4 use rustc_codegen_utils::codegen_backend::CodegenBackend;
5 use rustc_data_structures::fingerprint::Fingerprint;
6 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
7 #[cfg(parallel_compiler)]
8 use rustc_data_structures::jobserver;
9 use rustc_data_structures::stable_hasher::StableHasher;
10 use rustc_data_structures::sync::{Lock, Lrc};
11 use rustc_errors::registry::Registry;
12 use rustc_metadata::dynamic_lib::DynamicLibrary;
13 use rustc_resolve::{self, Resolver};
14 use rustc_session as session;
15 use rustc_session::config::{ErrorOutputType, Input, OutputFilenames};
16 use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
17 use rustc_session::parse::CrateConfig;
18 use rustc_session::CrateDisambiguator;
19 use rustc_session::{config, early_error, filesearch, DiagnosticOutput, Session};
20 use rustc_span::edition::Edition;
21 use rustc_span::source_map::{FileLoader, RealFileLoader, SourceMap};
22 use rustc_span::symbol::{sym, Symbol};
23 use smallvec::SmallVec;
25 use std::io::{self, Write};
27 use std::ops::DerefMut;
28 use std::path::{Path, PathBuf};
29 use std::sync::{Arc, Mutex, Once};
30 #[cfg(not(parallel_compiler))]
31 use std::{panic, thread};
32 use syntax::ast::{AttrVec, BlockCheckMode};
33 use syntax::mut_visit::{visit_clobber, MutVisitor, *};
35 use syntax::util::lev_distance::find_best_match_for_name;
36 use syntax::{self, ast};
38 /// Adds `target_feature = "..."` cfgs for a variety of platform
39 /// specific features (SSE, NEON etc.).
41 /// This is performed by checking whether a whitelisted set of
42 /// features is available on the target machine, by querying LLVM.
43 pub fn add_configuration(
44 cfg: &mut CrateConfig,
46 codegen_backend: &dyn CodegenBackend,
48 let tf = sym::target_feature;
50 cfg.extend(codegen_backend.target_features(sess).into_iter().map(|feat| (tf, Some(feat))));
52 if sess.crt_static_feature() {
53 cfg.insert((tf, Some(Symbol::intern("crt-static"))));
57 pub fn create_session(
58 sopts: config::Options,
59 cfg: FxHashSet<(String, Option<String>)>,
60 diagnostic_output: DiagnosticOutput,
61 file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
62 input_path: Option<PathBuf>,
63 lint_caps: FxHashMap<lint::LintId, lint::Level>,
64 descriptions: Registry,
65 ) -> (Lrc<Session>, Lrc<Box<dyn CodegenBackend>>, Lrc<SourceMap>) {
66 let loader = file_loader.unwrap_or(box RealFileLoader);
67 let source_map = Lrc::new(SourceMap::with_file_loader(loader, sopts.file_path_mapping()));
68 let mut sess = session::build_session_with_source_map(
77 let codegen_backend = get_codegen_backend(&sess);
79 let mut cfg = config::build_configuration(&sess, config::to_crate_config(cfg));
80 add_configuration(&mut cfg, &sess, &*codegen_backend);
81 sess.parse_sess.config = cfg;
83 (Lrc::new(sess), Lrc::new(codegen_backend), source_map)
86 // Temporarily have stack size set to 32MB to deal with various crates with long method
87 // chains or deep syntax trees, except when on Haiku.
88 // FIXME(oli-obk): get https://github.com/rust-lang/rust/pull/55617 the finish line
89 #[cfg(not(target_os = "haiku"))]
90 const STACK_SIZE: usize = 32 * 1024 * 1024;
92 #[cfg(target_os = "haiku")]
93 const STACK_SIZE: usize = 16 * 1024 * 1024;
95 fn get_stack_size() -> Option<usize> {
96 // FIXME: Hacks on hacks. If the env is trying to override the stack size
97 // then *don't* set it explicitly.
98 env::var_os("RUST_MIN_STACK").is_none().then_some(STACK_SIZE)
101 struct Sink(Arc<Mutex<Vec<u8>>>);
102 impl Write for Sink {
103 fn write(&mut self, data: &[u8]) -> io::Result<usize> {
104 Write::write(&mut *self.0.lock().unwrap(), data)
106 fn flush(&mut self) -> io::Result<()> {
111 #[cfg(not(parallel_compiler))]
112 pub fn scoped_thread<F: FnOnce() -> R + Send, R: Send>(cfg: thread::Builder, f: F) -> R {
114 unsafe impl Send for Ptr {}
115 unsafe impl Sync for Ptr {}
118 let run = Ptr(&mut f as *mut _ as *mut ());
119 let mut result = None;
120 let result_ptr = Ptr(&mut result as *mut _ as *mut ());
122 let thread = cfg.spawn(move || {
123 let run = unsafe { (*(run.0 as *mut Option<F>)).take().unwrap() };
124 let result = unsafe { &mut *(result_ptr.0 as *mut Option<R>) };
125 *result = Some(run());
128 match thread.unwrap().join() {
129 Ok(()) => result.unwrap(),
130 Err(p) => panic::resume_unwind(p),
134 #[cfg(not(parallel_compiler))]
135 pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
138 stderr: &Option<Arc<Mutex<Vec<u8>>>>,
141 let mut cfg = thread::Builder::new().name("rustc".to_string());
143 if let Some(size) = get_stack_size() {
144 cfg = cfg.stack_size(size);
147 crate::callbacks::setup_callbacks();
149 scoped_thread(cfg, || {
150 syntax::with_globals(edition, || {
151 ty::tls::GCX_PTR.set(&Lock::new(0), || {
152 if let Some(stderr) = stderr {
153 io::set_panic(Some(box Sink(stderr.clone())));
161 #[cfg(parallel_compiler)]
162 pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
165 stderr: &Option<Arc<Mutex<Vec<u8>>>>,
168 use rayon::{ThreadBuilder, ThreadPool, ThreadPoolBuilder};
170 let gcx_ptr = &Lock::new(0);
171 crate::callbacks::setup_callbacks();
173 let mut config = ThreadPoolBuilder::new()
174 .thread_name(|_| "rustc".to_string())
175 .acquire_thread_handler(jobserver::acquire_thread)
176 .release_thread_handler(jobserver::release_thread)
177 .num_threads(threads)
178 .deadlock_handler(|| unsafe { ty::query::handle_deadlock() });
180 if let Some(size) = get_stack_size() {
181 config = config.stack_size(size);
184 let with_pool = move |pool: &ThreadPool| pool.install(move || f());
186 syntax::with_globals(edition, || {
187 syntax::GLOBALS.with(|syntax_globals| {
188 rustc_span::GLOBALS.with(|rustc_span_globals| {
189 // The main handler runs for each Rayon worker thread and sets up
190 // the thread local rustc uses. syntax_globals and rustc_span_globals are
191 // captured and set on the new threads. ty::tls::with_thread_locals sets up
192 // thread local callbacks from libsyntax
193 let main_handler = move |thread: ThreadBuilder| {
194 syntax::GLOBALS.set(syntax_globals, || {
195 rustc_span::GLOBALS.set(rustc_span_globals, || {
196 if let Some(stderr) = stderr {
197 io::set_panic(Some(box Sink(stderr.clone())));
199 ty::tls::GCX_PTR.set(gcx_ptr, || thread.run())
204 config.build_scoped(main_handler, with_pool).unwrap()
210 fn load_backend_from_dylib(path: &Path) -> fn() -> Box<dyn CodegenBackend> {
211 let lib = DynamicLibrary::open(Some(path)).unwrap_or_else(|err| {
212 let err = format!("couldn't load codegen backend {:?}: {:?}", path, err);
213 early_error(ErrorOutputType::default(), &err);
216 match lib.symbol("__rustc_codegen_backend") {
219 mem::transmute::<*mut u8, _>(f)
223 "couldn't load codegen backend as it \
224 doesn't export the `__rustc_codegen_backend` \
228 early_error(ErrorOutputType::default(), &err);
234 pub fn get_codegen_backend(sess: &Session) -> Box<dyn CodegenBackend> {
235 static INIT: Once = Once::new();
237 static mut LOAD: fn() -> Box<dyn CodegenBackend> = || unreachable!();
240 let codegen_name = sess
245 .unwrap_or(&sess.target.target.options.codegen_backend);
246 let backend = match &codegen_name[..] {
247 filename if filename.contains(".") => load_backend_from_dylib(filename.as_ref()),
248 codegen_name => get_builtin_codegen_backend(codegen_name),
255 let backend = unsafe { LOAD() };
260 // This is used for rustdoc, but it uses similar machinery to codegen backend
261 // loading, so we leave the code here. It is potentially useful for other tools
262 // that want to invoke the rustc binary while linking to rustc as well.
263 pub fn rustc_path<'a>() -> Option<&'a Path> {
264 static RUSTC_PATH: once_cell::sync::OnceCell<Option<PathBuf>> =
265 once_cell::sync::OnceCell::new();
267 const BIN_PATH: &str = env!("RUSTC_INSTALL_BINDIR");
269 RUSTC_PATH.get_or_init(|| get_rustc_path_inner(BIN_PATH)).as_ref().map(|v| &**v)
272 fn get_rustc_path_inner(bin_path: &str) -> Option<PathBuf> {
275 .filter_map(|sysroot| {
276 let candidate = sysroot.join(bin_path).join(if cfg!(target_os = "windows") {
281 candidate.exists().then_some(candidate)
286 fn sysroot_candidates() -> Vec<PathBuf> {
287 let target = session::config::host_triple();
288 let mut sysroot_candidates = vec![filesearch::get_or_default_sysroot()];
289 let path = current_dll_path().and_then(|s| s.canonicalize().ok());
290 if let Some(dll) = path {
291 // use `parent` twice to chop off the file name and then also the
292 // directory containing the dll which should be either `lib` or `bin`.
293 if let Some(path) = dll.parent().and_then(|p| p.parent()) {
294 // The original `path` pointed at the `rustc_driver` crate's dll.
295 // Now that dll should only be in one of two locations. The first is
296 // in the compiler's libdir, for example `$sysroot/lib/*.dll`. The
297 // other is the target's libdir, for example
298 // `$sysroot/lib/rustlib/$target/lib/*.dll`.
300 // We don't know which, so let's assume that if our `path` above
301 // ends in `$target` we *could* be in the target libdir, and always
302 // assume that we may be in the main libdir.
303 sysroot_candidates.push(path.to_owned());
305 if path.ends_with(target) {
306 sysroot_candidates.extend(
307 path.parent() // chop off `$target`
308 .and_then(|p| p.parent()) // chop off `rustlib`
309 .and_then(|p| p.parent()) // chop off `lib`
310 .map(|s| s.to_owned()),
316 return sysroot_candidates;
319 fn current_dll_path() -> Option<PathBuf> {
320 use std::ffi::{CStr, OsStr};
321 use std::os::unix::prelude::*;
324 let addr = current_dll_path as usize as *mut _;
325 let mut info = mem::zeroed();
326 if libc::dladdr(addr, &mut info) == 0 {
327 info!("dladdr failed");
330 if info.dli_fname.is_null() {
331 info!("dladdr returned null pointer");
334 let bytes = CStr::from_ptr(info.dli_fname).to_bytes();
335 let os = OsStr::from_bytes(bytes);
336 Some(PathBuf::from(os))
341 fn current_dll_path() -> Option<PathBuf> {
342 use std::ffi::OsString;
343 use std::os::windows::prelude::*;
346 use winapi::um::libloaderapi::{
347 GetModuleFileNameW, GetModuleHandleExW, GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
351 let mut module = ptr::null_mut();
352 let r = GetModuleHandleExW(
353 GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
354 current_dll_path as usize as *mut _,
358 info!("GetModuleHandleExW failed: {}", io::Error::last_os_error());
361 let mut space = Vec::with_capacity(1024);
362 let r = GetModuleFileNameW(module, space.as_mut_ptr(), space.capacity() as u32);
364 info!("GetModuleFileNameW failed: {}", io::Error::last_os_error());
368 if r >= space.capacity() {
369 info!("our buffer was too small? {}", io::Error::last_os_error());
373 let os = OsString::from_wide(&space);
374 Some(PathBuf::from(os))
379 pub fn get_builtin_codegen_backend(backend_name: &str) -> fn() -> Box<dyn CodegenBackend> {
380 #[cfg(feature = "llvm")]
382 if backend_name == "llvm" {
383 return rustc_codegen_llvm::LlvmCodegenBackend::new;
387 let err = format!("unsupported builtin codegen backend `{}`", backend_name);
388 early_error(ErrorOutputType::default(), &err);
391 pub(crate) fn compute_crate_disambiguator(session: &Session) -> CrateDisambiguator {
392 use std::hash::Hasher;
394 // The crate_disambiguator is a 128 bit hash. The disambiguator is fed
395 // into various other hashes quite a bit (symbol hashes, incr. comp. hashes,
396 // debuginfo type IDs, etc), so we don't want it to be too wide. 128 bits
397 // should still be safe enough to avoid collisions in practice.
398 let mut hasher = StableHasher::new();
400 let mut metadata = session.opts.cg.metadata.clone();
401 // We don't want the crate_disambiguator to dependent on the order
402 // -C metadata arguments, so sort them:
404 // Every distinct -C metadata value is only incorporated once:
407 hasher.write(b"metadata");
409 // Also incorporate the length of a metadata string, so that we generate
410 // different values for `-Cmetadata=ab -Cmetadata=c` and
411 // `-Cmetadata=a -Cmetadata=bc`
412 hasher.write_usize(s.len());
413 hasher.write(s.as_bytes());
416 // Also incorporate crate type, so that we don't get symbol conflicts when
417 // linking against a library of the same name, if this is an executable.
418 let is_exe = session.crate_types.borrow().contains(&config::CrateType::Executable);
419 hasher.write(if is_exe { b"exe" } else { b"lib" });
421 CrateDisambiguator::from(hasher.finish::<Fingerprint>())
424 pub(crate) fn check_attr_crate_type(attrs: &[ast::Attribute], lint_buffer: &mut LintBuffer) {
425 // Unconditionally collect crate types from attributes to make them used
426 for a in attrs.iter() {
427 if a.check_name(sym::crate_type) {
428 if let Some(n) = a.value_str() {
429 if let Some(_) = categorize_crate_type(n) {
433 if let ast::MetaItemKind::NameValue(spanned) = a.meta().unwrap().kind {
434 let span = spanned.span;
435 let lev_candidate = find_best_match_for_name(
436 CRATE_TYPES.iter().map(|(k, _)| k),
440 if let Some(candidate) = lev_candidate {
441 lint_buffer.buffer_lint_with_diagnostic(
442 lint::builtin::UNKNOWN_CRATE_TYPES,
445 "invalid `crate_type` value",
446 BuiltinLintDiagnostics::UnknownCrateTypes(
448 "did you mean".to_string(),
449 format!("\"{}\"", candidate),
453 lint_buffer.buffer_lint(
454 lint::builtin::UNKNOWN_CRATE_TYPES,
457 "invalid `crate_type` value",
466 const CRATE_TYPES: &[(Symbol, config::CrateType)] = &[
467 (sym::rlib, config::CrateType::Rlib),
468 (sym::dylib, config::CrateType::Dylib),
469 (sym::cdylib, config::CrateType::Cdylib),
470 (sym::lib, config::default_lib_output()),
471 (sym::staticlib, config::CrateType::Staticlib),
472 (sym::proc_dash_macro, config::CrateType::ProcMacro),
473 (sym::bin, config::CrateType::Executable),
476 fn categorize_crate_type(s: Symbol) -> Option<config::CrateType> {
477 Some(CRATE_TYPES.iter().find(|(key, _)| *key == s)?.1)
480 pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<config::CrateType> {
481 // Unconditionally collect crate types from attributes to make them used
482 let attr_types: Vec<config::CrateType> = attrs
485 if a.check_name(sym::crate_type) {
486 match a.value_str() {
487 Some(s) => categorize_crate_type(s),
496 // If we're generating a test executable, then ignore all other output
497 // styles at all other locations
498 if session.opts.test {
499 return vec![config::CrateType::Executable];
502 // Only check command line flags if present. If no types are specified by
503 // command line, then reuse the empty `base` Vec to hold the types that
504 // will be found in crate attributes.
505 let mut base = session.opts.crate_types.clone();
507 base.extend(attr_types);
509 base.push(::rustc_codegen_utils::link::default_output_for_target(session));
516 base.retain(|crate_type| {
517 let res = !::rustc_codegen_utils::link::invalid_output_for_target(session, *crate_type);
520 session.warn(&format!(
521 "dropping unsupported crate type `{}` for target `{}`",
522 *crate_type, session.opts.target_triple
532 pub fn build_output_filenames(
534 odir: &Option<PathBuf>,
535 ofile: &Option<PathBuf>,
536 attrs: &[ast::Attribute],
538 ) -> OutputFilenames {
541 // "-" as input file will cause the parser to read from stdin so we
542 // have to make up a name
543 // We want to toss everything after the final '.'
544 let dirpath = (*odir).as_ref().cloned().unwrap_or_default();
546 // If a crate name is present, we use it as the link name
551 .or_else(|| rustc_attr::find_crate_name(attrs).map(|n| n.to_string()))
552 .unwrap_or_else(|| input.filestem().to_owned());
554 OutputFilenames::new(
558 sess.opts.cg.extra_filename.clone(),
559 sess.opts.output_types.clone(),
563 Some(ref out_file) => {
564 let unnamed_output_types =
565 sess.opts.output_types.values().filter(|a| a.is_none()).count();
566 let ofile = if unnamed_output_types > 1 {
568 "due to multiple output types requested, the explicitly specified \
569 output file name will be adapted for each output type",
573 if !sess.opts.cg.extra_filename.is_empty() {
574 sess.warn("ignoring -C extra-filename flag due to -o flag");
576 Some(out_file.clone())
579 sess.warn("ignoring --out-dir flag due to -o flag");
582 OutputFilenames::new(
583 out_file.parent().unwrap_or_else(|| Path::new("")).to_path_buf(),
584 out_file.file_stem().unwrap_or_default().to_str().unwrap().to_string(),
586 sess.opts.cg.extra_filename.clone(),
587 sess.opts.output_types.clone(),
593 // Note: Also used by librustdoc, see PR #43348. Consider moving this struct elsewhere.
595 // FIXME: Currently the `everybody_loops` transformation is not applied to:
596 // * `const fn`, due to issue #43636 that `loop` is not supported for const evaluation. We are
597 // waiting for miri to fix that.
598 // * `impl Trait`, due to issue #43869 that functions returning impl Trait cannot be diverging.
599 // Solving this may require `!` to implement every trait, which relies on the an even more
600 // ambitious form of the closed RFC #1637. See also [#34511].
602 // [#34511]: https://github.com/rust-lang/rust/issues/34511#issuecomment-322340401
603 pub struct ReplaceBodyWithLoop<'a, 'b> {
604 within_static_or_const: bool,
605 nested_blocks: Option<Vec<ast::Block>>,
606 resolver: &'a mut Resolver<'b>,
609 impl<'a, 'b> ReplaceBodyWithLoop<'a, 'b> {
610 pub fn new(resolver: &'a mut Resolver<'b>) -> ReplaceBodyWithLoop<'a, 'b> {
611 ReplaceBodyWithLoop { within_static_or_const: false, nested_blocks: None, resolver }
614 fn run<R, F: FnOnce(&mut Self) -> R>(&mut self, is_const: bool, action: F) -> R {
615 let old_const = mem::replace(&mut self.within_static_or_const, is_const);
616 let old_blocks = self.nested_blocks.take();
617 let ret = action(self);
618 self.within_static_or_const = old_const;
619 self.nested_blocks = old_blocks;
623 fn should_ignore_fn(ret_ty: &ast::FunctionRetTy) -> bool {
624 if let ast::FunctionRetTy::Ty(ref ty) = ret_ty {
625 fn involves_impl_trait(ty: &ast::Ty) -> bool {
627 ast::TyKind::ImplTrait(..) => true,
628 ast::TyKind::Slice(ref subty)
629 | ast::TyKind::Array(ref subty, _)
630 | ast::TyKind::Ptr(ast::MutTy { ty: ref subty, .. })
631 | ast::TyKind::Rptr(_, ast::MutTy { ty: ref subty, .. })
632 | ast::TyKind::Paren(ref subty) => involves_impl_trait(subty),
633 ast::TyKind::Tup(ref tys) => any_involves_impl_trait(tys.iter()),
634 ast::TyKind::Path(_, ref path) => path.segments.iter().any(|seg| {
635 match seg.args.as_ref().map(|generic_arg| &**generic_arg) {
637 Some(&ast::GenericArgs::AngleBracketed(ref data)) => {
638 let types = data.args.iter().filter_map(|arg| match arg {
639 ast::GenericArg::Type(ty) => Some(ty),
642 any_involves_impl_trait(types.into_iter())
643 || data.constraints.iter().any(|c| match c.kind {
644 ast::AssocTyConstraintKind::Bound { .. } => true,
645 ast::AssocTyConstraintKind::Equality { ref ty } => {
646 involves_impl_trait(ty)
650 Some(&ast::GenericArgs::Parenthesized(ref data)) => {
651 any_involves_impl_trait(data.inputs.iter())
652 || ReplaceBodyWithLoop::should_ignore_fn(&data.output)
660 fn any_involves_impl_trait<'a, I: Iterator<Item = &'a P<ast::Ty>>>(mut it: I) -> bool {
661 it.any(|subty| involves_impl_trait(subty))
664 involves_impl_trait(ty)
670 fn is_sig_const(sig: &ast::FnSig) -> bool {
671 matches!(sig.header.constness, ast::Const::Yes(_))
672 || ReplaceBodyWithLoop::should_ignore_fn(&sig.decl.output)
676 impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
677 fn visit_item_kind(&mut self, i: &mut ast::ItemKind) {
678 let is_const = match i {
679 ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => true,
680 ast::ItemKind::Fn(ref sig, _, _) => Self::is_sig_const(sig),
683 self.run(is_const, |s| noop_visit_item_kind(i, s))
686 fn flat_map_trait_item(&mut self, i: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
687 let is_const = match i.kind {
688 ast::AssocItemKind::Const(..) => true,
689 ast::AssocItemKind::Fn(ref sig, _, _) => Self::is_sig_const(sig),
692 self.run(is_const, |s| noop_flat_map_assoc_item(i, s))
695 fn flat_map_impl_item(&mut self, i: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
696 self.flat_map_trait_item(i)
699 fn visit_anon_const(&mut self, c: &mut ast::AnonConst) {
700 self.run(true, |s| noop_visit_anon_const(c, s))
703 fn visit_block(&mut self, b: &mut P<ast::Block>) {
705 rules: ast::BlockCheckMode,
706 s: Option<ast::Stmt>,
707 resolver: &mut Resolver<'_>,
710 stmts: s.into_iter().collect(),
712 id: resolver.next_node_id(),
713 span: rustc_span::DUMMY_SP,
717 fn block_to_stmt(b: ast::Block, resolver: &mut Resolver<'_>) -> ast::Stmt {
718 let expr = P(ast::Expr {
719 id: resolver.next_node_id(),
720 kind: ast::ExprKind::Block(P(b), None),
721 span: rustc_span::DUMMY_SP,
722 attrs: AttrVec::new(),
726 id: resolver.next_node_id(),
727 kind: ast::StmtKind::Expr(expr),
728 span: rustc_span::DUMMY_SP,
732 let empty_block = stmt_to_block(BlockCheckMode::Default, None, self.resolver);
733 let loop_expr = P(ast::Expr {
734 kind: ast::ExprKind::Loop(P(empty_block), None),
735 id: self.resolver.next_node_id(),
736 span: rustc_span::DUMMY_SP,
737 attrs: AttrVec::new(),
740 let loop_stmt = ast::Stmt {
741 id: self.resolver.next_node_id(),
742 span: rustc_span::DUMMY_SP,
743 kind: ast::StmtKind::Expr(loop_expr),
746 if self.within_static_or_const {
747 noop_visit_block(b, self)
749 visit_clobber(b.deref_mut(), |b| {
750 let mut stmts = vec![];
752 let old_blocks = self.nested_blocks.replace(vec![]);
754 stmts.extend(self.flat_map_stmt(s).into_iter().filter(|s| s.is_item()));
756 // we put a Some in there earlier with that replace(), so this is valid
757 let new_blocks = self.nested_blocks.take().unwrap();
758 self.nested_blocks = old_blocks;
759 stmts.extend(new_blocks.into_iter().map(|b| block_to_stmt(b, self.resolver)));
762 let mut new_block = ast::Block { stmts, ..b };
764 if let Some(old_blocks) = self.nested_blocks.as_mut() {
765 //push our fresh block onto the cache and yield an empty block with `loop {}`
766 if !new_block.stmts.is_empty() {
767 old_blocks.push(new_block);
770 stmt_to_block(b.rules, Some(loop_stmt), &mut self.resolver)
772 //push `loop {}` onto the end of our fresh block and yield that
773 new_block.stmts.push(loop_stmt);
781 // in general the pretty printer processes unexpanded code, so
782 // we override the default `visit_mac` method which panics.
783 fn visit_mac(&mut self, mac: &mut ast::Mac) {
784 noop_visit_mac(mac, self)