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Rollup merge of #81291 - sexxi-goose:fix-struct-update-functional-record-update-syntax-error, r=nikomatsakis

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Support FRU pattern with `[feature(capture_disjoint_fields)]`

In case of a functional record update syntax for creating a structure, `ExprUseVisitor` to only detect the precise use of some of the field in the `..x` part of the syntax. However, when we start building MIR, we
1. First, build the place for `x`
2. and then, add precise field projections so that only some parts of `x` end up getting read.

When `capture_disjoint_fields` is enabled, and FRU is used within a closure `x` won't be completely captured, and therefore the first step will fail. This PR updates `mir_build` to create a place builder in the first step and then create place from the builder only after applying the field projection.

Closes https://github.com/rust-lang/project-rfc-2229/issues/32
r? ``````@nikomatsakis``````
This commit is contained in:
Yuki Okushi 2021-01-30 13:36:46 +09:00 • committed by GitHub
commit 7fa991fb85
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4 changed files with 67 additions and 5 deletions
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2
compiler/rustc_mir_build/src/build/expr/as_place.rs
View file

@ -303,7 +303,7 @@ impl<'tcx> PlaceBuilder<'tcx> {
self.base
}
fn field(self, f: Field, ty: Ty<'tcx>) -> Self {
crate fn field(self, f: Field, ty: Ty<'tcx>) -> Self {
self.project(PlaceElem::Field(f, ty))
}

13
compiler/rustc_mir_build/src/build/expr/into.rs
View file

@ -296,7 +296,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let field_names = this.hir.all_fields(adt_def, variant_index);
let fields: Vec<_> = if let Some(FruInfo { base, field_types }) = base {
let base = unpack!(block = this.as_place(block, base));
let place_builder = unpack!(block = this.as_place_builder(block, base));
// MIR does not natively support FRU, so for each
// base-supplied field, generate an operand that
@ -306,9 +306,14 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
.zip(field_types.into_iter())
.map(|(n, ty)| match fields_map.get(&n) {
Some(v) => v.clone(),
None => this.consume_by_copy_or_move(
this.hir.tcx().mk_place_field(base, n, ty),
),
None => {
let place_builder = place_builder.clone();
this.consume_by_copy_or_move(
place_builder
.field(n, ty)
.into_place(this.hir.tcx(), this.hir.typeck_results()),
)
},
})
.collect()
} else {