Skip to content

Commit

Permalink
Auto merge of #65750 - nnethercote:cheaper-doc-comments, r=petrochenkov
Browse files Browse the repository at this point in the history
Cheaper doc comments

This PR implements the idea from #60935: represent doc comments more cheaply, rather than converting them into `#[doc="..."]` attribute form. Unlike #60936 (which is about coalescing doc comments to reduce their number), this approach does not have any backwards compatibility concerns, and it eliminates about 80-90% of the current cost of doc comments (as estimated using the numbers in #60930, which eliminated the cost of doc comments entirely by treating them as normal comments).

r? @petrochenkov
  • Loading branch information
bors committed Nov 7, 2019
2 parents 3804876 + eea6f23 commit caf0187
Show file tree
Hide file tree
Showing 25 changed files with 234 additions and 151 deletions.
16 changes: 11 additions & 5 deletions src/librustc/hir/lowering.rs
Original file line number Diff line number Diff line change
Expand Up @@ -997,14 +997,20 @@ impl<'a> LoweringContext<'a> {
// Note that we explicitly do not walk the path. Since we don't really
// lower attributes (we use the AST version) there is nowhere to keep
// the `HirId`s. We don't actually need HIR version of attributes anyway.
let kind = match attr.kind {
AttrKind::Normal(ref item) => {
AttrKind::Normal(AttrItem {
path: item.path.clone(),
tokens: self.lower_token_stream(item.tokens.clone()),
})
}
AttrKind::DocComment(comment) => AttrKind::DocComment(comment)
};

Attribute {
item: AttrItem {
path: attr.path.clone(),
tokens: self.lower_token_stream(attr.tokens.clone()),
},
kind,
id: attr.id,
style: attr.style,
is_sugared_doc: attr.is_sugared_doc,
span: attr.span,
}
}
Expand Down
25 changes: 11 additions & 14 deletions src/librustc/ich/impls_syntax.rs
Original file line number Diff line number Diff line change
Expand Up @@ -177,7 +177,7 @@ impl<'a> HashStable<StableHashingContext<'a>> for [ast::Attribute] {
let filtered: SmallVec<[&ast::Attribute; 8]> = self
.iter()
.filter(|attr| {
!attr.is_sugared_doc &&
!attr.is_doc_comment() &&
!attr.ident().map_or(false, |ident| hcx.is_ignored_attr(ident.name))
})
.collect();
Expand Down Expand Up @@ -207,19 +207,16 @@ impl<'a> HashStable<StableHashingContext<'a>> for ast::Attribute {
fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
// Make sure that these have been filtered out.
debug_assert!(!self.ident().map_or(false, |ident| hcx.is_ignored_attr(ident.name)));
debug_assert!(!self.is_sugared_doc);

let ast::Attribute {
ref item,
id: _,
style,
is_sugared_doc: _,
span,
} = *self;

item.hash_stable(hcx, hasher);
style.hash_stable(hcx, hasher);
span.hash_stable(hcx, hasher);
debug_assert!(!self.is_doc_comment());

let ast::Attribute { kind, id: _, style, span } = self;
if let ast::AttrKind::Normal(item) = kind {
item.hash_stable(hcx, hasher);
style.hash_stable(hcx, hasher);
span.hash_stable(hcx, hasher);
} else {
unreachable!();
}
}
}

Expand Down
6 changes: 3 additions & 3 deletions src/librustc_lint/builtin.rs
Original file line number Diff line number Diff line change
Expand Up @@ -706,7 +706,7 @@ impl EarlyLintPass for DeprecatedAttr {
}
}
if attr.check_name(sym::no_start) || attr.check_name(sym::crate_id) {
let path_str = pprust::path_to_string(&attr.path);
let path_str = pprust::path_to_string(&attr.get_normal_item().path);
let msg = format!("use of deprecated attribute `{}`: no longer used.", path_str);
lint_deprecated_attr(cx, attr, &msg, None);
}
Expand Down Expand Up @@ -736,7 +736,7 @@ impl UnusedDocComment {
let mut sugared_span: Option<Span> = None;

while let Some(attr) = attrs.next() {
if attr.is_sugared_doc {
if attr.is_doc_comment() {
sugared_span = Some(
sugared_span.map_or_else(
|| attr.span,
Expand All @@ -745,7 +745,7 @@ impl UnusedDocComment {
);
}

if attrs.peek().map(|next_attr| next_attr.is_sugared_doc).unwrap_or_default() {
if attrs.peek().map(|next_attr| next_attr.is_doc_comment()).unwrap_or_default() {
continue;
}

Expand Down
2 changes: 1 addition & 1 deletion src/librustc_metadata/link_args.rs
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ crate fn collect(tcx: TyCtxt<'_>) -> Vec<String> {
tcx.hir().krate().visit_all_item_likes(&mut collector);

for attr in tcx.hir().krate().attrs.iter() {
if attr.path == sym::link_args {
if attr.has_name(sym::link_args) {
if let Some(linkarg) = attr.value_str() {
collector.add_link_args(&linkarg.as_str());
}
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_passes/ast_validation.rs
Original file line number Diff line number Diff line change
Expand Up @@ -328,7 +328,7 @@ impl<'a> AstValidator<'a> {
let arr = [sym::allow, sym::cfg, sym::cfg_attr, sym::deny, sym::forbid, sym::warn];
!arr.contains(&attr.name_or_empty()) && is_builtin_attr(attr)
})
.for_each(|attr| if attr.is_sugared_doc {
.for_each(|attr| if attr.is_doc_comment() {
let mut err = self.err_handler().struct_span_err(
attr.span,
"documentation comments cannot be applied to function parameters"
Expand Down
6 changes: 4 additions & 2 deletions src/librustc_resolve/build_reduced_graph.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1229,8 +1229,10 @@ impl<'a, 'b> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b> {
}

fn visit_attribute(&mut self, attr: &'b ast::Attribute) {
if !attr.is_sugared_doc && is_builtin_attr(attr) {
self.r.builtin_attrs.push((attr.path.segments[0].ident, self.parent_scope));
if !attr.is_doc_comment() && is_builtin_attr(attr) {
self.r.builtin_attrs.push(
(attr.get_normal_item().path.segments[0].ident, self.parent_scope)
);
}
visit::walk_attribute(self, attr);
}
Expand Down
5 changes: 4 additions & 1 deletion src/librustc_resolve/macros.rs
Original file line number Diff line number Diff line change
Expand Up @@ -179,7 +179,10 @@ impl<'a> base::Resolver for Resolver<'a> {

let (path, kind, derives, after_derive) = match invoc.kind {
InvocationKind::Attr { ref attr, ref derives, after_derive, .. } =>
(&attr.path, MacroKind::Attr, self.arenas.alloc_ast_paths(derives), after_derive),
(&attr.get_normal_item().path,
MacroKind::Attr,
self.arenas.alloc_ast_paths(derives),
after_derive),
InvocationKind::Bang { ref mac, .. } =>
(&mac.path, MacroKind::Bang, &[][..], false),
InvocationKind::Derive { ref path, .. } =>
Expand Down
4 changes: 2 additions & 2 deletions src/librustc_save_analysis/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -885,7 +885,7 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
for attr in attrs {
if attr.check_name(sym::doc) {
if let Some(val) = attr.value_str() {
if attr.is_sugared_doc {
if attr.is_doc_comment() {
result.push_str(&strip_doc_comment_decoration(&val.as_str()));
} else {
result.push_str(&val.as_str());
Expand Down Expand Up @@ -1195,7 +1195,7 @@ fn null_id() -> rls_data::Id {
fn lower_attributes(attrs: Vec<Attribute>, scx: &SaveContext<'_, '_>) -> Vec<rls_data::Attribute> {
attrs.into_iter()
// Only retain real attributes. Doc comments are lowered separately.
.filter(|attr| attr.path != sym::doc)
.filter(|attr| !attr.has_name(sym::doc))
.map(|mut attr| {
// Remove the surrounding '#[..]' or '#![..]' of the pretty printed
// attribute. First normalize all inner attribute (#![..]) to outer
Expand Down
4 changes: 2 additions & 2 deletions src/librustc_typeck/collect.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2706,7 +2706,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
}

codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
if attr.path != sym::inline {
if !attr.has_name(sym::inline) {
return ia;
}
match attr.meta().map(|i| i.kind) {
Expand Down Expand Up @@ -2746,7 +2746,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, id: DefId) -> CodegenFnAttrs {
});

codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
if attr.path != sym::optimize {
if !attr.has_name(sym::optimize) {
return ia;
}
let err = |sp, s| span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s);
Expand Down
47 changes: 24 additions & 23 deletions src/librustdoc/clean/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,7 @@ use rustc::ty::{self, DefIdTree, TyCtxt, Region, RegionVid, Ty, AdtKind};
use rustc::ty::fold::TypeFolder;
use rustc::ty::layout::VariantIdx;
use rustc::util::nodemap::{FxHashMap, FxHashSet};
use syntax::ast::{self, Attribute, AttrStyle, AttrItem, Ident};
use syntax::ast::{self, Attribute, AttrStyle, AttrKind, Ident};
use syntax::attr;
use syntax::parse::lexer::comments;
use syntax::source_map::DUMMY_SP;
Expand Down Expand Up @@ -859,31 +859,32 @@ impl Attributes {
let mut cfg = Cfg::True;
let mut doc_line = 0;

/// Converts `attr` to a normal `#[doc="foo"]` comment, if it is a
/// comment like `///` or `/** */`. (Returns `attr` unchanged for
/// non-sugared doc attributes.)
pub fn with_desugared_doc<T>(attr: &Attribute, f: impl FnOnce(&Attribute) -> T) -> T {
if attr.is_sugared_doc {
let comment = attr.value_str().unwrap();
let meta = attr::mk_name_value_item_str(
Ident::with_dummy_span(sym::doc),
Symbol::intern(&comments::strip_doc_comment_decoration(&comment.as_str())),
DUMMY_SP,
);
f(&Attribute {
item: AttrItem { path: meta.path, tokens: meta.kind.tokens(meta.span) },
id: attr.id,
style: attr.style,
is_sugared_doc: true,
span: attr.span,
})
} else {
f(attr)
/// If `attr` is a doc comment, strips the leading and (if present)
/// trailing comments symbols, e.g. `///`, `/**`, and `*/`. Otherwise,
/// returns `attr` unchanged.
pub fn with_doc_comment_markers_stripped<T>(
attr: &Attribute,
f: impl FnOnce(&Attribute) -> T
) -> T {
match attr.kind {
AttrKind::Normal(_) => {
f(attr)
}
AttrKind::DocComment(comment) => {
let comment =
Symbol::intern(&comments::strip_doc_comment_decoration(&comment.as_str()));
f(&Attribute {
kind: AttrKind::DocComment(comment),
id: attr.id,
style: attr.style,
span: attr.span,
})
}
}
}

let other_attrs = attrs.iter().filter_map(|attr| {
with_desugared_doc(attr, |attr| {
with_doc_comment_markers_stripped(attr, |attr| {
if attr.check_name(sym::doc) {
if let Some(mi) = attr.meta() {
if let Some(value) = mi.value_str() {
Expand All @@ -892,7 +893,7 @@ impl Attributes {
let line = doc_line;
doc_line += value.lines().count();

if attr.is_sugared_doc {
if attr.is_doc_comment() {
doc_strings.push(DocFragment::SugaredDoc(line, attr.span, value));
} else {
doc_strings.push(DocFragment::RawDoc(line, attr.span, value));
Expand Down
21 changes: 14 additions & 7 deletions src/libsyntax/ast.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2190,22 +2190,29 @@ pub struct AttrItem {
}

/// Metadata associated with an item.
/// Doc-comments are promoted to attributes that have `is_sugared_doc = true`.
#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
pub struct Attribute {
pub item: AttrItem,
pub kind: AttrKind,
pub id: AttrId,
/// Denotes if the attribute decorates the following construct (outer)
/// or the construct this attribute is contained within (inner).
pub style: AttrStyle,
pub is_sugared_doc: bool,
pub span: Span,
}

// Compatibility impl to avoid churn, consider removing.
impl std::ops::Deref for Attribute {
type Target = AttrItem;
fn deref(&self) -> &Self::Target { &self.item }
#[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
pub enum AttrKind {
/// A normal attribute.
Normal(AttrItem),

/// A doc comment (e.g. `/// ...`, `//! ...`, `/** ... */`, `/*! ... */`).
/// Doc attributes (e.g. `#[doc="..."]`) are represented with the `Normal`
/// variant (which is much less compact and thus more expensive).
///
/// Note: `self.has_name(sym::doc)` and `self.check_name(sym::doc)` succeed
/// for this variant, but this may change in the future.
/// ```
DocComment(Symbol),
}

/// `TraitRef`s appear in impls.
Expand Down
8 changes: 4 additions & 4 deletions src/libsyntax/attr/builtin.rs
Original file line number Diff line number Diff line change
Expand Up @@ -228,18 +228,18 @@ fn find_stability_generic<'a, I>(sess: &ParseSess,
sym::stable,
sym::rustc_promotable,
sym::rustc_allow_const_fn_ptr,
].iter().any(|&s| attr.path == s) {
].iter().any(|&s| attr.has_name(s)) {
continue // not a stability level
}

mark_used(attr);

let meta = attr.meta();

if attr.path == sym::rustc_promotable {
if attr.has_name(sym::rustc_promotable) {
promotable = true;
}
if attr.path == sym::rustc_allow_const_fn_ptr {
if attr.has_name(sym::rustc_allow_const_fn_ptr) {
allow_const_fn_ptr = true;
}
// attributes with data
Expand Down Expand Up @@ -778,7 +778,7 @@ pub fn find_repr_attrs(sess: &ParseSess, attr: &Attribute) -> Vec<ReprAttr> {

let mut acc = Vec::new();
let diagnostic = &sess.span_diagnostic;
if attr.path == sym::repr {
if attr.has_name(sym::repr) {
if let Some(items) = attr.meta_item_list() {
mark_used(attr);
for item in items {
Expand Down
Loading

0 comments on commit caf0187

Please sign in to comment.