src/librustdoc/passes/stripper.rs

   1 //! A collection of utility functions for the `strip_*` passes.
   2 use rustc_hir::def_id::DefId;
   3 use rustc_middle::ty::{TyCtxt, Visibility};
   4 use rustc_span::symbol::sym;
   5 use std::mem;
   6
   7 use crate::clean::{self, Item, ItemId, ItemIdSet, NestedAttributesExt};
   8 use crate::fold::{strip_item, DocFolder};
   9 use crate::formats::cache::Cache;
  10 use crate::visit_lib::RustdocEffectiveVisibilities;
  11
  12 pub(crate) struct Stripper<'a, 'tcx> {
  13     pub(crate) retained: &'a mut ItemIdSet,
  14     pub(crate) effective_visibilities: &'a RustdocEffectiveVisibilities,
  15     pub(crate) update_retained: bool,
  16     pub(crate) is_json_output: bool,
  17     pub(crate) tcx: TyCtxt<'tcx>,
  18 }
  19
  20 // We need to handle this differently for the JSON output because some non exported items could
  21 // be used in public API. And so, we need these items as well. `is_exported` only checks if they
  22 // are in the public API, which is not enough.
  23 #[inline]
  24 fn is_item_reachable(
  25     tcx: TyCtxt<'_>,
  26     is_json_output: bool,
  27     effective_visibilities: &RustdocEffectiveVisibilities,
  28     item_id: ItemId,
  29 ) -> bool {
  30     if is_json_output {
  31         effective_visibilities.is_reachable(tcx, item_id.expect_def_id())
  32     } else {
  33         effective_visibilities.is_exported(tcx, item_id.expect_def_id())
  34     }
  35 }
  36
  37 impl<'a, 'tcx> DocFolder for Stripper<'a, 'tcx> {
  38     fn fold_item(&mut self, i: Item) -> Option<Item> {
  39         match *i.kind {
  40             clean::StrippedItem(..) => {
  41                 // We need to recurse into stripped modules to strip things
  42                 // like impl methods but when doing so we must not add any
  43                 // items to the `retained` set.
  44                 debug!("Stripper: recursing into stripped {:?} {:?}", i.type_(), i.name);
  45                 let old = mem::replace(&mut self.update_retained, false);
  46                 let ret = self.fold_item_recur(i);
  47                 self.update_retained = old;
  48                 return Some(ret);
  49             }
  50             // These items can all get re-exported
  51             clean::OpaqueTyItem(..)
  52             | clean::TypedefItem(..)
  53             | clean::StaticItem(..)
  54             | clean::StructItem(..)
  55             | clean::EnumItem(..)
  56             | clean::TraitItem(..)
  57             | clean::FunctionItem(..)
  58             | clean::VariantItem(..)
  59             | clean::MethodItem(..)
  60             | clean::ForeignFunctionItem(..)
  61             | clean::ForeignStaticItem(..)
  62             | clean::ConstantItem(..)
  63             | clean::UnionItem(..)
  64             | clean::AssocConstItem(..)
  65             | clean::AssocTypeItem(..)
  66             | clean::TraitAliasItem(..)
  67             | clean::MacroItem(..)
  68             | clean::ForeignTypeItem => {
  69                 let item_id = i.item_id;
  70                 if item_id.is_local()
  71                     && !is_item_reachable(
  72                         self.tcx,
  73                         self.is_json_output,
  74                         self.effective_visibilities,
  75                         item_id,
  76                     )
  77                 {
  78                     debug!("Stripper: stripping {:?} {:?}", i.type_(), i.name);
  79                     return None;
  80                 }
  81             }
  82
  83             clean::StructFieldItem(..) => {
  84                 if i.visibility(self.tcx) != Some(Visibility::Public) {
  85                     return Some(strip_item(i));
  86                 }
  87             }
  88
  89             clean::ModuleItem(..) => {
  90                 if i.item_id.is_local() && i.visibility(self.tcx) != Some(Visibility::Public) {
  91                     debug!("Stripper: stripping module {:?}", i.name);
  92                     let old = mem::replace(&mut self.update_retained, false);
  93                     let ret = strip_item(self.fold_item_recur(i));
  94                     self.update_retained = old;
  95                     return Some(ret);
  96                 }
  97             }
  98
  99             // handled in the `strip-priv-imports` pass
 100             clean::ExternCrateItem { .. } | clean::ImportItem(_) => {}
 101
 102             clean::ImplItem(..) => {}
 103
 104             // tymethods etc. have no control over privacy
 105             clean::TyMethodItem(..) | clean::TyAssocConstItem(..) | clean::TyAssocTypeItem(..) => {}
 106
 107             // Proc-macros are always public
 108             clean::ProcMacroItem(..) => {}
 109
 110             // Primitives are never stripped
 111             clean::PrimitiveItem(..) => {}
 112
 113             // Keywords are never stripped
 114             clean::KeywordItem => {}
 115         }
 116
 117         let fastreturn = match *i.kind {
 118             // nothing left to do for traits (don't want to filter their
 119             // methods out, visibility controlled by the trait)
 120             clean::TraitItem(..) => true,
 121
 122             // implementations of traits are always public.
 123             clean::ImplItem(ref imp) if imp.trait_.is_some() => true,
 124             // Variant fields have inherited visibility
 125             clean::VariantItem(clean::Variant {
 126                 kind: clean::VariantKind::Struct(..) | clean::VariantKind::Tuple(..),
 127                 ..
 128             }) => true,
 129             _ => false,
 130         };
 131
 132         let i = if fastreturn {
 133             if self.update_retained {
 134                 self.retained.insert(i.item_id);
 135             }
 136             return Some(i);
 137         } else {
 138             self.fold_item_recur(i)
 139         };
 140
 141         if self.update_retained {
 142             self.retained.insert(i.item_id);
 143         }
 144         Some(i)
 145     }
 146 }
 147
 148 /// This stripper discards all impls which reference stripped items
 149 pub(crate) struct ImplStripper<'a, 'tcx> {
 150     pub(crate) tcx: TyCtxt<'tcx>,
 151     pub(crate) retained: &'a ItemIdSet,
 152     pub(crate) cache: &'a Cache,
 153     pub(crate) is_json_output: bool,
 154     pub(crate) document_private: bool,
 155 }
 156
 157 impl<'a> ImplStripper<'a, '_> {
 158     #[inline]
 159     fn should_keep_impl(&self, item: &Item, for_def_id: DefId) -> bool {
 160         if !for_def_id.is_local() || self.retained.contains(&for_def_id.into()) {
 161             true
 162         } else if self.is_json_output {
 163             // If the "for" item is exported and the impl block isn't `#[doc(hidden)]`, then we
 164             // need to keep it.
 165             self.cache.effective_visibilities.is_exported(self.tcx, for_def_id)
 166                 && !item.attrs.lists(sym::doc).has_word(sym::hidden)
 167         } else {
 168             false
 169         }
 170     }
 171 }
 172
 173 impl<'a> DocFolder for ImplStripper<'a, '_> {
 174     fn fold_item(&mut self, i: Item) -> Option<Item> {
 175         if let clean::ImplItem(ref imp) = *i.kind {
 176             // Impl blocks can be skipped if they are: empty; not a trait impl; and have no
 177             // documentation.
 178             //
 179             // There is one special case: if the impl block contains only private items.
 180             if imp.trait_.is_none() {
 181                 // If the only items present are private ones and we're not rendering private items,
 182                 // we don't document it.
 183                 if !imp.items.is_empty()
 184                     && !self.document_private
 185                     && imp.items.iter().all(|i| {
 186                         let item_id = i.item_id;
 187                         item_id.is_local()
 188                             && !is_item_reachable(
 189                                 self.tcx,
 190                                 self.is_json_output,
 191                                 &self.cache.effective_visibilities,
 192                                 item_id,
 193                             )
 194                     })
 195                 {
 196                     return None;
 197                 } else if imp.items.is_empty() && i.doc_value().is_none() {
 198                     return None;
 199                 }
 200             }
 201             // Because we don't inline in `maybe_inline_local` if the output format is JSON,
 202             // we need to make a special check for JSON output: we want to keep it unless it has
 203             // a `#[doc(hidden)]` attribute if the `for_` type is exported.
 204             if let Some(did) = imp.for_.def_id(self.cache) &&
 205                 !imp.for_.is_assoc_ty() && !self.should_keep_impl(&i, did)
 206             {
 207                 debug!("ImplStripper: impl item for stripped type; removing");
 208                 return None;
 209             }
 210             if let Some(did) = imp.trait_.as_ref().map(|t| t.def_id()) &&
 211                 !self.should_keep_impl(&i, did) {
 212                 debug!("ImplStripper: impl item for stripped trait; removing");
 213                 return None;
 214             }
 215             if let Some(generics) = imp.trait_.as_ref().and_then(|t| t.generics()) {
 216                 for typaram in generics {
 217                     if let Some(did) = typaram.def_id(self.cache) && !self.should_keep_impl(&i, did)
 218                     {
 219                         debug!(
 220                             "ImplStripper: stripped item in trait's generics; removing impl"
 221                         );
 222                         return None;
 223                     }
 224                 }
 225             }
 226         }
 227         Some(self.fold_item_recur(i))
 228     }
 229 }
 230
 231 /// This stripper discards all private import statements (`use`, `extern crate`)
 232 pub(crate) struct ImportStripper<'tcx> {
 233     pub(crate) tcx: TyCtxt<'tcx>,
 234     pub(crate) is_json_output: bool,
 235 }
 236
 237 impl<'tcx> ImportStripper<'tcx> {
 238     fn import_should_be_hidden(&self, i: &Item, imp: &clean::Import) -> bool {
 239         if self.is_json_output {
 240             // FIXME: This should be handled the same way as for HTML output.
 241             imp.imported_item_is_doc_hidden(self.tcx)
 242         } else {
 243             i.attrs.lists(sym::doc).has_word(sym::hidden)
 244         }
 245     }
 246 }
 247
 248 impl<'tcx> DocFolder for ImportStripper<'tcx> {
 249     fn fold_item(&mut self, i: Item) -> Option<Item> {
 250         match *i.kind {
 251             clean::ImportItem(imp) if self.import_should_be_hidden(&i, &imp) => None,
 252             clean::ImportItem(_) if i.attrs.lists(sym::doc).has_word(sym::hidden) => None,
 253             clean::ExternCrateItem { .. } | clean::ImportItem(..)
 254                 if i.visibility(self.tcx) != Some(Visibility::Public) =>
 255             {
 256                 None
 257             }
 258             _ => Some(self.fold_item_recur(i)),
 259         }
 260     }
 261 }