1 use crate::util::check_builtin_macro_attribute;
4 use rustc_ast::{self as ast, FnHeader, FnSig, Generics, StmtKind};
5 use rustc_ast::{Fn, ItemKind, Stmt, TyKind, Unsafe};
6 use rustc_expand::base::{Annotatable, ExtCtxt};
7 use rustc_span::symbol::{kw, sym, Ident};
9 use thin_vec::thin_vec;
12 ecx: &mut ExtCtxt<'_>,
14 meta_item: &ast::MetaItem,
16 ) -> Vec<Annotatable> {
17 check_builtin_macro_attribute(ecx, meta_item, sym::alloc_error_handler);
19 let orig_item = item.clone();
20 let not_function = || {
24 .span_err(item.span(), "alloc_error_handler must be a function");
25 vec![orig_item.clone()]
28 // Allow using `#[alloc_error_handler]` on an item statement
29 // FIXME - if we get deref patterns, use them to reduce duplication here
30 let (item, is_stmt, sig_span) = match &item {
31 Annotatable::Item(item) => match item.kind {
32 ItemKind::Fn(ref fn_kind) => (item, false, ecx.with_def_site_ctxt(fn_kind.sig.span)),
33 _ => return not_function(),
35 Annotatable::Stmt(stmt) => match &stmt.kind {
36 StmtKind::Item(item_) => match item_.kind {
37 ItemKind::Fn(ref fn_kind) => {
38 (item_, true, ecx.with_def_site_ctxt(fn_kind.sig.span))
40 _ => return not_function(),
42 _ => return not_function(),
44 _ => return not_function(),
47 // Generate a bunch of new items using the AllocFnFactory
48 let span = ecx.with_def_site_ctxt(item.span);
50 // Generate item statements for the allocator methods.
51 let stmts = vec![generate_handler(ecx, item.ident, span, sig_span)];
53 // Generate anonymous constant serving as container for the allocator methods.
54 let const_ty = ecx.ty(sig_span, TyKind::Tup(Vec::new()));
55 let const_body = ecx.expr_block(ecx.block(span, stmts));
56 let const_item = ecx.item_const(span, Ident::new(kw::Underscore, span), const_ty, const_body);
57 let const_item = if is_stmt {
58 Annotatable::Stmt(P(ecx.stmt_item(span, const_item)))
60 Annotatable::Item(const_item)
63 // Return the original item and the new methods.
64 vec![orig_item, const_item]
67 // #[rustc_std_internal_symbol]
68 // unsafe fn __rg_oom(size: usize, align: usize) -> ! {
69 // handler(core::alloc::Layout::from_size_align_unchecked(size, align))
71 fn generate_handler(cx: &ExtCtxt<'_>, handler: Ident, span: Span, sig_span: Span) -> Stmt {
72 let usize = cx.path_ident(span, Ident::new(sym::usize, span));
73 let ty_usize = cx.ty_path(usize);
74 let size = Ident::from_str_and_span("size", span);
75 let align = Ident::from_str_and_span("align", span);
77 let layout_new = cx.std_path(&[sym::alloc, sym::Layout, sym::from_size_align_unchecked]);
78 let layout_new = cx.expr_path(cx.path(span, layout_new));
80 cx.expr_call(span, layout_new, vec![cx.expr_ident(span, size), cx.expr_ident(span, align)]);
82 let call = cx.expr_call_ident(sig_span, handler, vec![layout]);
84 let never = ast::FnRetTy::Ty(cx.ty(span, TyKind::Never));
85 let params = vec![cx.param(span, size, ty_usize.clone()), cx.param(span, align, ty_usize)];
86 let decl = cx.fn_decl(params, never);
87 let header = FnHeader { unsafety: Unsafe::Yes(span), ..FnHeader::default() };
88 let sig = FnSig { decl, header, span: span };
90 let body = Some(cx.block_expr(call));
91 let kind = ItemKind::Fn(Box::new(Fn {
92 defaultness: ast::Defaultness::Final,
94 generics: Generics::default(),
98 let special = sym::rustc_std_internal_symbol;
99 let special = cx.meta_word(span, special);
100 let attrs = thin_vec![cx.attribute(special)];
102 let item = cx.item(span, Ident::from_str_and_span("__rg_oom", span), attrs, kind);
103 cx.stmt_item(sig_span, item)