2 use crate::build::scope::DropKind;
3 use crate::hair::cx::Cx;
4 use crate::hair::{LintLevel, BindingMode, PatKind};
5 use crate::transform::MirSource;
6 use crate::util as mir_util;
9 use rustc::hir::def_id::DefId;
10 use rustc::middle::lang_items;
11 use rustc::middle::region;
13 use rustc::ty::{self, Ty, TyCtxt};
14 use rustc::ty::subst::Subst;
15 use rustc::util::nodemap::HirIdMap;
16 use rustc_target::spec::PanicStrategy;
17 use rustc_index::vec::{IndexVec, Idx};
19 use rustc_target::spec::abi::Abi;
20 use syntax::attr::{self, UnwindAttr};
21 use syntax::symbol::kw;
26 /// Construct the MIR for a given `DefId`.
27 pub fn mir_build(tcx: TyCtxt<'_>, def_id: DefId) -> Body<'_> {
28 let id = tcx.hir().as_local_hir_id(def_id).unwrap();
30 // Figure out what primary body this item has.
31 let (body_id, return_ty_span) = match tcx.hir().get(id) {
32 Node::Expr(hir::Expr { kind: hir::ExprKind::Closure(_, decl, body_id, _, _), .. })
35 kind: hir::ItemKind::Fn(hir::FnSig { decl, .. }, _, body_id),
41 kind: hir::ImplItemKind::Method(hir::FnSig { decl, .. }, body_id),
47 kind: hir::TraitItemKind::Method(
48 hir::FnSig { decl, .. },
49 hir::TraitMethod::Provided(body_id),
54 (*body_id, decl.output.span())
56 Node::Item(hir::Item { kind: hir::ItemKind::Static(ty, _, body_id), .. })
57 | Node::Item(hir::Item { kind: hir::ItemKind::Const(ty, body_id), .. })
58 | Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(ty, body_id), .. })
60 hir::TraitItem { kind: hir::TraitItemKind::Const(ty, Some(body_id)), .. }
64 Node::AnonConst(hir::AnonConst { body, hir_id, .. }) => {
65 (*body, tcx.hir().span(*hir_id))
68 _ => span_bug!(tcx.hir().span(id), "can't build MIR for {:?}", def_id),
71 tcx.infer_ctxt().enter(|infcx| {
72 let cx = Cx::new(&infcx, id);
73 let body = if cx.tables().tainted_by_errors {
74 build::construct_error(cx, body_id)
75 } else if cx.body_owner_kind.is_fn_or_closure() {
76 // fetch the fully liberated fn signature (that is, all bound
77 // types/lifetimes replaced)
78 let fn_sig = cx.tables().liberated_fn_sigs()[id].clone();
79 let fn_def_id = tcx.hir().local_def_id(id);
81 let ty = tcx.type_of(fn_def_id);
82 let mut abi = fn_sig.abi;
83 let implicit_argument = match ty.kind {
85 // HACK(eddyb) Avoid having RustCall on closures,
86 // as it adds unnecessary (and wrong) auto-tupling.
88 Some(ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None))
90 ty::Generator(..) => {
91 let gen_ty = tcx.body_tables(body_id).node_type(id);
92 Some(ArgInfo(gen_ty, None, None, None))
97 let safety = match fn_sig.unsafety {
98 hir::Unsafety::Normal => Safety::Safe,
99 hir::Unsafety::Unsafe => Safety::FnUnsafe,
102 let body = tcx.hir().body(body_id);
103 let explicit_arguments =
107 .map(|(index, arg)| {
108 let owner_id = tcx.hir().body_owner(body_id);
111 if let Some(ref fn_decl) = tcx.hir().fn_decl_by_hir_id(owner_id) {
112 opt_ty_info = fn_decl.inputs.get(index).map(|ty| ty.span);
113 self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
114 match fn_decl.implicit_self {
115 hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm),
116 hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut),
117 hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef),
118 hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef),
129 // C-variadic fns also have a `VaList` input that's not listed in `fn_sig`
130 // (as it's created inside the body itself, not passed in from outside).
131 let ty = if fn_sig.c_variadic && index == fn_sig.inputs().len() {
132 let va_list_did = tcx.require_lang_item(
133 lang_items::VaListTypeLangItem,
136 let region = tcx.mk_region(ty::ReScope(region::Scope {
137 id: body.value.hir_id.local_id,
138 data: region::ScopeData::CallSite
141 tcx.type_of(va_list_did).subst(tcx, &[region.into()])
143 fn_sig.inputs()[index]
146 ArgInfo(ty, opt_ty_info, Some(&arg), self_arg)
149 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
151 let (yield_ty, return_ty) = if body.generator_kind.is_some() {
152 let gen_sig = match ty.kind {
153 ty::Generator(gen_def_id, gen_substs, ..) =>
154 gen_substs.as_generator().sig(gen_def_id, tcx),
156 span_bug!(tcx.hir().span(id),
157 "generator w/o generator type: {:?}", ty),
159 (Some(gen_sig.yield_ty), gen_sig.return_ty)
161 (None, fn_sig.output())
164 build::construct_fn(cx, id, arguments, safety, abi,
165 return_ty, yield_ty, return_ty_span, body)
167 // Get the revealed type of this const. This is *not* the adjusted
168 // type of its body, which may be a subtype of this type. For
172 // static X: fn(&'static ()) = foo;
174 // The adjusted type of the body of X is `for<'a> fn(&'a ())` which
175 // is not the same as the type of X. We need the type of the return
176 // place to be the type of the constant because NLL typeck will
179 let return_ty = cx.tables().node_type(id);
181 build::construct_const(cx, body_id, return_ty, return_ty_span)
184 mir_util::dump_mir(tcx, None, "mir_map", &0,
185 MirSource::item(def_id), &body, |_, _| Ok(()) );
187 lints::check(tcx, &body, def_id);
193 ///////////////////////////////////////////////////////////////////////////
194 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
196 fn liberated_closure_env_ty(
198 closure_expr_id: hir::HirId,
199 body_id: hir::BodyId,
201 let closure_ty = tcx.body_tables(body_id).node_type(closure_expr_id);
203 let (closure_def_id, closure_substs) = match closure_ty.kind {
204 ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
205 _ => bug!("closure expr does not have closure type: {:?}", closure_ty)
208 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap();
209 tcx.liberate_late_bound_regions(closure_def_id, &closure_env_ty)
212 #[derive(Debug, PartialEq, Eq)]
213 pub enum BlockFrame {
214 /// Evaluation is currently within a statement.
216 /// Examples include:
218 /// 2. `let _ = EXPR;`
219 /// 3. `let x = EXPR;`
221 /// If true, then statement discards result from evaluating
222 /// the expression (such as examples 1 and 2 above).
223 ignores_expr_result: bool
226 /// Evaluation is currently within the tail expression of a block.
228 /// Example: `{ STMT_1; STMT_2; EXPR }`
230 /// If true, then the surrounding context of the block ignores
231 /// the result of evaluating the block's tail expression.
233 /// Example: `let _ = { STMT_1; EXPR };`
234 tail_result_is_ignored: bool
237 /// Generic mark meaning that the block occurred as a subexpression
238 /// where the result might be used.
240 /// Examples: `foo(EXPR)`, `match EXPR { ... }`
245 fn is_tail_expr(&self) -> bool {
247 BlockFrame::TailExpr { .. } => true,
249 BlockFrame::Statement { .. } |
250 BlockFrame::SubExpr => false,
253 fn is_statement(&self) -> bool {
255 BlockFrame::Statement { .. } => true,
257 BlockFrame::TailExpr { .. } |
258 BlockFrame::SubExpr => false,
264 struct BlockContext(Vec<BlockFrame>);
266 struct Builder<'a, 'tcx> {
274 /// The current set of scopes, updated as we traverse;
275 /// see the `scope` module for more details.
276 scopes: scope::Scopes<'tcx>,
278 /// The block-context: each time we build the code within an hair::Block,
279 /// we push a frame here tracking whether we are building a statement or
280 /// if we are pushing the tail expression of the block. This is used to
281 /// embed information in generated temps about whether they were created
282 /// for a block tail expression or not.
284 /// It would be great if we could fold this into `self.scopes`
285 /// somehow, but right now I think that is very tightly tied to
286 /// the code generation in ways that we cannot (or should not)
287 /// start just throwing new entries onto that vector in order to
288 /// distinguish the context of EXPR1 from the context of EXPR2 in
289 /// `{ STMTS; EXPR1 } + EXPR2`.
290 block_context: BlockContext,
292 /// The current unsafe block in scope, even if it is hidden by
293 /// a `PushUnsafeBlock`.
294 unpushed_unsafe: Safety,
296 /// The number of `push_unsafe_block` levels in scope.
297 push_unsafe_count: usize,
299 /// The vector of all scopes that we have created thus far;
300 /// we track this for debuginfo later.
301 source_scopes: IndexVec<SourceScope, SourceScopeData>,
302 source_scope_local_data: IndexVec<SourceScope, SourceScopeLocalData>,
303 source_scope: SourceScope,
305 /// The guard-context: each time we build the guard expression for
306 /// a match arm, we push onto this stack, and then pop when we
307 /// finish building it.
308 guard_context: Vec<GuardFrame>,
310 /// Maps `HirId`s of variable bindings to the `Local`s created for them.
311 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
312 var_indices: HirIdMap<LocalsForNode>,
313 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
314 canonical_user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
315 __upvar_debuginfo_codegen_only_do_not_use: Vec<UpvarDebuginfo>,
316 upvar_mutbls: Vec<Mutability>,
317 unit_temp: Option<Place<'tcx>>,
319 /// Cached block with the `RESUME` terminator; this is created
320 /// when first set of cleanups are built.
321 cached_resume_block: Option<BasicBlock>,
322 /// Cached block with the `RETURN` terminator.
323 cached_return_block: Option<BasicBlock>,
324 /// Cached block with the `UNREACHABLE` terminator.
325 cached_unreachable_block: Option<BasicBlock>,
328 impl<'a, 'tcx> Builder<'a, 'tcx> {
329 fn is_bound_var_in_guard(&self, id: hir::HirId) -> bool {
330 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
333 fn var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local {
334 self.var_indices[&id].local_id(for_guard)
339 fn new() -> Self { BlockContext(vec![]) }
340 fn push(&mut self, bf: BlockFrame) { self.0.push(bf); }
341 fn pop(&mut self) -> Option<BlockFrame> { self.0.pop() }
343 /// Traverses the frames on the `BlockContext`, searching for either
344 /// the first block-tail expression frame with no intervening
347 /// Notably, this skips over `SubExpr` frames; this method is
348 /// meant to be used in the context of understanding the
349 /// relationship of a temp (created within some complicated
350 /// expression) with its containing expression, and whether the
351 /// value of that *containing expression* (not the temp!) is
353 fn currently_in_block_tail(&self) -> Option<BlockTailInfo> {
354 for bf in self.0.iter().rev() {
356 BlockFrame::SubExpr => continue,
357 BlockFrame::Statement { .. } => break,
358 &BlockFrame::TailExpr { tail_result_is_ignored } =>
359 return Some(BlockTailInfo { tail_result_is_ignored })
366 /// Looks at the topmost frame on the BlockContext and reports
367 /// whether its one that would discard a block tail result.
369 /// Unlike `currently_within_ignored_tail_expression`, this does
370 /// *not* skip over `SubExpr` frames: here, we want to know
371 /// whether the block result itself is discarded.
372 fn currently_ignores_tail_results(&self) -> bool {
373 match self.0.last() {
374 // no context: conservatively assume result is read
377 // sub-expression: block result feeds into some computation
378 Some(BlockFrame::SubExpr) => false,
380 // otherwise: use accumulated is_ignored state.
381 Some(BlockFrame::TailExpr { tail_result_is_ignored: ignored }) |
382 Some(BlockFrame::Statement { ignores_expr_result: ignored }) => *ignored,
389 /// In the usual case, a `HirId` for an identifier maps to at most
390 /// one `Local` declaration.
393 /// The exceptional case is identifiers in a match arm's pattern
394 /// that are referenced in a guard of that match arm. For these,
395 /// we have `2` Locals.
397 /// * `for_arm_body` is the Local used in the arm body (which is
398 /// just like the `One` case above),
400 /// * `ref_for_guard` is the Local used in the arm's guard (which
401 /// is a reference to a temp that is an alias of
403 ForGuard { ref_for_guard: Local, for_arm_body: Local },
407 struct GuardFrameLocal {
411 impl GuardFrameLocal {
412 fn new(id: hir::HirId, _binding_mode: BindingMode) -> Self {
421 /// These are the id's of names that are bound by patterns of the
422 /// arm of *this* guard.
424 /// (Frames higher up the stack will have the id's bound in arms
425 /// further out, such as in a case like:
428 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
431 /// here, when building for FIXME.
432 locals: Vec<GuardFrameLocal>,
435 /// `ForGuard` indicates whether we are talking about:
436 /// 1. The variable for use outside of guard expressions, or
437 /// 2. The temp that holds reference to (1.), which is actually what the
438 /// guard expressions see.
439 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
446 fn local_id(&self, for_guard: ForGuard) -> Local {
447 match (self, for_guard) {
448 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard) |
449 (&LocalsForNode::ForGuard { ref_for_guard: local_id, .. }, ForGuard::RefWithinGuard) |
450 (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) =>
453 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) =>
454 bug!("anything with one local should never be within a guard."),
460 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
463 rustc_index::newtype_index! {
464 pub struct ScopeId { .. }
467 ///////////////////////////////////////////////////////////////////////////
468 /// The `BlockAnd` "monad" packages up the new basic block along with a
469 /// produced value (sometimes just unit, of course). The `unpack!`
470 /// macro (and methods below) makes working with `BlockAnd` much more
473 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
474 struct BlockAnd<T>(BasicBlock, T);
476 trait BlockAndExtension {
477 fn and<T>(self, v: T) -> BlockAnd<T>;
478 fn unit(self) -> BlockAnd<()>;
481 impl BlockAndExtension for BasicBlock {
482 fn and<T>(self, v: T) -> BlockAnd<T> {
486 fn unit(self) -> BlockAnd<()> {
491 /// Update a block pointer and return the value.
492 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
493 macro_rules! unpack {
494 ($x:ident = $c:expr) => {
496 let BlockAnd(b, v) = $c;
504 let BlockAnd(b, ()) = $c;
510 fn should_abort_on_panic(tcx: TyCtxt<'_>, fn_def_id: DefId, _abi: Abi) -> bool {
511 // Validate `#[unwind]` syntax regardless of platform-specific panic strategy.
512 let attrs = &tcx.get_attrs(fn_def_id);
513 let unwind_attr = attr::find_unwind_attr(Some(tcx.sess.diagnostic()), attrs);
515 // We never unwind, so it's not relevant to stop an unwind.
516 if tcx.sess.panic_strategy() != PanicStrategy::Unwind { return false; }
518 // We cannot add landing pads, so don't add one.
519 if tcx.sess.no_landing_pads() { return false; }
521 // This is a special case: some functions have a C abi but are meant to
522 // unwind anyway. Don't stop them.
524 None => false, // FIXME(#58794); should be `!(abi == Abi::Rust || abi == Abi::RustCall)`
525 Some(UnwindAttr::Allowed) => false,
526 Some(UnwindAttr::Aborts) => true,
530 ///////////////////////////////////////////////////////////////////////////
531 /// the main entry point for building MIR for a function
533 struct ArgInfo<'tcx>(Ty<'tcx>, Option<Span>, Option<&'tcx hir::Param>, Option<ImplicitSelfKind>);
535 fn construct_fn<'a, 'tcx, A>(
542 yield_ty: Option<Ty<'tcx>>,
543 return_ty_span: Span,
544 body: &'tcx hir::Body,
547 A: Iterator<Item=ArgInfo<'tcx>>
549 let arguments: Vec<_> = arguments.collect();
552 let tcx_hir = tcx.hir();
553 let span = tcx_hir.span(fn_id);
555 let hir_tables = hir.tables();
556 let fn_def_id = tcx_hir.local_def_id(fn_id);
558 // Gather the upvars of a closure, if any.
559 let mut upvar_mutbls = vec![];
560 // In analyze_closure() in upvar.rs we gathered a list of upvars used by a
561 // closure and we stored in a map called upvar_list in TypeckTables indexed
562 // with the closure's DefId. Here, we run through that vec of UpvarIds for
563 // the given closure and use the necessary information to create UpvarDecl.
564 let upvar_debuginfo: Vec<_> = hir_tables
569 .map(|(&var_hir_id, &upvar_id)| {
570 let capture = hir_tables.upvar_capture(upvar_id);
571 let by_ref = match capture {
572 ty::UpvarCapture::ByValue => false,
573 ty::UpvarCapture::ByRef(..) => true,
575 let mut debuginfo = UpvarDebuginfo {
576 debug_name: kw::Invalid,
579 let mut mutability = Mutability::Not;
580 if let Some(Node::Binding(pat)) = tcx_hir.find(var_hir_id) {
581 if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
582 debuginfo.debug_name = ident.name;
583 if let Some(&bm) = hir.tables.pat_binding_modes().get(pat.hir_id) {
584 if bm == ty::BindByValue(hir::Mutability::Mutable) {
585 mutability = Mutability::Mut;
587 mutability = Mutability::Not;
590 tcx.sess.delay_span_bug(pat.span, "missing binding mode");
594 upvar_mutbls.push(mutability);
599 let mut builder = Builder::new(hir,
607 body.generator_kind.is_some());
609 let call_site_scope = region::Scope {
610 id: body.value.hir_id.local_id,
611 data: region::ScopeData::CallSite
613 let arg_scope = region::Scope {
614 id: body.value.hir_id.local_id,
615 data: region::ScopeData::Arguments
617 let mut block = START_BLOCK;
618 let source_info = builder.source_info(span);
619 let call_site_s = (call_site_scope, source_info);
620 unpack!(block = builder.in_scope(call_site_s, LintLevel::Inherited, |builder| {
621 if should_abort_on_panic(tcx, fn_def_id, abi) {
622 builder.schedule_abort();
625 let arg_scope_s = (arg_scope, source_info);
626 // `return_block` is called when we evaluate a `return` expression, so
627 // we just use `START_BLOCK` here.
628 unpack!(block = builder.in_breakable_scope(
631 Place::return_place(),
633 builder.in_scope(arg_scope_s, LintLevel::Inherited, |builder| {
634 builder.args_and_body(block, &arguments, arg_scope, &body.value)
638 // Attribute epilogue to function's closing brace
639 let fn_end = span.shrink_to_hi();
640 let source_info = builder.source_info(fn_end);
641 let return_block = builder.return_block();
642 builder.cfg.terminate(block, source_info,
643 TerminatorKind::Goto { target: return_block });
644 builder.cfg.terminate(return_block, source_info,
645 TerminatorKind::Return);
646 // Attribute any unreachable codepaths to the function's closing brace
647 if let Some(unreachable_block) = builder.cached_unreachable_block {
648 builder.cfg.terminate(unreachable_block, source_info,
649 TerminatorKind::Unreachable);
653 assert_eq!(block, builder.return_block());
655 let mut spread_arg = None;
656 if abi == Abi::RustCall {
657 // RustCall pseudo-ABI untuples the last argument.
658 spread_arg = Some(Local::new(arguments.len()));
660 info!("fn_id {:?} has attrs {:?}", fn_def_id,
661 tcx.get_attrs(fn_def_id));
663 let mut body = builder.finish(yield_ty);
664 body.spread_arg = spread_arg;
668 fn construct_const<'a, 'tcx>(
670 body_id: hir::BodyId,
675 let owner_id = tcx.hir().body_owner(body_id);
676 let span = tcx.hir().span(owner_id);
677 let mut builder = Builder::new(
689 let mut block = START_BLOCK;
690 let ast_expr = &tcx.hir().body(body_id).value;
691 let expr = builder.hir.mirror(ast_expr);
692 unpack!(block = builder.into_expr(&Place::return_place(), block, expr));
694 let source_info = builder.source_info(span);
695 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
697 // Constants can't `return` so a return block should not be created.
698 assert_eq!(builder.cached_return_block, None);
700 // Constants may be match expressions in which case an unreachable block may
701 // be created, so terminate it properly.
702 if let Some(unreachable_block) = builder.cached_unreachable_block {
703 builder.cfg.terminate(unreachable_block, source_info,
704 TerminatorKind::Unreachable);
710 fn construct_error<'a, 'tcx>(
714 let owner_id = hir.tcx().hir().body_owner(body_id);
715 let span = hir.tcx().hir().span(owner_id);
716 let ty = hir.tcx().types.err;
717 let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty, span, vec![], vec![], false);
718 let source_info = builder.source_info(span);
719 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
723 impl<'a, 'tcx> Builder<'a, 'tcx> {
724 fn new(hir: Cx<'a, 'tcx>,
730 __upvar_debuginfo_codegen_only_do_not_use: Vec<UpvarDebuginfo>,
731 upvar_mutbls: Vec<Mutability>,
733 -> Builder<'a, 'tcx> {
734 let lint_level = LintLevel::Explicit(hir.root_lint_level);
735 let mut builder = Builder {
737 cfg: CFG { basic_blocks: IndexVec::new() },
741 scopes: Default::default(),
742 block_context: BlockContext::new(),
743 source_scopes: IndexVec::new(),
744 source_scope: OUTERMOST_SOURCE_SCOPE,
745 source_scope_local_data: IndexVec::new(),
746 guard_context: vec![],
747 push_unsafe_count: 0,
748 unpushed_unsafe: safety,
749 local_decls: IndexVec::from_elem_n(
750 LocalDecl::new_return_place(return_ty, return_span),
753 canonical_user_type_annotations: IndexVec::new(),
754 __upvar_debuginfo_codegen_only_do_not_use,
756 var_indices: Default::default(),
758 cached_resume_block: None,
759 cached_return_block: None,
760 cached_unreachable_block: None,
763 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
765 builder.new_source_scope(span, lint_level, Some(safety)),
766 OUTERMOST_SOURCE_SCOPE);
767 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
773 yield_ty: Option<Ty<'tcx>>)
775 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
776 if block.terminator.is_none() {
777 span_bug!(self.fn_span, "no terminator on block {:?}", index);
782 self.cfg.basic_blocks,
784 ClearCrossCrate::Set(self.source_scope_local_data),
787 self.canonical_user_type_annotations,
789 self.__upvar_debuginfo_codegen_only_do_not_use,
791 self.hir.control_flow_destroyed(),
795 fn args_and_body(&mut self,
796 mut block: BasicBlock,
797 arguments: &[ArgInfo<'tcx>],
798 argument_scope: region::Scope,
799 ast_body: &'tcx hir::Expr)
802 // Allocate locals for the function arguments
803 for &ArgInfo(ty, _, arg_opt, _) in arguments.iter() {
804 // If this is a simple binding pattern, give the local a name for
805 // debuginfo and so that error reporting knows that this is a user
806 // variable. For any other pattern the pattern introduces new
807 // variables which will be named instead.
808 let (name, span) = if let Some(arg) = arg_opt {
809 (arg.pat.simple_ident().map(|ident| ident.name), arg.pat.span)
814 let source_info = SourceInfo { scope: OUTERMOST_SOURCE_SCOPE, span, };
815 self.local_decls.push(LocalDecl {
816 mutability: Mutability::Mut,
818 user_ty: UserTypeProjections::none(),
820 visibility_scope: source_info.scope,
823 local_info: LocalInfo::Other,
828 let mut scope = None;
829 // Bind the argument patterns
830 for (index, arg_info) in arguments.iter().enumerate() {
831 // Function arguments always get the first Local indices after the return place
832 let local = Local::new(index + 1);
833 let place = Place::from(local);
834 let &ArgInfo(_, opt_ty_info, arg_opt, ref self_binding) = arg_info;
836 // Make sure we drop (parts of) the argument even when not matched on.
838 arg_opt.as_ref().map_or(ast_body.span, |arg| arg.pat.span),
839 argument_scope, local, DropKind::Value,
842 if let Some(arg) = arg_opt {
843 let pattern = self.hir.pattern_from_hir(&arg.pat);
844 let original_source_scope = self.source_scope;
845 let span = pattern.span;
846 self.set_correct_source_scope_for_arg(arg.hir_id, original_source_scope, span);
847 match *pattern.kind {
848 // Don't introduce extra copies for simple bindings
852 mode: BindingMode::ByValue,
856 self.local_decls[local].mutability = mutability;
857 self.local_decls[local].source_info.scope = self.source_scope;
858 self.local_decls[local].local_info =
859 if let Some(kind) = self_binding {
860 LocalInfo::User(ClearCrossCrate::Set(
861 BindingForm::ImplicitSelf(*kind),
864 let binding_mode = ty::BindingMode::BindByValue(mutability.into());
865 LocalInfo::User(ClearCrossCrate::Set(BindingForm::Var(
869 opt_match_place: Some((Some(place.clone()), span)),
874 self.var_indices.insert(var, LocalsForNode::One(local));
877 scope = self.declare_bindings(
881 matches::ArmHasGuard(false),
882 Some((Some(&place), span)),
884 unpack!(block = self.place_into_pattern(block, pattern, &place, false));
887 self.source_scope = original_source_scope;
891 // Enter the argument pattern bindings source scope, if it exists.
892 if let Some(source_scope) = scope {
893 self.source_scope = source_scope;
896 let body = self.hir.mirror(ast_body);
897 self.into(&Place::return_place(), block, body)
900 fn set_correct_source_scope_for_arg(
902 arg_hir_id: hir::HirId,
903 original_source_scope: SourceScope,
906 let tcx = self.hir.tcx();
907 let current_root = tcx.maybe_lint_level_root_bounded(
909 self.hir.root_lint_level
911 let parent_root = tcx.maybe_lint_level_root_bounded(
912 self.source_scope_local_data[original_source_scope].lint_root,
913 self.hir.root_lint_level,
915 if current_root != parent_root {
916 self.source_scope = self.new_source_scope(
918 LintLevel::Explicit(current_root),
924 fn get_unit_temp(&mut self) -> Place<'tcx> {
925 match self.unit_temp {
926 Some(ref tmp) => tmp.clone(),
928 let ty = self.hir.unit_ty();
929 let fn_span = self.fn_span;
930 let tmp = self.temp(ty, fn_span);
931 self.unit_temp = Some(tmp.clone());
937 fn return_block(&mut self) -> BasicBlock {
938 match self.cached_return_block {
941 let rb = self.cfg.start_new_block();
942 self.cached_return_block = Some(rb);
949 ///////////////////////////////////////////////////////////////////////////
950 // Builder methods are broken up into modules, depending on what kind
951 // of thing is being lowered. Note that they use the `unpack` macro
952 // above extensively.