1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use hir::map::DefPathData;
12 use hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
13 use ty::{self, Ty, TyCtxt};
14 use middle::cstore::{ExternCrate, ExternCrateSource};
16 use syntax::symbol::{keywords, LocalInternedString, Symbol};
17 use syntax_pos::edition::Edition;
23 static FORCE_ABSOLUTE: Cell<bool> = Cell::new(false);
24 static FORCE_IMPL_FILENAME_LINE: Cell<bool> = Cell::new(false);
25 static SHOULD_PREFIX_WITH_CRATE: Cell<bool> = Cell::new(false);
28 /// Enforces that item_path_str always returns an absolute path and
29 /// also enables "type-based" impl paths. This is used when building
30 /// symbols that contain types, where we want the crate name to be
31 /// part of the symbol.
32 pub fn with_forced_absolute_paths<F: FnOnce() -> R, R>(f: F) -> R {
33 FORCE_ABSOLUTE.with(|force| {
34 let old = force.get();
42 /// Force us to name impls with just the filename/line number. We
43 /// normally try to use types. But at some points, notably while printing
44 /// cycle errors, this can result in extra or suboptimal error output,
45 /// so this variable disables that check.
46 pub fn with_forced_impl_filename_line<F: FnOnce() -> R, R>(f: F) -> R {
47 FORCE_IMPL_FILENAME_LINE.with(|force| {
48 let old = force.get();
56 /// Add the `crate::` prefix to paths where appropriate.
57 pub fn with_crate_prefix<F: FnOnce() -> R, R>(f: F) -> R {
58 SHOULD_PREFIX_WITH_CRATE.with(|flag| {
67 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
68 /// Returns a string identifying this def-id. This string is
69 /// suitable for user output. It is relative to the current crate
70 /// root, unless with_forced_absolute_paths was used.
71 pub fn item_path_str(self, def_id: DefId) -> String {
72 let mode = FORCE_ABSOLUTE.with(|force| {
79 let mut buffer = LocalPathBuffer::new(mode);
80 debug!("item_path_str: buffer={:?} def_id={:?}", buffer, def_id);
81 self.push_item_path(&mut buffer, def_id, false);
85 /// Returns a string identifying this local node-id.
86 pub fn node_path_str(self, id: ast::NodeId) -> String {
87 self.item_path_str(self.hir.local_def_id(id))
90 /// Returns a string identifying this def-id. This string is
91 /// suitable for user output. It always begins with a crate identifier.
92 pub fn absolute_item_path_str(self, def_id: DefId) -> String {
93 let mut buffer = LocalPathBuffer::new(RootMode::Absolute);
94 debug!("absolute_item_path_str: buffer={:?} def_id={:?}", buffer, def_id);
95 self.push_item_path(&mut buffer, def_id, false);
99 /// Returns the "path" to a particular crate. This can proceed in
100 /// various ways, depending on the `root_mode` of the `buffer`.
101 /// (See `RootMode` enum for more details.)
103 /// `pushed_prelude_crate` argument should be `true` when the buffer
104 /// has had a prelude crate pushed to it. If this is the case, then
105 /// we do not want to prepend `crate::` (as that would not be a valid
107 pub fn push_krate_path<T>(self, buffer: &mut T, cnum: CrateNum, pushed_prelude_crate: bool)
108 where T: ItemPathBuffer + Debug
111 "push_krate_path: buffer={:?} cnum={:?} LOCAL_CRATE={:?}",
112 buffer, cnum, LOCAL_CRATE
114 match *buffer.root_mode() {
116 // In local mode, when we encounter a crate other than
117 // LOCAL_CRATE, execution proceeds in one of two ways:
119 // 1. for a direct dependency, where user added an
120 // `extern crate` manually, we put the `extern
121 // crate` as the parent. So you wind up with
122 // something relative to the current crate.
123 // 2. for an extern inferred from a path or an indirect crate,
124 // where there is no explicit `extern crate`, we just prepend
127 // Returns `None` for the local crate.
128 if cnum != LOCAL_CRATE {
129 let opt_extern_crate = self.extern_crate(cnum.as_def_id());
130 if let Some(ExternCrate {
131 src: ExternCrateSource::Extern(def_id),
134 }) = *opt_extern_crate
136 debug!("push_krate_path: def_id={:?}", def_id);
137 self.push_item_path(buffer, def_id, pushed_prelude_crate);
139 let name = self.crate_name(cnum).as_str();
140 debug!("push_krate_path: name={:?}", name);
143 } else if self.sess.edition() == Edition::Edition2018 && !pushed_prelude_crate {
144 SHOULD_PREFIX_WITH_CRATE.with(|flag| {
145 // We only add the `crate::` keyword where appropriate. In particular,
146 // when we've not previously pushed a prelude crate to this path.
148 buffer.push(&keywords::Crate.name().as_str())
153 RootMode::Absolute => {
154 // In absolute mode, just write the crate name
156 let name = self.original_crate_name(cnum).as_str();
157 debug!("push_krate_path: original_name={:?}", name);
163 /// If possible, this pushes a global path resolving to `external_def_id` that is visible
164 /// from at least one local module and returns true. If the crate defining `external_def_id` is
165 /// declared with an `extern crate`, the path is guaranteed to use the `extern crate`.
166 pub fn try_push_visible_item_path<T>(
169 external_def_id: DefId,
170 pushed_prelude_crate: bool,
172 where T: ItemPathBuffer + Debug
175 "try_push_visible_item_path: buffer={:?} external_def_id={:?}",
176 buffer, external_def_id
178 let visible_parent_map = self.visible_parent_map(LOCAL_CRATE);
180 let (mut cur_def, mut cur_path) = (external_def_id, Vec::<LocalInternedString>::new());
183 "try_push_visible_item_path: cur_def={:?} cur_path={:?} CRATE_DEF_INDEX={:?}",
184 cur_def, cur_path, CRATE_DEF_INDEX,
186 // If `cur_def` is a direct or injected extern crate, push the path to the crate
187 // followed by the path to the item within the crate and return.
188 if cur_def.index == CRATE_DEF_INDEX {
189 match *self.extern_crate(cur_def) {
191 src: ExternCrateSource::Extern(def_id),
195 debug!("try_push_visible_item_path: def_id={:?}", def_id);
196 self.push_item_path(buffer, def_id, pushed_prelude_crate);
197 cur_path.iter().rev().for_each(|segment| buffer.push(&segment));
201 buffer.push(&self.crate_name(cur_def.krate).as_str());
202 cur_path.iter().rev().for_each(|segment| buffer.push(&segment));
209 let mut cur_def_key = self.def_key(cur_def);
210 debug!("try_push_visible_item_path: cur_def_key={:?}", cur_def_key);
212 // For a UnitStruct or TupleStruct we want the name of its parent rather than <unnamed>.
213 if let DefPathData::StructCtor = cur_def_key.disambiguated_data.data {
215 krate: cur_def.krate,
216 index: cur_def_key.parent.expect("DefPathData::StructCtor missing a parent"),
219 cur_def_key = self.def_key(parent);
222 let data = cur_def_key.disambiguated_data.data;
223 let symbol = data.get_opt_name().map(|n| n.as_str()).unwrap_or_else(|| {
224 if let DefPathData::CrateRoot = data { // reexported `extern crate` (#43189)
225 self.original_crate_name(cur_def.krate).as_str()
227 Symbol::intern("<unnamed>").as_str()
230 debug!("try_push_visible_item_path: symbol={:?}", symbol);
231 cur_path.push(symbol);
233 match visible_parent_map.get(&cur_def) {
234 Some(&def) => cur_def = def,
235 None => return false,
240 pub fn push_item_path<T>(self, buffer: &mut T, def_id: DefId, pushed_prelude_crate: bool)
241 where T: ItemPathBuffer + Debug
244 "push_item_path: buffer={:?} def_id={:?} pushed_prelude_crate={:?}",
245 buffer, def_id, pushed_prelude_crate
247 match *buffer.root_mode() {
248 RootMode::Local if !def_id.is_local() =>
249 if self.try_push_visible_item_path(buffer, def_id, pushed_prelude_crate) { return },
253 let key = self.def_key(def_id);
254 debug!("push_item_path: key={:?}", key);
255 match key.disambiguated_data.data {
256 DefPathData::CrateRoot => {
257 assert!(key.parent.is_none());
258 self.push_krate_path(buffer, def_id.krate, pushed_prelude_crate);
261 DefPathData::Impl => {
262 self.push_impl_path(buffer, def_id, pushed_prelude_crate);
265 // Unclear if there is any value in distinguishing these.
266 // Probably eventually (and maybe we would even want
267 // finer-grained distinctions, e.g. between enum/struct).
268 data @ DefPathData::Misc |
269 data @ DefPathData::TypeNs(..) |
270 data @ DefPathData::Trait(..) |
271 data @ DefPathData::AssocTypeInTrait(..) |
272 data @ DefPathData::AssocTypeInImpl(..) |
273 data @ DefPathData::AssocExistentialInImpl(..) |
274 data @ DefPathData::ValueNs(..) |
275 data @ DefPathData::Module(..) |
276 data @ DefPathData::TypeParam(..) |
277 data @ DefPathData::LifetimeParam(..) |
278 data @ DefPathData::EnumVariant(..) |
279 data @ DefPathData::Field(..) |
280 data @ DefPathData::AnonConst |
281 data @ DefPathData::MacroDef(..) |
282 data @ DefPathData::ClosureExpr |
283 data @ DefPathData::ImplTrait |
284 data @ DefPathData::GlobalMetaData(..) => {
285 let parent_did = self.parent_def_id(def_id).unwrap();
287 // Keep track of whether we are one recursion away from the `CrateRoot` and
288 // pushing the name of a prelude crate. If we are, we'll want to know this when
289 // printing the `CrateRoot` so we don't prepend a `crate::` to paths.
290 let mut is_prelude_crate = false;
291 if let DefPathData::CrateRoot = self.def_key(parent_did).disambiguated_data.data {
292 if self.sess.extern_prelude.contains(&data.as_interned_str().as_symbol()) {
293 is_prelude_crate = true;
298 buffer, parent_did, pushed_prelude_crate || is_prelude_crate
300 buffer.push(&data.as_interned_str().as_symbol().as_str());
303 DefPathData::StructCtor => { // present `X` instead of `X::{{constructor}}`
304 let parent_def_id = self.parent_def_id(def_id).unwrap();
305 self.push_item_path(buffer, parent_def_id, pushed_prelude_crate);
310 fn push_impl_path<T>(
314 pushed_prelude_crate: bool,
316 where T: ItemPathBuffer + Debug
318 debug!("push_impl_path: buffer={:?} impl_def_id={:?}", buffer, impl_def_id);
319 let parent_def_id = self.parent_def_id(impl_def_id).unwrap();
321 // Always use types for non-local impls, where types are always
322 // available, and filename/line-number is mostly uninteresting.
323 let use_types = !impl_def_id.is_local() || {
324 // Otherwise, use filename/line-number if forced.
325 let force_no_types = FORCE_IMPL_FILENAME_LINE.with(|f| f.get());
330 return self.push_impl_path_fallback(buffer, impl_def_id, pushed_prelude_crate);
333 // Decide whether to print the parent path for the impl.
334 // Logically, since impls are global, it's never needed, but
335 // users may find it useful. Currently, we omit the parent if
336 // the impl is either in the same module as the self-type or
338 let self_ty = self.type_of(impl_def_id);
339 let in_self_mod = match characteristic_def_id_of_type(self_ty) {
341 Some(ty_def_id) => self.parent_def_id(ty_def_id) == Some(parent_def_id),
344 let impl_trait_ref = self.impl_trait_ref(impl_def_id);
345 let in_trait_mod = match impl_trait_ref {
347 Some(trait_ref) => self.parent_def_id(trait_ref.def_id) == Some(parent_def_id),
350 if !in_self_mod && !in_trait_mod {
351 // If the impl is not co-located with either self-type or
352 // trait-type, then fallback to a format that identifies
353 // the module more clearly.
354 self.push_item_path(buffer, parent_def_id, pushed_prelude_crate);
355 if let Some(trait_ref) = impl_trait_ref {
356 buffer.push(&format!("<impl {} for {}>", trait_ref, self_ty));
358 buffer.push(&format!("<impl {}>", self_ty));
363 // Otherwise, try to give a good form that would be valid language
364 // syntax. Preferably using associated item notation.
366 if let Some(trait_ref) = impl_trait_ref {
368 buffer.push(&format!("<{} as {}>",
374 // Inherent impls. Try to print `Foo::bar` for an inherent
375 // impl on `Foo`, but fallback to `<Foo>::bar` if self-type is
376 // anything other than a simple path.
378 ty::Adt(adt_def, substs) => {
379 if substs.types().next().is_none() { // ignore regions
380 self.push_item_path(buffer, adt_def.did, pushed_prelude_crate);
382 buffer.push(&format!("<{}>", self_ty));
386 ty::Foreign(did) => self.push_item_path(buffer, did, pushed_prelude_crate),
394 buffer.push(&self_ty.to_string());
398 buffer.push(&format!("<{}>", self_ty));
403 fn push_impl_path_fallback<T>(
407 pushed_prelude_crate: bool,
409 where T: ItemPathBuffer + Debug
411 // If no type info is available, fall back to
412 // pretty printing some span information. This should
413 // only occur very early in the compiler pipeline.
414 let parent_def_id = self.parent_def_id(impl_def_id).unwrap();
415 self.push_item_path(buffer, parent_def_id, pushed_prelude_crate);
416 let node_id = self.hir.as_local_node_id(impl_def_id).unwrap();
417 let item = self.hir.expect_item(node_id);
418 let span_str = self.sess.source_map().span_to_string(item.span);
419 buffer.push(&format!("<impl at {}>", span_str));
422 /// Returns the def-id of `def_id`'s parent in the def tree. If
423 /// this returns `None`, then `def_id` represents a crate root or
425 pub fn parent_def_id(self, def_id: DefId) -> Option<DefId> {
426 let key = self.def_key(def_id);
427 key.parent.map(|index| DefId { krate: def_id.krate, index: index })
431 /// As a heuristic, when we see an impl, if we see that the
432 /// 'self-type' is a type defined in the same module as the impl,
433 /// we can omit including the path to the impl itself. This
434 /// function tries to find a "characteristic def-id" for a
435 /// type. It's just a heuristic so it makes some questionable
436 /// decisions and we may want to adjust it later.
437 pub fn characteristic_def_id_of_type(ty: Ty<'_>) -> Option<DefId> {
439 ty::Adt(adt_def, _) => Some(adt_def.did),
441 ty::Dynamic(data, ..) => data.principal().map(|p| p.def_id()),
443 ty::Array(subty, _) |
444 ty::Slice(subty) => characteristic_def_id_of_type(subty),
446 ty::RawPtr(mt) => characteristic_def_id_of_type(mt.ty),
448 ty::Ref(_, ty, _) => characteristic_def_id_of_type(ty),
450 ty::Tuple(ref tys) => tys.iter()
451 .filter_map(|ty| characteristic_def_id_of_type(ty))
454 ty::FnDef(def_id, _) |
455 ty::Closure(def_id, _) |
456 ty::Generator(def_id, _, _) |
457 ty::Foreign(def_id) => Some(def_id),
470 ty::GeneratorWitness(..) |
472 ty::Float(_) => None,
476 /// Unifying Trait for different kinds of item paths we might
477 /// construct. The basic interface is that components get pushed: the
478 /// instance can also customize how we handle the root of a crate.
479 pub trait ItemPathBuffer {
480 fn root_mode(&self) -> &RootMode;
481 fn push(&mut self, text: &str);
486 /// Try to make a path relative to the local crate. In
487 /// particular, local paths have no prefix, and if the path comes
488 /// from an extern crate, start with the path to the `extern
489 /// crate` declaration.
492 /// Always prepend the crate name to the path, forming an absolute
493 /// path from within a given set of crates.
498 struct LocalPathBuffer {
503 impl LocalPathBuffer {
504 fn new(root_mode: RootMode) -> LocalPathBuffer {
511 fn into_string(self) -> String {
516 impl ItemPathBuffer for LocalPathBuffer {
517 fn root_mode(&self) -> &RootMode {
521 fn push(&mut self, text: &str) {
522 if !self.str.is_empty() {
523 self.str.push_str("::");
525 self.str.push_str(text);