Auto merge of #47046 - Manishearth:intra-doc-links, r=eddyb,GuillaumeGomez,QuietMisdreavus,Manishearth

Implement RFC 1946 - intra-rustdoc links

rust-lang/rfcs#1946 #43466

Note for reviewers: The plain line counts are a little inflated because of how the markdown link parsing was done. [Read the file diff with "whitespace only" changes removed](https://github.com/rust-lang/rust/pull/47046/files?w=1) to get a better view of what actually changed there.

This pulls the name/path resolution mechanisms out of the compiler and runs it on the markdown in a crate's docs, so that links can be made to `SomeStruct` directly rather than finding the folder path to `struct.SomeStruct.html`. Check the `src/test/rustdoc/intra-paths.rs` test in this PR for a demo. The change was... a little invasive, but unlocks a really powerful mechanism for writing documentation that doesn't care about where an item was written to on the hard disk.

Items included:

 - [x] Make work with the hoedown renderer
 - [x] Handle relative paths
 - [x] Parse out the "path ambiguities" qualifiers (`[crate foo]`, `[struct Foo]`, `[foo()]`, `[static FOO]`, `[foo!]`, etc)
 - [x] Resolve foreign macros
 - [x] Resolve local macros
 - [x] Handle the use of inner/outer attributes giving different resolution scopes (handling for non-modules pushed to different PR)

Items not included:

 - [ ] Make sure cross-crate inlining works (blocked on refactor described in #47046 (comment))
 - [ ] Implied Shortcut Reference Links (where just doing `[::std::iter::Iterator][]` without a reference anchor will resolve using the reference name rather than the link target) (requires modifying the markdown parser - blocked on Hoedown/Pulldown switch and pulldown-cmark/pulldown-cmark#121)
 - [ ] Handle enum variants and UFCS methods (Enum variants link to the enum page, associated methods don't link at all)
 - [ ] Emit more warnings/errors when things fail to resolve (linking to a value-namespaced item without a qualifier will emit an error, otherwise the link is just treated as a url, not a rust path)
 - [ ] Give better spans for resolution errors (currently the span for the first doc comment is used)
 - [ ] Check for inner doc comments on things that aren't modules

I'm making the PR, but it should be noted that most of the work was done by Misdreavus 😄

(Editor's note: This has become a lie, check that commit log, Manish did a ton of work after this PR was opened `>_>`)

Author: bors

src/librustc/hir/lowering.rs

@@ -151,6 +151,11 @@ pub trait Resolver {
     /// We must keep the set of definitions up to date as we add nodes that weren't in the AST.
     /// This should only return `None` during testing.
     fn definitions(&mut self) -> &mut Definitions;
+
+    /// Given suffix ["b","c","d"], creates a HIR path for `[::crate_root]::b::c::d` and resolves
+    /// it based on `is_value`.
+    fn resolve_str_path(&mut self, span: Span, crate_root: Option<&str>,
+                components: &[&str], is_value: bool) -> hir::Path;
 }
 
 #[derive(Clone, Copy, Debug)]
@@ -3625,16 +3630,7 @@ impl<'a> LoweringContext<'a> {
     /// `fld.cx.use_std`, and `::core::b::c::d` otherwise.
     /// The path is also resolved according to `is_value`.
     fn std_path(&mut self, span: Span, components: &[&str], is_value: bool) -> hir::Path {
-        let mut path = hir::Path {
-            span,
-            def: Def::Err,
-            segments: iter::once(keywords::CrateRoot.name()).chain({
-                self.crate_root.into_iter().chain(components.iter().cloned()).map(Symbol::intern)
-            }).map(hir::PathSegment::from_name).collect(),
-        };
-
-        self.resolver.resolve_hir_path(&mut path, is_value);
-        path
+        self.resolver.resolve_str_path(span, self.crate_root, components, is_value)
     }
 
     fn signal_block_expr(&mut self,

src/librustc_driver/driver.rs

@@ -28,7 +28,7 @@ use rustc::util::common::{ErrorReported, time};
 use rustc_allocator as allocator;
 use rustc_borrowck as borrowck;
 use rustc_incremental;
-use rustc_resolve::{MakeGlobMap, Resolver};
+use rustc_resolve::{MakeGlobMap, Resolver, ResolverArenas};
 use rustc_metadata::creader::CrateLoader;
 use rustc_metadata::cstore::{self, CStore};
 use rustc_trans_utils::trans_crate::TransCrate;
@@ -139,6 +139,7 @@ pub fn compile_input(trans: Box<TransCrate>,
 
         let crate_name =
             ::rustc_trans_utils::link::find_crate_name(Some(sess), &krate.attrs, input);
+
         let ExpansionResult { expanded_crate, defs, analysis, resolutions, mut hir_forest } = {
             phase_2_configure_and_expand(
                 sess,
@@ -562,6 +563,12 @@ pub struct ExpansionResult {
     pub hir_forest: hir_map::Forest,
 }
 
+pub struct InnerExpansionResult<'a> {
+    pub expanded_crate: ast::Crate,
+    pub resolver: Resolver<'a>,
+    pub hir_forest: hir_map::Forest,
+}
+
 /// Run the "early phases" of the compiler: initial `cfg` processing,
 /// loading compiler plugins (including those from `addl_plugins`),
 /// syntax expansion, secondary `cfg` expansion, synthesis of a test
@@ -578,6 +585,55 @@ pub fn phase_2_configure_and_expand<F>(sess: &Session,
                                        make_glob_map: MakeGlobMap,
                                        after_expand: F)
                                        -> Result<ExpansionResult, CompileIncomplete>
+    where F: FnOnce(&ast::Crate) -> CompileResult {
+    // Currently, we ignore the name resolution data structures for the purposes of dependency
+    // tracking. Instead we will run name resolution and include its output in the hash of each
+    // item, much like we do for macro expansion. In other words, the hash reflects not just
+    // its contents but the results of name resolution on those contents. Hopefully we'll push
+    // this back at some point.
+    let mut crate_loader = CrateLoader::new(sess, &cstore, &crate_name);
+    let resolver_arenas = Resolver::arenas();
+    let result = phase_2_configure_and_expand_inner(sess, cstore, krate, registry, crate_name,
+                                                    addl_plugins, make_glob_map, &resolver_arenas,
+                                                    &mut crate_loader, after_expand);
+    match result {
+        Ok(InnerExpansionResult {expanded_crate, resolver, hir_forest}) => {
+            Ok(ExpansionResult {
+                expanded_crate,
+                defs: resolver.definitions,
+                hir_forest,
+                resolutions: Resolutions {
+                    freevars: resolver.freevars,
+                    export_map: resolver.export_map,
+                    trait_map: resolver.trait_map,
+                    maybe_unused_trait_imports: resolver.maybe_unused_trait_imports,
+                    maybe_unused_extern_crates: resolver.maybe_unused_extern_crates,
+                },
+
+                analysis: ty::CrateAnalysis {
+                    access_levels: Rc::new(AccessLevels::default()),
+                    name: crate_name.to_string(),
+                    glob_map: if resolver.make_glob_map { Some(resolver.glob_map) } else { None },
+                },
+            })
+        }
+        Err(x) => Err(x)
+    }
+}
+
+/// Same as phase_2_configure_and_expand, but doesn't let you keep the resolver
+/// around
+pub fn phase_2_configure_and_expand_inner<'a, F>(sess: &'a Session,
+                                       cstore: &'a CStore,
+                                       krate: ast::Crate,
+                                       registry: Option<Registry>,
+                                       crate_name: &str,
+                                       addl_plugins: Option<Vec<String>>,
+                                       make_glob_map: MakeGlobMap,
+                                       resolver_arenas: &'a ResolverArenas<'a>,
+                                       crate_loader: &'a mut CrateLoader,
+                                       after_expand: F)
+                                       -> Result<InnerExpansionResult<'a>, CompileIncomplete>
     where F: FnOnce(&ast::Crate) -> CompileResult,
 {
     let time_passes = sess.time_passes();
@@ -666,19 +722,12 @@ pub fn phase_2_configure_and_expand<F>(sess: &Session,
         return Err(CompileIncomplete::Stopped);
     }
 
-    // Currently, we ignore the name resolution data structures for the purposes of dependency
-    // tracking. Instead we will run name resolution and include its output in the hash of each
-    // item, much like we do for macro expansion. In other words, the hash reflects not just
-    // its contents but the results of name resolution on those contents. Hopefully we'll push
-    // this back at some point.
-    let mut crate_loader = CrateLoader::new(sess, &cstore, crate_name);
-    let resolver_arenas = Resolver::arenas();
     let mut resolver = Resolver::new(sess,
                                      cstore,
                                      &krate,
                                      crate_name,
                                      make_glob_map,
-                                     &mut crate_loader,
+                                     crate_loader,
                                      &resolver_arenas);
     resolver.whitelisted_legacy_custom_derives = whitelisted_legacy_custom_derives;
     syntax_ext::register_builtins(&mut resolver, syntax_exts, sess.features.borrow().quote);
@@ -855,21 +904,9 @@ pub fn phase_2_configure_and_expand<F>(sess: &Session,
         syntax::ext::hygiene::clear_markings();
     }
 
-    Ok(ExpansionResult {
+    Ok(InnerExpansionResult {
         expanded_crate: krate,
-        defs: resolver.definitions,
-        analysis: ty::CrateAnalysis {
-            access_levels: Rc::new(AccessLevels::default()),
-            name: crate_name.to_string(),
-            glob_map: if resolver.make_glob_map { Some(resolver.glob_map) } else { None },
-        },
-        resolutions: Resolutions {
-            freevars: resolver.freevars,
-            export_map: resolver.export_map,
-            trait_map: resolver.trait_map,
-            maybe_unused_trait_imports: resolver.maybe_unused_trait_imports,
-            maybe_unused_extern_crates: resolver.maybe_unused_extern_crates,
-        },
+        resolver,
         hir_forest,
     })
 }

src/librustc_resolve/lib.rs

@@ -67,6 +67,7 @@ use std::cell::{Cell, RefCell};
 use std::cmp;
 use std::collections::BTreeSet;
 use std::fmt;
+use std::iter;
 use std::mem::replace;
 use std::rc::Rc;
 
@@ -1320,6 +1321,7 @@ pub struct Resolver<'a> {
     crate_loader: &'a mut CrateLoader,
     macro_names: FxHashSet<Ident>,
     global_macros: FxHashMap<Name, &'a NameBinding<'a>>,
+    pub all_macros: FxHashMap<Name, Def>,
     lexical_macro_resolutions: Vec<(Ident, &'a Cell<LegacyScope<'a>>)>,
     macro_map: FxHashMap<DefId, Rc<SyntaxExtension>>,
     macro_defs: FxHashMap<Mark, DefId>,
@@ -1407,6 +1409,71 @@ impl<'a, 'b: 'a> ty::DefIdTree for &'a Resolver<'b> {
 
 impl<'a> hir::lowering::Resolver for Resolver<'a> {
     fn resolve_hir_path(&mut self, path: &mut hir::Path, is_value: bool) {
+        self.resolve_hir_path_cb(path, is_value,
+                                 |resolver, span, error| resolve_error(resolver, span, error))
+    }
+
+    fn resolve_str_path(&mut self, span: Span, crate_root: Option<&str>,
+                        components: &[&str], is_value: bool) -> hir::Path {
+        let mut path = hir::Path {
+            span,
+            def: Def::Err,
+            segments: iter::once(keywords::CrateRoot.name()).chain({
+                crate_root.into_iter().chain(components.iter().cloned()).map(Symbol::intern)
+            }).map(hir::PathSegment::from_name).collect(),
+        };
+
+        self.resolve_hir_path(&mut path, is_value);
+        path
+    }
+
+    fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution> {
+        self.def_map.get(&id).cloned()
+    }
+
+    fn definitions(&mut self) -> &mut Definitions {
+        &mut self.definitions
+    }
+}
+
+impl<'a> Resolver<'a> {
+    /// Rustdoc uses this to resolve things in a recoverable way. ResolutionError<'a>
+    /// isn't something that can be returned because it can't be made to live that long,
+    /// and also it's a private type. Fortunately rustdoc doesn't need to know the error,
+    /// just that an error occured.
+    pub fn resolve_str_path_error(&mut self, span: Span, path_str: &str, is_value: bool)
+        -> Result<hir::Path, ()> {
+        use std::iter;
+        let mut errored = false;
+
+        let mut path = if path_str.starts_with("::") {
+            hir::Path {
+                span,
+                def: Def::Err,
+                segments: iter::once(keywords::CrateRoot.name()).chain({
+                    path_str.split("::").skip(1).map(Symbol::intern)
+                }).map(hir::PathSegment::from_name).collect(),
+            }
+        } else {
+            hir::Path {
+                span,
+                def: Def::Err,
+                segments: path_str.split("::").map(Symbol::intern)
+                                  .map(hir::PathSegment::from_name).collect(),
+            }
+        };
+        self.resolve_hir_path_cb(&mut path, is_value, |_, _, _| errored = true);
+        if errored || path.def == Def::Err {
+            Err(())
+        } else {
+            Ok(path)
+        }
+    }
+
+    /// resolve_hir_path, but takes a callback in case there was an error
+    fn resolve_hir_path_cb<F>(&mut self, path: &mut hir::Path, is_value: bool, error_callback: F)
+            where F: for<'c, 'b> FnOnce(&'c mut Resolver, Span, ResolutionError<'b>)
+        {
         let namespace = if is_value { ValueNS } else { TypeNS };
         let hir::Path { ref segments, span, ref mut def } = *path;
         let path: Vec<SpannedIdent> = segments.iter()
@@ -1418,24 +1485,16 @@ impl<'a> hir::lowering::Resolver for Resolver<'a> {
                 *def = path_res.base_def(),
             PathResult::NonModule(..) => match self.resolve_path(&path, None, true, span) {
                 PathResult::Failed(span, msg, _) => {
-                    resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
+                    error_callback(self, span, ResolutionError::FailedToResolve(&msg));
                 }
                 _ => {}
             },
             PathResult::Indeterminate => unreachable!(),
             PathResult::Failed(span, msg, _) => {
-                resolve_error(self, span, ResolutionError::FailedToResolve(&msg));
+                error_callback(self, span, ResolutionError::FailedToResolve(&msg));
             }
         }
     }
-
-    fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution> {
-        self.def_map.get(&id).cloned()
-    }
-
-    fn definitions(&mut self) -> &mut Definitions {
-        &mut self.definitions
-    }
 }
 
 impl<'a> Resolver<'a> {
@@ -1538,6 +1597,7 @@ impl<'a> Resolver<'a> {
             crate_loader,
             macro_names: FxHashSet(),
             global_macros: FxHashMap(),
+            all_macros: FxHashMap(),
             lexical_macro_resolutions: Vec::new(),
             macro_map: FxHashMap(),
             macro_exports: Vec::new(),
@@ -1833,8 +1893,8 @@ impl<'a> Resolver<'a> {
     // generate a fake "implementation scope" containing all the
     // implementations thus found, for compatibility with old resolve pass.
 
-    fn with_scope<F>(&mut self, id: NodeId, f: F)
-        where F: FnOnce(&mut Resolver)
+    pub fn with_scope<F, T>(&mut self, id: NodeId, f: F) -> T
+        where F: FnOnce(&mut Resolver) -> T
     {
         let id = self.definitions.local_def_id(id);
         let module = self.module_map.get(&id).cloned(); // clones a reference
@@ -1845,13 +1905,14 @@ impl<'a> Resolver<'a> {
             self.ribs[TypeNS].push(Rib::new(ModuleRibKind(module)));
 
             self.finalize_current_module_macro_resolutions();
-            f(self);
+            let ret = f(self);
 
             self.current_module = orig_module;
             self.ribs[ValueNS].pop();
             self.ribs[TypeNS].pop();
+            ret
         } else {
-            f(self);
+            f(self)
         }
     }
 

src/librustc_resolve/macros.rs

@@ -409,7 +409,7 @@ impl<'a> Resolver<'a> {
         def
     }
 
-    fn resolve_macro_to_def_inner(&mut self, scope: Mark, path: &ast::Path,
+    pub fn resolve_macro_to_def_inner(&mut self, scope: Mark, path: &ast::Path,
                                   kind: MacroKind, force: bool)
                                   -> Result<Def, Determinacy> {
         let ast::Path { ref segments, span } = *path;
@@ -755,8 +755,9 @@ impl<'a> Resolver<'a> {
             *legacy_scope = LegacyScope::Binding(self.arenas.alloc_legacy_binding(LegacyBinding {
                 parent: Cell::new(*legacy_scope), ident: ident, def_id: def_id, span: item.span,
             }));
+            let def = Def::Macro(def_id, MacroKind::Bang);
+            self.all_macros.insert(ident.name, def);
             if attr::contains_name(&item.attrs, "macro_export") {
-                let def = Def::Macro(def_id, MacroKind::Bang);
                 self.macro_exports.push(Export {
                     ident: ident.modern(),
                     def: def,

src/librustdoc/clean/inline.rs

@@ -135,7 +135,11 @@ pub fn record_extern_fqn(cx: &DocContext, did: DefId, kind: clean::TypeKind) {
             None
         }
     });
-    let fqn = once(crate_name).chain(relative).collect();
+    let fqn = if let clean::TypeKind::Macro = kind {
+        vec![crate_name, relative.last().unwrap()]
+    } else {
+        once(crate_name).chain(relative).collect()
+    };
     cx.renderinfo.borrow_mut().external_paths.insert(did, (fqn, kind));
 }