2 use rustc_ast::ast::{AttrVec, BlockCheckMode};
3 use rustc_ast::mut_visit::{visit_clobber, MutVisitor, *};
5 use rustc_ast::util::lev_distance::find_best_match_for_name;
6 use rustc_ast::{self, ast};
7 use rustc_codegen_ssa::traits::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;
17 use rustc_resolve::{self, Resolver};
18 use rustc_session as session;
19 use rustc_session::config::{self, CrateType};
20 use rustc_session::config::{ErrorOutputType, Input, OutputFilenames};
21 use rustc_session::lint::{self, BuiltinLintDiagnostics, LintBuffer};
22 use rustc_session::parse::CrateConfig;
23 use rustc_session::CrateDisambiguator;
24 use rustc_session::{early_error, filesearch, output, DiagnosticOutput, Session};
25 use rustc_span::edition::Edition;
26 use rustc_span::source_map::{FileLoader, SourceMap};
27 use rustc_span::symbol::{sym, Symbol};
28 use smallvec::SmallVec;
30 use std::io::{self, Write};
32 use std::ops::DerefMut;
33 use std::path::{Path, PathBuf};
34 use std::sync::{Arc, Mutex, Once};
35 #[cfg(not(parallel_compiler))]
36 use std::{panic, thread};
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(None) {
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 (mut sess, source_map) = session::build_session_with_source_map(
75 let codegen_backend = get_codegen_backend(&sess);
77 let mut cfg = config::build_configuration(&sess, config::to_crate_config(cfg));
78 add_configuration(&mut cfg, &sess, &*codegen_backend);
79 sess.parse_sess.config = cfg;
81 (Lrc::new(sess), Lrc::new(codegen_backend), source_map)
84 const STACK_SIZE: usize = 8 * 1024 * 1024;
86 fn get_stack_size() -> Option<usize> {
87 // FIXME: Hacks on hacks. If the env is trying to override the stack size
88 // then *don't* set it explicitly.
89 env::var_os("RUST_MIN_STACK").is_none().then_some(STACK_SIZE)
92 struct Sink(Arc<Mutex<Vec<u8>>>);
94 fn write(&mut self, data: &[u8]) -> io::Result<usize> {
95 Write::write(&mut *self.0.lock().unwrap(), data)
97 fn flush(&mut self) -> io::Result<()> {
102 #[cfg(not(parallel_compiler))]
103 pub fn scoped_thread<F: FnOnce() -> R + Send, R: Send>(cfg: thread::Builder, f: F) -> R {
105 unsafe impl Send for Ptr {}
106 unsafe impl Sync for Ptr {}
109 let run = Ptr(&mut f as *mut _ as *mut ());
110 let mut result = None;
111 let result_ptr = Ptr(&mut result as *mut _ as *mut ());
113 let thread = cfg.spawn(move || {
114 let run = unsafe { (*(run.0 as *mut Option<F>)).take().unwrap() };
115 let result = unsafe { &mut *(result_ptr.0 as *mut Option<R>) };
116 *result = Some(run());
119 match thread.unwrap().join() {
120 Ok(()) => result.unwrap(),
121 Err(p) => panic::resume_unwind(p),
125 #[cfg(not(parallel_compiler))]
126 pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
129 stderr: &Option<Arc<Mutex<Vec<u8>>>>,
132 let mut cfg = thread::Builder::new().name("rustc".to_string());
134 if let Some(size) = get_stack_size() {
135 cfg = cfg.stack_size(size);
138 crate::callbacks::setup_callbacks();
140 scoped_thread(cfg, || {
141 rustc_ast::with_globals(edition, || {
142 ty::tls::GCX_PTR.set(&Lock::new(0), || {
143 if let Some(stderr) = stderr {
144 io::set_panic(Some(box Sink(stderr.clone())));
152 #[cfg(parallel_compiler)]
153 pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
156 stderr: &Option<Arc<Mutex<Vec<u8>>>>,
159 use rayon::{ThreadBuilder, ThreadPool, ThreadPoolBuilder};
161 let gcx_ptr = &Lock::new(0);
162 crate::callbacks::setup_callbacks();
164 let mut config = ThreadPoolBuilder::new()
165 .thread_name(|_| "rustc".to_string())
166 .acquire_thread_handler(jobserver::acquire_thread)
167 .release_thread_handler(jobserver::release_thread)
168 .num_threads(threads)
169 .deadlock_handler(|| unsafe { ty::query::handle_deadlock() });
171 if let Some(size) = get_stack_size() {
172 config = config.stack_size(size);
175 let with_pool = move |pool: &ThreadPool| pool.install(move || f());
177 rustc_ast::with_globals(edition, || {
178 rustc_ast::GLOBALS.with(|syntax_globals| {
179 rustc_span::GLOBALS.with(|rustc_span_globals| {
180 // The main handler runs for each Rayon worker thread and sets up
181 // the thread local rustc uses. syntax_globals and rustc_span_globals are
182 // captured and set on the new threads. ty::tls::with_thread_locals sets up
183 // thread local callbacks from librustc_ast
184 let main_handler = move |thread: ThreadBuilder| {
185 rustc_ast::GLOBALS.set(syntax_globals, || {
186 rustc_span::GLOBALS.set(rustc_span_globals, || {
187 if let Some(stderr) = stderr {
188 io::set_panic(Some(box Sink(stderr.clone())));
190 ty::tls::GCX_PTR.set(gcx_ptr, || thread.run())
195 config.build_scoped(main_handler, with_pool).unwrap()
201 fn load_backend_from_dylib(path: &Path) -> fn() -> Box<dyn CodegenBackend> {
202 let lib = DynamicLibrary::open(path).unwrap_or_else(|err| {
203 let err = format!("couldn't load codegen backend {:?}: {:?}", path, err);
204 early_error(ErrorOutputType::default(), &err);
207 match lib.symbol("__rustc_codegen_backend") {
210 mem::transmute::<*mut u8, _>(f)
214 "couldn't load codegen backend as it \
215 doesn't export the `__rustc_codegen_backend` \
219 early_error(ErrorOutputType::default(), &err);
225 pub fn get_codegen_backend(sess: &Session) -> Box<dyn CodegenBackend> {
226 static INIT: Once = Once::new();
228 static mut LOAD: fn() -> Box<dyn CodegenBackend> = || unreachable!();
231 let codegen_name = sess
236 .unwrap_or(&sess.target.target.options.codegen_backend);
237 let backend = match &codegen_name[..] {
238 filename if filename.contains('.') => load_backend_from_dylib(filename.as_ref()),
239 codegen_name => get_builtin_codegen_backend(codegen_name),
246 let backend = unsafe { LOAD() };
251 // This is used for rustdoc, but it uses similar machinery to codegen backend
252 // loading, so we leave the code here. It is potentially useful for other tools
253 // that want to invoke the rustc binary while linking to rustc as well.
254 pub fn rustc_path<'a>() -> Option<&'a Path> {
255 static RUSTC_PATH: once_cell::sync::OnceCell<Option<PathBuf>> =
256 once_cell::sync::OnceCell::new();
258 const BIN_PATH: &str = env!("RUSTC_INSTALL_BINDIR");
260 RUSTC_PATH.get_or_init(|| get_rustc_path_inner(BIN_PATH)).as_ref().map(|v| &**v)
263 fn get_rustc_path_inner(bin_path: &str) -> Option<PathBuf> {
264 sysroot_candidates().iter().find_map(|sysroot| {
265 let candidate = sysroot.join(bin_path).join(if cfg!(target_os = "windows") {
270 candidate.exists().then_some(candidate)
274 fn sysroot_candidates() -> Vec<PathBuf> {
275 let target = session::config::host_triple();
276 let mut sysroot_candidates = vec![filesearch::get_or_default_sysroot()];
277 let path = current_dll_path().and_then(|s| s.canonicalize().ok());
278 if let Some(dll) = path {
279 // use `parent` twice to chop off the file name and then also the
280 // directory containing the dll which should be either `lib` or `bin`.
281 if let Some(path) = dll.parent().and_then(|p| p.parent()) {
282 // The original `path` pointed at the `rustc_driver` crate's dll.
283 // Now that dll should only be in one of two locations. The first is
284 // in the compiler's libdir, for example `$sysroot/lib/*.dll`. The
285 // other is the target's libdir, for example
286 // `$sysroot/lib/rustlib/$target/lib/*.dll`.
288 // We don't know which, so let's assume that if our `path` above
289 // ends in `$target` we *could* be in the target libdir, and always
290 // assume that we may be in the main libdir.
291 sysroot_candidates.push(path.to_owned());
293 if path.ends_with(target) {
294 sysroot_candidates.extend(
295 path.parent() // chop off `$target`
296 .and_then(|p| p.parent()) // chop off `rustlib`
297 .and_then(|p| p.parent()) // chop off `lib`
298 .map(|s| s.to_owned()),
304 return sysroot_candidates;
307 fn current_dll_path() -> Option<PathBuf> {
308 use std::ffi::{CStr, OsStr};
309 use std::os::unix::prelude::*;
312 let addr = current_dll_path as usize as *mut _;
313 let mut info = mem::zeroed();
314 if libc::dladdr(addr, &mut info) == 0 {
315 info!("dladdr failed");
318 if info.dli_fname.is_null() {
319 info!("dladdr returned null pointer");
322 let bytes = CStr::from_ptr(info.dli_fname).to_bytes();
323 let os = OsStr::from_bytes(bytes);
324 Some(PathBuf::from(os))
329 fn current_dll_path() -> Option<PathBuf> {
330 use std::ffi::OsString;
331 use std::os::windows::prelude::*;
334 use winapi::um::libloaderapi::{
335 GetModuleFileNameW, GetModuleHandleExW, GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
339 let mut module = ptr::null_mut();
340 let r = GetModuleHandleExW(
341 GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
342 current_dll_path as usize as *mut _,
346 info!("GetModuleHandleExW failed: {}", io::Error::last_os_error());
349 let mut space = Vec::with_capacity(1024);
350 let r = GetModuleFileNameW(module, space.as_mut_ptr(), space.capacity() as u32);
352 info!("GetModuleFileNameW failed: {}", io::Error::last_os_error());
356 if r >= space.capacity() {
357 info!("our buffer was too small? {}", io::Error::last_os_error());
361 let os = OsString::from_wide(&space);
362 Some(PathBuf::from(os))
367 pub fn get_builtin_codegen_backend(backend_name: &str) -> fn() -> Box<dyn CodegenBackend> {
368 #[cfg(feature = "llvm")]
370 if backend_name == "llvm" {
371 return rustc_codegen_llvm::LlvmCodegenBackend::new;
375 let err = format!("unsupported builtin codegen backend `{}`", backend_name);
376 early_error(ErrorOutputType::default(), &err);
379 pub(crate) fn compute_crate_disambiguator(session: &Session) -> CrateDisambiguator {
380 use std::hash::Hasher;
382 // The crate_disambiguator is a 128 bit hash. The disambiguator is fed
383 // into various other hashes quite a bit (symbol hashes, incr. comp. hashes,
384 // debuginfo type IDs, etc), so we don't want it to be too wide. 128 bits
385 // should still be safe enough to avoid collisions in practice.
386 let mut hasher = StableHasher::new();
388 let mut metadata = session.opts.cg.metadata.clone();
389 // We don't want the crate_disambiguator to dependent on the order
390 // -C metadata arguments, so sort them:
392 // Every distinct -C metadata value is only incorporated once:
395 hasher.write(b"metadata");
397 // Also incorporate the length of a metadata string, so that we generate
398 // different values for `-Cmetadata=ab -Cmetadata=c` and
399 // `-Cmetadata=a -Cmetadata=bc`
400 hasher.write_usize(s.len());
401 hasher.write(s.as_bytes());
404 // Also incorporate crate type, so that we don't get symbol conflicts when
405 // linking against a library of the same name, if this is an executable.
406 let is_exe = session.crate_types.borrow().contains(&CrateType::Executable);
407 hasher.write(if is_exe { b"exe" } else { b"lib" });
409 CrateDisambiguator::from(hasher.finish::<Fingerprint>())
412 pub(crate) fn check_attr_crate_type(attrs: &[ast::Attribute], lint_buffer: &mut LintBuffer) {
413 // Unconditionally collect crate types from attributes to make them used
414 for a in attrs.iter() {
415 if a.check_name(sym::crate_type) {
416 if let Some(n) = a.value_str() {
417 if categorize_crate_type(n).is_some() {
421 if let ast::MetaItemKind::NameValue(spanned) = a.meta().unwrap().kind {
422 let span = spanned.span;
423 let lev_candidate = find_best_match_for_name(
424 CRATE_TYPES.iter().map(|(k, _)| k),
428 if let Some(candidate) = lev_candidate {
429 lint_buffer.buffer_lint_with_diagnostic(
430 lint::builtin::UNKNOWN_CRATE_TYPES,
433 "invalid `crate_type` value",
434 BuiltinLintDiagnostics::UnknownCrateTypes(
436 "did you mean".to_string(),
437 format!("\"{}\"", candidate),
441 lint_buffer.buffer_lint(
442 lint::builtin::UNKNOWN_CRATE_TYPES,
445 "invalid `crate_type` value",
454 const CRATE_TYPES: &[(Symbol, CrateType)] = &[
455 (sym::rlib, CrateType::Rlib),
456 (sym::dylib, CrateType::Dylib),
457 (sym::cdylib, CrateType::Cdylib),
458 (sym::lib, config::default_lib_output()),
459 (sym::staticlib, CrateType::Staticlib),
460 (sym::proc_dash_macro, CrateType::ProcMacro),
461 (sym::bin, CrateType::Executable),
464 fn categorize_crate_type(s: Symbol) -> Option<CrateType> {
465 Some(CRATE_TYPES.iter().find(|(key, _)| *key == s)?.1)
468 pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<CrateType> {
469 // Unconditionally collect crate types from attributes to make them used
470 let attr_types: Vec<CrateType> = attrs
473 if a.check_name(sym::crate_type) {
474 match a.value_str() {
475 Some(s) => categorize_crate_type(s),
484 // If we're generating a test executable, then ignore all other output
485 // styles at all other locations
486 if session.opts.test {
487 return vec![CrateType::Executable];
490 // Only check command line flags if present. If no types are specified by
491 // command line, then reuse the empty `base` Vec to hold the types that
492 // will be found in crate attributes.
493 let mut base = session.opts.crate_types.clone();
495 base.extend(attr_types);
497 base.push(output::default_output_for_target(session));
504 base.retain(|crate_type| {
505 let res = !output::invalid_output_for_target(session, *crate_type);
508 session.warn(&format!(
509 "dropping unsupported crate type `{}` for target `{}`",
510 *crate_type, session.opts.target_triple
520 pub fn build_output_filenames(
522 odir: &Option<PathBuf>,
523 ofile: &Option<PathBuf>,
524 attrs: &[ast::Attribute],
526 ) -> OutputFilenames {
529 // "-" as input file will cause the parser to read from stdin so we
530 // have to make up a name
531 // We want to toss everything after the final '.'
532 let dirpath = (*odir).as_ref().cloned().unwrap_or_default();
534 // If a crate name is present, we use it as the link name
539 .or_else(|| rustc_attr::find_crate_name(attrs).map(|n| n.to_string()))
540 .unwrap_or_else(|| input.filestem().to_owned());
542 OutputFilenames::new(
546 sess.opts.cg.extra_filename.clone(),
547 sess.opts.output_types.clone(),
551 Some(ref out_file) => {
552 let unnamed_output_types =
553 sess.opts.output_types.values().filter(|a| a.is_none()).count();
554 let ofile = if unnamed_output_types > 1 {
556 "due to multiple output types requested, the explicitly specified \
557 output file name will be adapted for each output type",
561 if !sess.opts.cg.extra_filename.is_empty() {
562 sess.warn("ignoring -C extra-filename flag due to -o flag");
564 Some(out_file.clone())
567 sess.warn("ignoring --out-dir flag due to -o flag");
570 OutputFilenames::new(
571 out_file.parent().unwrap_or_else(|| Path::new("")).to_path_buf(),
572 out_file.file_stem().unwrap_or_default().to_str().unwrap().to_string(),
574 sess.opts.cg.extra_filename.clone(),
575 sess.opts.output_types.clone(),
581 // Note: Also used by librustdoc, see PR #43348. Consider moving this struct elsewhere.
583 // FIXME: Currently the `everybody_loops` transformation is not applied to:
584 // * `const fn`, due to issue #43636 that `loop` is not supported for const evaluation. We are
585 // waiting for miri to fix that.
586 // * `impl Trait`, due to issue #43869 that functions returning impl Trait cannot be diverging.
587 // Solving this may require `!` to implement every trait, which relies on the an even more
588 // ambitious form of the closed RFC #1637. See also [#34511].
590 // [#34511]: https://github.com/rust-lang/rust/issues/34511#issuecomment-322340401
591 pub struct ReplaceBodyWithLoop<'a, 'b> {
592 within_static_or_const: bool,
593 nested_blocks: Option<Vec<ast::Block>>,
594 resolver: &'a mut Resolver<'b>,
597 impl<'a, 'b> ReplaceBodyWithLoop<'a, 'b> {
598 pub fn new(resolver: &'a mut Resolver<'b>) -> ReplaceBodyWithLoop<'a, 'b> {
599 ReplaceBodyWithLoop { within_static_or_const: false, nested_blocks: None, resolver }
602 fn run<R, F: FnOnce(&mut Self) -> R>(&mut self, is_const: bool, action: F) -> R {
603 let old_const = mem::replace(&mut self.within_static_or_const, is_const);
604 let old_blocks = self.nested_blocks.take();
605 let ret = action(self);
606 self.within_static_or_const = old_const;
607 self.nested_blocks = old_blocks;
611 fn should_ignore_fn(ret_ty: &ast::FnRetTy) -> bool {
612 if let ast::FnRetTy::Ty(ref ty) = ret_ty {
613 fn involves_impl_trait(ty: &ast::Ty) -> bool {
615 ast::TyKind::ImplTrait(..) => true,
616 ast::TyKind::Slice(ref subty)
617 | ast::TyKind::Array(ref subty, _)
618 | ast::TyKind::Ptr(ast::MutTy { ty: ref subty, .. })
619 | ast::TyKind::Rptr(_, ast::MutTy { ty: ref subty, .. })
620 | ast::TyKind::Paren(ref subty) => involves_impl_trait(subty),
621 ast::TyKind::Tup(ref tys) => any_involves_impl_trait(tys.iter()),
622 ast::TyKind::Path(_, ref path) => {
623 path.segments.iter().any(|seg| match seg.args.as_deref() {
625 Some(&ast::GenericArgs::AngleBracketed(ref data)) => {
626 data.args.iter().any(|arg| match arg {
627 ast::AngleBracketedArg::Arg(arg) => match arg {
628 ast::GenericArg::Type(ty) => involves_impl_trait(ty),
629 ast::GenericArg::Lifetime(_)
630 | ast::GenericArg::Const(_) => false,
632 ast::AngleBracketedArg::Constraint(c) => match c.kind {
633 ast::AssocTyConstraintKind::Bound { .. } => true,
634 ast::AssocTyConstraintKind::Equality { ref ty } => {
635 involves_impl_trait(ty)
640 Some(&ast::GenericArgs::Parenthesized(ref data)) => {
641 any_involves_impl_trait(data.inputs.iter())
642 || ReplaceBodyWithLoop::should_ignore_fn(&data.output)
650 fn any_involves_impl_trait<'a, I: Iterator<Item = &'a P<ast::Ty>>>(mut it: I) -> bool {
651 it.any(|subty| involves_impl_trait(subty))
654 involves_impl_trait(ty)
660 fn is_sig_const(sig: &ast::FnSig) -> bool {
661 matches!(sig.header.constness, ast::Const::Yes(_))
662 || ReplaceBodyWithLoop::should_ignore_fn(&sig.decl.output)
666 impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
667 fn visit_item_kind(&mut self, i: &mut ast::ItemKind) {
668 let is_const = match i {
669 ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => true,
670 ast::ItemKind::Fn(_, ref sig, _, _) => Self::is_sig_const(sig),
673 self.run(is_const, |s| noop_visit_item_kind(i, s))
676 fn flat_map_trait_item(&mut self, i: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
677 let is_const = match i.kind {
678 ast::AssocItemKind::Const(..) => true,
679 ast::AssocItemKind::Fn(_, ref sig, _, _) => Self::is_sig_const(sig),
682 self.run(is_const, |s| noop_flat_map_assoc_item(i, s))
685 fn flat_map_impl_item(&mut self, i: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
686 self.flat_map_trait_item(i)
689 fn visit_anon_const(&mut self, c: &mut ast::AnonConst) {
690 self.run(true, |s| noop_visit_anon_const(c, s))
693 fn visit_block(&mut self, b: &mut P<ast::Block>) {
695 rules: ast::BlockCheckMode,
696 s: Option<ast::Stmt>,
697 resolver: &mut Resolver<'_>,
700 stmts: s.into_iter().collect(),
702 id: resolver.next_node_id(),
703 span: rustc_span::DUMMY_SP,
707 fn block_to_stmt(b: ast::Block, resolver: &mut Resolver<'_>) -> ast::Stmt {
708 let expr = P(ast::Expr {
709 id: resolver.next_node_id(),
710 kind: ast::ExprKind::Block(P(b), None),
711 span: rustc_span::DUMMY_SP,
712 attrs: AttrVec::new(),
716 id: resolver.next_node_id(),
717 kind: ast::StmtKind::Expr(expr),
718 span: rustc_span::DUMMY_SP,
722 let empty_block = stmt_to_block(BlockCheckMode::Default, None, self.resolver);
723 let loop_expr = P(ast::Expr {
724 kind: ast::ExprKind::Loop(P(empty_block), None),
725 id: self.resolver.next_node_id(),
726 span: rustc_span::DUMMY_SP,
727 attrs: AttrVec::new(),
730 let loop_stmt = ast::Stmt {
731 id: self.resolver.next_node_id(),
732 span: rustc_span::DUMMY_SP,
733 kind: ast::StmtKind::Expr(loop_expr),
736 if self.within_static_or_const {
737 noop_visit_block(b, self)
739 visit_clobber(b.deref_mut(), |b| {
740 let mut stmts = vec![];
742 let old_blocks = self.nested_blocks.replace(vec![]);
744 stmts.extend(self.flat_map_stmt(s).into_iter().filter(|s| s.is_item()));
746 // we put a Some in there earlier with that replace(), so this is valid
747 let new_blocks = self.nested_blocks.take().unwrap();
748 self.nested_blocks = old_blocks;
749 stmts.extend(new_blocks.into_iter().map(|b| block_to_stmt(b, self.resolver)));
752 let mut new_block = ast::Block { stmts, ..b };
754 if let Some(old_blocks) = self.nested_blocks.as_mut() {
755 //push our fresh block onto the cache and yield an empty block with `loop {}`
756 if !new_block.stmts.is_empty() {
757 old_blocks.push(new_block);
760 stmt_to_block(b.rules, Some(loop_stmt), &mut self.resolver)
762 //push `loop {}` onto the end of our fresh block and yield that
763 new_block.stmts.push(loop_stmt);
771 // in general the pretty printer processes unexpanded code, so
772 // we override the default `visit_mac` method which panics.
773 fn visit_mac(&mut self, mac: &mut ast::MacCall) {
774 noop_visit_mac(mac, self)