util::check_builtin_macro_attribute; |
| 3 | + |
| 4 | +use rustc_ast::ptr::P; |
| 5 | +use rustc_ast::{self as ast, FnHeader, FnSig, Generics, StmtKind}; |
| 6 | +use rustc_ast::{Fn, ItemKind, Stmt, TyKind, Unsafe}; |
| 7 | +use rustc_expand::base::{Annotatable, ExtCtxt}; |
| 8 | +use rustc_span::symbol::{kw, sym, Ident}; |
| 9 | +use rustc_span::Span; |
| 10 | +use thin_vec::{thin_vec, ThinVec}; |
| 11 | + |
| 12 | +pub fn expand( |
| 13 | + ecx: &mut ExtCtxt<'_>, |
| 14 | + _span: Span, |
| 15 | + meta_item: &ast::MetaItem, |
| 16 | + item: Annotatable, |
| 17 | +) -> Vec<Annotatable> { |
| 18 | + check_builtin_macro_attribute(ecx, meta_item, sym::alloc_error_handler); |
| 19 | + |
| 20 | + let orig_item = item.clone(); |
| 21 | + |
| 22 | + // Allow using `#[alloc_error_handler]` on an item statement |
| 23 | + // FIXME - if we get deref patterns, use them to reduce duplication here |
| 24 | + let (item, is_stmt, sig_span) = |
| 25 | + if let Annotatable::Item(item) = &item |
| 26 | + && let ItemKind::Fn(fn_kind) = &item.kind |
| 27 | + { |
| 28 | + (item, false, ecx.with_def_site_ctxt(fn_kind.sig.span)) |
| 29 | + } else if let Annotatable::Stmt(stmt) = &item |
| 30 | + && let StmtKind::Item(item) = &stmt.kind |
| 31 | + && let ItemKind::Fn(fn_kind) = &item.kind |
| 32 | + { |
| 33 | + (item, true, ecx.with_def_site_ctxt(fn_kind.sig.span)) |
| 34 | + } else { |
| 35 | + ecx.sess.parse_sess.span_diagnostic.emit_err(errors::AllocErrorMustBeFn {span: item.span() }); |
| 36 | + return vec![orig_item]; |
| 37 | + }; |
| 38 | + |
| 39 | + // Generate a bunch of new items using the AllocFnFactory |
| 40 | + let span = ecx.with_def_site_ctxt(item.span); |
| 41 | + |
| 42 | + // Generate item statements for the allocator methods. |
| 43 | + let stmts = thin_vec![generate_handler(ecx, item.ident, span, sig_span)]; |
| 44 | + |
| 45 | + // Generate anonymous constant serving as container for the allocator methods. |
| 46 | + let const_ty = ecx.ty(sig_span, TyKind::Tup(ThinVec::new())); |
| 47 | + let const_body = ecx.expr_block(ecx.block(span, stmts)); |
| 48 | + let const_item = ecx.item_const(span, Ident::new(kw::Underscore, span), const_ty, const_body); |
| 49 | + let const_item = if is_stmt { |
| 50 | + Annotatable::Stmt(P(ecx.stmt_item(span, const_item))) |
| 51 | + } else { |
| 52 | + Annotatable::Item(const_item) |
| 53 | + }; |
| 54 | + |
| 55 | + // Return the original item and the new methods. |
| 56 | + vec![orig_item, const_item] |
| 57 | +} |
| 58 | + |
| 59 | +// #[rustc_std_internal_symbol] |
| 60 | +// unsafe fn __rg_oom(size: usize, align: usize) -> ! { |
| 61 | +// handler(core::alloc::Layout::from_size_align_unchecked(size, align)) |
| 62 | +// } |
| 63 | +fn generate_handler(cx: &ExtCtxt<'_>, handler: Ident, span: Span, sig_span: Span) -> Stmt { |
| 64 | + let usize = cx.path_ident(span, Ident::new(sym::usize, span)); |
| 65 | + let ty_usize = cx.ty_path(usize); |
| 66 | + let size = Ident::from_str_and_span("size", span); |
| 67 | + let align = Ident::from_str_and_span("align", span); |
| 68 | + |
| 69 | + let layout_new = cx.std_path(&[sym::alloc, sym::Layout, sym::from_size_align_unchecked]); |
| 70 | + let layout_new = cx.expr_path(cx.path(span, layout_new)); |
| 71 | + let layout = cx.expr_call( |
| 72 | + span, |
| 73 | + layout_new, |
| 74 | + thin_vec![cx.expr_ident(span, size), cx.expr_ident(span, align)], |
| 75 | + ); |
| 76 | + |
| 77 | + let call = cx.expr_call_ident(sig_span, handler, thin_vec![layout]); |
| 78 | + |
| 79 | + let never = ast::FnRetTy::Ty(cx.ty(span, TyKind::Never)); |
| 80 | + let params = thin_vec![cx.param(span, size, ty_usize.clone()), cx.param(span, align, ty_usize)]; |
| 81 | + let decl = cx.fn_decl(params, never); |
| 82 | + let header = FnHeader { unsafety: Unsafe::Yes(span), ..FnHeader::default() }; |
| 83 | + let sig = FnSig { decl, header, span: span }; |
| 84 | + |
| 85 | + let body = Some(cx.block_expr(call)); |
| 86 | + let kind = ItemKind::Fn(Box::new(Fn { |
| 87 | + defaultness: ast::Defaultness::Final, |
| 88 | + sig, |
| 89 | + generics: Generics::default(), |
| 90 | + body, |
| 91 | + })); |
| 92 | + |
| 93 | + let attrs = thin_vec![cx.attr_word(sym::rustc_std_internal_symbol, span)]; |
| 94 | + |
| 95 | + let item = cx.item(span, Ident::from_str_and_span("__rg_oom", span), attrs, kind); |
| 96 | + cx.stmt_item(sig_span, item) |
| 97 | +} |
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