3 use rustc::session::config::{ErrorOutputType, Input, OutputFilenames};
4 use rustc::session::CrateDisambiguator;
5 use rustc::session::{self, config, early_error, filesearch, DiagnosticOutput, Session};
7 use rustc_codegen_utils::codegen_backend::CodegenBackend;
8 use rustc_data_structures::fingerprint::Fingerprint;
9 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
10 #[cfg(parallel_compiler)]
11 use rustc_data_structures::jobserver;
12 use rustc_data_structures::stable_hasher::StableHasher;
13 use rustc_data_structures::sync::{Lock, Lrc};
14 use rustc_errors::registry::Registry;
15 use rustc_metadata::dynamic_lib::DynamicLibrary;
16 use rustc_resolve::{self, Resolver};
17 use rustc_span::edition::Edition;
18 use rustc_span::source_map::{FileLoader, RealFileLoader, SourceMap};
19 use rustc_span::symbol::{sym, Symbol};
20 use smallvec::SmallVec;
22 use std::io::{self, Write};
24 use std::ops::DerefMut;
25 use std::path::{Path, PathBuf};
26 use std::sync::{Arc, Mutex, Once};
27 #[cfg(not(parallel_compiler))]
28 use std::{panic, thread};
29 use syntax::ast::{AttrVec, BlockCheckMode};
30 use syntax::mut_visit::{visit_clobber, MutVisitor, *};
32 use syntax::util::lev_distance::find_best_match_for_name;
33 use syntax::{self, ast, attr};
35 /// Adds `target_feature = "..."` cfgs for a variety of platform
36 /// specific features (SSE, NEON etc.).
38 /// This is performed by checking whether a whitelisted set of
39 /// features is available on the target machine, by querying LLVM.
40 pub fn add_configuration(
41 cfg: &mut ast::CrateConfig,
43 codegen_backend: &dyn CodegenBackend,
45 let tf = sym::target_feature;
47 cfg.extend(codegen_backend.target_features(sess).into_iter().map(|feat| (tf, Some(feat))));
49 if sess.crt_static_feature() {
50 cfg.insert((tf, Some(Symbol::intern("crt-static"))));
54 pub fn create_session(
55 sopts: config::Options,
56 cfg: FxHashSet<(String, Option<String>)>,
57 diagnostic_output: DiagnosticOutput,
58 file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
59 input_path: Option<PathBuf>,
60 lint_caps: FxHashMap<lint::LintId, lint::Level>,
61 descriptions: Registry,
62 ) -> (Lrc<Session>, Lrc<Box<dyn CodegenBackend>>, Lrc<SourceMap>) {
63 let loader = file_loader.unwrap_or(box RealFileLoader);
64 let source_map = Lrc::new(SourceMap::with_file_loader(loader, sopts.file_path_mapping()));
65 let mut sess = session::build_session_with_source_map(
74 let codegen_backend = get_codegen_backend(&sess);
76 let mut cfg = config::build_configuration(&sess, config::to_crate_config(cfg));
77 add_configuration(&mut cfg, &sess, &*codegen_backend);
78 sess.parse_sess.config = cfg;
80 (Lrc::new(sess), Lrc::new(codegen_backend), source_map)
83 // Temporarily have stack size set to 32MB to deal with various crates with long method
84 // chains or deep syntax trees, except when on Haiku.
85 // FIXME(oli-obk): get https://github.com/rust-lang/rust/pull/55617 the finish line
86 #[cfg(not(target_os = "haiku"))]
87 const STACK_SIZE: usize = 32 * 1024 * 1024;
89 #[cfg(target_os = "haiku")]
90 const STACK_SIZE: usize = 16 * 1024 * 1024;
92 fn get_stack_size() -> Option<usize> {
93 // FIXME: Hacks on hacks. If the env is trying to override the stack size
94 // then *don't* set it explicitly.
95 env::var_os("RUST_MIN_STACK").is_none().then_some(STACK_SIZE)
98 struct Sink(Arc<Mutex<Vec<u8>>>);
100 fn write(&mut self, data: &[u8]) -> io::Result<usize> {
101 Write::write(&mut *self.0.lock().unwrap(), data)
103 fn flush(&mut self) -> io::Result<()> {
108 #[cfg(not(parallel_compiler))]
109 pub fn scoped_thread<F: FnOnce() -> R + Send, R: Send>(cfg: thread::Builder, f: F) -> R {
111 unsafe impl Send for Ptr {}
112 unsafe impl Sync for Ptr {}
115 let run = Ptr(&mut f as *mut _ as *mut ());
116 let mut result = None;
117 let result_ptr = Ptr(&mut result as *mut _ as *mut ());
119 let thread = cfg.spawn(move || {
120 let run = unsafe { (*(run.0 as *mut Option<F>)).take().unwrap() };
121 let result = unsafe { &mut *(result_ptr.0 as *mut Option<R>) };
122 *result = Some(run());
125 match thread.unwrap().join() {
126 Ok(()) => result.unwrap(),
127 Err(p) => panic::resume_unwind(p),
131 #[cfg(not(parallel_compiler))]
132 pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
135 stderr: &Option<Arc<Mutex<Vec<u8>>>>,
138 let mut cfg = thread::Builder::new().name("rustc".to_string());
140 if let Some(size) = get_stack_size() {
141 cfg = cfg.stack_size(size);
144 crate::callbacks::setup_callbacks();
146 scoped_thread(cfg, || {
147 syntax::with_globals(edition, || {
148 ty::tls::GCX_PTR.set(&Lock::new(0), || {
149 if let Some(stderr) = stderr {
150 io::set_panic(Some(box Sink(stderr.clone())));
158 #[cfg(parallel_compiler)]
159 pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
162 stderr: &Option<Arc<Mutex<Vec<u8>>>>,
165 use rayon::{ThreadBuilder, ThreadPool, ThreadPoolBuilder};
167 let gcx_ptr = &Lock::new(0);
168 crate::callbacks::setup_callbacks();
170 let mut config = ThreadPoolBuilder::new()
171 .thread_name(|_| "rustc".to_string())
172 .acquire_thread_handler(jobserver::acquire_thread)
173 .release_thread_handler(jobserver::release_thread)
174 .num_threads(threads)
175 .deadlock_handler(|| unsafe { ty::query::handle_deadlock() });
177 if let Some(size) = get_stack_size() {
178 config = config.stack_size(size);
181 let with_pool = move |pool: &ThreadPool| pool.install(move || f());
183 syntax::with_globals(edition, || {
184 syntax::GLOBALS.with(|syntax_globals| {
185 rustc_span::GLOBALS.with(|rustc_span_globals| {
186 // The main handler runs for each Rayon worker thread and sets up
187 // the thread local rustc uses. syntax_globals and rustc_span_globals are
188 // captured and set on the new threads. ty::tls::with_thread_locals sets up
189 // thread local callbacks from libsyntax
190 let main_handler = move |thread: ThreadBuilder| {
191 syntax::GLOBALS.set(syntax_globals, || {
192 rustc_span::GLOBALS.set(rustc_span_globals, || {
193 if let Some(stderr) = stderr {
194 io::set_panic(Some(box Sink(stderr.clone())));
196 ty::tls::GCX_PTR.set(gcx_ptr, || thread.run())
201 config.build_scoped(main_handler, with_pool).unwrap()
207 fn load_backend_from_dylib(path: &Path) -> fn() -> Box<dyn CodegenBackend> {
208 let lib = DynamicLibrary::open(Some(path)).unwrap_or_else(|err| {
209 let err = format!("couldn't load codegen backend {:?}: {:?}", path, err);
210 early_error(ErrorOutputType::default(), &err);
213 match lib.symbol("__rustc_codegen_backend") {
216 mem::transmute::<*mut u8, _>(f)
220 "couldn't load codegen backend as it \
221 doesn't export the `__rustc_codegen_backend` \
225 early_error(ErrorOutputType::default(), &err);
231 pub fn get_codegen_backend(sess: &Session) -> Box<dyn CodegenBackend> {
232 static INIT: Once = Once::new();
234 static mut LOAD: fn() -> Box<dyn CodegenBackend> = || unreachable!();
237 let codegen_name = sess
242 .unwrap_or(&sess.target.target.options.codegen_backend);
243 let backend = match &codegen_name[..] {
244 filename if filename.contains(".") => load_backend_from_dylib(filename.as_ref()),
245 codegen_name => get_builtin_codegen_backend(codegen_name),
252 let backend = unsafe { LOAD() };
257 // This is used for rustdoc, but it uses similar machinery to codegen backend
258 // loading, so we leave the code here. It is potentially useful for other tools
259 // that want to invoke the rustc binary while linking to rustc as well.
260 pub fn rustc_path<'a>() -> Option<&'a Path> {
261 static RUSTC_PATH: once_cell::sync::OnceCell<Option<PathBuf>> =
262 once_cell::sync::OnceCell::new();
264 const BIN_PATH: &str = env!("RUSTC_INSTALL_BINDIR");
266 RUSTC_PATH.get_or_init(|| get_rustc_path_inner(BIN_PATH)).as_ref().map(|v| &**v)
269 fn get_rustc_path_inner(bin_path: &str) -> Option<PathBuf> {
272 .filter_map(|sysroot| {
273 let candidate = sysroot.join(bin_path).join(if cfg!(target_os = "windows") {
278 candidate.exists().then_some(candidate)
283 fn sysroot_candidates() -> Vec<PathBuf> {
284 let target = session::config::host_triple();
285 let mut sysroot_candidates = vec![filesearch::get_or_default_sysroot()];
286 let path = current_dll_path().and_then(|s| s.canonicalize().ok());
287 if let Some(dll) = path {
288 // use `parent` twice to chop off the file name and then also the
289 // directory containing the dll which should be either `lib` or `bin`.
290 if let Some(path) = dll.parent().and_then(|p| p.parent()) {
291 // The original `path` pointed at the `rustc_driver` crate's dll.
292 // Now that dll should only be in one of two locations. The first is
293 // in the compiler's libdir, for example `$sysroot/lib/*.dll`. The
294 // other is the target's libdir, for example
295 // `$sysroot/lib/rustlib/$target/lib/*.dll`.
297 // We don't know which, so let's assume that if our `path` above
298 // ends in `$target` we *could* be in the target libdir, and always
299 // assume that we may be in the main libdir.
300 sysroot_candidates.push(path.to_owned());
302 if path.ends_with(target) {
303 sysroot_candidates.extend(
304 path.parent() // chop off `$target`
305 .and_then(|p| p.parent()) // chop off `rustlib`
306 .and_then(|p| p.parent()) // chop off `lib`
307 .map(|s| s.to_owned()),
313 return sysroot_candidates;
316 fn current_dll_path() -> Option<PathBuf> {
317 use std::ffi::{CStr, OsStr};
318 use std::os::unix::prelude::*;
321 let addr = current_dll_path as usize as *mut _;
322 let mut info = mem::zeroed();
323 if libc::dladdr(addr, &mut info) == 0 {
324 info!("dladdr failed");
327 if info.dli_fname.is_null() {
328 info!("dladdr returned null pointer");
331 let bytes = CStr::from_ptr(info.dli_fname).to_bytes();
332 let os = OsStr::from_bytes(bytes);
333 Some(PathBuf::from(os))
338 fn current_dll_path() -> Option<PathBuf> {
339 use std::ffi::OsString;
340 use std::os::windows::prelude::*;
343 fn GetModuleHandleExW(dwFlags: u32, lpModuleName: usize, phModule: *mut usize) -> i32;
344 fn GetModuleFileNameW(hModule: usize, lpFilename: *mut u16, nSize: u32) -> u32;
347 const GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS: u32 = 0x00000004;
351 let r = GetModuleHandleExW(
352 GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
353 current_dll_path as usize,
357 info!("GetModuleHandleExW failed: {}", io::Error::last_os_error());
360 let mut space = Vec::with_capacity(1024);
361 let r = GetModuleFileNameW(module, space.as_mut_ptr(), space.capacity() as u32);
363 info!("GetModuleFileNameW failed: {}", io::Error::last_os_error());
367 if r >= space.capacity() {
368 info!("our buffer was too small? {}", io::Error::last_os_error());
372 let os = OsString::from_wide(&space);
373 Some(PathBuf::from(os))
378 pub fn get_builtin_codegen_backend(backend_name: &str) -> fn() -> Box<dyn CodegenBackend> {
379 #[cfg(feature = "llvm")]
381 if backend_name == "llvm" {
382 return rustc_codegen_llvm::LlvmCodegenBackend::new;
386 let err = format!("unsupported builtin codegen backend `{}`", backend_name);
387 early_error(ErrorOutputType::default(), &err);
390 pub(crate) fn compute_crate_disambiguator(session: &Session) -> CrateDisambiguator {
391 use std::hash::Hasher;
393 // The crate_disambiguator is a 128 bit hash. The disambiguator is fed
394 // into various other hashes quite a bit (symbol hashes, incr. comp. hashes,
395 // debuginfo type IDs, etc), so we don't want it to be too wide. 128 bits
396 // should still be safe enough to avoid collisions in practice.
397 let mut hasher = StableHasher::new();
399 let mut metadata = session.opts.cg.metadata.clone();
400 // We don't want the crate_disambiguator to dependent on the order
401 // -C metadata arguments, so sort them:
403 // Every distinct -C metadata value is only incorporated once:
406 hasher.write(b"metadata");
408 // Also incorporate the length of a metadata string, so that we generate
409 // different values for `-Cmetadata=ab -Cmetadata=c` and
410 // `-Cmetadata=a -Cmetadata=bc`
411 hasher.write_usize(s.len());
412 hasher.write(s.as_bytes());
415 // Also incorporate crate type, so that we don't get symbol conflicts when
416 // linking against a library of the same name, if this is an executable.
417 let is_exe = session.crate_types.borrow().contains(&config::CrateType::Executable);
418 hasher.write(if is_exe { b"exe" } else { b"lib" });
420 CrateDisambiguator::from(hasher.finish::<Fingerprint>())
423 pub(crate) fn check_attr_crate_type(attrs: &[ast::Attribute], lint_buffer: &mut lint::LintBuffer) {
424 // Unconditionally collect crate types from attributes to make them used
425 for a in attrs.iter() {
426 if a.check_name(sym::crate_type) {
427 if let Some(n) = a.value_str() {
428 if let Some(_) = categorize_crate_type(n) {
432 if let ast::MetaItemKind::NameValue(spanned) = a.meta().unwrap().kind {
433 let span = spanned.span;
434 let lev_candidate = find_best_match_for_name(
435 CRATE_TYPES.iter().map(|(k, _)| k),
439 if let Some(candidate) = lev_candidate {
440 lint_buffer.buffer_lint_with_diagnostic(
441 lint::builtin::UNKNOWN_CRATE_TYPES,
444 "invalid `crate_type` value",
445 lint::builtin::BuiltinLintDiagnostics::UnknownCrateTypes(
447 "did you mean".to_string(),
448 format!("\"{}\"", candidate),
452 lint_buffer.buffer_lint(
453 lint::builtin::UNKNOWN_CRATE_TYPES,
456 "invalid `crate_type` value",
465 const CRATE_TYPES: &[(Symbol, config::CrateType)] = &[
466 (sym::rlib, config::CrateType::Rlib),
467 (sym::dylib, config::CrateType::Dylib),
468 (sym::cdylib, config::CrateType::Cdylib),
469 (sym::lib, config::default_lib_output()),
470 (sym::staticlib, config::CrateType::Staticlib),
471 (sym::proc_dash_macro, config::CrateType::ProcMacro),
472 (sym::bin, config::CrateType::Executable),
475 fn categorize_crate_type(s: Symbol) -> Option<config::CrateType> {
476 Some(CRATE_TYPES.iter().find(|(key, _)| *key == s)?.1)
479 pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<config::CrateType> {
480 // Unconditionally collect crate types from attributes to make them used
481 let attr_types: Vec<config::CrateType> = attrs
484 if a.check_name(sym::crate_type) {
485 match a.value_str() {
486 Some(s) => categorize_crate_type(s),
495 // If we're generating a test executable, then ignore all other output
496 // styles at all other locations
497 if session.opts.test {
498 return vec![config::CrateType::Executable];
501 // Only check command line flags if present. If no types are specified by
502 // command line, then reuse the empty `base` Vec to hold the types that
503 // will be found in crate attributes.
504 let mut base = session.opts.crate_types.clone();
506 base.extend(attr_types);
508 base.push(::rustc_codegen_utils::link::default_output_for_target(session));
515 base.retain(|crate_type| {
516 let res = !::rustc_codegen_utils::link::invalid_output_for_target(session, *crate_type);
519 session.warn(&format!(
520 "dropping unsupported crate type `{}` for target `{}`",
521 *crate_type, session.opts.target_triple
531 pub fn build_output_filenames(
533 odir: &Option<PathBuf>,
534 ofile: &Option<PathBuf>,
535 attrs: &[ast::Attribute],
537 ) -> OutputFilenames {
540 // "-" as input file will cause the parser to read from stdin so we
541 // have to make up a name
542 // We want to toss everything after the final '.'
543 let dirpath = (*odir).as_ref().cloned().unwrap_or_default();
545 // If a crate name is present, we use it as the link name
550 .or_else(|| attr::find_crate_name(attrs).map(|n| n.to_string()))
551 .unwrap_or_else(|| input.filestem().to_owned());
554 out_directory: dirpath,
556 single_output_file: None,
557 extra: sess.opts.cg.extra_filename.clone(),
558 outputs: sess.opts.output_types.clone(),
562 Some(ref out_file) => {
563 let unnamed_output_types =
564 sess.opts.output_types.values().filter(|a| a.is_none()).count();
565 let ofile = if unnamed_output_types > 1 {
567 "due to multiple output types requested, the explicitly specified \
568 output file name will be adapted for each output type",
572 if !sess.opts.cg.extra_filename.is_empty() {
573 sess.warn("ignoring -C extra-filename flag due to -o flag");
575 Some(out_file.clone())
578 sess.warn("ignoring --out-dir flag due to -o flag");
582 out_directory: out_file.parent().unwrap_or_else(|| Path::new("")).to_path_buf(),
583 out_filestem: out_file
589 single_output_file: ofile,
590 extra: sess.opts.cg.extra_filename.clone(),
591 outputs: sess.opts.output_types.clone(),
597 // Note: Also used by librustdoc, see PR #43348. Consider moving this struct elsewhere.
599 // FIXME: Currently the `everybody_loops` transformation is not applied to:
600 // * `const fn`, due to issue #43636 that `loop` is not supported for const evaluation. We are
601 // waiting for miri to fix that.
602 // * `impl Trait`, due to issue #43869 that functions returning impl Trait cannot be diverging.
603 // Solving this may require `!` to implement every trait, which relies on the an even more
604 // ambitious form of the closed RFC #1637. See also [#34511].
606 // [#34511]: https://github.com/rust-lang/rust/issues/34511#issuecomment-322340401
607 pub struct ReplaceBodyWithLoop<'a, 'b> {
608 within_static_or_const: bool,
609 nested_blocks: Option<Vec<ast::Block>>,
610 resolver: &'a mut Resolver<'b>,
613 impl<'a, 'b> ReplaceBodyWithLoop<'a, 'b> {
614 pub fn new(resolver: &'a mut Resolver<'b>) -> ReplaceBodyWithLoop<'a, 'b> {
615 ReplaceBodyWithLoop { within_static_or_const: false, nested_blocks: None, resolver }
618 fn run<R, F: FnOnce(&mut Self) -> R>(&mut self, is_const: bool, action: F) -> R {
619 let old_const = mem::replace(&mut self.within_static_or_const, is_const);
620 let old_blocks = self.nested_blocks.take();
621 let ret = action(self);
622 self.within_static_or_const = old_const;
623 self.nested_blocks = old_blocks;
627 fn should_ignore_fn(ret_ty: &ast::FunctionRetTy) -> bool {
628 if let ast::FunctionRetTy::Ty(ref ty) = ret_ty {
629 fn involves_impl_trait(ty: &ast::Ty) -> bool {
631 ast::TyKind::ImplTrait(..) => true,
632 ast::TyKind::Slice(ref subty)
633 | ast::TyKind::Array(ref subty, _)
634 | ast::TyKind::Ptr(ast::MutTy { ty: ref subty, .. })
635 | ast::TyKind::Rptr(_, ast::MutTy { ty: ref subty, .. })
636 | ast::TyKind::Paren(ref subty) => involves_impl_trait(subty),
637 ast::TyKind::Tup(ref tys) => any_involves_impl_trait(tys.iter()),
638 ast::TyKind::Path(_, ref path) => path.segments.iter().any(|seg| {
639 match seg.args.as_ref().map(|generic_arg| &**generic_arg) {
641 Some(&ast::GenericArgs::AngleBracketed(ref data)) => {
642 let types = data.args.iter().filter_map(|arg| match arg {
643 ast::GenericArg::Type(ty) => Some(ty),
646 any_involves_impl_trait(types.into_iter())
647 || data.constraints.iter().any(|c| match c.kind {
648 ast::AssocTyConstraintKind::Bound { .. } => true,
649 ast::AssocTyConstraintKind::Equality { ref ty } => {
650 involves_impl_trait(ty)
654 Some(&ast::GenericArgs::Parenthesized(ref data)) => {
655 any_involves_impl_trait(data.inputs.iter())
656 || ReplaceBodyWithLoop::should_ignore_fn(&data.output)
664 fn any_involves_impl_trait<'a, I: Iterator<Item = &'a P<ast::Ty>>>(mut it: I) -> bool {
665 it.any(|subty| involves_impl_trait(subty))
668 involves_impl_trait(ty)
674 fn is_sig_const(sig: &ast::FnSig) -> bool {
675 sig.header.constness.node == ast::Constness::Const
676 || ReplaceBodyWithLoop::should_ignore_fn(&sig.decl.output)
680 impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
681 fn visit_item_kind(&mut self, i: &mut ast::ItemKind) {
682 let is_const = match i {
683 ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => true,
684 ast::ItemKind::Fn(ref sig, _, _) => Self::is_sig_const(sig),
687 self.run(is_const, |s| noop_visit_item_kind(i, s))
690 fn flat_map_trait_item(&mut self, i: ast::AssocItem) -> SmallVec<[ast::AssocItem; 1]> {
691 let is_const = match i.kind {
692 ast::AssocItemKind::Const(..) => true,
693 ast::AssocItemKind::Fn(ref sig, _) => Self::is_sig_const(sig),
696 self.run(is_const, |s| noop_flat_map_assoc_item(i, s))
699 fn flat_map_impl_item(&mut self, i: ast::AssocItem) -> SmallVec<[ast::AssocItem; 1]> {
700 self.flat_map_trait_item(i)
703 fn visit_anon_const(&mut self, c: &mut ast::AnonConst) {
704 self.run(true, |s| noop_visit_anon_const(c, s))
707 fn visit_block(&mut self, b: &mut P<ast::Block>) {
709 rules: ast::BlockCheckMode,
710 s: Option<ast::Stmt>,
711 resolver: &mut Resolver<'_>,
714 stmts: s.into_iter().collect(),
716 id: resolver.next_node_id(),
717 span: rustc_span::DUMMY_SP,
721 fn block_to_stmt(b: ast::Block, resolver: &mut Resolver<'_>) -> ast::Stmt {
722 let expr = P(ast::Expr {
723 id: resolver.next_node_id(),
724 kind: ast::ExprKind::Block(P(b), None),
725 span: rustc_span::DUMMY_SP,
726 attrs: AttrVec::new(),
730 id: resolver.next_node_id(),
731 kind: ast::StmtKind::Expr(expr),
732 span: rustc_span::DUMMY_SP,
736 let empty_block = stmt_to_block(BlockCheckMode::Default, None, self.resolver);
737 let loop_expr = P(ast::Expr {
738 kind: ast::ExprKind::Loop(P(empty_block), None),
739 id: self.resolver.next_node_id(),
740 span: rustc_span::DUMMY_SP,
741 attrs: AttrVec::new(),
744 let loop_stmt = ast::Stmt {
745 id: self.resolver.next_node_id(),
746 span: rustc_span::DUMMY_SP,
747 kind: ast::StmtKind::Expr(loop_expr),
750 if self.within_static_or_const {
751 noop_visit_block(b, self)
753 visit_clobber(b.deref_mut(), |b| {
754 let mut stmts = vec![];
756 let old_blocks = self.nested_blocks.replace(vec![]);
758 stmts.extend(self.flat_map_stmt(s).into_iter().filter(|s| s.is_item()));
760 // we put a Some in there earlier with that replace(), so this is valid
761 let new_blocks = self.nested_blocks.take().unwrap();
762 self.nested_blocks = old_blocks;
763 stmts.extend(new_blocks.into_iter().map(|b| block_to_stmt(b, self.resolver)));
766 let mut new_block = ast::Block { stmts, ..b };
768 if let Some(old_blocks) = self.nested_blocks.as_mut() {
769 //push our fresh block onto the cache and yield an empty block with `loop {}`
770 if !new_block.stmts.is_empty() {
771 old_blocks.push(new_block);
774 stmt_to_block(b.rules, Some(loop_stmt), &mut self.resolver)
776 //push `loop {}` onto the end of our fresh block and yield that
777 new_block.stmts.push(loop_stmt);
785 // in general the pretty printer processes unexpanded code, so
786 // we override the default `visit_mac` method which panics.
787 fn visit_mac(&mut self, mac: &mut ast::Mac) {
788 noop_visit_mac(mac, self)