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 smallvec::SmallVec;
19 use std::io::{self, Write};
21 use std::ops::DerefMut;
22 use std::path::{Path, PathBuf};
23 use std::sync::{Arc, Mutex, Once};
24 #[cfg(not(parallel_compiler))]
25 use std::{panic, thread};
26 use syntax::ast::{AttrVec, BlockCheckMode};
27 use syntax::mut_visit::{visit_clobber, MutVisitor, *};
29 use syntax::source_map::{FileLoader, RealFileLoader, SourceMap};
30 use syntax::symbol::{sym, Symbol};
31 use syntax::util::lev_distance::find_best_match_for_name;
32 use syntax::{self, ast, attr};
33 use syntax_pos::edition::Edition;
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 sess.prof.register_queries(|profiler| {
75 rustc::ty::query::QueryName::register_with_profiler(&profiler);
78 let codegen_backend = get_codegen_backend(&sess);
80 let mut cfg = config::build_configuration(&sess, config::to_crate_config(cfg));
81 add_configuration(&mut cfg, &sess, &*codegen_backend);
82 sess.parse_sess.config = cfg;
84 (Lrc::new(sess), Lrc::new(codegen_backend), source_map)
87 // Temporarily have stack size set to 32MB to deal with various crates with long method
88 // chains or deep syntax trees, except when on Haiku.
89 // FIXME(oli-obk): get https://github.com/rust-lang/rust/pull/55617 the finish line
90 #[cfg(not(target_os = "haiku"))]
91 const STACK_SIZE: usize = 32 * 1024 * 1024;
93 #[cfg(target_os = "haiku")]
94 const STACK_SIZE: usize = 16 * 1024 * 1024;
96 fn get_stack_size() -> Option<usize> {
97 // FIXME: Hacks on hacks. If the env is trying to override the stack size
98 // then *don't* set it explicitly.
99 env::var_os("RUST_MIN_STACK").is_none().then_some(STACK_SIZE)
102 struct Sink(Arc<Mutex<Vec<u8>>>);
103 impl Write for Sink {
104 fn write(&mut self, data: &[u8]) -> io::Result<usize> {
105 Write::write(&mut *self.0.lock().unwrap(), data)
107 fn flush(&mut self) -> io::Result<()> {
112 #[cfg(not(parallel_compiler))]
113 pub fn scoped_thread<F: FnOnce() -> R + Send, R: Send>(cfg: thread::Builder, f: F) -> R {
115 unsafe impl Send for Ptr {}
116 unsafe impl Sync for Ptr {}
119 let run = Ptr(&mut f as *mut _ as *mut ());
120 let mut result = None;
121 let result_ptr = Ptr(&mut result as *mut _ as *mut ());
123 let thread = cfg.spawn(move || {
124 let run = unsafe { (*(run.0 as *mut Option<F>)).take().unwrap() };
125 let result = unsafe { &mut *(result_ptr.0 as *mut Option<R>) };
126 *result = Some(run());
129 match thread.unwrap().join() {
130 Ok(()) => result.unwrap(),
131 Err(p) => panic::resume_unwind(p),
135 #[cfg(not(parallel_compiler))]
136 pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
139 stderr: &Option<Arc<Mutex<Vec<u8>>>>,
142 let mut cfg = thread::Builder::new().name("rustc".to_string());
144 if let Some(size) = get_stack_size() {
145 cfg = cfg.stack_size(size);
148 crate::callbacks::setup_callbacks();
150 scoped_thread(cfg, || {
151 syntax::with_globals(edition, || {
152 ty::tls::GCX_PTR.set(&Lock::new(0), || {
153 if let Some(stderr) = stderr {
154 io::set_panic(Some(box Sink(stderr.clone())));
162 #[cfg(parallel_compiler)]
163 pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
166 stderr: &Option<Arc<Mutex<Vec<u8>>>>,
169 use rayon::{ThreadBuilder, ThreadPool, ThreadPoolBuilder};
171 let gcx_ptr = &Lock::new(0);
172 crate::callbacks::setup_callbacks();
174 let mut config = ThreadPoolBuilder::new()
175 .thread_name(|_| "rustc".to_string())
176 .acquire_thread_handler(jobserver::acquire_thread)
177 .release_thread_handler(jobserver::release_thread)
178 .num_threads(threads)
179 .deadlock_handler(|| unsafe { ty::query::handle_deadlock() });
181 if let Some(size) = get_stack_size() {
182 config = config.stack_size(size);
185 let with_pool = move |pool: &ThreadPool| pool.install(move || f());
187 syntax::with_globals(edition, || {
188 syntax::GLOBALS.with(|syntax_globals| {
189 syntax_pos::GLOBALS.with(|syntax_pos_globals| {
190 // The main handler runs for each Rayon worker thread and sets up
191 // the thread local rustc uses. syntax_globals and syntax_pos_globals are
192 // captured and set on the new threads. ty::tls::with_thread_locals sets up
193 // thread local callbacks from libsyntax
194 let main_handler = move |thread: ThreadBuilder| {
195 syntax::GLOBALS.set(syntax_globals, || {
196 syntax_pos::GLOBALS.set(syntax_pos_globals, || {
197 if let Some(stderr) = stderr {
198 io::set_panic(Some(box Sink(stderr.clone())));
200 ty::tls::GCX_PTR.set(gcx_ptr, || thread.run())
205 config.build_scoped(main_handler, with_pool).unwrap()
211 fn load_backend_from_dylib(path: &Path) -> fn() -> Box<dyn CodegenBackend> {
212 let lib = DynamicLibrary::open(Some(path)).unwrap_or_else(|err| {
213 let err = format!("couldn't load codegen backend {:?}: {:?}", path, err);
214 early_error(ErrorOutputType::default(), &err);
217 match lib.symbol("__rustc_codegen_backend") {
220 mem::transmute::<*mut u8, _>(f)
224 "couldn't load codegen backend as it \
225 doesn't export the `__rustc_codegen_backend` \
229 early_error(ErrorOutputType::default(), &err);
235 pub fn get_codegen_backend(sess: &Session) -> Box<dyn CodegenBackend> {
236 static INIT: Once = Once::new();
238 static mut LOAD: fn() -> Box<dyn CodegenBackend> = || unreachable!();
241 let codegen_name = sess
246 .unwrap_or(&sess.target.target.options.codegen_backend);
247 let backend = match &codegen_name[..] {
248 filename if filename.contains(".") => load_backend_from_dylib(filename.as_ref()),
249 codegen_name => get_builtin_codegen_backend(codegen_name),
256 let backend = unsafe { LOAD() };
261 // This is used for rustdoc, but it uses similar machinery to codegen backend
262 // loading, so we leave the code here. It is potentially useful for other tools
263 // that want to invoke the rustc binary while linking to rustc as well.
264 pub fn rustc_path<'a>() -> Option<&'a Path> {
265 static RUSTC_PATH: once_cell::sync::OnceCell<Option<PathBuf>> =
266 once_cell::sync::OnceCell::new();
268 const BIN_PATH: &str = env!("RUSTC_INSTALL_BINDIR");
270 RUSTC_PATH.get_or_init(|| get_rustc_path_inner(BIN_PATH)).as_ref().map(|v| &**v)
273 fn get_rustc_path_inner(bin_path: &str) -> Option<PathBuf> {
276 .filter_map(|sysroot| {
277 let candidate = sysroot.join(bin_path).join(if cfg!(target_os = "windows") {
282 candidate.exists().then_some(candidate)
287 fn sysroot_candidates() -> Vec<PathBuf> {
288 let target = session::config::host_triple();
289 let mut sysroot_candidates = vec![filesearch::get_or_default_sysroot()];
290 let path = current_dll_path().and_then(|s| s.canonicalize().ok());
291 if let Some(dll) = path {
292 // use `parent` twice to chop off the file name and then also the
293 // directory containing the dll which should be either `lib` or `bin`.
294 if let Some(path) = dll.parent().and_then(|p| p.parent()) {
295 // The original `path` pointed at the `rustc_driver` crate's dll.
296 // Now that dll should only be in one of two locations. The first is
297 // in the compiler's libdir, for example `$sysroot/lib/*.dll`. The
298 // other is the target's libdir, for example
299 // `$sysroot/lib/rustlib/$target/lib/*.dll`.
301 // We don't know which, so let's assume that if our `path` above
302 // ends in `$target` we *could* be in the target libdir, and always
303 // assume that we may be in the main libdir.
304 sysroot_candidates.push(path.to_owned());
306 if path.ends_with(target) {
307 sysroot_candidates.extend(
308 path.parent() // chop off `$target`
309 .and_then(|p| p.parent()) // chop off `rustlib`
310 .and_then(|p| p.parent()) // chop off `lib`
311 .map(|s| s.to_owned()),
317 return sysroot_candidates;
320 fn current_dll_path() -> Option<PathBuf> {
321 use std::ffi::{CStr, OsStr};
322 use std::os::unix::prelude::*;
325 let addr = current_dll_path as usize as *mut _;
326 let mut info = mem::zeroed();
327 if libc::dladdr(addr, &mut info) == 0 {
328 info!("dladdr failed");
331 if info.dli_fname.is_null() {
332 info!("dladdr returned null pointer");
335 let bytes = CStr::from_ptr(info.dli_fname).to_bytes();
336 let os = OsStr::from_bytes(bytes);
337 Some(PathBuf::from(os))
342 fn current_dll_path() -> Option<PathBuf> {
343 use std::ffi::OsString;
344 use std::os::windows::prelude::*;
347 fn GetModuleHandleExW(dwFlags: u32, lpModuleName: usize, phModule: *mut usize) -> i32;
348 fn GetModuleFileNameW(hModule: usize, lpFilename: *mut u16, nSize: u32) -> u32;
351 const GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS: u32 = 0x00000004;
355 let r = GetModuleHandleExW(
356 GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
357 current_dll_path as usize,
361 info!("GetModuleHandleExW failed: {}", io::Error::last_os_error());
364 let mut space = Vec::with_capacity(1024);
365 let r = GetModuleFileNameW(module, space.as_mut_ptr(), space.capacity() as u32);
367 info!("GetModuleFileNameW failed: {}", io::Error::last_os_error());
371 if r >= space.capacity() {
372 info!("our buffer was too small? {}", io::Error::last_os_error());
376 let os = OsString::from_wide(&space);
377 Some(PathBuf::from(os))
382 pub fn get_builtin_codegen_backend(backend_name: &str) -> fn() -> Box<dyn CodegenBackend> {
383 #[cfg(feature = "llvm")]
385 if backend_name == "llvm" {
386 return rustc_codegen_llvm::LlvmCodegenBackend::new;
390 let err = format!("unsupported builtin codegen backend `{}`", backend_name);
391 early_error(ErrorOutputType::default(), &err);
394 pub(crate) fn compute_crate_disambiguator(session: &Session) -> CrateDisambiguator {
395 use std::hash::Hasher;
397 // The crate_disambiguator is a 128 bit hash. The disambiguator is fed
398 // into various other hashes quite a bit (symbol hashes, incr. comp. hashes,
399 // debuginfo type IDs, etc), so we don't want it to be too wide. 128 bits
400 // should still be safe enough to avoid collisions in practice.
401 let mut hasher = StableHasher::new();
403 let mut metadata = session.opts.cg.metadata.clone();
404 // We don't want the crate_disambiguator to dependent on the order
405 // -C metadata arguments, so sort them:
407 // Every distinct -C metadata value is only incorporated once:
410 hasher.write(b"metadata");
412 // Also incorporate the length of a metadata string, so that we generate
413 // different values for `-Cmetadata=ab -Cmetadata=c` and
414 // `-Cmetadata=a -Cmetadata=bc`
415 hasher.write_usize(s.len());
416 hasher.write(s.as_bytes());
419 // Also incorporate crate type, so that we don't get symbol conflicts when
420 // linking against a library of the same name, if this is an executable.
421 let is_exe = session.crate_types.borrow().contains(&config::CrateType::Executable);
422 hasher.write(if is_exe { b"exe" } else { b"lib" });
424 CrateDisambiguator::from(hasher.finish::<Fingerprint>())
427 pub(crate) fn check_attr_crate_type(attrs: &[ast::Attribute], lint_buffer: &mut lint::LintBuffer) {
428 // Unconditionally collect crate types from attributes to make them used
429 for a in attrs.iter() {
430 if a.check_name(sym::crate_type) {
431 if let Some(n) = a.value_str() {
432 if let Some(_) = categorize_crate_type(n) {
436 if let ast::MetaItemKind::NameValue(spanned) = a.meta().unwrap().kind {
437 let span = spanned.span;
438 let lev_candidate = find_best_match_for_name(
439 CRATE_TYPES.iter().map(|(k, _)| k),
443 if let Some(candidate) = lev_candidate {
444 lint_buffer.buffer_lint_with_diagnostic(
445 lint::builtin::UNKNOWN_CRATE_TYPES,
448 "invalid `crate_type` value",
449 lint::builtin::BuiltinLintDiagnostics::UnknownCrateTypes(
451 "did you mean".to_string(),
452 format!("\"{}\"", candidate),
456 lint_buffer.buffer_lint(
457 lint::builtin::UNKNOWN_CRATE_TYPES,
460 "invalid `crate_type` value",
469 const CRATE_TYPES: &[(Symbol, config::CrateType)] = &[
470 (sym::rlib, config::CrateType::Rlib),
471 (sym::dylib, config::CrateType::Dylib),
472 (sym::cdylib, config::CrateType::Cdylib),
473 (sym::lib, config::default_lib_output()),
474 (sym::staticlib, config::CrateType::Staticlib),
475 (sym::proc_dash_macro, config::CrateType::ProcMacro),
476 (sym::bin, config::CrateType::Executable),
479 fn categorize_crate_type(s: Symbol) -> Option<config::CrateType> {
480 Some(CRATE_TYPES.iter().find(|(key, _)| *key == s)?.1)
483 pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<config::CrateType> {
484 // Unconditionally collect crate types from attributes to make them used
485 let attr_types: Vec<config::CrateType> = attrs
488 if a.check_name(sym::crate_type) {
489 match a.value_str() {
490 Some(s) => categorize_crate_type(s),
499 // If we're generating a test executable, then ignore all other output
500 // styles at all other locations
501 if session.opts.test {
502 return vec![config::CrateType::Executable];
505 // Only check command line flags if present. If no types are specified by
506 // command line, then reuse the empty `base` Vec to hold the types that
507 // will be found in crate attributes.
508 let mut base = session.opts.crate_types.clone();
510 base.extend(attr_types);
512 base.push(::rustc_codegen_utils::link::default_output_for_target(session));
519 base.retain(|crate_type| {
520 let res = !::rustc_codegen_utils::link::invalid_output_for_target(session, *crate_type);
523 session.warn(&format!(
524 "dropping unsupported crate type `{}` for target `{}`",
525 *crate_type, session.opts.target_triple
535 pub fn build_output_filenames(
537 odir: &Option<PathBuf>,
538 ofile: &Option<PathBuf>,
539 attrs: &[ast::Attribute],
541 ) -> OutputFilenames {
544 // "-" as input file will cause the parser to read from stdin so we
545 // have to make up a name
546 // We want to toss everything after the final '.'
547 let dirpath = (*odir).as_ref().cloned().unwrap_or_default();
549 // If a crate name is present, we use it as the link name
554 .or_else(|| attr::find_crate_name(attrs).map(|n| n.to_string()))
555 .unwrap_or_else(|| input.filestem().to_owned());
558 out_directory: dirpath,
560 single_output_file: None,
561 extra: sess.opts.cg.extra_filename.clone(),
562 outputs: sess.opts.output_types.clone(),
566 Some(ref out_file) => {
567 let unnamed_output_types =
568 sess.opts.output_types.values().filter(|a| a.is_none()).count();
569 let ofile = if unnamed_output_types > 1 {
571 "due to multiple output types requested, the explicitly specified \
572 output file name will be adapted for each output type",
576 if !sess.opts.cg.extra_filename.is_empty() {
577 sess.warn("ignoring -C extra-filename flag due to -o flag");
579 Some(out_file.clone())
582 sess.warn("ignoring --out-dir flag due to -o flag");
586 out_directory: out_file.parent().unwrap_or_else(|| Path::new("")).to_path_buf(),
587 out_filestem: out_file
593 single_output_file: ofile,
594 extra: sess.opts.cg.extra_filename.clone(),
595 outputs: sess.opts.output_types.clone(),
601 // Note: Also used by librustdoc, see PR #43348. Consider moving this struct elsewhere.
603 // FIXME: Currently the `everybody_loops` transformation is not applied to:
604 // * `const fn`, due to issue #43636 that `loop` is not supported for const evaluation. We are
605 // waiting for miri to fix that.
606 // * `impl Trait`, due to issue #43869 that functions returning impl Trait cannot be diverging.
607 // Solving this may require `!` to implement every trait, which relies on the an even more
608 // ambitious form of the closed RFC #1637. See also [#34511].
610 // [#34511]: https://github.com/rust-lang/rust/issues/34511#issuecomment-322340401
611 pub struct ReplaceBodyWithLoop<'a, 'b> {
612 within_static_or_const: bool,
613 nested_blocks: Option<Vec<ast::Block>>,
614 resolver: &'a mut Resolver<'b>,
617 impl<'a, 'b> ReplaceBodyWithLoop<'a, 'b> {
618 pub fn new(resolver: &'a mut Resolver<'b>) -> ReplaceBodyWithLoop<'a, 'b> {
619 ReplaceBodyWithLoop { within_static_or_const: false, nested_blocks: None, resolver }
622 fn run<R, F: FnOnce(&mut Self) -> R>(&mut self, is_const: bool, action: F) -> R {
623 let old_const = mem::replace(&mut self.within_static_or_const, is_const);
624 let old_blocks = self.nested_blocks.take();
625 let ret = action(self);
626 self.within_static_or_const = old_const;
627 self.nested_blocks = old_blocks;
631 fn should_ignore_fn(ret_ty: &ast::FunctionRetTy) -> bool {
632 if let ast::FunctionRetTy::Ty(ref ty) = ret_ty {
633 fn involves_impl_trait(ty: &ast::Ty) -> bool {
635 ast::TyKind::ImplTrait(..) => true,
636 ast::TyKind::Slice(ref subty)
637 | ast::TyKind::Array(ref subty, _)
638 | ast::TyKind::Ptr(ast::MutTy { ty: ref subty, .. })
639 | ast::TyKind::Rptr(_, ast::MutTy { ty: ref subty, .. })
640 | ast::TyKind::Paren(ref subty) => involves_impl_trait(subty),
641 ast::TyKind::Tup(ref tys) => any_involves_impl_trait(tys.iter()),
642 ast::TyKind::Path(_, ref path) => path.segments.iter().any(|seg| {
643 match seg.args.as_ref().map(|generic_arg| &**generic_arg) {
645 Some(&ast::GenericArgs::AngleBracketed(ref data)) => {
646 let types = data.args.iter().filter_map(|arg| match arg {
647 ast::GenericArg::Type(ty) => Some(ty),
650 any_involves_impl_trait(types.into_iter())
651 || data.constraints.iter().any(|c| match c.kind {
652 ast::AssocTyConstraintKind::Bound { .. } => true,
653 ast::AssocTyConstraintKind::Equality { ref ty } => {
654 involves_impl_trait(ty)
658 Some(&ast::GenericArgs::Parenthesized(ref data)) => {
659 any_involves_impl_trait(data.inputs.iter())
660 || ReplaceBodyWithLoop::should_ignore_fn(&data.output)
668 fn any_involves_impl_trait<'a, I: Iterator<Item = &'a P<ast::Ty>>>(mut it: I) -> bool {
669 it.any(|subty| involves_impl_trait(subty))
672 involves_impl_trait(ty)
678 fn is_sig_const(sig: &ast::FnSig) -> bool {
679 sig.header.constness.node == ast::Constness::Const
680 || ReplaceBodyWithLoop::should_ignore_fn(&sig.decl.output)
684 impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
685 fn visit_item_kind(&mut self, i: &mut ast::ItemKind) {
686 let is_const = match i {
687 ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => true,
688 ast::ItemKind::Fn(ref sig, _, _) => Self::is_sig_const(sig),
691 self.run(is_const, |s| noop_visit_item_kind(i, s))
694 fn flat_map_trait_item(&mut self, i: ast::AssocItem) -> SmallVec<[ast::AssocItem; 1]> {
695 let is_const = match i.kind {
696 ast::AssocItemKind::Const(..) => true,
697 ast::AssocItemKind::Fn(ref sig, _) => Self::is_sig_const(sig),
700 self.run(is_const, |s| noop_flat_map_assoc_item(i, s))
703 fn flat_map_impl_item(&mut self, i: ast::AssocItem) -> SmallVec<[ast::AssocItem; 1]> {
704 self.flat_map_trait_item(i)
707 fn visit_anon_const(&mut self, c: &mut ast::AnonConst) {
708 self.run(true, |s| noop_visit_anon_const(c, s))
711 fn visit_block(&mut self, b: &mut P<ast::Block>) {
713 rules: ast::BlockCheckMode,
714 s: Option<ast::Stmt>,
715 resolver: &mut Resolver<'_>,
718 stmts: s.into_iter().collect(),
720 id: resolver.next_node_id(),
721 span: syntax_pos::DUMMY_SP,
725 fn block_to_stmt(b: ast::Block, resolver: &mut Resolver<'_>) -> ast::Stmt {
726 let expr = P(ast::Expr {
727 id: resolver.next_node_id(),
728 kind: ast::ExprKind::Block(P(b), None),
729 span: syntax_pos::DUMMY_SP,
730 attrs: AttrVec::new(),
734 id: resolver.next_node_id(),
735 kind: ast::StmtKind::Expr(expr),
736 span: syntax_pos::DUMMY_SP,
740 let empty_block = stmt_to_block(BlockCheckMode::Default, None, self.resolver);
741 let loop_expr = P(ast::Expr {
742 kind: ast::ExprKind::Loop(P(empty_block), None),
743 id: self.resolver.next_node_id(),
744 span: syntax_pos::DUMMY_SP,
745 attrs: AttrVec::new(),
748 let loop_stmt = ast::Stmt {
749 id: self.resolver.next_node_id(),
750 span: syntax_pos::DUMMY_SP,
751 kind: ast::StmtKind::Expr(loop_expr),
754 if self.within_static_or_const {
755 noop_visit_block(b, self)
757 visit_clobber(b.deref_mut(), |b| {
758 let mut stmts = vec![];
760 let old_blocks = self.nested_blocks.replace(vec![]);
762 stmts.extend(self.flat_map_stmt(s).into_iter().filter(|s| s.is_item()));
764 // we put a Some in there earlier with that replace(), so this is valid
765 let new_blocks = self.nested_blocks.take().unwrap();
766 self.nested_blocks = old_blocks;
767 stmts.extend(new_blocks.into_iter().map(|b| block_to_stmt(b, self.resolver)));
770 let mut new_block = ast::Block { stmts, ..b };
772 if let Some(old_blocks) = self.nested_blocks.as_mut() {
773 //push our fresh block onto the cache and yield an empty block with `loop {}`
774 if !new_block.stmts.is_empty() {
775 old_blocks.push(new_block);
778 stmt_to_block(b.rules, Some(loop_stmt), &mut self.resolver)
780 //push `loop {}` onto the end of our fresh block and yield that
781 new_block.stmts.push(loop_stmt);
789 // in general the pretty printer processes unexpanded code, so
790 // we override the default `visit_mac` method which panics.
791 fn visit_mac(&mut self, mac: &mut ast::Mac) {
792 noop_visit_mac(mac, self)