syntax_ext: Turn #[global_allocator] into a regular attribute macro
This commit is contained in:
Vadim Petrochenkov
parent
a93fdfedf3
commit
433024147a
19 changed files with 206 additions and 236 deletions
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@ -1,162 +1,95 @@
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use log::debug;
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use smallvec::{smallvec, SmallVec};
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use syntax::{
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ast::{
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self, Arg, Attribute, Crate, Expr, FnHeader, Generics, Ident, Item, ItemKind,
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Mac, Mod, Mutability, Ty, TyKind, Unsafety, VisibilityKind,
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},
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attr,
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source_map::{
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respan, ExpnInfo, ExpnKind,
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},
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ext::{
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allocator::{AllocatorKind, AllocatorMethod, AllocatorTy, ALLOCATOR_METHODS},
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base::{ExtCtxt, MacroKind, Resolver},
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build::AstBuilder,
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expand::ExpansionConfig,
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hygiene::ExpnId,
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},
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mut_visit::{self, MutVisitor},
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parse::ParseSess,
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ptr::P,
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symbol::{kw, sym}
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};
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use errors::Applicability;
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use syntax::ast::{self, Arg, Attribute, Expr, FnHeader, Generics, Ident, Item};
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use syntax::ast::{ItemKind, Mutability, Ty, TyKind, Unsafety, VisibilityKind};
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use syntax::source_map::respan;
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use syntax::ext::allocator::{AllocatorKind, AllocatorMethod, AllocatorTy, ALLOCATOR_METHODS};
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use syntax::ext::base::{Annotatable, ExtCtxt};
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use syntax::ext::build::AstBuilder;
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use syntax::ext::hygiene::SyntaxContext;
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use syntax::ptr::P;
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use syntax::symbol::{kw, sym};
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use syntax_pos::Span;
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pub fn modify(
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sess: &ParseSess,
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resolver: &mut dyn Resolver,
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krate: &mut Crate,
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crate_name: String,
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handler: &errors::Handler,
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) {
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ExpandAllocatorDirectives {
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handler,
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sess,
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resolver,
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found: false,
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crate_name: Some(crate_name),
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in_submod: -1, // -1 to account for the "root" module
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}.visit_crate(krate);
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}
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struct ExpandAllocatorDirectives<'a> {
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found: bool,
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handler: &'a errors::Handler,
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sess: &'a ParseSess,
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resolver: &'a mut dyn Resolver,
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crate_name: Option<String>,
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// For now, we disallow `global_allocator` in submodules because hygiene is hard. Keep track of
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// whether we are in a submodule or not. If `in_submod > 0` we are in a submodule.
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in_submod: isize,
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}
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impl MutVisitor for ExpandAllocatorDirectives<'_> {
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fn flat_map_item(&mut self, item: P<Item>) -> SmallVec<[P<Item>; 1]> {
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debug!("in submodule {}", self.in_submod);
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if !attr::contains_name(&item.attrs, sym::global_allocator) {
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return mut_visit::noop_flat_map_item(item, self);
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}
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match item.node {
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ItemKind::Static(..) => {}
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_ => {
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self.handler
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.span_err(item.span, "allocators must be statics");
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return smallvec![item];
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}
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}
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if self.in_submod > 0 {
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self.handler
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.span_err(item.span, "`global_allocator` cannot be used in submodules");
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return smallvec![item];
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}
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if self.found {
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self.handler
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.span_err(item.span, "cannot define more than one `#[global_allocator]`");
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return smallvec![item];
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}
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self.found = true;
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// Create a new expansion for the generated allocator code.
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let span = item.span.fresh_expansion(ExpnId::root(), ExpnInfo::allow_unstable(
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ExpnKind::Macro(MacroKind::Attr, sym::global_allocator), item.span, self.sess.edition,
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[sym::rustc_attrs][..].into(),
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));
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// Create an expansion config
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let ecfg = ExpansionConfig::default(self.crate_name.take().unwrap());
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// Generate a bunch of new items using the AllocFnFactory
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let mut f = AllocFnFactory {
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span,
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kind: AllocatorKind::Global,
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global: item.ident,
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core: Ident::with_empty_ctxt(sym::core),
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cx: ExtCtxt::new(self.sess, ecfg, self.resolver),
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};
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// We will generate a new submodule. To `use` the static from that module, we need to get
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// the `super::...` path.
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let super_path = f.cx.path(f.span, vec![Ident::with_empty_ctxt(kw::Super), f.global]);
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// Generate the items in the submodule
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let mut items = vec![
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// import `core` to use allocators
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f.cx.item_extern_crate(f.span, f.core),
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// `use` the `global_allocator` in `super`
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f.cx.item_use_simple(
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f.span,
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respan(f.span.shrink_to_lo(), VisibilityKind::Inherited),
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super_path,
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),
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];
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// Add the allocator methods to the submodule
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items.extend(
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ALLOCATOR_METHODS
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.iter()
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.map(|method| f.allocator_fn(method)),
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);
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// Generate the submodule itself
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let name = f.kind.fn_name("allocator_abi");
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let allocator_abi = Ident::from_str(&name).gensym();
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let module = f.cx.item_mod(span, span, allocator_abi, Vec::new(), items);
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let module = f.cx.monotonic_expander().flat_map_item(module).pop().unwrap();
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// Return the item and new submodule
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smallvec![item, module]
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pub fn expand(
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ecx: &mut ExtCtxt<'_>,
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span: Span,
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meta_item: &ast::MetaItem,
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item: Annotatable,
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) -> Vec<Annotatable> {
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if !meta_item.is_word() {
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let msg = format!("malformed `{}` attribute input", meta_item.path);
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ecx.parse_sess.span_diagnostic.struct_span_err(span, &msg)
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.span_suggestion(
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span,
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"must be of the form",
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format!("`#[{}]`", meta_item.path),
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Applicability::MachineApplicable
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).emit();
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}
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// If we enter a submodule, take note.
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fn visit_mod(&mut self, m: &mut Mod) {
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debug!("enter submodule");
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self.in_submod += 1;
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mut_visit::noop_visit_mod(m, self);
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self.in_submod -= 1;
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debug!("exit submodule");
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}
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let not_static = |item: Annotatable| {
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ecx.parse_sess.span_diagnostic.span_err(item.span(), "allocators must be statics");
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vec![item]
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};
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let item = match item {
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Annotatable::Item(item) => match item.node {
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ItemKind::Static(..) => item,
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_ => return not_static(Annotatable::Item(item)),
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}
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_ => return not_static(item),
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};
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// `visit_mac` is disabled by default. Enable it here.
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fn visit_mac(&mut self, mac: &mut Mac) {
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mut_visit::noop_visit_mac(mac, self)
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}
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// Generate a bunch of new items using the AllocFnFactory
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let span = item.span.with_ctxt(SyntaxContext::empty().apply_mark(ecx.current_expansion.mark));
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let f = AllocFnFactory {
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span,
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kind: AllocatorKind::Global,
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global: item.ident,
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core: Ident::with_empty_ctxt(sym::core),
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cx: ecx,
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};
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// We will generate a new submodule. To `use` the static from that module, we need to get
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// the `super::...` path.
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let super_path = f.cx.path(f.span, vec![Ident::with_empty_ctxt(kw::Super), f.global]);
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// Generate the items in the submodule
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let mut items = vec![
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// import `core` to use allocators
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f.cx.item_extern_crate(f.span, f.core),
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// `use` the `global_allocator` in `super`
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f.cx.item_use_simple(
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f.span,
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respan(f.span.shrink_to_lo(), VisibilityKind::Inherited),
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super_path,
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),
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];
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// Add the allocator methods to the submodule
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items.extend(
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ALLOCATOR_METHODS
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.iter()
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.map(|method| f.allocator_fn(method)),
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);
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// Generate the submodule itself
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let name = f.kind.fn_name("allocator_abi");
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let allocator_abi = Ident::from_str(&name).gensym();
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let module = f.cx.item_mod(span, span, allocator_abi, Vec::new(), items);
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// Return the item and new submodule
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vec![Annotatable::Item(item), Annotatable::Item(module)]
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}
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struct AllocFnFactory<'a> {
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struct AllocFnFactory<'a, 'b> {
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span: Span,
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kind: AllocatorKind,
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global: Ident,
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core: Ident,
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cx: ExtCtxt<'a>,
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cx: &'b ExtCtxt<'a>,
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}
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impl AllocFnFactory<'_> {
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impl AllocFnFactory<'_, '_> {
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fn allocator_fn(&self, method: &AllocatorMethod) -> P<Item> {
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let mut abi_args = Vec::new();
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let mut i = 0;
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