rust/src/libsyntax/feature_gate.rs
bors cc56c20ba4 Auto merge of #25168 - Manishearth:register_attr, r=eddyb
This lets plugin authors opt attributes out of the `custom_attribute`
and `unused_attribute` checks.


cc @thepowersgang
2015-05-24 09:38:26 +00:00

796 lines
30 KiB
Rust

// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Feature gating
//!
//! This module implements the gating necessary for preventing certain compiler
//! features from being used by default. This module will crawl a pre-expanded
//! AST to ensure that there are no features which are used that are not
//! enabled.
//!
//! Features are enabled in programs via the crate-level attributes of
//! `#![feature(...)]` with a comma-separated list of features.
//!
//! For the purpose of future feature-tracking, once code for detection of feature
//! gate usage is added, *do not remove it again* even once the feature
//! becomes stable.
use self::Status::*;
use self::AttributeType::*;
use abi::Abi;
use ast::NodeId;
use ast;
use attr;
use attr::AttrMetaMethods;
use codemap::{CodeMap, Span};
use diagnostic::SpanHandler;
use visit;
use visit::Visitor;
use parse::token::{self, InternedString};
use std::ascii::AsciiExt;
// If you change this list without updating src/doc/reference.md, @cmr will be sad
// Don't ever remove anything from this list; set them to 'Removed'.
// The version numbers here correspond to the version in which the current status
// was set. This is most important for knowing when a particular feature became
// stable (active).
// NB: The featureck.py script parses this information directly out of the source
// so take care when modifying it.
const KNOWN_FEATURES: &'static [(&'static str, &'static str, Status)] = &[
("globs", "1.0.0", Accepted),
("macro_rules", "1.0.0", Accepted),
("struct_variant", "1.0.0", Accepted),
("asm", "1.0.0", Active),
("managed_boxes", "1.0.0", Removed),
("non_ascii_idents", "1.0.0", Active),
("thread_local", "1.0.0", Active),
("link_args", "1.0.0", Active),
("plugin_registrar", "1.0.0", Active),
("log_syntax", "1.0.0", Active),
("trace_macros", "1.0.0", Active),
("concat_idents", "1.0.0", Active),
("intrinsics", "1.0.0", Active),
("lang_items", "1.0.0", Active),
("simd", "1.0.0", Active),
("default_type_params", "1.0.0", Accepted),
("quote", "1.0.0", Active),
("link_llvm_intrinsics", "1.0.0", Active),
("linkage", "1.0.0", Active),
("struct_inherit", "1.0.0", Removed),
("quad_precision_float", "1.0.0", Removed),
("rustc_diagnostic_macros", "1.0.0", Active),
("unboxed_closures", "1.0.0", Active),
("reflect", "1.0.0", Active),
("import_shadowing", "1.0.0", Removed),
("advanced_slice_patterns", "1.0.0", Active),
("tuple_indexing", "1.0.0", Accepted),
("associated_types", "1.0.0", Accepted),
("visible_private_types", "1.0.0", Active),
("slicing_syntax", "1.0.0", Accepted),
("box_syntax", "1.0.0", Active),
("on_unimplemented", "1.0.0", Active),
("simd_ffi", "1.0.0", Active),
("allocator", "1.0.0", Active),
("if_let", "1.0.0", Accepted),
("while_let", "1.0.0", Accepted),
("plugin", "1.0.0", Active),
("start", "1.0.0", Active),
("main", "1.0.0", Active),
("fundamental", "1.0.0", Active),
// A temporary feature gate used to enable parser extensions needed
// to bootstrap fix for #5723.
("issue_5723_bootstrap", "1.0.0", Accepted),
// A way to temporarily opt out of opt in copy. This will *never* be accepted.
("opt_out_copy", "1.0.0", Removed),
// OIBIT specific features
("optin_builtin_traits", "1.0.0", Active),
// macro reexport needs more discussion and stabilization
("macro_reexport", "1.0.0", Active),
// These are used to test this portion of the compiler, they don't actually
// mean anything
("test_accepted_feature", "1.0.0", Accepted),
("test_removed_feature", "1.0.0", Removed),
// Allows use of #[staged_api]
("staged_api", "1.0.0", Active),
// Allows using items which are missing stability attributes
("unmarked_api", "1.0.0", Active),
// Allows using #![no_std]
("no_std", "1.0.0", Active),
// Allows using `box` in patterns; RFC 469
("box_patterns", "1.0.0", Active),
// Allows using the unsafe_no_drop_flag attribute (unlikely to
// switch to Accepted; see RFC 320)
("unsafe_no_drop_flag", "1.0.0", Active),
// Allows the use of custom attributes; RFC 572
("custom_attribute", "1.0.0", Active),
// Allows the use of #[derive(Anything)] as sugar for
// #[derive_Anything].
("custom_derive", "1.0.0", Active),
// Allows the use of rustc_* attributes; RFC 572
("rustc_attrs", "1.0.0", Active),
// Allows the use of `static_assert`
("static_assert", "1.0.0", Active),
// Allows the use of #[allow_internal_unstable]. This is an
// attribute on macro_rules! and can't use the attribute handling
// below (it has to be checked before expansion possibly makes
// macros disappear).
("allow_internal_unstable", "1.0.0", Active),
// #23121. Array patterns have some hazards yet.
("slice_patterns", "1.0.0", Active),
// Allows use of unary negate on unsigned integers, e.g. -e for e: u8
("negate_unsigned", "1.0.0", Active),
// Allows the definition of associated constants in `trait` or `impl`
// blocks.
("associated_consts", "1.0.0", Active),
];
// (changing above list without updating src/doc/reference.md makes @cmr sad)
enum Status {
/// Represents an active feature that is currently being implemented or
/// currently being considered for addition/removal.
Active,
/// Represents a feature which has since been removed (it was once Active)
Removed,
/// This language feature has since been Accepted (it was once Active)
Accepted,
}
// Attributes that have a special meaning to rustc or rustdoc
pub const KNOWN_ATTRIBUTES: &'static [(&'static str, AttributeType)] = &[
// Normal attributes
("warn", Normal),
("allow", Normal),
("forbid", Normal),
("deny", Normal),
("macro_reexport", Normal),
("macro_use", Normal),
("macro_export", Normal),
("plugin_registrar", Normal),
("cfg", Normal),
("cfg_attr", Normal),
("main", Normal),
("start", Normal),
("test", Normal),
("bench", Normal),
("simd", Normal),
("repr", Normal),
("path", Normal),
("abi", Normal),
("automatically_derived", Normal),
("no_mangle", Normal),
("no_link", Normal),
("derive", Normal),
("should_panic", Normal),
("ignore", Normal),
("no_implicit_prelude", Normal),
("reexport_test_harness_main", Normal),
("link_args", Normal),
("macro_escape", Normal),
("staged_api", Gated("staged_api",
"staged_api is for use by rustc only")),
("plugin", Gated("plugin",
"compiler plugins are experimental \
and possibly buggy")),
("no_std", Gated("no_std",
"no_std is experimental")),
("lang", Gated("lang_items",
"language items are subject to change")),
("linkage", Gated("linkage",
"the `linkage` attribute is experimental \
and not portable across platforms")),
("thread_local", Gated("thread_local",
"`#[thread_local]` is an experimental feature, and does not \
currently handle destructors. There is no corresponding \
`#[task_local]` mapping to the task model")),
("rustc_on_unimplemented", Gated("on_unimplemented",
"the `#[rustc_on_unimplemented]` attribute \
is an experimental feature")),
("allocator", Gated("allocator",
"the `#[allocator]` attribute is an experimental feature")),
("rustc_variance", Gated("rustc_attrs",
"the `#[rustc_variance]` attribute \
is an experimental feature")),
("rustc_error", Gated("rustc_attrs",
"the `#[rustc_error]` attribute \
is an experimental feature")),
("rustc_move_fragments", Gated("rustc_attrs",
"the `#[rustc_move_fragments]` attribute \
is an experimental feature")),
("allow_internal_unstable", Gated("allow_internal_unstable",
EXPLAIN_ALLOW_INTERNAL_UNSTABLE)),
("fundamental", Gated("fundamental",
"the `#[fundamental]` attribute \
is an experimental feature")),
// FIXME: #14408 whitelist docs since rustdoc looks at them
("doc", Whitelisted),
// FIXME: #14406 these are processed in trans, which happens after the
// lint pass
("cold", Whitelisted),
("export_name", Whitelisted),
("inline", Whitelisted),
("link", Whitelisted),
("link_name", Whitelisted),
("link_section", Whitelisted),
("no_builtins", Whitelisted),
("no_mangle", Whitelisted),
("no_stack_check", Whitelisted),
("static_assert", Gated("static_assert",
"`#[static_assert]` is an experimental feature, and has a poor API")),
("no_debug", Whitelisted),
("omit_gdb_pretty_printer_section", Whitelisted),
("unsafe_no_drop_flag", Gated("unsafe_no_drop_flag",
"unsafe_no_drop_flag has unstable semantics \
and may be removed in the future")),
// used in resolve
("prelude_import", Whitelisted),
// FIXME: #14407 these are only looked at on-demand so we can't
// guarantee they'll have already been checked
("deprecated", Whitelisted),
("must_use", Whitelisted),
("stable", Whitelisted),
("unstable", Whitelisted),
("rustc_paren_sugar", Gated("unboxed_closures",
"unboxed_closures are still evolving")),
("rustc_reflect_like", Gated("reflect",
"defining reflective traits is still evolving")),
// Crate level attributes
("crate_name", CrateLevel),
("crate_type", CrateLevel),
("crate_id", CrateLevel),
("feature", CrateLevel),
("no_start", CrateLevel),
("no_main", CrateLevel),
("no_builtins", CrateLevel),
("recursion_limit", CrateLevel),
];
#[derive(PartialEq, Copy, Clone, Debug)]
pub enum AttributeType {
/// Normal, builtin attribute that is consumed
/// by the compiler before the unused_attribute check
Normal,
/// Builtin attribute that may not be consumed by the compiler
/// before the unused_attribute check. These attributes
/// will be ignored by the unused_attribute lint
Whitelisted,
/// Is gated by a given feature gate and reason
/// These get whitelisted too
Gated(&'static str, &'static str),
/// Builtin attribute that is only allowed at the crate level
CrateLevel,
}
/// A set of features to be used by later passes.
pub struct Features {
pub unboxed_closures: bool,
pub rustc_diagnostic_macros: bool,
pub visible_private_types: bool,
pub allow_quote: bool,
pub allow_asm: bool,
pub allow_log_syntax: bool,
pub allow_concat_idents: bool,
pub allow_trace_macros: bool,
pub allow_internal_unstable: bool,
pub allow_custom_derive: bool,
pub simd_ffi: bool,
pub unmarked_api: bool,
pub negate_unsigned: bool,
/// spans of #![feature] attrs for stable language features. for error reporting
pub declared_stable_lang_features: Vec<Span>,
/// #![feature] attrs for non-language (library) features
pub declared_lib_features: Vec<(InternedString, Span)>
}
impl Features {
pub fn new() -> Features {
Features {
unboxed_closures: false,
rustc_diagnostic_macros: false,
visible_private_types: false,
allow_quote: false,
allow_asm: false,
allow_log_syntax: false,
allow_concat_idents: false,
allow_trace_macros: false,
allow_internal_unstable: false,
allow_custom_derive: false,
simd_ffi: false,
unmarked_api: false,
negate_unsigned: false,
declared_stable_lang_features: Vec::new(),
declared_lib_features: Vec::new()
}
}
}
struct Context<'a> {
features: Vec<&'static str>,
span_handler: &'a SpanHandler,
cm: &'a CodeMap,
plugin_attributes: &'a [(String, AttributeType)],
}
impl<'a> Context<'a> {
fn gate_feature(&self, feature: &str, span: Span, explain: &str) {
let has_feature = self.has_feature(feature);
debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", feature, span, has_feature);
if !has_feature {
emit_feature_err(self.span_handler, feature, span, explain);
}
}
fn has_feature(&self, feature: &str) -> bool {
self.features.iter().any(|&n| n == feature)
}
fn check_attribute(&self, attr: &ast::Attribute, is_macro: bool) {
debug!("check_attribute(attr = {:?})", attr);
let name = &*attr.name();
for &(n, ty) in KNOWN_ATTRIBUTES {
if n == name {
if let Gated(gate, desc) = ty {
self.gate_feature(gate, attr.span, desc);
}
debug!("check_attribute: {:?} is known, {:?}", name, ty);
return;
}
}
for &(ref n, ref ty) in self.plugin_attributes.iter() {
if &*n == name {
// Plugins can't gate attributes, so we don't check for it
// unlike the code above; we only use this loop to
// short-circuit to avoid the checks below
debug!("check_attribute: {:?} is registered by a plugin, {:?}", name, ty);
return;
}
}
if name.starts_with("rustc_") {
self.gate_feature("rustc_attrs", attr.span,
"unless otherwise specified, attributes \
with the prefix `rustc_` \
are reserved for internal compiler diagnostics");
} else if name.starts_with("derive_") {
self.gate_feature("custom_derive", attr.span,
"attributes of the form `#[derive_*]` are reserved \
for the compiler");
} else {
// Only run the custom attribute lint during regular
// feature gate checking. Macro gating runs
// before the plugin attributes are registered
// so we skip this then
if !is_macro {
self.gate_feature("custom_attribute", attr.span,
&format!("The attribute `{}` is currently \
unknown to the compiler and \
may have meaning \
added to it in the future",
name));
}
}
}
}
pub fn emit_feature_err(diag: &SpanHandler, feature: &str, span: Span, explain: &str) {
diag.span_err(span, explain);
// #23973: do not suggest `#![feature(...)]` if we are in beta/stable
if option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_some() { return; }
diag.fileline_help(span, &format!("add #![feature({})] to the \
crate attributes to enable",
feature));
}
pub fn emit_feature_warn(diag: &SpanHandler, feature: &str, span: Span, explain: &str) {
diag.span_warn(span, explain);
// #23973: do not suggest `#![feature(...)]` if we are in beta/stable
if option_env!("CFG_DISABLE_UNSTABLE_FEATURES").is_some() { return; }
if diag.handler.can_emit_warnings {
diag.fileline_help(span, &format!("add #![feature({})] to the \
crate attributes to silence this warning",
feature));
}
}
pub const EXPLAIN_ASM: &'static str =
"inline assembly is not stable enough for use and is subject to change";
pub const EXPLAIN_LOG_SYNTAX: &'static str =
"`log_syntax!` is not stable enough for use and is subject to change";
pub const EXPLAIN_CONCAT_IDENTS: &'static str =
"`concat_idents` is not stable enough for use and is subject to change";
pub const EXPLAIN_TRACE_MACROS: &'static str =
"`trace_macros` is not stable enough for use and is subject to change";
pub const EXPLAIN_ALLOW_INTERNAL_UNSTABLE: &'static str =
"allow_internal_unstable side-steps feature gating and stability checks";
pub const EXPLAIN_CUSTOM_DERIVE: &'static str =
"`#[derive]` for custom traits is not stable enough for use and is subject to change";
struct MacroVisitor<'a> {
context: &'a Context<'a>
}
impl<'a, 'v> Visitor<'v> for MacroVisitor<'a> {
fn visit_mac(&mut self, mac: &ast::Mac) {
let ast::MacInvocTT(ref path, _, _) = mac.node;
let id = path.segments.last().unwrap().identifier;
// Issue 22234: If you add a new case here, make sure to also
// add code to catch the macro during or after expansion.
//
// We still keep this MacroVisitor (rather than *solely*
// relying on catching cases during or after expansion) to
// catch uses of these macros within conditionally-compiled
// code, e.g. `#[cfg]`-guarded functions.
if id == token::str_to_ident("asm") {
self.context.gate_feature("asm", path.span, EXPLAIN_ASM);
}
else if id == token::str_to_ident("log_syntax") {
self.context.gate_feature("log_syntax", path.span, EXPLAIN_LOG_SYNTAX);
}
else if id == token::str_to_ident("trace_macros") {
self.context.gate_feature("trace_macros", path.span, EXPLAIN_TRACE_MACROS);
}
else if id == token::str_to_ident("concat_idents") {
self.context.gate_feature("concat_idents", path.span, EXPLAIN_CONCAT_IDENTS);
}
}
fn visit_attribute(&mut self, attr: &'v ast::Attribute) {
self.context.check_attribute(attr, true);
}
}
struct PostExpansionVisitor<'a> {
context: &'a Context<'a>
}
impl<'a> PostExpansionVisitor<'a> {
fn gate_feature(&self, feature: &str, span: Span, explain: &str) {
if !self.context.cm.span_allows_unstable(span) {
self.context.gate_feature(feature, span, explain)
}
}
}
impl<'a, 'v> Visitor<'v> for PostExpansionVisitor<'a> {
fn visit_attribute(&mut self, attr: &ast::Attribute) {
if !self.context.cm.span_allows_unstable(attr.span) {
self.context.check_attribute(attr, false);
}
}
fn visit_name(&mut self, sp: Span, name: ast::Name) {
if !token::get_name(name).is_ascii() {
self.gate_feature("non_ascii_idents", sp,
"non-ascii idents are not fully supported.");
}
}
fn visit_item(&mut self, i: &ast::Item) {
match i.node {
ast::ItemExternCrate(_) => {
if attr::contains_name(&i.attrs[..], "macro_reexport") {
self.gate_feature("macro_reexport", i.span,
"macros reexports are experimental \
and possibly buggy");
}
}
ast::ItemForeignMod(ref foreign_module) => {
if attr::contains_name(&i.attrs[..], "link_args") {
self.gate_feature("link_args", i.span,
"the `link_args` attribute is not portable \
across platforms, it is recommended to \
use `#[link(name = \"foo\")]` instead")
}
if foreign_module.abi == Abi::RustIntrinsic {
self.gate_feature("intrinsics",
i.span,
"intrinsics are subject to change")
}
}
ast::ItemFn(..) => {
if attr::contains_name(&i.attrs[..], "plugin_registrar") {
self.gate_feature("plugin_registrar", i.span,
"compiler plugins are experimental and possibly buggy");
}
if attr::contains_name(&i.attrs[..], "start") {
self.gate_feature("start", i.span,
"a #[start] function is an experimental \
feature whose signature may change \
over time");
}
if attr::contains_name(&i.attrs[..], "main") {
self.gate_feature("main", i.span,
"declaration of a nonstandard #[main] \
function may change over time, for now \
a top-level `fn main()` is required");
}
}
ast::ItemStruct(..) => {
if attr::contains_name(&i.attrs[..], "simd") {
self.gate_feature("simd", i.span,
"SIMD types are experimental and possibly buggy");
}
}
ast::ItemDefaultImpl(..) => {
self.gate_feature("optin_builtin_traits",
i.span,
"default trait implementations are experimental \
and possibly buggy");
}
ast::ItemImpl(_, polarity, _, _, _, _) => {
match polarity {
ast::ImplPolarity::Negative => {
self.gate_feature("optin_builtin_traits",
i.span,
"negative trait bounds are not yet fully implemented; \
use marker types for now");
},
_ => {}
}
}
_ => {}
}
visit::walk_item(self, i);
}
fn visit_foreign_item(&mut self, i: &ast::ForeignItem) {
let links_to_llvm = match attr::first_attr_value_str_by_name(&i.attrs,
"link_name") {
Some(val) => val.starts_with("llvm."),
_ => false
};
if links_to_llvm {
self.gate_feature("link_llvm_intrinsics", i.span,
"linking to LLVM intrinsics is experimental");
}
visit::walk_foreign_item(self, i)
}
fn visit_expr(&mut self, e: &ast::Expr) {
match e.node {
ast::ExprBox(..) | ast::ExprUnary(ast::UnOp::UnUniq, _) => {
self.gate_feature("box_syntax",
e.span,
"box expression syntax is experimental; \
you can call `Box::new` instead.");
}
_ => {}
}
visit::walk_expr(self, e);
}
fn visit_pat(&mut self, pattern: &ast::Pat) {
match pattern.node {
ast::PatVec(_, Some(_), ref last) if !last.is_empty() => {
self.gate_feature("advanced_slice_patterns",
pattern.span,
"multiple-element slice matches anywhere \
but at the end of a slice (e.g. \
`[0, ..xs, 0]`) are experimental")
}
ast::PatVec(..) => {
self.gate_feature("slice_patterns",
pattern.span,
"slice pattern syntax is experimental");
}
ast::PatBox(..) => {
self.gate_feature("box_patterns",
pattern.span,
"box pattern syntax is experimental");
}
_ => {}
}
visit::walk_pat(self, pattern)
}
fn visit_fn(&mut self,
fn_kind: visit::FnKind<'v>,
fn_decl: &'v ast::FnDecl,
block: &'v ast::Block,
span: Span,
_node_id: NodeId) {
match fn_kind {
visit::FkItemFn(_, _, _, abi, _) if abi == Abi::RustIntrinsic => {
self.gate_feature("intrinsics",
span,
"intrinsics are subject to change")
}
visit::FkItemFn(_, _, _, abi, _) |
visit::FkMethod(_, &ast::MethodSig { abi, .. }, _) if abi == Abi::RustCall => {
self.gate_feature("unboxed_closures",
span,
"rust-call ABI is subject to change")
}
_ => {}
}
visit::walk_fn(self, fn_kind, fn_decl, block, span);
}
fn visit_trait_item(&mut self, ti: &'v ast::TraitItem) {
match ti.node {
ast::ConstTraitItem(..) => {
self.gate_feature("associated_consts",
ti.span,
"associated constants are experimental")
}
_ => {}
}
visit::walk_trait_item(self, ti);
}
fn visit_impl_item(&mut self, ii: &'v ast::ImplItem) {
match ii.node {
ast::ConstImplItem(..) => {
self.gate_feature("associated_consts",
ii.span,
"associated constants are experimental")
}
_ => {}
}
visit::walk_impl_item(self, ii);
}
}
fn check_crate_inner<F>(cm: &CodeMap, span_handler: &SpanHandler,
krate: &ast::Crate,
plugin_attributes: &[(String, AttributeType)],
check: F)
-> Features
where F: FnOnce(&mut Context, &ast::Crate)
{
let mut cx = Context {
features: Vec::new(),
span_handler: span_handler,
cm: cm,
plugin_attributes: plugin_attributes,
};
let mut accepted_features = Vec::new();
let mut unknown_features = Vec::new();
for attr in &krate.attrs {
if !attr.check_name("feature") {
continue
}
match attr.meta_item_list() {
None => {
span_handler.span_err(attr.span, "malformed feature attribute, \
expected #![feature(...)]");
}
Some(list) => {
for mi in list {
let name = match mi.node {
ast::MetaWord(ref word) => (*word).clone(),
_ => {
span_handler.span_err(mi.span,
"malformed feature, expected just \
one word");
continue
}
};
match KNOWN_FEATURES.iter()
.find(|& &(n, _, _)| name == n) {
Some(&(name, _, Active)) => {
cx.features.push(name);
}
Some(&(_, _, Removed)) => {
span_handler.span_err(mi.span, "feature has been removed");
}
Some(&(_, _, Accepted)) => {
accepted_features.push(mi.span);
}
None => {
unknown_features.push((name, mi.span));
}
}
}
}
}
}
check(&mut cx, krate);
// FIXME (pnkfelix): Before adding the 99th entry below, change it
// to a single-pass (instead of N calls to `.has_feature`).
Features {
unboxed_closures: cx.has_feature("unboxed_closures"),
rustc_diagnostic_macros: cx.has_feature("rustc_diagnostic_macros"),
visible_private_types: cx.has_feature("visible_private_types"),
allow_quote: cx.has_feature("quote"),
allow_asm: cx.has_feature("asm"),
allow_log_syntax: cx.has_feature("log_syntax"),
allow_concat_idents: cx.has_feature("concat_idents"),
allow_trace_macros: cx.has_feature("trace_macros"),
allow_internal_unstable: cx.has_feature("allow_internal_unstable"),
allow_custom_derive: cx.has_feature("custom_derive"),
simd_ffi: cx.has_feature("simd_ffi"),
unmarked_api: cx.has_feature("unmarked_api"),
negate_unsigned: cx.has_feature("negate_unsigned"),
declared_stable_lang_features: accepted_features,
declared_lib_features: unknown_features
}
}
pub fn check_crate_macros(cm: &CodeMap, span_handler: &SpanHandler, krate: &ast::Crate)
-> Features {
check_crate_inner(cm, span_handler, krate, &[] as &'static [_],
|ctx, krate| visit::walk_crate(&mut MacroVisitor { context: ctx }, krate))
}
pub fn check_crate(cm: &CodeMap, span_handler: &SpanHandler, krate: &ast::Crate,
plugin_attributes: &[(String, AttributeType)]) -> Features
{
check_crate_inner(cm, span_handler, krate, plugin_attributes,
|ctx, krate| visit::walk_crate(&mut PostExpansionVisitor { context: ctx },
krate))
}