rust/src/librustc_interface/util.rs
2020-02-01 18:59:49 +01:00

787 lines
29 KiB
Rust

use log::info;
use rustc::lint;
use rustc::ty;
use rustc_codegen_utils::codegen_backend::CodegenBackend;
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
#[cfg(parallel_compiler)]
use rustc_data_structures::jobserver;
use rustc_data_structures::stable_hasher::StableHasher;
use rustc_data_structures::sync::{Lock, Lrc};
use rustc_errors::registry::Registry;
use rustc_metadata::dynamic_lib::DynamicLibrary;
use rustc_resolve::{self, Resolver};
use rustc_session as session;
use rustc_session::config::{ErrorOutputType, Input, OutputFilenames};
use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
use rustc_session::parse::CrateConfig;
use rustc_session::CrateDisambiguator;
use rustc_session::{config, early_error, filesearch, DiagnosticOutput, Session};
use rustc_span::edition::Edition;
use rustc_span::source_map::{FileLoader, RealFileLoader, SourceMap};
use rustc_span::symbol::{sym, Symbol};
use smallvec::SmallVec;
use std::env;
use std::io::{self, Write};
use std::mem;
use std::ops::DerefMut;
use std::path::{Path, PathBuf};
use std::sync::{Arc, Mutex, Once};
#[cfg(not(parallel_compiler))]
use std::{panic, thread};
use syntax::ast::{AttrVec, BlockCheckMode};
use syntax::mut_visit::{visit_clobber, MutVisitor, *};
use syntax::ptr::P;
use syntax::util::lev_distance::find_best_match_for_name;
use syntax::{self, ast};
/// Adds `target_feature = "..."` cfgs for a variety of platform
/// specific features (SSE, NEON etc.).
///
/// This is performed by checking whether a whitelisted set of
/// features is available on the target machine, by querying LLVM.
pub fn add_configuration(
cfg: &mut CrateConfig,
sess: &Session,
codegen_backend: &dyn CodegenBackend,
) {
let tf = sym::target_feature;
cfg.extend(codegen_backend.target_features(sess).into_iter().map(|feat| (tf, Some(feat))));
if sess.crt_static_feature() {
cfg.insert((tf, Some(Symbol::intern("crt-static"))));
}
}
pub fn create_session(
sopts: config::Options,
cfg: FxHashSet<(String, Option<String>)>,
diagnostic_output: DiagnosticOutput,
file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
input_path: Option<PathBuf>,
lint_caps: FxHashMap<lint::LintId, lint::Level>,
descriptions: Registry,
) -> (Lrc<Session>, Lrc<Box<dyn CodegenBackend>>, Lrc<SourceMap>) {
let loader = file_loader.unwrap_or(box RealFileLoader);
let source_map = Lrc::new(SourceMap::with_file_loader(loader, sopts.file_path_mapping()));
let mut sess = session::build_session_with_source_map(
sopts,
input_path,
descriptions,
source_map.clone(),
diagnostic_output,
lint_caps,
);
let codegen_backend = get_codegen_backend(&sess);
let mut cfg = config::build_configuration(&sess, config::to_crate_config(cfg));
add_configuration(&mut cfg, &sess, &*codegen_backend);
sess.parse_sess.config = cfg;
(Lrc::new(sess), Lrc::new(codegen_backend), source_map)
}
// Temporarily have stack size set to 32MB to deal with various crates with long method
// chains or deep syntax trees, except when on Haiku.
// FIXME(oli-obk): get https://github.com/rust-lang/rust/pull/55617 the finish line
#[cfg(not(target_os = "haiku"))]
const STACK_SIZE: usize = 32 * 1024 * 1024;
#[cfg(target_os = "haiku")]
const STACK_SIZE: usize = 16 * 1024 * 1024;
fn get_stack_size() -> Option<usize> {
// FIXME: Hacks on hacks. If the env is trying to override the stack size
// then *don't* set it explicitly.
env::var_os("RUST_MIN_STACK").is_none().then_some(STACK_SIZE)
}
struct Sink(Arc<Mutex<Vec<u8>>>);
impl Write for Sink {
fn write(&mut self, data: &[u8]) -> io::Result<usize> {
Write::write(&mut *self.0.lock().unwrap(), data)
}
fn flush(&mut self) -> io::Result<()> {
Ok(())
}
}
#[cfg(not(parallel_compiler))]
pub fn scoped_thread<F: FnOnce() -> R + Send, R: Send>(cfg: thread::Builder, f: F) -> R {
struct Ptr(*mut ());
unsafe impl Send for Ptr {}
unsafe impl Sync for Ptr {}
let mut f = Some(f);
let run = Ptr(&mut f as *mut _ as *mut ());
let mut result = None;
let result_ptr = Ptr(&mut result as *mut _ as *mut ());
let thread = cfg.spawn(move || {
let run = unsafe { (*(run.0 as *mut Option<F>)).take().unwrap() };
let result = unsafe { &mut *(result_ptr.0 as *mut Option<R>) };
*result = Some(run());
});
match thread.unwrap().join() {
Ok(()) => result.unwrap(),
Err(p) => panic::resume_unwind(p),
}
}
#[cfg(not(parallel_compiler))]
pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
edition: Edition,
_threads: usize,
stderr: &Option<Arc<Mutex<Vec<u8>>>>,
f: F,
) -> R {
let mut cfg = thread::Builder::new().name("rustc".to_string());
if let Some(size) = get_stack_size() {
cfg = cfg.stack_size(size);
}
crate::callbacks::setup_callbacks();
scoped_thread(cfg, || {
syntax::with_globals(edition, || {
ty::tls::GCX_PTR.set(&Lock::new(0), || {
if let Some(stderr) = stderr {
io::set_panic(Some(box Sink(stderr.clone())));
}
f()
})
})
})
}
#[cfg(parallel_compiler)]
pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
edition: Edition,
threads: usize,
stderr: &Option<Arc<Mutex<Vec<u8>>>>,
f: F,
) -> R {
use rayon::{ThreadBuilder, ThreadPool, ThreadPoolBuilder};
let gcx_ptr = &Lock::new(0);
crate::callbacks::setup_callbacks();
let mut config = ThreadPoolBuilder::new()
.thread_name(|_| "rustc".to_string())
.acquire_thread_handler(jobserver::acquire_thread)
.release_thread_handler(jobserver::release_thread)
.num_threads(threads)
.deadlock_handler(|| unsafe { ty::query::handle_deadlock() });
if let Some(size) = get_stack_size() {
config = config.stack_size(size);
}
let with_pool = move |pool: &ThreadPool| pool.install(move || f());
syntax::with_globals(edition, || {
syntax::GLOBALS.with(|syntax_globals| {
rustc_span::GLOBALS.with(|rustc_span_globals| {
// The main handler runs for each Rayon worker thread and sets up
// the thread local rustc uses. syntax_globals and rustc_span_globals are
// captured and set on the new threads. ty::tls::with_thread_locals sets up
// thread local callbacks from libsyntax
let main_handler = move |thread: ThreadBuilder| {
syntax::GLOBALS.set(syntax_globals, || {
rustc_span::GLOBALS.set(rustc_span_globals, || {
if let Some(stderr) = stderr {
io::set_panic(Some(box Sink(stderr.clone())));
}
ty::tls::GCX_PTR.set(gcx_ptr, || thread.run())
})
})
};
config.build_scoped(main_handler, with_pool).unwrap()
})
})
})
}
fn load_backend_from_dylib(path: &Path) -> fn() -> Box<dyn CodegenBackend> {
let lib = DynamicLibrary::open(Some(path)).unwrap_or_else(|err| {
let err = format!("couldn't load codegen backend {:?}: {:?}", path, err);
early_error(ErrorOutputType::default(), &err);
});
unsafe {
match lib.symbol("__rustc_codegen_backend") {
Ok(f) => {
mem::forget(lib);
mem::transmute::<*mut u8, _>(f)
}
Err(e) => {
let err = format!(
"couldn't load codegen backend as it \
doesn't export the `__rustc_codegen_backend` \
symbol: {:?}",
e
);
early_error(ErrorOutputType::default(), &err);
}
}
}
}
pub fn get_codegen_backend(sess: &Session) -> Box<dyn CodegenBackend> {
static INIT: Once = Once::new();
static mut LOAD: fn() -> Box<dyn CodegenBackend> = || unreachable!();
INIT.call_once(|| {
let codegen_name = sess
.opts
.debugging_opts
.codegen_backend
.as_ref()
.unwrap_or(&sess.target.target.options.codegen_backend);
let backend = match &codegen_name[..] {
filename if filename.contains(".") => load_backend_from_dylib(filename.as_ref()),
codegen_name => get_builtin_codegen_backend(codegen_name),
};
unsafe {
LOAD = backend;
}
});
let backend = unsafe { LOAD() };
backend.init(sess);
backend
}
// This is used for rustdoc, but it uses similar machinery to codegen backend
// loading, so we leave the code here. It is potentially useful for other tools
// that want to invoke the rustc binary while linking to rustc as well.
pub fn rustc_path<'a>() -> Option<&'a Path> {
static RUSTC_PATH: once_cell::sync::OnceCell<Option<PathBuf>> =
once_cell::sync::OnceCell::new();
const BIN_PATH: &str = env!("RUSTC_INSTALL_BINDIR");
RUSTC_PATH.get_or_init(|| get_rustc_path_inner(BIN_PATH)).as_ref().map(|v| &**v)
}
fn get_rustc_path_inner(bin_path: &str) -> Option<PathBuf> {
sysroot_candidates()
.iter()
.filter_map(|sysroot| {
let candidate = sysroot.join(bin_path).join(if cfg!(target_os = "windows") {
"rustc.exe"
} else {
"rustc"
});
candidate.exists().then_some(candidate)
})
.next()
}
fn sysroot_candidates() -> Vec<PathBuf> {
let target = session::config::host_triple();
let mut sysroot_candidates = vec![filesearch::get_or_default_sysroot()];
let path = current_dll_path().and_then(|s| s.canonicalize().ok());
if let Some(dll) = path {
// use `parent` twice to chop off the file name and then also the
// directory containing the dll which should be either `lib` or `bin`.
if let Some(path) = dll.parent().and_then(|p| p.parent()) {
// The original `path` pointed at the `rustc_driver` crate's dll.
// Now that dll should only be in one of two locations. The first is
// in the compiler's libdir, for example `$sysroot/lib/*.dll`. The
// other is the target's libdir, for example
// `$sysroot/lib/rustlib/$target/lib/*.dll`.
//
// We don't know which, so let's assume that if our `path` above
// ends in `$target` we *could* be in the target libdir, and always
// assume that we may be in the main libdir.
sysroot_candidates.push(path.to_owned());
if path.ends_with(target) {
sysroot_candidates.extend(
path.parent() // chop off `$target`
.and_then(|p| p.parent()) // chop off `rustlib`
.and_then(|p| p.parent()) // chop off `lib`
.map(|s| s.to_owned()),
);
}
}
}
return sysroot_candidates;
#[cfg(unix)]
fn current_dll_path() -> Option<PathBuf> {
use std::ffi::{CStr, OsStr};
use std::os::unix::prelude::*;
unsafe {
let addr = current_dll_path as usize as *mut _;
let mut info = mem::zeroed();
if libc::dladdr(addr, &mut info) == 0 {
info!("dladdr failed");
return None;
}
if info.dli_fname.is_null() {
info!("dladdr returned null pointer");
return None;
}
let bytes = CStr::from_ptr(info.dli_fname).to_bytes();
let os = OsStr::from_bytes(bytes);
Some(PathBuf::from(os))
}
}
#[cfg(windows)]
fn current_dll_path() -> Option<PathBuf> {
use std::ffi::OsString;
use std::os::windows::prelude::*;
use std::ptr;
use winapi::um::libloaderapi::{
GetModuleFileNameW, GetModuleHandleExW, GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
};
unsafe {
let mut module = ptr::null_mut();
let r = GetModuleHandleExW(
GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
current_dll_path as usize as *mut _,
&mut module,
);
if r == 0 {
info!("GetModuleHandleExW failed: {}", io::Error::last_os_error());
return None;
}
let mut space = Vec::with_capacity(1024);
let r = GetModuleFileNameW(module, space.as_mut_ptr(), space.capacity() as u32);
if r == 0 {
info!("GetModuleFileNameW failed: {}", io::Error::last_os_error());
return None;
}
let r = r as usize;
if r >= space.capacity() {
info!("our buffer was too small? {}", io::Error::last_os_error());
return None;
}
space.set_len(r);
let os = OsString::from_wide(&space);
Some(PathBuf::from(os))
}
}
}
pub fn get_builtin_codegen_backend(backend_name: &str) -> fn() -> Box<dyn CodegenBackend> {
#[cfg(feature = "llvm")]
{
if backend_name == "llvm" {
return rustc_codegen_llvm::LlvmCodegenBackend::new;
}
}
let err = format!("unsupported builtin codegen backend `{}`", backend_name);
early_error(ErrorOutputType::default(), &err);
}
pub(crate) fn compute_crate_disambiguator(session: &Session) -> CrateDisambiguator {
use std::hash::Hasher;
// The crate_disambiguator is a 128 bit hash. The disambiguator is fed
// into various other hashes quite a bit (symbol hashes, incr. comp. hashes,
// debuginfo type IDs, etc), so we don't want it to be too wide. 128 bits
// should still be safe enough to avoid collisions in practice.
let mut hasher = StableHasher::new();
let mut metadata = session.opts.cg.metadata.clone();
// We don't want the crate_disambiguator to dependent on the order
// -C metadata arguments, so sort them:
metadata.sort();
// Every distinct -C metadata value is only incorporated once:
metadata.dedup();
hasher.write(b"metadata");
for s in &metadata {
// Also incorporate the length of a metadata string, so that we generate
// different values for `-Cmetadata=ab -Cmetadata=c` and
// `-Cmetadata=a -Cmetadata=bc`
hasher.write_usize(s.len());
hasher.write(s.as_bytes());
}
// Also incorporate crate type, so that we don't get symbol conflicts when
// linking against a library of the same name, if this is an executable.
let is_exe = session.crate_types.borrow().contains(&config::CrateType::Executable);
hasher.write(if is_exe { b"exe" } else { b"lib" });
CrateDisambiguator::from(hasher.finish::<Fingerprint>())
}
pub(crate) fn check_attr_crate_type(attrs: &[ast::Attribute], lint_buffer: &mut LintBuffer) {
// Unconditionally collect crate types from attributes to make them used
for a in attrs.iter() {
if a.check_name(sym::crate_type) {
if let Some(n) = a.value_str() {
if let Some(_) = categorize_crate_type(n) {
return;
}
if let ast::MetaItemKind::NameValue(spanned) = a.meta().unwrap().kind {
let span = spanned.span;
let lev_candidate = find_best_match_for_name(
CRATE_TYPES.iter().map(|(k, _)| k),
&n.as_str(),
None,
);
if let Some(candidate) = lev_candidate {
lint_buffer.buffer_lint_with_diagnostic(
lint::builtin::UNKNOWN_CRATE_TYPES,
ast::CRATE_NODE_ID,
span,
"invalid `crate_type` value",
BuiltinLintDiagnostics::UnknownCrateTypes(
span,
"did you mean".to_string(),
format!("\"{}\"", candidate),
),
);
} else {
lint_buffer.buffer_lint(
lint::builtin::UNKNOWN_CRATE_TYPES,
ast::CRATE_NODE_ID,
span,
"invalid `crate_type` value",
);
}
}
}
}
}
}
const CRATE_TYPES: &[(Symbol, config::CrateType)] = &[
(sym::rlib, config::CrateType::Rlib),
(sym::dylib, config::CrateType::Dylib),
(sym::cdylib, config::CrateType::Cdylib),
(sym::lib, config::default_lib_output()),
(sym::staticlib, config::CrateType::Staticlib),
(sym::proc_dash_macro, config::CrateType::ProcMacro),
(sym::bin, config::CrateType::Executable),
];
fn categorize_crate_type(s: Symbol) -> Option<config::CrateType> {
Some(CRATE_TYPES.iter().find(|(key, _)| *key == s)?.1)
}
pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<config::CrateType> {
// Unconditionally collect crate types from attributes to make them used
let attr_types: Vec<config::CrateType> = attrs
.iter()
.filter_map(|a| {
if a.check_name(sym::crate_type) {
match a.value_str() {
Some(s) => categorize_crate_type(s),
_ => None,
}
} else {
None
}
})
.collect();
// If we're generating a test executable, then ignore all other output
// styles at all other locations
if session.opts.test {
return vec![config::CrateType::Executable];
}
// Only check command line flags if present. If no types are specified by
// command line, then reuse the empty `base` Vec to hold the types that
// will be found in crate attributes.
let mut base = session.opts.crate_types.clone();
if base.is_empty() {
base.extend(attr_types);
if base.is_empty() {
base.push(::rustc_codegen_utils::link::default_output_for_target(session));
} else {
base.sort();
base.dedup();
}
}
base.retain(|crate_type| {
let res = !::rustc_codegen_utils::link::invalid_output_for_target(session, *crate_type);
if !res {
session.warn(&format!(
"dropping unsupported crate type `{}` for target `{}`",
*crate_type, session.opts.target_triple
));
}
res
});
base
}
pub fn build_output_filenames(
input: &Input,
odir: &Option<PathBuf>,
ofile: &Option<PathBuf>,
attrs: &[ast::Attribute],
sess: &Session,
) -> OutputFilenames {
match *ofile {
None => {
// "-" as input file will cause the parser to read from stdin so we
// have to make up a name
// We want to toss everything after the final '.'
let dirpath = (*odir).as_ref().cloned().unwrap_or_default();
// If a crate name is present, we use it as the link name
let stem = sess
.opts
.crate_name
.clone()
.or_else(|| rustc_attr::find_crate_name(attrs).map(|n| n.to_string()))
.unwrap_or_else(|| input.filestem().to_owned());
OutputFilenames::new(
dirpath,
stem,
None,
sess.opts.cg.extra_filename.clone(),
sess.opts.output_types.clone(),
)
}
Some(ref out_file) => {
let unnamed_output_types =
sess.opts.output_types.values().filter(|a| a.is_none()).count();
let ofile = if unnamed_output_types > 1 {
sess.warn(
"due to multiple output types requested, the explicitly specified \
output file name will be adapted for each output type",
);
None
} else {
if !sess.opts.cg.extra_filename.is_empty() {
sess.warn("ignoring -C extra-filename flag due to -o flag");
}
Some(out_file.clone())
};
if *odir != None {
sess.warn("ignoring --out-dir flag due to -o flag");
}
OutputFilenames::new(
out_file.parent().unwrap_or_else(|| Path::new("")).to_path_buf(),
out_file.file_stem().unwrap_or_default().to_str().unwrap().to_string(),
ofile,
sess.opts.cg.extra_filename.clone(),
sess.opts.output_types.clone(),
)
}
}
}
// Note: Also used by librustdoc, see PR #43348. Consider moving this struct elsewhere.
//
// FIXME: Currently the `everybody_loops` transformation is not applied to:
// * `const fn`, due to issue #43636 that `loop` is not supported for const evaluation. We are
// waiting for miri to fix that.
// * `impl Trait`, due to issue #43869 that functions returning impl Trait cannot be diverging.
// Solving this may require `!` to implement every trait, which relies on the an even more
// ambitious form of the closed RFC #1637. See also [#34511].
//
// [#34511]: https://github.com/rust-lang/rust/issues/34511#issuecomment-322340401
pub struct ReplaceBodyWithLoop<'a, 'b> {
within_static_or_const: bool,
nested_blocks: Option<Vec<ast::Block>>,
resolver: &'a mut Resolver<'b>,
}
impl<'a, 'b> ReplaceBodyWithLoop<'a, 'b> {
pub fn new(resolver: &'a mut Resolver<'b>) -> ReplaceBodyWithLoop<'a, 'b> {
ReplaceBodyWithLoop { within_static_or_const: false, nested_blocks: None, resolver }
}
fn run<R, F: FnOnce(&mut Self) -> R>(&mut self, is_const: bool, action: F) -> R {
let old_const = mem::replace(&mut self.within_static_or_const, is_const);
let old_blocks = self.nested_blocks.take();
let ret = action(self);
self.within_static_or_const = old_const;
self.nested_blocks = old_blocks;
ret
}
fn should_ignore_fn(ret_ty: &ast::FunctionRetTy) -> bool {
if let ast::FunctionRetTy::Ty(ref ty) = ret_ty {
fn involves_impl_trait(ty: &ast::Ty) -> bool {
match ty.kind {
ast::TyKind::ImplTrait(..) => true,
ast::TyKind::Slice(ref subty)
| ast::TyKind::Array(ref subty, _)
| ast::TyKind::Ptr(ast::MutTy { ty: ref subty, .. })
| ast::TyKind::Rptr(_, ast::MutTy { ty: ref subty, .. })
| ast::TyKind::Paren(ref subty) => involves_impl_trait(subty),
ast::TyKind::Tup(ref tys) => any_involves_impl_trait(tys.iter()),
ast::TyKind::Path(_, ref path) => path.segments.iter().any(|seg| {
match seg.args.as_ref().map(|generic_arg| &**generic_arg) {
None => false,
Some(&ast::GenericArgs::AngleBracketed(ref data)) => {
let types = data.args.iter().filter_map(|arg| match arg {
ast::GenericArg::Type(ty) => Some(ty),
_ => None,
});
any_involves_impl_trait(types.into_iter())
|| data.constraints.iter().any(|c| match c.kind {
ast::AssocTyConstraintKind::Bound { .. } => true,
ast::AssocTyConstraintKind::Equality { ref ty } => {
involves_impl_trait(ty)
}
})
}
Some(&ast::GenericArgs::Parenthesized(ref data)) => {
any_involves_impl_trait(data.inputs.iter())
|| ReplaceBodyWithLoop::should_ignore_fn(&data.output)
}
}
}),
_ => false,
}
}
fn any_involves_impl_trait<'a, I: Iterator<Item = &'a P<ast::Ty>>>(mut it: I) -> bool {
it.any(|subty| involves_impl_trait(subty))
}
involves_impl_trait(ty)
} else {
false
}
}
fn is_sig_const(sig: &ast::FnSig) -> bool {
sig.header.constness.node == ast::Constness::Const
|| ReplaceBodyWithLoop::should_ignore_fn(&sig.decl.output)
}
}
impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
fn visit_item_kind(&mut self, i: &mut ast::ItemKind) {
let is_const = match i {
ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => true,
ast::ItemKind::Fn(ref sig, _, _) => Self::is_sig_const(sig),
_ => false,
};
self.run(is_const, |s| noop_visit_item_kind(i, s))
}
fn flat_map_trait_item(&mut self, i: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
let is_const = match i.kind {
ast::AssocItemKind::Const(..) => true,
ast::AssocItemKind::Fn(ref sig, _) => Self::is_sig_const(sig),
_ => false,
};
self.run(is_const, |s| noop_flat_map_assoc_item(i, s))
}
fn flat_map_impl_item(&mut self, i: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
self.flat_map_trait_item(i)
}
fn visit_anon_const(&mut self, c: &mut ast::AnonConst) {
self.run(true, |s| noop_visit_anon_const(c, s))
}
fn visit_block(&mut self, b: &mut P<ast::Block>) {
fn stmt_to_block(
rules: ast::BlockCheckMode,
s: Option<ast::Stmt>,
resolver: &mut Resolver<'_>,
) -> ast::Block {
ast::Block {
stmts: s.into_iter().collect(),
rules,
id: resolver.next_node_id(),
span: rustc_span::DUMMY_SP,
}
}
fn block_to_stmt(b: ast::Block, resolver: &mut Resolver<'_>) -> ast::Stmt {
let expr = P(ast::Expr {
id: resolver.next_node_id(),
kind: ast::ExprKind::Block(P(b), None),
span: rustc_span::DUMMY_SP,
attrs: AttrVec::new(),
});
ast::Stmt {
id: resolver.next_node_id(),
kind: ast::StmtKind::Expr(expr),
span: rustc_span::DUMMY_SP,
}
}
let empty_block = stmt_to_block(BlockCheckMode::Default, None, self.resolver);
let loop_expr = P(ast::Expr {
kind: ast::ExprKind::Loop(P(empty_block), None),
id: self.resolver.next_node_id(),
span: rustc_span::DUMMY_SP,
attrs: AttrVec::new(),
});
let loop_stmt = ast::Stmt {
id: self.resolver.next_node_id(),
span: rustc_span::DUMMY_SP,
kind: ast::StmtKind::Expr(loop_expr),
};
if self.within_static_or_const {
noop_visit_block(b, self)
} else {
visit_clobber(b.deref_mut(), |b| {
let mut stmts = vec![];
for s in b.stmts {
let old_blocks = self.nested_blocks.replace(vec![]);
stmts.extend(self.flat_map_stmt(s).into_iter().filter(|s| s.is_item()));
// we put a Some in there earlier with that replace(), so this is valid
let new_blocks = self.nested_blocks.take().unwrap();
self.nested_blocks = old_blocks;
stmts.extend(new_blocks.into_iter().map(|b| block_to_stmt(b, self.resolver)));
}
let mut new_block = ast::Block { stmts, ..b };
if let Some(old_blocks) = self.nested_blocks.as_mut() {
//push our fresh block onto the cache and yield an empty block with `loop {}`
if !new_block.stmts.is_empty() {
old_blocks.push(new_block);
}
stmt_to_block(b.rules, Some(loop_stmt), &mut self.resolver)
} else {
//push `loop {}` onto the end of our fresh block and yield that
new_block.stmts.push(loop_stmt);
new_block
}
})
}
}
// in general the pretty printer processes unexpanded code, so
// we override the default `visit_mac` method which panics.
fn visit_mac(&mut self, mac: &mut ast::Mac) {
noop_visit_mac(mac, self)
}
}