rust/src/librustc/middle/stability.rs

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// Copyright 2014 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.
//! A pass that annotates every item and method with its stability level,
//! propagating default levels lexically from parent to children ast nodes.
use session::Session;
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use lint;
use middle::def;
use middle::ty;
use middle::privacy::PublicItems;
use metadata::csearch;
use syntax::parse::token::InternedString;
use syntax::codemap::{Span, DUMMY_SP};
use syntax::{attr, visit};
use syntax::ast;
use syntax::ast::{Attribute, Block, Crate, DefId, FnDecl, NodeId, Variant};
use syntax::ast::{Item, Generics, StructField};
use syntax::ast_util::is_local;
use syntax::attr::{Stability, AttrMetaMethods};
use syntax::visit::{FnKind, Visitor};
use syntax::feature_gate::emit_feature_warn;
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use util::nodemap::{NodeMap, DefIdMap, FnvHashSet, FnvHashMap};
use util::ppaux::Repr;
use std::mem::replace;
/// A stability index, giving the stability level for items and methods.
pub struct Index {
// Indicates whether this crate has #![feature(staged_api)]
staged_api: bool,
// stability for crate-local items; unmarked stability == no entry
local: NodeMap<Stability>,
// cache for extern-crate items; unmarked stability == entry with None
extern_cache: DefIdMap<Option<Stability>>
}
// A private tree-walker for producing an Index.
struct Annotator<'a> {
sess: &'a Session,
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index: &'a mut Index,
parent: Option<Stability>,
export_map: &'a PublicItems,
}
impl<'a> Annotator<'a> {
// Determine the stability for a node based on its attributes and inherited
// stability. The stability is recorded in the index and used as the parent.
fn annotate<F>(&mut self, id: NodeId, use_parent: bool,
attrs: &Vec<Attribute>, item_sp: Span, f: F, required: bool) where
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F: FnOnce(&mut Annotator),
{
debug!("annotate(id = {:?}, attrs = {:?})", id, attrs);
match attr::find_stability(self.sess.diagnostic(), attrs, item_sp) {
Some(stab) => {
debug!("annotate: found {:?}", stab);
self.index.local.insert(id, stab.clone());
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// Don't inherit #[stable(feature = "rust1", since = "1.0.0")]
if stab.level != attr::Stable {
let parent = replace(&mut self.parent, Some(stab));
f(self);
self.parent = parent;
} else {
f(self);
}
}
None => {
debug!("annotate: not found, use_parent = {:?}, parent = {:?}",
use_parent, self.parent);
if use_parent {
if let Some(stab) = self.parent.clone() {
self.index.local.insert(id, stab);
} else if self.index.staged_api && required
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&& self.export_map.contains(&id)
&& !self.sess.opts.test {
self.sess.span_err(item_sp,
"This node does not have a stability attribute");
}
}
f(self);
}
}
}
}
impl<'a, 'v> Visitor<'v> for Annotator<'a> {
fn visit_item(&mut self, i: &Item) {
// FIXME (#18969): the following is a hack around the fact
// that we cannot currently annotate the stability of
// `deriving`. Basically, we do *not* allow stability
// inheritance on trait implementations, so that derived
// implementations appear to be unannotated. This then allows
// derived implementations to be automatically tagged with the
// stability of the trait. This is WRONG, but expedient to get
// libstd stabilized for the 1.0 release.
let use_parent = match i.node {
ast::ItemImpl(_, _, _, Some(_), _, _) => false,
_ => true,
};
// In case of a `pub use <mod>;`, we should not error since the stability
// is inherited from the module itself
let required = match i.node {
ast::ItemUse(_) => i.vis != ast::Public,
_ => true
};
self.annotate(i.id, use_parent, &i.attrs, i.span,
|v| visit::walk_item(v, i), required);
if let ast::ItemStruct(ref sd, _) = i.node {
sd.ctor_id.map(|id| {
self.annotate(id, true, &i.attrs, i.span, |_| {}, true)
});
}
}
fn visit_fn(&mut self, _: FnKind<'v>, _: &'v FnDecl,
_: &'v Block, _: Span, _: NodeId) {
// Items defined in a function body have no reason to have
// a stability attribute, so we don't recurse.
}
fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
self.annotate(ti.id, true, &ti.attrs, ti.span,
|v| visit::walk_trait_item(v, ti), true);
}
fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
self.annotate(ii.id, true, &ii.attrs, ii.span,
|v| visit::walk_impl_item(v, ii), true);
}
fn visit_variant(&mut self, var: &Variant, g: &'v Generics) {
self.annotate(var.node.id, true, &var.node.attrs, var.span,
|v| visit::walk_variant(v, var, g), true)
}
fn visit_struct_field(&mut self, s: &StructField) {
self.annotate(s.node.id, true, &s.node.attrs, s.span,
|v| visit::walk_struct_field(v, s), true);
}
fn visit_foreign_item(&mut self, i: &ast::ForeignItem) {
self.annotate(i.id, true, &i.attrs, i.span, |_| {}, true);
}
}
impl Index {
/// Construct the stability index for a crate being compiled.
pub fn build(&mut self, sess: &Session, krate: &Crate, export_map: &PublicItems) {
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if !self.staged_api {
return;
}
let mut annotator = Annotator {
sess: sess,
index: self,
parent: None,
export_map: export_map,
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};
annotator.annotate(ast::CRATE_NODE_ID, true, &krate.attrs, krate.span,
|v| visit::walk_crate(v, krate), true);
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}
pub fn new(krate: &Crate) -> Index {
let mut staged_api = false;
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for attr in &krate.attrs {
if &attr.name()[..] == "staged_api" {
match attr.node.value.node {
ast::MetaWord(_) => {
attr::mark_used(attr);
staged_api = true;
}
_ => (/*pass*/)
}
}
}
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Index {
staged_api: staged_api,
local: NodeMap(),
extern_cache: DefIdMap()
}
}
}
/// Cross-references the feature names of unstable APIs with enabled
/// features and possibly prints errors. Returns a list of all
/// features used.
pub fn check_unstable_api_usage(tcx: &ty::ctxt)
-> FnvHashMap<InternedString, attr::StabilityLevel> {
let ref active_lib_features = tcx.sess.features.borrow().declared_lib_features;
// Put the active features into a map for quick lookup
let active_features = active_lib_features.iter().map(|&(ref s, _)| s.clone()).collect();
let mut checker = Checker {
tcx: tcx,
active_features: active_features,
used_features: FnvHashMap()
};
let krate = tcx.map.krate();
visit::walk_crate(&mut checker, krate);
let used_features = checker.used_features;
return used_features;
}
struct Checker<'a, 'tcx: 'a> {
tcx: &'a ty::ctxt<'tcx>,
active_features: FnvHashSet<InternedString>,
used_features: FnvHashMap<InternedString, attr::StabilityLevel>
}
impl<'a, 'tcx> Checker<'a, 'tcx> {
fn check(&mut self, id: ast::DefId, span: Span, stab: &Option<Stability>) {
// Only the cross-crate scenario matters when checking unstable APIs
let cross_crate = !is_local(id);
if !cross_crate { return }
match *stab {
Some(Stability { level: attr::Unstable, ref feature, ref reason, .. }) => {
self.used_features.insert(feature.clone(), attr::Unstable);
if !self.active_features.contains(feature) {
let msg = match *reason {
Some(ref r) => format!("use of unstable library feature '{}': {}",
&feature, &r),
None => format!("use of unstable library feature '{}'", &feature)
};
emit_feature_warn(&self.tcx.sess.parse_sess.span_diagnostic,
&feature, span, &msg);
}
}
Some(Stability { level, ref feature, .. }) => {
self.used_features.insert(feature.clone(), level);
// Stable APIs are always ok to call and deprecated APIs are
// handled by a lint.
}
None => {
// This is an 'unmarked' API, which should not exist
// in the standard library.
if self.tcx.sess.features.borrow().unmarked_api {
self.tcx.sess.span_warn(span, "use of unmarked library feature");
self.tcx.sess.span_note(span, "this is either a bug in the library you are \
using or a bug in the compiler - please \
report it in both places");
} else {
self.tcx.sess.span_err(span, "use of unmarked library feature");
self.tcx.sess.span_note(span, "this is either a bug in the library you are \
using or a bug in the compiler - please \
report it in both places");
self.tcx.sess.span_note(span, "use #![feature(unmarked_api)] in the \
crate attributes to override this");
}
}
}
}
}
impl<'a, 'v, 'tcx> Visitor<'v> for Checker<'a, 'tcx> {
fn visit_item(&mut self, item: &ast::Item) {
// When compiling with --test we don't enforce stability on the
// compiler-generated test module, demarcated with `DUMMY_SP` plus the
// name `__test`
if item.span == DUMMY_SP && item.ident.as_str() == "__test" { return }
check_item(self.tcx, item, true,
&mut |id, sp, stab| self.check(id, sp, stab));
visit::walk_item(self, item);
}
fn visit_expr(&mut self, ex: &ast::Expr) {
check_expr(self.tcx, ex,
&mut |id, sp, stab| self.check(id, sp, stab));
visit::walk_expr(self, ex);
}
fn visit_path(&mut self, path: &ast::Path, id: ast::NodeId) {
check_path(self.tcx, path, id,
&mut |id, sp, stab| self.check(id, sp, stab));
visit::walk_path(self, path)
}
fn visit_pat(&mut self, pat: &ast::Pat) {
check_pat(self.tcx, pat,
&mut |id, sp, stab| self.check(id, sp, stab));
visit::walk_pat(self, pat)
}
}
/// Helper for discovering nodes to check for stability
pub fn check_item(tcx: &ty::ctxt, item: &ast::Item, warn_about_defns: bool,
cb: &mut FnMut(ast::DefId, Span, &Option<Stability>)) {
match item.node {
ast::ItemExternCrate(_) => {
// compiler-generated `extern crate` items have a dummy span.
if item.span == DUMMY_SP { return }
let cnum = match tcx.sess.cstore.find_extern_mod_stmt_cnum(item.id) {
Some(cnum) => cnum,
None => return,
};
let id = ast::DefId { krate: cnum, node: ast::CRATE_NODE_ID };
maybe_do_stability_check(tcx, id, item.span, cb);
}
// For implementations of traits, check the stability of each item
// individually as it's possible to have a stable trait with unstable
// items.
ast::ItemImpl(_, _, _, Some(ref t), _, ref impl_items) => {
let trait_did = tcx.def_map.borrow()[t.ref_id].def_id();
let trait_items = ty::trait_items(tcx, trait_did);
for impl_item in impl_items {
let item = trait_items.iter().find(|item| {
item.name() == impl_item.ident.name
}).unwrap();
if warn_about_defns {
maybe_do_stability_check(tcx, item.def_id(), impl_item.span, cb);
}
}
}
_ => (/* pass */)
}
}
/// Helper for discovering nodes to check for stability
pub fn check_expr(tcx: &ty::ctxt, e: &ast::Expr,
cb: &mut FnMut(ast::DefId, Span, &Option<Stability>)) {
let span;
let id = match e.node {
ast::ExprMethodCall(i, _, _) => {
span = i.span;
let method_call = ty::MethodCall::expr(e.id);
match tcx.method_map.borrow().get(&method_call) {
Some(method) => {
match method.origin {
ty::MethodStatic(def_id) => {
def_id
}
ty::MethodStaticClosure(def_id) => {
def_id
}
ty::MethodTypeParam(ty::MethodParam {
ref trait_ref,
method_num: index,
..
}) |
ty::MethodTraitObject(ty::MethodObject {
ref trait_ref,
method_num: index,
..
}) => {
ty::trait_item(tcx, trait_ref.def_id, index).def_id()
}
}
}
None => return
}
}
ast::ExprField(ref base_e, ref field) => {
span = field.span;
match ty::expr_ty_adjusted(tcx, base_e).sty {
ty::ty_struct(did, _) => {
ty::lookup_struct_fields(tcx, did)
.iter()
.find(|f| f.name == field.node.name)
.unwrap_or_else(|| {
tcx.sess.span_bug(field.span,
"stability::check_expr: unknown named field access")
})
.id
}
_ => tcx.sess.span_bug(e.span,
"stability::check_expr: named field access on non-struct")
}
}
ast::ExprTupField(ref base_e, ref field) => {
span = field.span;
match ty::expr_ty_adjusted(tcx, base_e).sty {
ty::ty_struct(did, _) => {
ty::lookup_struct_fields(tcx, did)
.get(field.node)
.unwrap_or_else(|| {
tcx.sess.span_bug(field.span,
"stability::check_expr: unknown unnamed field access")
})
.id
}
ty::ty_tup(..) => return,
_ => tcx.sess.span_bug(e.span,
"stability::check_expr: unnamed field access on \
something other than a tuple or struct")
}
}
ast::ExprStruct(_, ref expr_fields, _) => {
let type_ = ty::expr_ty(tcx, e);
match type_.sty {
ty::ty_struct(did, _) => {
let struct_fields = ty::lookup_struct_fields(tcx, did);
// check the stability of each field that appears
// in the construction expression.
for field in expr_fields {
let did = struct_fields
.iter()
.find(|f| f.name == field.ident.node.name)
.unwrap_or_else(|| {
tcx.sess.span_bug(field.span,
"stability::check_expr: unknown named \
field access")
})
.id;
maybe_do_stability_check(tcx, did, field.span, cb);
}
// we're done.
return
}
// we don't look at stability attributes on
// struct-like enums (yet...), but it's definitely not
// a bug to have construct one.
ty::ty_enum(..) => return,
_ => {
tcx.sess.span_bug(e.span,
&format!("stability::check_expr: struct construction \
of non-struct, type {:?}",
type_.repr(tcx)));
}
}
}
_ => return
};
maybe_do_stability_check(tcx, id, span, cb);
}
pub fn check_path(tcx: &ty::ctxt, path: &ast::Path, id: ast::NodeId,
cb: &mut FnMut(ast::DefId, Span, &Option<Stability>)) {
match tcx.def_map.borrow().get(&id).map(|d| d.full_def()) {
Some(def::DefPrimTy(..)) => {}
Some(def) => {
maybe_do_stability_check(tcx, def.def_id(), path.span, cb);
}
None => {}
}
}
pub fn check_pat(tcx: &ty::ctxt, pat: &ast::Pat,
cb: &mut FnMut(ast::DefId, Span, &Option<Stability>)) {
debug!("check_pat(pat = {:?})", pat);
if is_internal(tcx, pat.span) { return; }
let did = match ty::pat_ty_opt(tcx, pat) {
Some(&ty::TyS { sty: ty::ty_struct(did, _), .. }) => did,
Some(_) | None => return,
};
let struct_fields = ty::lookup_struct_fields(tcx, did);
match pat.node {
// Foo(a, b, c)
ast::PatEnum(_, Some(ref pat_fields)) => {
for (field, struct_field) in pat_fields.iter().zip(struct_fields.iter()) {
// a .. pattern is fine, but anything positional is
// not.
if let ast::PatWild(ast::PatWildMulti) = field.node {
continue
}
maybe_do_stability_check(tcx, struct_field.id, field.span, cb)
}
}
// Foo { a, b, c }
ast::PatStruct(_, ref pat_fields, _) => {
for field in pat_fields {
let did = struct_fields
.iter()
.find(|f| f.name == field.node.ident.name)
.unwrap_or_else(|| {
tcx.sess.span_bug(field.span,
"stability::check_pat: unknown named field access")
})
.id;
maybe_do_stability_check(tcx, did, field.span, cb);
}
}
// everything else is fine.
_ => {}
}
}
fn maybe_do_stability_check(tcx: &ty::ctxt, id: ast::DefId, span: Span,
cb: &mut FnMut(ast::DefId, Span, &Option<Stability>)) {
if !is_staged_api(tcx, id) { return }
if is_internal(tcx, span) { return }
let ref stability = lookup(tcx, id);
cb(id, span, stability);
}
fn is_internal(tcx: &ty::ctxt, span: Span) -> bool {
tcx.sess.codemap().span_allows_unstable(span)
}
fn is_staged_api(tcx: &ty::ctxt, id: DefId) -> bool {
match ty::trait_item_of_item(tcx, id) {
Some(ty::MethodTraitItemId(trait_method_id))
if trait_method_id != id => {
is_staged_api(tcx, trait_method_id)
}
_ if is_local(id) => {
tcx.stability.borrow().staged_api
}
_ => {
csearch::is_staged_api(&tcx.sess.cstore, id)
}
}
}
/// Lookup the stability for a node, loading external crate
/// metadata as necessary.
pub fn lookup(tcx: &ty::ctxt, id: DefId) -> Option<Stability> {
debug!("lookup(id={})",
id.repr(tcx));
// is this definition the implementation of a trait method?
match ty::trait_item_of_item(tcx, id) {
Some(ty::MethodTraitItemId(trait_method_id)) if trait_method_id != id => {
debug!("lookup: trait_method_id={:?}", trait_method_id);
return lookup(tcx, trait_method_id)
}
_ => {}
}
let item_stab = if is_local(id) {
tcx.stability.borrow().local.get(&id.node).cloned()
} else {
let stab = csearch::get_stability(&tcx.sess.cstore, id);
let mut index = tcx.stability.borrow_mut();
(*index).extern_cache.insert(id, stab.clone());
stab
};
item_stab.or_else(|| {
if let Some(trait_id) = ty::trait_id_of_impl(tcx, id) {
// FIXME (#18969): for the time being, simply use the
// stability of the trait to determine the stability of any
// unmarked impls for it. See FIXME above for more details.
debug!("lookup: trait_id={:?}", trait_id);
lookup(tcx, trait_id)
} else {
None
}
})
}
Preliminary feature staging This partially implements the feature staging described in the [release channel RFC][rc]. It does not yet fully conform to the RFC as written, but does accomplish its goals sufficiently for the 1.0 alpha release. It has three primary user-visible effects: * On the nightly channel, use of unstable APIs generates a warning. * On the beta channel, use of unstable APIs generates a warning. * On the beta channel, use of feature gates generates a warning. Code that does not trigger these warnings is considered 'stable', modulo pre-1.0 bugs. Disabling the warnings for unstable APIs continues to be done in the existing (i.e. old) style, via `#[allow(...)]`, not that specified in the RFC. I deem this marginally acceptable since any code that must do this is not using the stable dialect of Rust. Use of feature gates is itself gated with the new 'unstable_features' lint, on nightly set to 'allow', and on beta 'warn'. The attribute scheme used here corresponds to an older version of the RFC, with the `#[staged_api]` crate attribute toggling the staging behavior of the stability attributes, but the user impact is only in-tree so I'm not concerned about having to make design changes later (and I may ultimately prefer the scheme here after all, with the `#[staged_api]` crate attribute). Since the Rust codebase itself makes use of unstable features the compiler and build system to a midly elaborate dance to allow it to bootstrap while disobeying these lints (which would otherwise be errors because Rust builds with `-D warnings`). This patch includes one significant hack that causes a regression. Because the `format_args!` macro emits calls to unstable APIs it would trigger the lint. I added a hack to the lint to make it not trigger, but this in turn causes arguments to `println!` not to be checked for feature gates. I don't presently understand macro expansion well enough to fix. This is bug #20661. Closes #16678 [rc]: https://github.com/rust-lang/rfcs/blob/master/text/0507-release-channels.md
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/// Given the list of enabled features that were not language features (i.e. that
/// were expected to be library features), and the list of features used from
/// libraries, identify activated features that don't exist and error about them.
pub fn check_unused_or_stable_features(sess: &Session,
lib_features_used: &FnvHashMap<InternedString,
attr::StabilityLevel>) {
let ref declared_lib_features = sess.features.borrow().declared_lib_features;
let mut remaining_lib_features: FnvHashMap<InternedString, Span>
= declared_lib_features.clone().into_iter().collect();
let stable_msg = "this feature is stable. attribute no longer needed";
for &span in sess.features.borrow().declared_stable_lang_features.iter() {
sess.add_lint(lint::builtin::STABLE_FEATURES,
ast::CRATE_NODE_ID,
span,
stable_msg.to_string());
}
for (used_lib_feature, level) in lib_features_used.iter() {
match remaining_lib_features.remove(used_lib_feature) {
Some(span) => {
if *level == attr::Stable {
sess.add_lint(lint::builtin::STABLE_FEATURES,
ast::CRATE_NODE_ID,
span,
stable_msg.to_string());
}
}
None => ( /* used but undeclared, handled during the previous ast visit */ )
}
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}
for (_, &span) in remaining_lib_features.iter() {
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sess.add_lint(lint::builtin::UNUSED_FEATURES,
ast::CRATE_NODE_ID,
span,
"unused or unknown feature".to_string());
}
Preliminary feature staging This partially implements the feature staging described in the [release channel RFC][rc]. It does not yet fully conform to the RFC as written, but does accomplish its goals sufficiently for the 1.0 alpha release. It has three primary user-visible effects: * On the nightly channel, use of unstable APIs generates a warning. * On the beta channel, use of unstable APIs generates a warning. * On the beta channel, use of feature gates generates a warning. Code that does not trigger these warnings is considered 'stable', modulo pre-1.0 bugs. Disabling the warnings for unstable APIs continues to be done in the existing (i.e. old) style, via `#[allow(...)]`, not that specified in the RFC. I deem this marginally acceptable since any code that must do this is not using the stable dialect of Rust. Use of feature gates is itself gated with the new 'unstable_features' lint, on nightly set to 'allow', and on beta 'warn'. The attribute scheme used here corresponds to an older version of the RFC, with the `#[staged_api]` crate attribute toggling the staging behavior of the stability attributes, but the user impact is only in-tree so I'm not concerned about having to make design changes later (and I may ultimately prefer the scheme here after all, with the `#[staged_api]` crate attribute). Since the Rust codebase itself makes use of unstable features the compiler and build system to a midly elaborate dance to allow it to bootstrap while disobeying these lints (which would otherwise be errors because Rust builds with `-D warnings`). This patch includes one significant hack that causes a regression. Because the `format_args!` macro emits calls to unstable APIs it would trigger the lint. I added a hack to the lint to make it not trigger, but this in turn causes arguments to `println!` not to be checked for feature gates. I don't presently understand macro expansion well enough to fix. This is bug #20661. Closes #16678 [rc]: https://github.com/rust-lang/rfcs/blob/master/text/0507-release-channels.md
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}