2 use crate::build::scope::DropKind;
3 use crate::hair::cx::Cx;
4 use crate::hair::{LintLevel, BindingMode, PatternKind};
5 use crate::transform::MirSource;
6 use crate::util as mir_util;
9 use rustc::hir::def_id::DefId;
10 use rustc::middle::region;
12 use rustc::ty::{self, Ty, TyCtxt};
13 use rustc::util::nodemap::HirIdMap;
14 use rustc_target::spec::PanicStrategy;
15 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
17 use rustc_target::spec::abi::Abi;
18 use syntax::attr::{self, UnwindAttr};
19 use syntax::symbol::kw;
24 /// Construct the MIR for a given `DefId`.
25 pub fn mir_build(tcx: TyCtxt<'_>, def_id: DefId) -> Body<'_> {
26 let id = tcx.hir().as_local_hir_id(def_id).unwrap();
28 // Figure out what primary body this item has.
29 let (body_id, return_ty_span) = match tcx.hir().get(id) {
30 Node::Expr(hir::Expr { node: hir::ExprKind::Closure(_, decl, body_id, _, _), .. })
31 | Node::Item(hir::Item { node: hir::ItemKind::Fn(decl, _, _, body_id), .. })
34 node: hir::ImplItemKind::Method(hir::MethodSig { decl, .. }, body_id),
40 node: hir::TraitItemKind::Method(
41 hir::MethodSig { decl, .. },
42 hir::TraitMethod::Provided(body_id),
47 (*body_id, decl.output.span())
49 Node::Item(hir::Item { node: hir::ItemKind::Static(ty, _, body_id), .. })
50 | Node::Item(hir::Item { node: hir::ItemKind::Const(ty, body_id), .. })
51 | Node::ImplItem(hir::ImplItem { node: hir::ImplItemKind::Const(ty, body_id), .. })
53 hir::TraitItem { node: hir::TraitItemKind::Const(ty, Some(body_id)), .. }
57 Node::AnonConst(hir::AnonConst { body, hir_id, .. }) => {
58 (*body, tcx.hir().span(*hir_id))
61 _ => span_bug!(tcx.hir().span(id), "can't build MIR for {:?}", def_id),
64 tcx.infer_ctxt().enter(|infcx| {
65 let cx = Cx::new(&infcx, id);
66 let body = if cx.tables().tainted_by_errors {
67 build::construct_error(cx, body_id)
68 } else if cx.body_owner_kind.is_fn_or_closure() {
69 // fetch the fully liberated fn signature (that is, all bound
70 // types/lifetimes replaced)
71 let fn_sig = cx.tables().liberated_fn_sigs()[id].clone();
72 let fn_def_id = tcx.hir().local_def_id(id);
74 let ty = tcx.type_of(fn_def_id);
75 let mut abi = fn_sig.abi;
76 let implicit_argument = match ty.sty {
78 // HACK(eddyb) Avoid having RustCall on closures,
79 // as it adds unnecessary (and wrong) auto-tupling.
81 Some(ArgInfo(liberated_closure_env_ty(tcx, id, body_id), None, None, None))
83 ty::Generator(..) => {
84 let gen_ty = tcx.body_tables(body_id).node_type(id);
85 Some(ArgInfo(gen_ty, None, None, None))
90 let safety = match fn_sig.unsafety {
91 hir::Unsafety::Normal => Safety::Safe,
92 hir::Unsafety::Unsafe => Safety::FnUnsafe,
95 let body = tcx.hir().body(body_id);
96 let explicit_arguments =
100 .map(|(index, arg)| {
101 let owner_id = tcx.hir().body_owner(body_id);
104 if let Some(ref fn_decl) = tcx.hir().fn_decl_by_hir_id(owner_id) {
105 let ty_hir_id = fn_decl.inputs[index].hir_id;
106 let ty_span = tcx.hir().span(ty_hir_id);
107 opt_ty_info = Some(ty_span);
108 self_arg = if index == 0 && fn_decl.implicit_self.has_implicit_self() {
109 match fn_decl.implicit_self {
110 hir::ImplicitSelfKind::Imm => Some(ImplicitSelfKind::Imm),
111 hir::ImplicitSelfKind::Mut => Some(ImplicitSelfKind::Mut),
112 hir::ImplicitSelfKind::ImmRef => Some(ImplicitSelfKind::ImmRef),
113 hir::ImplicitSelfKind::MutRef => Some(ImplicitSelfKind::MutRef),
124 ArgInfo(fn_sig.inputs()[index], opt_ty_info, Some(&*arg.pat), self_arg)
127 let arguments = implicit_argument.into_iter().chain(explicit_arguments);
129 let (yield_ty, return_ty) = if body.generator_kind.is_some() {
130 let gen_sig = match ty.sty {
131 ty::Generator(gen_def_id, gen_substs, ..) =>
132 gen_substs.sig(gen_def_id, tcx),
134 span_bug!(tcx.hir().span(id),
135 "generator w/o generator type: {:?}", ty),
137 (Some(gen_sig.yield_ty), gen_sig.return_ty)
139 (None, fn_sig.output())
142 build::construct_fn(cx, id, arguments, safety, abi,
143 return_ty, yield_ty, return_ty_span, body)
145 // Get the revealed type of this const. This is *not* the adjusted
146 // type of its body, which may be a subtype of this type. For
150 // static X: fn(&'static ()) = foo;
152 // The adjusted type of the body of X is `for<'a> fn(&'a ())` which
153 // is not the same as the type of X. We need the type of the return
154 // place to be the type of the constant because NLL typeck will
157 let return_ty = cx.tables().node_type(id);
159 build::construct_const(cx, body_id, return_ty, return_ty_span)
162 mir_util::dump_mir(tcx, None, "mir_map", &0,
163 MirSource::item(def_id), &body, |_, _| Ok(()) );
165 lints::check(tcx, &body, def_id);
171 ///////////////////////////////////////////////////////////////////////////
172 // BuildMir -- walks a crate, looking for fn items and methods to build MIR from
174 fn liberated_closure_env_ty(
176 closure_expr_id: hir::HirId,
177 body_id: hir::BodyId,
179 let closure_ty = tcx.body_tables(body_id).node_type(closure_expr_id);
181 let (closure_def_id, closure_substs) = match closure_ty.sty {
182 ty::Closure(closure_def_id, closure_substs) => (closure_def_id, closure_substs),
183 _ => bug!("closure expr does not have closure type: {:?}", closure_ty)
186 let closure_env_ty = tcx.closure_env_ty(closure_def_id, closure_substs).unwrap();
187 tcx.liberate_late_bound_regions(closure_def_id, &closure_env_ty)
190 #[derive(Debug, PartialEq, Eq)]
191 pub enum BlockFrame {
192 /// Evaluation is currently within a statement.
194 /// Examples include:
196 /// 2. `let _ = EXPR;`
197 /// 3. `let x = EXPR;`
199 /// If true, then statement discards result from evaluating
200 /// the expression (such as examples 1 and 2 above).
201 ignores_expr_result: bool
204 /// Evaluation is currently within the tail expression of a block.
206 /// Example: `{ STMT_1; STMT_2; EXPR }`
208 /// If true, then the surrounding context of the block ignores
209 /// the result of evaluating the block's tail expression.
211 /// Example: `let _ = { STMT_1; EXPR };`
212 tail_result_is_ignored: bool
215 /// Generic mark meaning that the block occurred as a subexpression
216 /// where the result might be used.
218 /// Examples: `foo(EXPR)`, `match EXPR { ... }`
223 fn is_tail_expr(&self) -> bool {
225 BlockFrame::TailExpr { .. } => true,
227 BlockFrame::Statement { .. } |
228 BlockFrame::SubExpr => false,
231 fn is_statement(&self) -> bool {
233 BlockFrame::Statement { .. } => true,
235 BlockFrame::TailExpr { .. } |
236 BlockFrame::SubExpr => false,
242 struct BlockContext(Vec<BlockFrame>);
244 struct Builder<'a, 'tcx> {
252 /// The current set of scopes, updated as we traverse;
253 /// see the `scope` module for more details.
254 scopes: scope::Scopes<'tcx>,
256 /// The block-context: each time we build the code within an hair::Block,
257 /// we push a frame here tracking whether we are building a statement or
258 /// if we are pushing the tail expression of the block. This is used to
259 /// embed information in generated temps about whether they were created
260 /// for a block tail expression or not.
262 /// It would be great if we could fold this into `self.scopes`
263 /// somehow, but right now I think that is very tightly tied to
264 /// the code generation in ways that we cannot (or should not)
265 /// start just throwing new entries onto that vector in order to
266 /// distinguish the context of EXPR1 from the context of EXPR2 in
267 /// `{ STMTS; EXPR1 } + EXPR2`.
268 block_context: BlockContext,
270 /// The current unsafe block in scope, even if it is hidden by
271 /// a `PushUnsafeBlock`.
272 unpushed_unsafe: Safety,
274 /// The number of `push_unsafe_block` levels in scope.
275 push_unsafe_count: usize,
277 /// The vector of all scopes that we have created thus far;
278 /// we track this for debuginfo later.
279 source_scopes: IndexVec<SourceScope, SourceScopeData>,
280 source_scope_local_data: IndexVec<SourceScope, SourceScopeLocalData>,
281 source_scope: SourceScope,
283 /// The guard-context: each time we build the guard expression for
284 /// a match arm, we push onto this stack, and then pop when we
285 /// finish building it.
286 guard_context: Vec<GuardFrame>,
288 /// Maps `HirId`s of variable bindings to the `Local`s created for them.
289 /// (A match binding can have two locals; the 2nd is for the arm's guard.)
290 var_indices: HirIdMap<LocalsForNode>,
291 local_decls: IndexVec<Local, LocalDecl<'tcx>>,
292 canonical_user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
293 __upvar_debuginfo_codegen_only_do_not_use: Vec<UpvarDebuginfo>,
294 upvar_mutbls: Vec<Mutability>,
295 unit_temp: Option<Place<'tcx>>,
297 /// Cached block with the `RESUME` terminator; this is created
298 /// when first set of cleanups are built.
299 cached_resume_block: Option<BasicBlock>,
300 /// Cached block with the `RETURN` terminator.
301 cached_return_block: Option<BasicBlock>,
302 /// Cached block with the `UNREACHABLE` terminator.
303 cached_unreachable_block: Option<BasicBlock>,
306 impl<'a, 'tcx> Builder<'a, 'tcx> {
307 fn is_bound_var_in_guard(&self, id: hir::HirId) -> bool {
308 self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
311 fn var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local {
312 self.var_indices[&id].local_id(for_guard)
317 fn new() -> Self { BlockContext(vec![]) }
318 fn push(&mut self, bf: BlockFrame) { self.0.push(bf); }
319 fn pop(&mut self) -> Option<BlockFrame> { self.0.pop() }
321 /// Traverses the frames on the `BlockContext`, searching for either
322 /// the first block-tail expression frame with no intervening
325 /// Notably, this skips over `SubExpr` frames; this method is
326 /// meant to be used in the context of understanding the
327 /// relationship of a temp (created within some complicated
328 /// expression) with its containing expression, and whether the
329 /// value of that *containing expression* (not the temp!) is
331 fn currently_in_block_tail(&self) -> Option<BlockTailInfo> {
332 for bf in self.0.iter().rev() {
334 BlockFrame::SubExpr => continue,
335 BlockFrame::Statement { .. } => break,
336 &BlockFrame::TailExpr { tail_result_is_ignored } =>
337 return Some(BlockTailInfo { tail_result_is_ignored })
344 /// Looks at the topmost frame on the BlockContext and reports
345 /// whether its one that would discard a block tail result.
347 /// Unlike `currently_within_ignored_tail_expression`, this does
348 /// *not* skip over `SubExpr` frames: here, we want to know
349 /// whether the block result itself is discarded.
350 fn currently_ignores_tail_results(&self) -> bool {
351 match self.0.last() {
352 // no context: conservatively assume result is read
355 // sub-expression: block result feeds into some computation
356 Some(BlockFrame::SubExpr) => false,
358 // otherwise: use accumulated is_ignored state.
359 Some(BlockFrame::TailExpr { tail_result_is_ignored: ignored }) |
360 Some(BlockFrame::Statement { ignores_expr_result: ignored }) => *ignored,
367 /// In the usual case, a `HirId` for an identifier maps to at most
368 /// one `Local` declaration.
371 /// The exceptional case is identifiers in a match arm's pattern
372 /// that are referenced in a guard of that match arm. For these,
373 /// we have `2` Locals.
375 /// * `for_arm_body` is the Local used in the arm body (which is
376 /// just like the `One` case above),
378 /// * `ref_for_guard` is the Local used in the arm's guard (which
379 /// is a reference to a temp that is an alias of
381 ForGuard { ref_for_guard: Local, for_arm_body: Local },
385 struct GuardFrameLocal {
389 impl GuardFrameLocal {
390 fn new(id: hir::HirId, _binding_mode: BindingMode) -> Self {
399 /// These are the id's of names that are bound by patterns of the
400 /// arm of *this* guard.
402 /// (Frames higher up the stack will have the id's bound in arms
403 /// further out, such as in a case like:
406 /// P1(id1) if (... (match E2 { P2(id2) if ... => B2 })) => B1,
409 /// here, when building for FIXME.
410 locals: Vec<GuardFrameLocal>,
413 /// `ForGuard` indicates whether we are talking about:
414 /// 1. The variable for use outside of guard expressions, or
415 /// 2. The temp that holds reference to (1.), which is actually what the
416 /// guard expressions see.
417 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
424 fn local_id(&self, for_guard: ForGuard) -> Local {
425 match (self, for_guard) {
426 (&LocalsForNode::One(local_id), ForGuard::OutsideGuard) |
427 (&LocalsForNode::ForGuard { ref_for_guard: local_id, .. }, ForGuard::RefWithinGuard) |
428 (&LocalsForNode::ForGuard { for_arm_body: local_id, .. }, ForGuard::OutsideGuard) =>
431 (&LocalsForNode::One(_), ForGuard::RefWithinGuard) =>
432 bug!("anything with one local should never be within a guard."),
438 basic_blocks: IndexVec<BasicBlock, BasicBlockData<'tcx>>,
442 pub struct ScopeId { .. }
445 ///////////////////////////////////////////////////////////////////////////
446 /// The `BlockAnd` "monad" packages up the new basic block along with a
447 /// produced value (sometimes just unit, of course). The `unpack!`
448 /// macro (and methods below) makes working with `BlockAnd` much more
451 #[must_use = "if you don't use one of these results, you're leaving a dangling edge"]
452 struct BlockAnd<T>(BasicBlock, T);
454 trait BlockAndExtension {
455 fn and<T>(self, v: T) -> BlockAnd<T>;
456 fn unit(self) -> BlockAnd<()>;
459 impl BlockAndExtension for BasicBlock {
460 fn and<T>(self, v: T) -> BlockAnd<T> {
464 fn unit(self) -> BlockAnd<()> {
469 /// Update a block pointer and return the value.
470 /// Use it like `let x = unpack!(block = self.foo(block, foo))`.
471 macro_rules! unpack {
472 ($x:ident = $c:expr) => {
474 let BlockAnd(b, v) = $c;
482 let BlockAnd(b, ()) = $c;
488 fn should_abort_on_panic(tcx: TyCtxt<'_>, fn_def_id: DefId, abi: Abi) -> bool {
489 // Not callable from C, so we can safely unwind through these
490 if abi == Abi::Rust || abi == Abi::RustCall { return false; }
492 // Validate `#[unwind]` syntax regardless of platform-specific panic strategy
493 let attrs = &tcx.get_attrs(fn_def_id);
494 let unwind_attr = attr::find_unwind_attr(Some(tcx.sess.diagnostic()), attrs);
496 // We never unwind, so it's not relevant to stop an unwind
497 if tcx.sess.panic_strategy() != PanicStrategy::Unwind { return false; }
499 // We cannot add landing pads, so don't add one
500 if tcx.sess.no_landing_pads() { return false; }
502 // This is a special case: some functions have a C abi but are meant to
503 // unwind anyway. Don't stop them.
506 Some(UnwindAttr::Allowed) => false,
507 Some(UnwindAttr::Aborts) => true,
511 ///////////////////////////////////////////////////////////////////////////
512 /// the main entry point for building MIR for a function
514 struct ArgInfo<'tcx>(Ty<'tcx>, Option<Span>, Option<&'tcx hir::Pat>, Option<ImplicitSelfKind>);
516 fn construct_fn<'a, 'tcx, A>(
523 yield_ty: Option<Ty<'tcx>>,
524 return_ty_span: Span,
525 body: &'tcx hir::Body,
528 A: Iterator<Item=ArgInfo<'tcx>>
530 let arguments: Vec<_> = arguments.collect();
533 let tcx_hir = tcx.hir();
534 let span = tcx_hir.span(fn_id);
536 let hir_tables = hir.tables();
537 let fn_def_id = tcx_hir.local_def_id(fn_id);
539 // Gather the upvars of a closure, if any.
540 let mut upvar_mutbls = vec![];
541 // In analyze_closure() in upvar.rs we gathered a list of upvars used by a
542 // closure and we stored in a map called upvar_list in TypeckTables indexed
543 // with the closure's DefId. Here, we run through that vec of UpvarIds for
544 // the given closure and use the necessary information to create UpvarDecl.
545 let upvar_debuginfo: Vec<_> = hir_tables
550 .map(|(&var_hir_id, &upvar_id)| {
551 let capture = hir_tables.upvar_capture(upvar_id);
552 let by_ref = match capture {
553 ty::UpvarCapture::ByValue => false,
554 ty::UpvarCapture::ByRef(..) => true,
556 let mut debuginfo = UpvarDebuginfo {
557 debug_name: kw::Invalid,
560 let mut mutability = Mutability::Not;
561 if let Some(Node::Binding(pat)) = tcx_hir.find(var_hir_id) {
562 if let hir::PatKind::Binding(_, _, ident, _) = pat.node {
563 debuginfo.debug_name = ident.name;
564 if let Some(&bm) = hir.tables.pat_binding_modes().get(pat.hir_id) {
565 if bm == ty::BindByValue(hir::MutMutable) {
566 mutability = Mutability::Mut;
568 mutability = Mutability::Not;
571 tcx.sess.delay_span_bug(pat.span, "missing binding mode");
575 upvar_mutbls.push(mutability);
580 let mut builder = Builder::new(hir,
588 body.generator_kind.is_some());
590 let call_site_scope = region::Scope {
591 id: body.value.hir_id.local_id,
592 data: region::ScopeData::CallSite
594 let arg_scope = region::Scope {
595 id: body.value.hir_id.local_id,
596 data: region::ScopeData::Arguments
598 let mut block = START_BLOCK;
599 let source_info = builder.source_info(span);
600 let call_site_s = (call_site_scope, source_info);
601 unpack!(block = builder.in_scope(call_site_s, LintLevel::Inherited, |builder| {
602 if should_abort_on_panic(tcx, fn_def_id, abi) {
603 builder.schedule_abort();
606 let arg_scope_s = (arg_scope, source_info);
607 // `return_block` is called when we evaluate a `return` expression, so
608 // we just use `START_BLOCK` here.
609 unpack!(block = builder.in_breakable_scope(
614 builder.in_scope(arg_scope_s, LintLevel::Inherited, |builder| {
615 builder.args_and_body(block, &arguments, arg_scope, &body.value)
619 // Attribute epilogue to function's closing brace
620 let fn_end = span.shrink_to_hi();
621 let source_info = builder.source_info(fn_end);
622 let return_block = builder.return_block();
623 builder.cfg.terminate(block, source_info,
624 TerminatorKind::Goto { target: return_block });
625 builder.cfg.terminate(return_block, source_info,
626 TerminatorKind::Return);
627 // Attribute any unreachable codepaths to the function's closing brace
628 if let Some(unreachable_block) = builder.cached_unreachable_block {
629 builder.cfg.terminate(unreachable_block, source_info,
630 TerminatorKind::Unreachable);
634 assert_eq!(block, builder.return_block());
636 let mut spread_arg = None;
637 if abi == Abi::RustCall {
638 // RustCall pseudo-ABI untuples the last argument.
639 spread_arg = Some(Local::new(arguments.len()));
641 info!("fn_id {:?} has attrs {:?}", fn_def_id,
642 tcx.get_attrs(fn_def_id));
644 let mut body = builder.finish(yield_ty);
645 body.spread_arg = spread_arg;
649 fn construct_const<'a, 'tcx>(
651 body_id: hir::BodyId,
656 let owner_id = tcx.hir().body_owner(body_id);
657 let span = tcx.hir().span(owner_id);
658 let mut builder = Builder::new(
670 let mut block = START_BLOCK;
671 let ast_expr = &tcx.hir().body(body_id).value;
672 let expr = builder.hir.mirror(ast_expr);
673 unpack!(block = builder.into_expr(&Place::RETURN_PLACE, block, expr));
675 let source_info = builder.source_info(span);
676 builder.cfg.terminate(block, source_info, TerminatorKind::Return);
678 // Constants can't `return` so a return block should not be created.
679 assert_eq!(builder.cached_return_block, None);
681 // Constants may be match expressions in which case an unreachable block may
682 // be created, so terminate it properly.
683 if let Some(unreachable_block) = builder.cached_unreachable_block {
684 builder.cfg.terminate(unreachable_block, source_info,
685 TerminatorKind::Unreachable);
691 fn construct_error<'a, 'tcx>(
695 let owner_id = hir.tcx().hir().body_owner(body_id);
696 let span = hir.tcx().hir().span(owner_id);
697 let ty = hir.tcx().types.err;
698 let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty, span, vec![], vec![], false);
699 let source_info = builder.source_info(span);
700 builder.cfg.terminate(START_BLOCK, source_info, TerminatorKind::Unreachable);
704 impl<'a, 'tcx> Builder<'a, 'tcx> {
705 fn new(hir: Cx<'a, 'tcx>,
711 __upvar_debuginfo_codegen_only_do_not_use: Vec<UpvarDebuginfo>,
712 upvar_mutbls: Vec<Mutability>,
714 -> Builder<'a, 'tcx> {
715 let lint_level = LintLevel::Explicit(hir.root_lint_level);
716 let mut builder = Builder {
718 cfg: CFG { basic_blocks: IndexVec::new() },
722 scopes: Default::default(),
723 block_context: BlockContext::new(),
724 source_scopes: IndexVec::new(),
725 source_scope: OUTERMOST_SOURCE_SCOPE,
726 source_scope_local_data: IndexVec::new(),
727 guard_context: vec![],
728 push_unsafe_count: 0,
729 unpushed_unsafe: safety,
730 local_decls: IndexVec::from_elem_n(
731 LocalDecl::new_return_place(return_ty, return_span),
734 canonical_user_type_annotations: IndexVec::new(),
735 __upvar_debuginfo_codegen_only_do_not_use,
737 var_indices: Default::default(),
739 cached_resume_block: None,
740 cached_return_block: None,
741 cached_unreachable_block: None,
744 assert_eq!(builder.cfg.start_new_block(), START_BLOCK);
746 builder.new_source_scope(span, lint_level, Some(safety)),
747 OUTERMOST_SOURCE_SCOPE);
748 builder.source_scopes[OUTERMOST_SOURCE_SCOPE].parent_scope = None;
754 yield_ty: Option<Ty<'tcx>>)
756 for (index, block) in self.cfg.basic_blocks.iter().enumerate() {
757 if block.terminator.is_none() {
758 span_bug!(self.fn_span, "no terminator on block {:?}", index);
763 self.cfg.basic_blocks,
765 ClearCrossCrate::Set(self.source_scope_local_data),
769 self.canonical_user_type_annotations,
771 self.__upvar_debuginfo_codegen_only_do_not_use,
773 self.hir.control_flow_destroyed(),
777 fn args_and_body(&mut self,
778 mut block: BasicBlock,
779 arguments: &[ArgInfo<'tcx>],
780 argument_scope: region::Scope,
781 ast_body: &'tcx hir::Expr)
784 // Allocate locals for the function arguments
785 for &ArgInfo(ty, _, pattern, _) in arguments.iter() {
786 // If this is a simple binding pattern, give the local a name for
787 // debuginfo and so that error reporting knows that this is a user
788 // variable. For any other pattern the pattern introduces new
789 // variables which will be named instead.
790 let (name, span) = if let Some(pat) = pattern {
791 (pat.simple_ident().map(|ident| ident.name), pat.span)
796 let source_info = SourceInfo { scope: OUTERMOST_SOURCE_SCOPE, span, };
797 self.local_decls.push(LocalDecl {
798 mutability: Mutability::Mut,
800 user_ty: UserTypeProjections::none(),
802 visibility_scope: source_info.scope,
805 is_user_variable: None,
810 let mut scope = None;
811 // Bind the argument patterns
812 for (index, arg_info) in arguments.iter().enumerate() {
813 // Function arguments always get the first Local indices after the return place
814 let local = Local::new(index + 1);
815 let place = Place::from(local);
816 let &ArgInfo(ty, opt_ty_info, pattern, ref self_binding) = arg_info;
818 // Make sure we drop (parts of) the argument even when not matched on.
820 pattern.as_ref().map_or(ast_body.span, |pat| pat.span),
821 argument_scope, local, ty, DropKind::Value,
824 if let Some(pattern) = pattern {
825 let pattern = self.hir.pattern_from_hir(pattern);
826 let span = pattern.span;
828 match *pattern.kind {
829 // Don't introduce extra copies for simple bindings
830 PatternKind::Binding {
833 mode: BindingMode::ByValue,
837 self.local_decls[local].mutability = mutability;
838 self.local_decls[local].is_user_variable =
839 if let Some(kind) = self_binding {
840 Some(ClearCrossCrate::Set(BindingForm::ImplicitSelf(*kind)))
842 let binding_mode = ty::BindingMode::BindByValue(mutability.into());
843 Some(ClearCrossCrate::Set(BindingForm::Var(VarBindingForm {
846 opt_match_place: Some((Some(place.clone()), span)),
850 self.var_indices.insert(var, LocalsForNode::One(local));
853 scope = self.declare_bindings(
857 matches::ArmHasGuard(false),
858 Some((Some(&place), span)),
860 unpack!(block = self.place_into_pattern(block, pattern, &place, false));
866 // Enter the argument pattern bindings source scope, if it exists.
867 if let Some(source_scope) = scope {
868 self.source_scope = source_scope;
871 let body = self.hir.mirror(ast_body);
872 self.into(&Place::RETURN_PLACE, block, body)
875 fn get_unit_temp(&mut self) -> Place<'tcx> {
876 match self.unit_temp {
877 Some(ref tmp) => tmp.clone(),
879 let ty = self.hir.unit_ty();
880 let fn_span = self.fn_span;
881 let tmp = self.temp(ty, fn_span);
882 self.unit_temp = Some(tmp.clone());
888 fn return_block(&mut self) -> BasicBlock {
889 match self.cached_return_block {
892 let rb = self.cfg.start_new_block();
893 self.cached_return_block = Some(rb);
900 ///////////////////////////////////////////////////////////////////////////
901 // Builder methods are broken up into modules, depending on what kind
902 // of thing is being lowered. Note that they use the `unpack` macro
903 // above extensively.