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Auto merge of #85020 - lrh2000:named-upvars, r=tmandry

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Name the captured upvars for closures/generators in debuginfo

Previously, debuggers print closures as something like
```
y::main::closure-0 (0x7fffffffdd34)
```
The pointer actually references to an upvar. It is not very obvious, especially for beginners.

It's because upvars don't have names before, as they are packed into a tuple. This PR names the upvars, so we can expect to see something like
```
y::main::closure-0 {_captured_ref__b: 0x[...]}
```

r? `@tmandry`
Discussed at https://github.com/rust-lang/rust/pull/84752#issuecomment-831639489 .
This commit is contained in:
bors 2021-08-14 07:01:36 +00:00
commit 99efc51dae
9 changed files with 276 additions and 23 deletions
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21
compiler/rustc_mir_build/src/build/mod.rs
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@ -15,7 +15,7 @@ use rustc_middle::mir::*;
use rustc_middle::thir::{BindingMode, Expr, ExprId, LintLevel, PatKind, Thir};
use rustc_middle::ty::subst::Subst;
use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeckResults};
use rustc_span::symbol::{kw, sym};
use rustc_span::symbol::sym;
use rustc_span::Span;
use rustc_target::spec::abi::Abi;
@ -902,13 +902,16 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
ty::Generator(_, substs, _) => ty::UpvarSubsts::Generator(substs),
_ => span_bug!(self.fn_span, "upvars with non-closure env ty {:?}", closure_ty),
};
let def_id = self.def_id.as_local().unwrap();
let capture_syms = tcx.symbols_for_closure_captures((def_id, fn_def_id));
let capture_tys = upvar_substs.upvar_tys();
let captures_with_tys =
hir_typeck_results.closure_min_captures_flattened(fn_def_id).zip(capture_tys);
let captures_with_tys = hir_typeck_results
.closure_min_captures_flattened(fn_def_id)
.zip(capture_tys.zip(capture_syms));
self.upvar_mutbls = captures_with_tys
.enumerate()
.map(|(i, (captured_place, ty))| {
.map(|(i, (captured_place, (ty, sym)))| {
let capture = captured_place.info.capture_kind;
let var_id = match captured_place.place.base {
HirPlaceBase::Upvar(upvar_id) => upvar_id.var_path.hir_id,
@ -917,14 +920,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
let mutability = captured_place.mutability;
// FIXME(project-rfc-2229#8): Store more precise information
let mut name = kw::Empty;
if let Some(Node::Binding(pat)) = tcx_hir.find(var_id) {
if let hir::PatKind::Binding(_, _, ident, _) = pat.kind {
name = ident.name;
}
}
let mut projs = closure_env_projs.clone();
projs.push(ProjectionElem::Field(Field::new(i), ty));
match capture {
@ -935,7 +930,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
};
self.var_debug_info.push(VarDebugInfo {
name,
name: sym,
source_info: SourceInfo::outermost(tcx_hir.span(var_id)),
value: VarDebugInfoContents::Place(Place {
local: ty::CAPTURE_STRUCT_LOCAL,