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::CrateDisambiguator;
18 use rustc_session::{config, early_error, filesearch, DiagnosticOutput, Session};
19 use rustc_span::edition::Edition;
20 use rustc_span::source_map::{FileLoader, RealFileLoader, SourceMap};
21 use rustc_span::symbol::{sym, Symbol};
22 use smallvec::SmallVec;
24 use std::io::{self, Write};
26 use std::ops::DerefMut;
27 use std::path::{Path, PathBuf};
28 use std::sync::{Arc, Mutex, Once};
29 #[cfg(not(parallel_compiler))]
30 use std::{panic, thread};
31 use syntax::ast::{AttrVec, BlockCheckMode};
32 use syntax::mut_visit::{visit_clobber, MutVisitor, *};
34 use syntax::util::lev_distance::find_best_match_for_name;
35 use syntax::{self, ast, attr};
37 /// Adds `target_feature = "..."` cfgs for a variety of platform
38 /// specific features (SSE, NEON etc.).
40 /// This is performed by checking whether a whitelisted set of
41 /// features is available on the target machine, by querying LLVM.
42 pub fn add_configuration(
43 cfg: &mut ast::CrateConfig,
45 codegen_backend: &dyn CodegenBackend,
47 let tf = sym::target_feature;
49 cfg.extend(codegen_backend.target_features(sess).into_iter().map(|feat| (tf, Some(feat))));
51 if sess.crt_static_feature() {
52 cfg.insert((tf, Some(Symbol::intern("crt-static"))));
56 pub fn create_session(
57 sopts: config::Options,
58 cfg: FxHashSet<(String, Option<String>)>,
59 diagnostic_output: DiagnosticOutput,
60 file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
61 input_path: Option<PathBuf>,
62 lint_caps: FxHashMap<lint::LintId, lint::Level>,
63 descriptions: Registry,
64 ) -> (Lrc<Session>, Lrc<Box<dyn CodegenBackend>>, Lrc<SourceMap>) {
65 let loader = file_loader.unwrap_or(box RealFileLoader);
66 let source_map = Lrc::new(SourceMap::with_file_loader(loader, sopts.file_path_mapping()));
67 let mut sess = session::build_session_with_source_map(
76 let codegen_backend = get_codegen_backend(&sess);
78 let mut cfg = config::build_configuration(&sess, config::to_crate_config(cfg));
79 add_configuration(&mut cfg, &sess, &*codegen_backend);
80 sess.parse_sess.config = cfg;
82 (Lrc::new(sess), Lrc::new(codegen_backend), source_map)
85 // Temporarily have stack size set to 32MB to deal with various crates with long method
86 // chains or deep syntax trees, except when on Haiku.
87 // FIXME(oli-obk): get https://github.com/rust-lang/rust/pull/55617 the finish line
88 #[cfg(not(target_os = "haiku"))]
89 const STACK_SIZE: usize = 32 * 1024 * 1024;
91 #[cfg(target_os = "haiku")]
92 const STACK_SIZE: usize = 16 * 1024 * 1024;
94 fn get_stack_size() -> Option<usize> {
95 // FIXME: Hacks on hacks. If the env is trying to override the stack size
96 // then *don't* set it explicitly.
97 env::var_os("RUST_MIN_STACK").is_none().then_some(STACK_SIZE)
100 struct Sink(Arc<Mutex<Vec<u8>>>);
101 impl Write for Sink {
102 fn write(&mut self, data: &[u8]) -> io::Result<usize> {
103 Write::write(&mut *self.0.lock().unwrap(), data)
105 fn flush(&mut self) -> io::Result<()> {
110 #[cfg(not(parallel_compiler))]
111 pub fn scoped_thread<F: FnOnce() -> R + Send, R: Send>(cfg: thread::Builder, f: F) -> R {
113 unsafe impl Send for Ptr {}
114 unsafe impl Sync for Ptr {}
117 let run = Ptr(&mut f as *mut _ as *mut ());
118 let mut result = None;
119 let result_ptr = Ptr(&mut result as *mut _ as *mut ());
121 let thread = cfg.spawn(move || {
122 let run = unsafe { (*(run.0 as *mut Option<F>)).take().unwrap() };
123 let result = unsafe { &mut *(result_ptr.0 as *mut Option<R>) };
124 *result = Some(run());
127 match thread.unwrap().join() {
128 Ok(()) => result.unwrap(),
129 Err(p) => panic::resume_unwind(p),
133 #[cfg(not(parallel_compiler))]
134 pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
137 stderr: &Option<Arc<Mutex<Vec<u8>>>>,
140 let mut cfg = thread::Builder::new().name("rustc".to_string());
142 if let Some(size) = get_stack_size() {
143 cfg = cfg.stack_size(size);
146 crate::callbacks::setup_callbacks();
148 scoped_thread(cfg, || {
149 syntax::with_globals(edition, || {
150 ty::tls::GCX_PTR.set(&Lock::new(0), || {
151 if let Some(stderr) = stderr {
152 io::set_panic(Some(box Sink(stderr.clone())));
160 #[cfg(parallel_compiler)]
161 pub fn spawn_thread_pool<F: FnOnce() -> R + Send, R: Send>(
164 stderr: &Option<Arc<Mutex<Vec<u8>>>>,
167 use rayon::{ThreadBuilder, ThreadPool, ThreadPoolBuilder};
169 let gcx_ptr = &Lock::new(0);
170 crate::callbacks::setup_callbacks();
172 let mut config = ThreadPoolBuilder::new()
173 .thread_name(|_| "rustc".to_string())
174 .acquire_thread_handler(jobserver::acquire_thread)
175 .release_thread_handler(jobserver::release_thread)
176 .num_threads(threads)
177 .deadlock_handler(|| unsafe { ty::query::handle_deadlock() });
179 if let Some(size) = get_stack_size() {
180 config = config.stack_size(size);
183 let with_pool = move |pool: &ThreadPool| pool.install(move || f());
185 syntax::with_globals(edition, || {
186 syntax::GLOBALS.with(|syntax_globals| {
187 rustc_span::GLOBALS.with(|rustc_span_globals| {
188 // The main handler runs for each Rayon worker thread and sets up
189 // the thread local rustc uses. syntax_globals and rustc_span_globals are
190 // captured and set on the new threads. ty::tls::with_thread_locals sets up
191 // thread local callbacks from libsyntax
192 let main_handler = move |thread: ThreadBuilder| {
193 syntax::GLOBALS.set(syntax_globals, || {
194 rustc_span::GLOBALS.set(rustc_span_globals, || {
195 if let Some(stderr) = stderr {
196 io::set_panic(Some(box Sink(stderr.clone())));
198 ty::tls::GCX_PTR.set(gcx_ptr, || thread.run())
203 config.build_scoped(main_handler, with_pool).unwrap()
209 fn load_backend_from_dylib(path: &Path) -> fn() -> Box<dyn CodegenBackend> {
210 let lib = DynamicLibrary::open(Some(path)).unwrap_or_else(|err| {
211 let err = format!("couldn't load codegen backend {:?}: {:?}", path, err);
212 early_error(ErrorOutputType::default(), &err);
215 match lib.symbol("__rustc_codegen_backend") {
218 mem::transmute::<*mut u8, _>(f)
222 "couldn't load codegen backend as it \
223 doesn't export the `__rustc_codegen_backend` \
227 early_error(ErrorOutputType::default(), &err);
233 pub fn get_codegen_backend(sess: &Session) -> Box<dyn CodegenBackend> {
234 static INIT: Once = Once::new();
236 static mut LOAD: fn() -> Box<dyn CodegenBackend> = || unreachable!();
239 let codegen_name = sess
244 .unwrap_or(&sess.target.target.options.codegen_backend);
245 let backend = match &codegen_name[..] {
246 filename if filename.contains(".") => load_backend_from_dylib(filename.as_ref()),
247 codegen_name => get_builtin_codegen_backend(codegen_name),
254 let backend = unsafe { LOAD() };
259 // This is used for rustdoc, but it uses similar machinery to codegen backend
260 // loading, so we leave the code here. It is potentially useful for other tools
261 // that want to invoke the rustc binary while linking to rustc as well.
262 pub fn rustc_path<'a>() -> Option<&'a Path> {
263 static RUSTC_PATH: once_cell::sync::OnceCell<Option<PathBuf>> =
264 once_cell::sync::OnceCell::new();
266 const BIN_PATH: &str = env!("RUSTC_INSTALL_BINDIR");
268 RUSTC_PATH.get_or_init(|| get_rustc_path_inner(BIN_PATH)).as_ref().map(|v| &**v)
271 fn get_rustc_path_inner(bin_path: &str) -> Option<PathBuf> {
274 .filter_map(|sysroot| {
275 let candidate = sysroot.join(bin_path).join(if cfg!(target_os = "windows") {
280 candidate.exists().then_some(candidate)
285 fn sysroot_candidates() -> Vec<PathBuf> {
286 let target = session::config::host_triple();
287 let mut sysroot_candidates = vec![filesearch::get_or_default_sysroot()];
288 let path = current_dll_path().and_then(|s| s.canonicalize().ok());
289 if let Some(dll) = path {
290 // use `parent` twice to chop off the file name and then also the
291 // directory containing the dll which should be either `lib` or `bin`.
292 if let Some(path) = dll.parent().and_then(|p| p.parent()) {
293 // The original `path` pointed at the `rustc_driver` crate's dll.
294 // Now that dll should only be in one of two locations. The first is
295 // in the compiler's libdir, for example `$sysroot/lib/*.dll`. The
296 // other is the target's libdir, for example
297 // `$sysroot/lib/rustlib/$target/lib/*.dll`.
299 // We don't know which, so let's assume that if our `path` above
300 // ends in `$target` we *could* be in the target libdir, and always
301 // assume that we may be in the main libdir.
302 sysroot_candidates.push(path.to_owned());
304 if path.ends_with(target) {
305 sysroot_candidates.extend(
306 path.parent() // chop off `$target`
307 .and_then(|p| p.parent()) // chop off `rustlib`
308 .and_then(|p| p.parent()) // chop off `lib`
309 .map(|s| s.to_owned()),
315 return sysroot_candidates;
318 fn current_dll_path() -> Option<PathBuf> {
319 use std::ffi::{CStr, OsStr};
320 use std::os::unix::prelude::*;
323 let addr = current_dll_path as usize as *mut _;
324 let mut info = mem::zeroed();
325 if libc::dladdr(addr, &mut info) == 0 {
326 info!("dladdr failed");
329 if info.dli_fname.is_null() {
330 info!("dladdr returned null pointer");
333 let bytes = CStr::from_ptr(info.dli_fname).to_bytes();
334 let os = OsStr::from_bytes(bytes);
335 Some(PathBuf::from(os))
340 fn current_dll_path() -> Option<PathBuf> {
341 use std::ffi::OsString;
342 use std::os::windows::prelude::*;
345 fn GetModuleHandleExW(dwFlags: u32, lpModuleName: usize, phModule: *mut usize) -> i32;
346 fn GetModuleFileNameW(hModule: usize, lpFilename: *mut u16, nSize: u32) -> u32;
349 const GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS: u32 = 0x00000004;
353 let r = GetModuleHandleExW(
354 GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS,
355 current_dll_path as usize,
359 info!("GetModuleHandleExW failed: {}", io::Error::last_os_error());
362 let mut space = Vec::with_capacity(1024);
363 let r = GetModuleFileNameW(module, space.as_mut_ptr(), space.capacity() as u32);
365 info!("GetModuleFileNameW failed: {}", io::Error::last_os_error());
369 if r >= space.capacity() {
370 info!("our buffer was too small? {}", io::Error::last_os_error());
374 let os = OsString::from_wide(&space);
375 Some(PathBuf::from(os))
380 pub fn get_builtin_codegen_backend(backend_name: &str) -> fn() -> Box<dyn CodegenBackend> {
381 #[cfg(feature = "llvm")]
383 if backend_name == "llvm" {
384 return rustc_codegen_llvm::LlvmCodegenBackend::new;
388 let err = format!("unsupported builtin codegen backend `{}`", backend_name);
389 early_error(ErrorOutputType::default(), &err);
392 pub(crate) fn compute_crate_disambiguator(session: &Session) -> CrateDisambiguator {
393 use std::hash::Hasher;
395 // The crate_disambiguator is a 128 bit hash. The disambiguator is fed
396 // into various other hashes quite a bit (symbol hashes, incr. comp. hashes,
397 // debuginfo type IDs, etc), so we don't want it to be too wide. 128 bits
398 // should still be safe enough to avoid collisions in practice.
399 let mut hasher = StableHasher::new();
401 let mut metadata = session.opts.cg.metadata.clone();
402 // We don't want the crate_disambiguator to dependent on the order
403 // -C metadata arguments, so sort them:
405 // Every distinct -C metadata value is only incorporated once:
408 hasher.write(b"metadata");
410 // Also incorporate the length of a metadata string, so that we generate
411 // different values for `-Cmetadata=ab -Cmetadata=c` and
412 // `-Cmetadata=a -Cmetadata=bc`
413 hasher.write_usize(s.len());
414 hasher.write(s.as_bytes());
417 // Also incorporate crate type, so that we don't get symbol conflicts when
418 // linking against a library of the same name, if this is an executable.
419 let is_exe = session.crate_types.borrow().contains(&config::CrateType::Executable);
420 hasher.write(if is_exe { b"exe" } else { b"lib" });
422 CrateDisambiguator::from(hasher.finish::<Fingerprint>())
425 pub(crate) fn check_attr_crate_type(attrs: &[ast::Attribute], lint_buffer: &mut LintBuffer) {
426 // Unconditionally collect crate types from attributes to make them used
427 for a in attrs.iter() {
428 if a.check_name(sym::crate_type) {
429 if let Some(n) = a.value_str() {
430 if let Some(_) = categorize_crate_type(n) {
434 if let ast::MetaItemKind::NameValue(spanned) = a.meta().unwrap().kind {
435 let span = spanned.span;
436 let lev_candidate = find_best_match_for_name(
437 CRATE_TYPES.iter().map(|(k, _)| k),
441 if let Some(candidate) = lev_candidate {
442 lint_buffer.buffer_lint_with_diagnostic(
443 lint::builtin::UNKNOWN_CRATE_TYPES,
446 "invalid `crate_type` value",
447 BuiltinLintDiagnostics::UnknownCrateTypes(
449 "did you mean".to_string(),
450 format!("\"{}\"", candidate),
454 lint_buffer.buffer_lint(
455 lint::builtin::UNKNOWN_CRATE_TYPES,
458 "invalid `crate_type` value",
467 const CRATE_TYPES: &[(Symbol, config::CrateType)] = &[
468 (sym::rlib, config::CrateType::Rlib),
469 (sym::dylib, config::CrateType::Dylib),
470 (sym::cdylib, config::CrateType::Cdylib),
471 (sym::lib, config::default_lib_output()),
472 (sym::staticlib, config::CrateType::Staticlib),
473 (sym::proc_dash_macro, config::CrateType::ProcMacro),
474 (sym::bin, config::CrateType::Executable),
477 fn categorize_crate_type(s: Symbol) -> Option<config::CrateType> {
478 Some(CRATE_TYPES.iter().find(|(key, _)| *key == s)?.1)
481 pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<config::CrateType> {
482 // Unconditionally collect crate types from attributes to make them used
483 let attr_types: Vec<config::CrateType> = attrs
486 if a.check_name(sym::crate_type) {
487 match a.value_str() {
488 Some(s) => categorize_crate_type(s),
497 // If we're generating a test executable, then ignore all other output
498 // styles at all other locations
499 if session.opts.test {
500 return vec![config::CrateType::Executable];
503 // Only check command line flags if present. If no types are specified by
504 // command line, then reuse the empty `base` Vec to hold the types that
505 // will be found in crate attributes.
506 let mut base = session.opts.crate_types.clone();
508 base.extend(attr_types);
510 base.push(::rustc_codegen_utils::link::default_output_for_target(session));
517 base.retain(|crate_type| {
518 let res = !::rustc_codegen_utils::link::invalid_output_for_target(session, *crate_type);
521 session.warn(&format!(
522 "dropping unsupported crate type `{}` for target `{}`",
523 *crate_type, session.opts.target_triple
533 pub fn build_output_filenames(
535 odir: &Option<PathBuf>,
536 ofile: &Option<PathBuf>,
537 attrs: &[ast::Attribute],
539 ) -> OutputFilenames {
542 // "-" as input file will cause the parser to read from stdin so we
543 // have to make up a name
544 // We want to toss everything after the final '.'
545 let dirpath = (*odir).as_ref().cloned().unwrap_or_default();
547 // If a crate name is present, we use it as the link name
552 .or_else(|| attr::find_crate_name(attrs).map(|n| n.to_string()))
553 .unwrap_or_else(|| input.filestem().to_owned());
556 out_directory: dirpath,
558 single_output_file: None,
559 extra: sess.opts.cg.extra_filename.clone(),
560 outputs: sess.opts.output_types.clone(),
564 Some(ref out_file) => {
565 let unnamed_output_types =
566 sess.opts.output_types.values().filter(|a| a.is_none()).count();
567 let ofile = if unnamed_output_types > 1 {
569 "due to multiple output types requested, the explicitly specified \
570 output file name will be adapted for each output type",
574 if !sess.opts.cg.extra_filename.is_empty() {
575 sess.warn("ignoring -C extra-filename flag due to -o flag");
577 Some(out_file.clone())
580 sess.warn("ignoring --out-dir flag due to -o flag");
584 out_directory: out_file.parent().unwrap_or_else(|| Path::new("")).to_path_buf(),
585 out_filestem: out_file
591 single_output_file: ofile,
592 extra: sess.opts.cg.extra_filename.clone(),
593 outputs: sess.opts.output_types.clone(),
599 // Note: Also used by librustdoc, see PR #43348. Consider moving this struct elsewhere.
601 // FIXME: Currently the `everybody_loops` transformation is not applied to:
602 // * `const fn`, due to issue #43636 that `loop` is not supported for const evaluation. We are
603 // waiting for miri to fix that.
604 // * `impl Trait`, due to issue #43869 that functions returning impl Trait cannot be diverging.
605 // Solving this may require `!` to implement every trait, which relies on the an even more
606 // ambitious form of the closed RFC #1637. See also [#34511].
608 // [#34511]: https://github.com/rust-lang/rust/issues/34511#issuecomment-322340401
609 pub struct ReplaceBodyWithLoop<'a, 'b> {
610 within_static_or_const: bool,
611 nested_blocks: Option<Vec<ast::Block>>,
612 resolver: &'a mut Resolver<'b>,
615 impl<'a, 'b> ReplaceBodyWithLoop<'a, 'b> {
616 pub fn new(resolver: &'a mut Resolver<'b>) -> ReplaceBodyWithLoop<'a, 'b> {
617 ReplaceBodyWithLoop { within_static_or_const: false, nested_blocks: None, resolver }
620 fn run<R, F: FnOnce(&mut Self) -> R>(&mut self, is_const: bool, action: F) -> R {
621 let old_const = mem::replace(&mut self.within_static_or_const, is_const);
622 let old_blocks = self.nested_blocks.take();
623 let ret = action(self);
624 self.within_static_or_const = old_const;
625 self.nested_blocks = old_blocks;
629 fn should_ignore_fn(ret_ty: &ast::FunctionRetTy) -> bool {
630 if let ast::FunctionRetTy::Ty(ref ty) = ret_ty {
631 fn involves_impl_trait(ty: &ast::Ty) -> bool {
633 ast::TyKind::ImplTrait(..) => true,
634 ast::TyKind::Slice(ref subty)
635 | ast::TyKind::Array(ref subty, _)
636 | ast::TyKind::Ptr(ast::MutTy { ty: ref subty, .. })
637 | ast::TyKind::Rptr(_, ast::MutTy { ty: ref subty, .. })
638 | ast::TyKind::Paren(ref subty) => involves_impl_trait(subty),
639 ast::TyKind::Tup(ref tys) => any_involves_impl_trait(tys.iter()),
640 ast::TyKind::Path(_, ref path) => path.segments.iter().any(|seg| {
641 match seg.args.as_ref().map(|generic_arg| &**generic_arg) {
643 Some(&ast::GenericArgs::AngleBracketed(ref data)) => {
644 let types = data.args.iter().filter_map(|arg| match arg {
645 ast::GenericArg::Type(ty) => Some(ty),
648 any_involves_impl_trait(types.into_iter())
649 || data.constraints.iter().any(|c| match c.kind {
650 ast::AssocTyConstraintKind::Bound { .. } => true,
651 ast::AssocTyConstraintKind::Equality { ref ty } => {
652 involves_impl_trait(ty)
656 Some(&ast::GenericArgs::Parenthesized(ref data)) => {
657 any_involves_impl_trait(data.inputs.iter())
658 || ReplaceBodyWithLoop::should_ignore_fn(&data.output)
666 fn any_involves_impl_trait<'a, I: Iterator<Item = &'a P<ast::Ty>>>(mut it: I) -> bool {
667 it.any(|subty| involves_impl_trait(subty))
670 involves_impl_trait(ty)
676 fn is_sig_const(sig: &ast::FnSig) -> bool {
677 sig.header.constness.node == ast::Constness::Const
678 || ReplaceBodyWithLoop::should_ignore_fn(&sig.decl.output)
682 impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
683 fn visit_item_kind(&mut self, i: &mut ast::ItemKind) {
684 let is_const = match i {
685 ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => true,
686 ast::ItemKind::Fn(ref sig, _, _) => Self::is_sig_const(sig),
689 self.run(is_const, |s| noop_visit_item_kind(i, s))
692 fn flat_map_trait_item(&mut self, i: ast::AssocItem) -> SmallVec<[ast::AssocItem; 1]> {
693 let is_const = match i.kind {
694 ast::AssocItemKind::Const(..) => true,
695 ast::AssocItemKind::Fn(ref sig, _) => Self::is_sig_const(sig),
698 self.run(is_const, |s| noop_flat_map_assoc_item(i, s))
701 fn flat_map_impl_item(&mut self, i: ast::AssocItem) -> SmallVec<[ast::AssocItem; 1]> {
702 self.flat_map_trait_item(i)
705 fn visit_anon_const(&mut self, c: &mut ast::AnonConst) {
706 self.run(true, |s| noop_visit_anon_const(c, s))
709 fn visit_block(&mut self, b: &mut P<ast::Block>) {
711 rules: ast::BlockCheckMode,
712 s: Option<ast::Stmt>,
713 resolver: &mut Resolver<'_>,
716 stmts: s.into_iter().collect(),
718 id: resolver.next_node_id(),
719 span: rustc_span::DUMMY_SP,
723 fn block_to_stmt(b: ast::Block, resolver: &mut Resolver<'_>) -> ast::Stmt {
724 let expr = P(ast::Expr {
725 id: resolver.next_node_id(),
726 kind: ast::ExprKind::Block(P(b), None),
727 span: rustc_span::DUMMY_SP,
728 attrs: AttrVec::new(),
732 id: resolver.next_node_id(),
733 kind: ast::StmtKind::Expr(expr),
734 span: rustc_span::DUMMY_SP,
738 let empty_block = stmt_to_block(BlockCheckMode::Default, None, self.resolver);
739 let loop_expr = P(ast::Expr {
740 kind: ast::ExprKind::Loop(P(empty_block), None),
741 id: self.resolver.next_node_id(),
742 span: rustc_span::DUMMY_SP,
743 attrs: AttrVec::new(),
746 let loop_stmt = ast::Stmt {
747 id: self.resolver.next_node_id(),
748 span: rustc_span::DUMMY_SP,
749 kind: ast::StmtKind::Expr(loop_expr),
752 if self.within_static_or_const {
753 noop_visit_block(b, self)
755 visit_clobber(b.deref_mut(), |b| {
756 let mut stmts = vec![];
758 let old_blocks = self.nested_blocks.replace(vec![]);
760 stmts.extend(self.flat_map_stmt(s).into_iter().filter(|s| s.is_item()));
762 // we put a Some in there earlier with that replace(), so this is valid
763 let new_blocks = self.nested_blocks.take().unwrap();
764 self.nested_blocks = old_blocks;
765 stmts.extend(new_blocks.into_iter().map(|b| block_to_stmt(b, self.resolver)));
768 let mut new_block = ast::Block { stmts, ..b };
770 if let Some(old_blocks) = self.nested_blocks.as_mut() {
771 //push our fresh block onto the cache and yield an empty block with `loop {}`
772 if !new_block.stmts.is_empty() {
773 old_blocks.push(new_block);
776 stmt_to_block(b.rules, Some(loop_stmt), &mut self.resolver)
778 //push `loop {}` onto the end of our fresh block and yield that
779 new_block.stmts.push(loop_stmt);
787 // in general the pretty printer processes unexpanded code, so
788 // we override the default `visit_mac` method which panics.
789 fn visit_mac(&mut self, mac: &mut ast::Mac) {
790 noop_visit_mac(mac, self)