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1 | // Copyright 2015 The Rust Project Developers. See the COPYRIGHT |
2 | // file at the top-level directory of this distribution and at | |
3 | // http://rust-lang.org/COPYRIGHT. | |
4 | // | |
5 | // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | |
6 | // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | |
7 | // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | |
8 | // option. This file may not be copied, modified, or distributed | |
9 | // except according to those terms. | |
10 | ||
9cc50fc6 | 11 | use build::{BlockAnd, BlockAndExtension, Builder}; |
e9174d1e | 12 | use hair::*; |
c30ab7b3 | 13 | use rustc::mir::*; |
54a0048b | 14 | use rustc::hir; |
e9174d1e | 15 | |
a7813a04 | 16 | impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> { |
e9174d1e | 17 | pub fn ast_block(&mut self, |
b039eaaf | 18 | destination: &Lvalue<'tcx>, |
a7813a04 XL |
19 | // FIXME(#32959): temporary measure for the issue |
20 | dest_is_unit: bool, | |
e9174d1e | 21 | mut block: BasicBlock, |
b039eaaf | 22 | ast_block: &'tcx hir::Block) |
e9174d1e | 23 | -> BlockAnd<()> { |
9cc50fc6 | 24 | let Block { extent, span, stmts, expr } = self.hir.mirror(ast_block); |
3157f602 | 25 | self.in_scope(extent, block, move |this| { |
54a0048b SL |
26 | // This convoluted structure is to avoid using recursion as we walk down a list |
27 | // of statements. Basically, the structure we get back is something like: | |
28 | // | |
29 | // let x = <init> in { | |
30 | // expr1; | |
31 | // let y = <init> in { | |
32 | // expr2; | |
33 | // expr3; | |
34 | // ... | |
35 | // } | |
36 | // } | |
37 | // | |
38 | // The let bindings are valid till the end of block so all we have to do is to pop all | |
39 | // the let-scopes at the end. | |
40 | // | |
41 | // First we build all the statements in the block. | |
42 | let mut let_extent_stack = Vec::with_capacity(8); | |
3157f602 | 43 | let outer_visibility_scope = this.visibility_scope; |
54a0048b SL |
44 | for stmt in stmts { |
45 | let Stmt { span: _, kind } = this.hir.mirror(stmt); | |
46 | match kind { | |
47 | StmtKind::Expr { scope, expr } => { | |
3157f602 | 48 | unpack!(block = this.in_scope(scope, block, |this| { |
54a0048b | 49 | let expr = this.hir.mirror(expr); |
a7813a04 | 50 | this.stmt_expr(block, expr) |
54a0048b SL |
51 | })); |
52 | } | |
53 | StmtKind::Let { remainder_scope, init_scope, pattern, initializer } => { | |
3157f602 XL |
54 | let tcx = this.hir.tcx(); |
55 | ||
56 | // Enter the remainder scope, i.e. the bindings' destruction scope. | |
57 | this.push_scope(remainder_scope, block); | |
54a0048b | 58 | let_extent_stack.push(remainder_scope); |
3157f602 XL |
59 | |
60 | // Declare the bindings, which may create a visibility scope. | |
61 | let remainder_span = remainder_scope.span(&tcx.region_maps, &tcx.map); | |
62 | let remainder_span = remainder_span.unwrap_or(span); | |
63 | let scope = this.declare_bindings(None, remainder_span, &pattern); | |
64 | ||
65 | // Evaluate the initializer, if present. | |
66 | if let Some(init) = initializer { | |
67 | unpack!(block = this.in_scope(init_scope, block, move |this| { | |
68 | // FIXME #30046 ^~~~ | |
69 | this.expr_into_pattern(block, pattern, init) | |
70 | })); | |
5bcae85e SL |
71 | } else { |
72 | this.storage_live_for_bindings(block, &pattern); | |
3157f602 XL |
73 | } |
74 | ||
75 | // Enter the visibility scope, after evaluating the initializer. | |
76 | if let Some(visibility_scope) = scope { | |
77 | this.visibility_scope = visibility_scope; | |
78 | } | |
54a0048b | 79 | } |
9cc50fc6 SL |
80 | } |
81 | } | |
54a0048b SL |
82 | // Then, the block may have an optional trailing expression which is a “return” value |
83 | // of the block. | |
84 | if let Some(expr) = expr { | |
85 | unpack!(block = this.into(destination, block, expr)); | |
a7813a04 | 86 | } else if dest_is_unit { |
54a0048b | 87 | // FIXME(#31472) |
3157f602 XL |
88 | let source_info = this.source_info(span); |
89 | this.cfg.push_assign_unit(block, source_info, destination); | |
54a0048b SL |
90 | } |
91 | // Finally, we pop all the let scopes before exiting out from the scope of block | |
92 | // itself. | |
93 | for extent in let_extent_stack.into_iter().rev() { | |
94 | unpack!(block = this.pop_scope(extent, block)); | |
95 | } | |
3157f602 XL |
96 | // Restore the original visibility scope. |
97 | this.visibility_scope = outer_visibility_scope; | |
54a0048b | 98 | block.unit() |
e9174d1e SL |
99 | }) |
100 | } | |
101 | } |