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Rustdoc: Report Layout of enum variants #86263

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merged 5 commits into from
Sep 8, 2021
Merged

Rustdoc: Report Layout of enum variants #86263

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aff4cd5
Report Layout of enum variants
fee1-dead Jun 13, 2021
c349b79
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fee1-dead Jul 9, 2021
8096910
Report variant size without the discriminant
fee1-dead Jul 10, 2021
5f1505e
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fee1-dead Aug 31, 2021
c0451f7
Correctly handle niche of enum
fee1-dead Sep 6, 2021
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@fee1-dead
fee1-dead committed Aug 31, 2021
commit c349b79029770e39963fadf5021cfa6a6cfe5472
44 changes: 18 additions & 26 deletions src/librustdoc/html/render/print_item.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,13 +7,13 @@ use rustc_data_structures::fx::FxHashMap;
use rustc_hir as hir;
use rustc_hir::def::CtorKind;
use rustc_hir::def_id::DefId;
use rustc_middle::bug;
use rustc_middle::middle::stability;
use rustc_middle::span_bug;
use rustc_middle::ty::layout::LayoutError;
use rustc_middle::ty::{Adt, TyCtxt};
use rustc_span::hygiene::MacroKind;
use rustc_span::symbol::{kw, sym, Symbol};
use rustc_target::abi::Variants;
use rustc_target::abi::{Layout, Variants};

use super::{
collect_paths_for_type, document, ensure_trailing_slash, item_ty_to_strs, notable_traits_decl,
Expand Down Expand Up @@ -1606,6 +1606,15 @@ fn document_non_exhaustive(w: &mut Buffer, item: &clean::Item) {
}

fn document_type_layout(w: &mut Buffer, cx: &Context<'_>, ty_def_id: DefId) {
fn write_size_of_layout(w: &mut Buffer, layout: &Layout) {
if layout.abi.is_unsized() {
write!(w, "(unsized)");
} else {
let bytes = layout.size.bytes();
write!(w, "{size} byte{pl}", size = bytes, pl = if bytes == 1 { "" } else { "s" },);
}
}

if !cx.shared.show_type_layout {
return;
}
Expand All @@ -1627,17 +1636,9 @@ fn document_type_layout(w: &mut Buffer, cx: &Context<'_>, ty_def_id: DefId) {
<a href=\"https://doc.rust-lang.org/reference/type-layout.html\">“Type Layout”</a> \
chapter for details on type layout guarantees.</p></div>"
);
if ty_layout.layout.abi.is_unsized() {
writeln!(w, "<p><strong>Size:</strong> (unsized)</p>");
} else {
let bytes = ty_layout.layout.size.bytes();
writeln!(
w,
"<p><strong>Size:</strong> {size} byte{pl}</p>",
size = bytes,
pl = if bytes == 1 { "" } else { "s" },
);
}
w.write_str("<p><strong>Size:</strong> ");
write_size_of_layout(w, ty_layout.layout);
writeln!(w, "</p>");
if let Variants::Multiple { variants, .. } = &ty_layout.layout.variants {
if !variants.is_empty() {
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Can you test what happens for the empty case? Does it show 0 bytes or unsized? I think ideally it would show "uninhabited" or something.

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It shows 0 bytes. I think it would be more suitable for a separate PR as a followup of the original PR.

w.write_str(
Expand All @@ -1649,23 +1650,14 @@ fn document_type_layout(w: &mut Buffer, cx: &Context<'_>, ty_def_id: DefId) {
let adt = if let Adt(adt, _) = ty_layout.ty.kind() {
adt
} else {
bug!("not an adt")
span_bug!(tcx.def_span(ty_def_id), "not an adt")
};

for (index, layout) in variants.iter_enumerated() {
let ident = adt.variants[index].ident;
if layout.abi.is_unsized() {
writeln!(w, "<li><code>{name}</code> (unsized)</li>", name = ident);
} else {
let bytes = layout.size.bytes();
writeln!(
w,
"<li><code>{name}</code>: {size} byte{pl}</li>",
name = ident,
size = bytes,
pl = if bytes == 1 { "" } else { "s" },
);
}
write!(w, "<li><code>{name}</code> ", name = ident);
write_size_of_layout(w, layout);
writeln!(w, "</li>");
}
w.write_str("</ul></p>");
}
Expand Down