Auto merge of rust-lang#73767 - P1n3appl3:rustdoc-formats, r=tmandry

Refactor librustdoc html backend

This PR moves several types out of the librustdoc::html module so that they can be used by a future json backend. These changes are a re-implementation of [some work done 6 months ago](rust-lang/rust@master...GuillaumeGomez:multiple-output-formats) by @GuillaumeGomez. I'm currently working on said json backend and will put up an RFC soon with the proposed implementation.

There are a couple of changes that are more substantial than relocating structs to a different module:
1. The `Cache` is no longer part of the `html::render::Context` type and therefor it needs to be explicitly passed to any functions that access it.
2. The driving function `html::render::run` has been rewritten to use the `FormatRenderer` trait which should allow different backends to re-use the driving code.

r? @GuillaumeGomez

cc @tmandry @betamos

src/librustdoc/clean/types.rs

@@ -32,8 +32,9 @@ use crate::clean::inline;
 use crate::clean::types::Type::{QPath, ResolvedPath};
 use crate::core::DocContext;
 use crate::doctree;
-use crate::html::item_type::ItemType;
-use crate::html::render::{cache, ExternalLocation};
+use crate::formats::cache::cache;
+use crate::formats::item_type::ItemType;
+use crate::html::render::cache::ExternalLocation;
 
 use self::FnRetTy::*;
 use self::ItemEnum::*;
@@ -1172,7 +1173,7 @@ impl GetDefId for Type {
     fn def_id(&self) -> Option<DefId> {
         match *self {
             ResolvedPath { did, .. } => Some(did),
-            Primitive(p) => crate::html::render::cache().primitive_locations.get(&p).cloned(),
+            Primitive(p) => cache().primitive_locations.get(&p).cloned(),
             BorrowedRef { type_: box Generic(..), .. } => {
                 Primitive(PrimitiveType::Reference).def_id()
             }

src/librustdoc/config.rs

@@ -4,6 +4,9 @@ use std::ffi::OsStr;
 use std::fmt;
 use std::path::PathBuf;
 
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_hir::def_id::DefId;
+use rustc_middle::middle::privacy::AccessLevels;
 use rustc_session::config::{self, parse_crate_types_from_list, parse_externs, CrateType};
 use rustc_session::config::{
     build_codegen_options, build_debugging_options, get_cmd_lint_options, host_triple,
@@ -249,6 +252,20 @@ pub struct RenderOptions {
     pub document_hidden: bool,
 }
 
+/// Temporary storage for data obtained during `RustdocVisitor::clean()`.
+/// Later on moved into `CACHE_KEY`.
+#[derive(Default, Clone)]
+pub struct RenderInfo {
+    pub inlined: FxHashSet<DefId>,
+    pub external_paths: crate::core::ExternalPaths,
+    pub exact_paths: FxHashMap<DefId, Vec<String>>,
+    pub access_levels: AccessLevels<DefId>,
+    pub deref_trait_did: Option<DefId>,
+    pub deref_mut_trait_did: Option<DefId>,
+    pub owned_box_did: Option<DefId>,
+    pub output_format: Option<OutputFormat>,
+}
+
 impl Options {
     /// Parses the given command-line for options. If an error message or other early-return has
     /// been printed, returns `Err` with the exit code.

src/librustdoc/core.rs

@@ -32,8 +32,8 @@ use std::rc::Rc;
 
 use crate::clean;
 use crate::clean::{AttributesExt, MAX_DEF_ID};
+use crate::config::RenderInfo;
 use crate::config::{Options as RustdocOptions, RenderOptions};
-use crate::html::render::RenderInfo;
 use crate::passes::{self, Condition::*, ConditionalPass};
 
 pub use rustc_session::config::{CodegenOptions, DebuggingOptions, Input, Options};
@@ -44,9 +44,9 @@ pub type ExternalPaths = FxHashMap<DefId, (Vec<String>, clean::TypeKind)>;
 pub struct DocContext<'tcx> {
     pub tcx: TyCtxt<'tcx>,
     pub resolver: Rc<RefCell<interface::BoxedResolver>>,
-    /// Later on moved into `html::render::CACHE_KEY`
+    /// Later on moved into `CACHE_KEY`
     pub renderinfo: RefCell<RenderInfo>,
-    /// Later on moved through `clean::Crate` into `html::render::CACHE_KEY`
+    /// Later on moved through `clean::Crate` into `CACHE_KEY`
     pub external_traits: Rc<RefCell<FxHashMap<DefId, clean::Trait>>>,
     /// Used while populating `external_traits` to ensure we don't process the same trait twice at
     /// the same time.

src/librustdoc/docfs.rs

@@ -13,8 +13,7 @@ use std::fs;
 use std::io;
 use std::path::Path;
 use std::string::ToString;
-use std::sync::mpsc::{channel, Receiver, Sender};
-use std::sync::Arc;
+use std::sync::mpsc::Sender;
 
 macro_rules! try_err {
     ($e:expr, $file:expr) => {
@@ -31,47 +30,24 @@ pub trait PathError {
         S: ToString + Sized;
 }
 
-pub struct ErrorStorage {
-    sender: Option<Sender<Option<String>>>,
-    receiver: Receiver<Option<String>>,
-}
-
-impl ErrorStorage {
-    pub fn new() -> ErrorStorage {
-        let (sender, receiver) = channel();
-        ErrorStorage { sender: Some(sender), receiver }
-    }
-
-    /// Prints all stored errors. Returns the number of printed errors.
-    pub fn write_errors(&mut self, diag: &rustc_errors::Handler) -> usize {
-        let mut printed = 0;
-        // In order to drop the sender part of the channel.
-        self.sender = None;
-
-        for msg in self.receiver.iter() {
-            if let Some(ref error) = msg {
-                diag.struct_err(&error).emit();
-                printed += 1;
-            }
-        }
-        printed
-    }
-}
-
 pub struct DocFS {
     sync_only: bool,
-    errors: Arc<ErrorStorage>,
+    errors: Option<Sender<String>>,
 }
 
 impl DocFS {
-    pub fn new(errors: &Arc<ErrorStorage>) -> DocFS {
-        DocFS { sync_only: false, errors: Arc::clone(errors) }
+    pub fn new(errors: Sender<String>) -> DocFS {
+        DocFS { sync_only: false, errors: Some(errors) }
     }
 
     pub fn set_sync_only(&mut self, sync_only: bool) {
         self.sync_only = sync_only;
     }
 
+    pub fn close(&mut self) {
+        self.errors = None;
+    }
+
     pub fn create_dir_all<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
         // For now, dir creation isn't a huge time consideration, do it
         // synchronously, which avoids needing ordering between write() actions
@@ -88,20 +64,15 @@ impl DocFS {
         if !self.sync_only && cfg!(windows) {
             // A possible future enhancement after more detailed profiling would
             // be to create the file sync so errors are reported eagerly.
-            let contents = contents.as_ref().to_vec();
             let path = path.as_ref().to_path_buf();
-            let sender = self.errors.sender.clone().unwrap();
-            rayon::spawn(move || match fs::write(&path, &contents) {
-                Ok(_) => {
-                    sender.send(None).unwrap_or_else(|_| {
-                        panic!("failed to send error on \"{}\"", path.display())
-                    });
-                }
-                Err(e) => {
-                    sender.send(Some(format!("\"{}\": {}", path.display(), e))).unwrap_or_else(
-                        |_| panic!("failed to send non-error on \"{}\"", path.display()),
-                    );
-                }
+            let contents = contents.as_ref().to_vec();
+            let sender = self.errors.clone().expect("can't write after closing");
+            rayon::spawn(move || {
+                fs::write(&path, contents).unwrap_or_else(|e| {
+                    sender
+                        .send(format!("\"{}\": {}", path.display(), e))
+                        .expect(&format!("failed to send error on \"{}\"", path.display()));
+                });
             });
             Ok(())
         } else {

src/librustdoc/error.rs

@@ -0,0 +1,56 @@
+use std::error;
+use std::fmt::{self, Formatter};
+use std::path::{Path, PathBuf};
+
+use crate::docfs::PathError;
+
+#[derive(Debug)]
+pub struct Error {
+    pub file: PathBuf,
+    pub error: String,
+}
+
+impl error::Error for Error {}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        let file = self.file.display().to_string();
+        if file.is_empty() {
+            write!(f, "{}", self.error)
+        } else {
+            write!(f, "\"{}\": {}", self.file.display(), self.error)
+        }
+    }
+}
+
+impl PathError for Error {
+    fn new<S, P: AsRef<Path>>(e: S, path: P) -> Error
+    where
+        S: ToString + Sized,
+    {
+        Error { file: path.as_ref().to_path_buf(), error: e.to_string() }
+    }
+}
+
+#[macro_export]
+macro_rules! try_none {
+    ($e:expr, $file:expr) => {{
+        use std::io;
+        match $e {
+            Some(e) => e,
+            None => {
+                return Err(Error::new(io::Error::new(io::ErrorKind::Other, "not found"), $file));
+            }
+        }
+    }};
+}
+
+#[macro_export]
+macro_rules! try_err {
+    ($e:expr, $file:expr) => {{
+        match $e {
+            Ok(e) => e,
+            Err(e) => return Err(Error::new(e, $file)),
+        }
+    }};
+}