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Commit | Line | Data |
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487cf647 FG |
1 | use crate::util::check_builtin_macro_attribute; |
2 | ||
3 | use rustc_ast::ptr::P; | |
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}; | |
8 | use rustc_span::Span; | |
9ffffee4 | 9 | use thin_vec::{thin_vec, ThinVec}; |
487cf647 FG |
10 | |
11 | pub fn expand( | |
12 | ecx: &mut ExtCtxt<'_>, | |
13 | _span: Span, | |
14 | meta_item: &ast::MetaItem, | |
15 | item: Annotatable, | |
16 | ) -> Vec<Annotatable> { | |
17 | check_builtin_macro_attribute(ecx, meta_item, sym::alloc_error_handler); | |
18 | ||
19 | let orig_item = item.clone(); | |
20 | ||
21 | // Allow using `#[alloc_error_handler]` on an item statement | |
22 | // FIXME - if we get deref patterns, use them to reduce duplication here | |
23 | let (item, is_stmt, sig_span) = | |
24 | if let Annotatable::Item(item) = &item | |
25 | && let ItemKind::Fn(fn_kind) = &item.kind | |
26 | { | |
27 | (item, false, ecx.with_def_site_ctxt(fn_kind.sig.span)) | |
28 | } else if let Annotatable::Stmt(stmt) = &item | |
29 | && let StmtKind::Item(item) = &stmt.kind | |
30 | && let ItemKind::Fn(fn_kind) = &item.kind | |
31 | { | |
32 | (item, true, ecx.with_def_site_ctxt(fn_kind.sig.span)) | |
33 | } else { | |
34 | ecx.sess.parse_sess.span_diagnostic.span_err(item.span(), "alloc_error_handler must be a function"); | |
9c376795 | 35 | return vec![orig_item]; |
487cf647 FG |
36 | }; |
37 | ||
38 | // Generate a bunch of new items using the AllocFnFactory | |
39 | let span = ecx.with_def_site_ctxt(item.span); | |
40 | ||
41 | // Generate item statements for the allocator methods. | |
9ffffee4 | 42 | let stmts = thin_vec![generate_handler(ecx, item.ident, span, sig_span)]; |
487cf647 FG |
43 | |
44 | // Generate anonymous constant serving as container for the allocator methods. | |
9ffffee4 | 45 | let const_ty = ecx.ty(sig_span, TyKind::Tup(ThinVec::new())); |
487cf647 FG |
46 | let const_body = ecx.expr_block(ecx.block(span, stmts)); |
47 | let const_item = ecx.item_const(span, Ident::new(kw::Underscore, span), const_ty, const_body); | |
48 | let const_item = if is_stmt { | |
49 | Annotatable::Stmt(P(ecx.stmt_item(span, const_item))) | |
50 | } else { | |
51 | Annotatable::Item(const_item) | |
52 | }; | |
53 | ||
54 | // Return the original item and the new methods. | |
55 | vec![orig_item, const_item] | |
56 | } | |
57 | ||
58 | // #[rustc_std_internal_symbol] | |
59 | // unsafe fn __rg_oom(size: usize, align: usize) -> ! { | |
60 | // handler(core::alloc::Layout::from_size_align_unchecked(size, align)) | |
61 | // } | |
62 | fn generate_handler(cx: &ExtCtxt<'_>, handler: Ident, span: Span, sig_span: Span) -> Stmt { | |
63 | let usize = cx.path_ident(span, Ident::new(sym::usize, span)); | |
64 | let ty_usize = cx.ty_path(usize); | |
65 | let size = Ident::from_str_and_span("size", span); | |
66 | let align = Ident::from_str_and_span("align", span); | |
67 | ||
68 | let layout_new = cx.std_path(&[sym::alloc, sym::Layout, sym::from_size_align_unchecked]); | |
69 | let layout_new = cx.expr_path(cx.path(span, layout_new)); | |
9ffffee4 FG |
70 | let layout = cx.expr_call( |
71 | span, | |
72 | layout_new, | |
73 | thin_vec![cx.expr_ident(span, size), cx.expr_ident(span, align)], | |
74 | ); | |
487cf647 | 75 | |
9ffffee4 | 76 | let call = cx.expr_call_ident(sig_span, handler, thin_vec![layout]); |
487cf647 FG |
77 | |
78 | let never = ast::FnRetTy::Ty(cx.ty(span, TyKind::Never)); | |
9ffffee4 | 79 | let params = thin_vec![cx.param(span, size, ty_usize.clone()), cx.param(span, align, ty_usize)]; |
487cf647 FG |
80 | let decl = cx.fn_decl(params, never); |
81 | let header = FnHeader { unsafety: Unsafe::Yes(span), ..FnHeader::default() }; | |
82 | let sig = FnSig { decl, header, span: span }; | |
83 | ||
84 | let body = Some(cx.block_expr(call)); | |
85 | let kind = ItemKind::Fn(Box::new(Fn { | |
86 | defaultness: ast::Defaultness::Final, | |
87 | sig, | |
88 | generics: Generics::default(), | |
89 | body, | |
90 | })); | |
91 | ||
92 | let attrs = thin_vec![cx.attr_word(sym::rustc_std_internal_symbol, span)]; | |
93 | ||
94 | let item = cx.item(span, Ident::from_str_and_span("__rg_oom", span), attrs, kind); | |
95 | cx.stmt_item(sig_span, item) | |
96 | } |