rust/src/librustc/middle/weak_lang_items.rs

147 lines
4.6 KiB
Rust

// 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.
//! Validity checking for weak lang items
use session::config;
use session::Session;
use middle::lang_items;
use rustc_back::PanicStrategy;
use syntax::ast;
use syntax::symbol::Symbol;
use syntax_pos::Span;
use hir::intravisit::{Visitor, NestedVisitorMap};
use hir::intravisit;
use hir;
use std::collections::HashSet;
macro_rules! weak_lang_items {
($($name:ident, $item:ident, $sym:ident;)*) => (
struct Context<'a> {
sess: &'a Session,
items: &'a mut lang_items::LanguageItems,
}
/// Checks the crate for usage of weak lang items, returning a vector of all the
/// language items required by this crate, but not defined yet.
pub fn check_crate(krate: &hir::Crate,
sess: &Session,
items: &mut lang_items::LanguageItems) {
// These are never called by user code, they're generated by the compiler.
// They will never implicitly be added to the `missing` array unless we do
// so here.
if items.eh_personality().is_none() {
items.missing.push(lang_items::EhPersonalityLangItem);
}
if sess.target.target.options.custom_unwind_resume &
items.eh_unwind_resume().is_none() {
items.missing.push(lang_items::EhUnwindResumeLangItem);
}
{
let mut cx = Context { sess: sess, items: items };
krate.visit_all_item_likes(&mut cx.as_deep_visitor());
}
verify(sess, items);
}
pub fn link_name(attrs: &[ast::Attribute]) -> Option<Symbol> {
lang_items::extract(attrs).and_then(|name| {
$(if name == stringify!($name) {
Some(Symbol::intern(stringify!($sym)))
} else)* {
None
}
})
}
fn verify(sess: &Session, items: &lang_items::LanguageItems) {
// We only need to check for the presence of weak lang items if we're
// emitting something that's not an rlib.
let needs_check = sess.crate_types.borrow().iter().any(|kind| {
match *kind {
config::CrateTypeDylib |
config::CrateTypeProcMacro |
config::CrateTypeCdylib |
config::CrateTypeExecutable |
config::CrateTypeStaticlib => true,
config::CrateTypeRlib |
config::CrateTypeMetadata => false,
}
});
if !needs_check {
return
}
let mut missing = HashSet::new();
for cnum in sess.cstore.crates() {
for item in sess.cstore.missing_lang_items(cnum) {
missing.insert(item);
}
}
// If we're not compiling with unwinding, we won't actually need these
// symbols. Other panic runtimes ensure that the relevant symbols are
// available to link things together, but they're never exercised.
let mut whitelisted = HashSet::new();
if sess.panic_strategy() != PanicStrategy::Unwind {
whitelisted.insert(lang_items::EhPersonalityLangItem);
whitelisted.insert(lang_items::EhUnwindResumeLangItem);
}
$(
if missing.contains(&lang_items::$item) &&
!whitelisted.contains(&lang_items::$item) &&
items.$name().is_none() {
sess.err(&format!("language item required, but not found: `{}`",
stringify!($name)));
}
)*
}
impl<'a> Context<'a> {
fn register(&mut self, name: &str, span: Span) {
$(if name == stringify!($name) {
if self.items.$name().is_none() {
self.items.missing.push(lang_items::$item);
}
} else)* {
span_err!(self.sess, span, E0264,
"unknown external lang item: `{}`",
name);
}
}
}
impl<'a, 'v> Visitor<'v> for Context<'a> {
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'v> {
NestedVisitorMap::None
}
fn visit_foreign_item(&mut self, i: &hir::ForeignItem) {
if let Some(lang_item) = lang_items::extract(&i.attrs) {
self.register(&lang_item.as_str(), i.span);
}
intravisit::walk_foreign_item(self, i)
}
}
) }
weak_lang_items! {
panic_fmt, PanicFmtLangItem, rust_begin_unwind;
eh_personality, EhPersonalityLangItem, rust_eh_personality;
eh_unwind_resume, EhUnwindResumeLangItem, rust_eh_unwind_resume;
}