Add unstable option to only emit shared/crate-specific files

The intended use case is for docs.rs, which can now copy exactly the
files it cares about, rather than having to guess based on whether they
have a resource suffix or not. In particular, some files have a resource
suffix but cannot be shared between crates: https://github.com/rust-lang/docs.rs/pull/1312#issuecomment-798783688

The end goal is to fix https://github.com/rust-lang/docs.rs/issues/1327
by reverting https://github.com/rust-lang/docs.rs/pull/1324.

This obsoletes `--print=unversioned-files`, which I plan to remove as
soon as docs.rs stops using it.

src/librustdoc/config.rs

@@ -3,6 +3,7 @@ use std::convert::TryFrom;
 use std::ffi::OsStr;
 use std::fmt;
 use std::path::PathBuf;
+use std::str::FromStr;
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_session::config::{self, parse_crate_types_from_list, parse_externs, CrateType};
@@ -266,6 +267,34 @@ crate struct RenderOptions {
     /// If `true`, generate a JSON file in the crate folder instead of HTML redirection files.
     crate generate_redirect_map: bool,
     crate unstable_features: rustc_feature::UnstableFeatures,
+    crate emit: Vec<EmitType>,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+crate enum EmitType {
+    Unversioned,
+    Toolchain,
+    CrateSpecific,
+}
+
+impl FromStr for EmitType {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        use EmitType::*;
+        match s {
+            "unversioned-shared-resources" => Ok(Unversioned),
+            "toolchain-shared-resources" => Ok(Toolchain),
+            "crate-specific" => Ok(CrateSpecific),
+            _ => Err(()),
+        }
+    }
+}
+
+impl RenderOptions {
+    crate fn should_emit_crate(&self) -> bool {
+        self.emit.is_empty() || self.emit.contains(&EmitType::CrateSpecific)
+    }
 }
 
 impl Options {
@@ -334,6 +363,19 @@ impl Options {
         // check for deprecated options
         check_deprecated_options(&matches, &diag);
 
+        let mut emit = Vec::new();
+        for list in matches.opt_strs("emit") {
+            for kind in list.split(',') {
+                match kind.parse() {
+                    Ok(kind) => emit.push(kind),
+                    Err(()) => {
+                        diag.err(&format!("unrecognized emission type: {}", kind));
+                        return Err(1);
+                    }
+                }
+            }
+        }
+
         let to_check = matches.opt_strs("check-theme");
         if !to_check.is_empty() {
             let paths = theme::load_css_paths(static_files::themes::LIGHT.as_bytes());
@@ -641,6 +683,7 @@ impl Options {
                 unstable_features: rustc_feature::UnstableFeatures::from_environment(
                     crate_name.as_deref(),
                 ),
+                emit,
             },
             crate_name,
             output_format,

src/librustdoc/formats/renderer.rs

@@ -58,10 +58,15 @@ crate fn run_format<'tcx, T: FormatRenderer<'tcx>>(
 ) -> Result<(), Error> {
     let prof = &tcx.sess.prof;
 
+    let emit_crate = options.should_emit_crate();
     let (mut format_renderer, krate) = prof
         .extra_verbose_generic_activity("create_renderer", T::descr())
         .run(|| T::init(krate, options, edition, cache, tcx))?;
 
+    if !emit_crate {
+        return Ok(());
+    }
+
     // Render the crate documentation
     let crate_name = krate.name;
     let mut work = vec![(format_renderer.make_child_renderer(), krate.module)];

src/librustdoc/html/render/context.rs

@@ -288,6 +288,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
     ) -> Result<(Self, clean::Crate), Error> {
         // need to save a copy of the options for rendering the index page
         let md_opts = options.clone();
+        let emit_crate = options.should_emit_crate();
         let RenderOptions {
             output,
             external_html,
@@ -393,7 +394,9 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
 
         let dst = output;
         scx.ensure_dir(&dst)?;
+        if emit_crate {
             krate = sources::render(&dst, &mut scx, krate)?;
+        }
 
         // Build our search index
         let index = build_index(&krate, &mut cache, tcx);

src/librustdoc/html/render/write_shared.rs

@@ -13,7 +13,7 @@ use serde::Serialize;
 
 use super::{collect_paths_for_type, ensure_trailing_slash, Context, BASIC_KEYWORDS};
 use crate::clean::Crate;
-use crate::config::RenderOptions;
+use crate::config::{EmitType, RenderOptions};
 use crate::docfs::PathError;
 use crate::error::Error;
 use crate::formats::FormatRenderer;
@@ -72,6 +72,18 @@ impl SharedResource<'_> {
             SharedResource::CrateSpecific { basename } => cx.suffix_path(basename),
         }
     }
+
+    fn should_emit(&self, emit: &[EmitType]) -> bool {
+        if emit.is_empty() {
+            return true;
+        }
+        let kind = match self {
+            SharedResource::Unversioned { .. } => EmitType::Unversioned,
+            SharedResource::ToolchainSpecific { .. } => EmitType::Toolchain,
+            SharedResource::CrateSpecific { .. } => EmitType::CrateSpecific,
+        };
+        emit.contains(&kind)
+    }
 }
 
 impl Context<'_> {
@@ -86,9 +98,17 @@ impl Context<'_> {
         self.dst.join(&filename)
     }
 
-    fn write_shared<C: AsRef<[u8]>>(&self, resource: SharedResource<'_>, contents: C) -> Result<(), Error>
+    fn write_shared<C: AsRef<[u8]>>(
-    {
+        &self,
+        resource: SharedResource<'_>,
+        contents: C,
+        emit: &[EmitType],
+    ) -> Result<(), Error> {
+        if resource.should_emit(emit) {
             self.shared.fs.write(resource.path(self), contents)
+        } else {
+            Ok(())
+        }
     }
 
     fn write_minify(
@@ -96,6 +116,7 @@ impl Context<'_> {
         resource: SharedResource<'_>,
         contents: &str,
         minify: bool,
+        emit: &[EmitType],
     ) -> Result<(), Error> {
         let tmp;
         let contents = if minify {
@@ -111,7 +132,7 @@ impl Context<'_> {
             contents.as_bytes()
         };
 
-        self.write_shared(resource, contents)
+        self.write_shared(resource, contents, emit)
     }
 }
 
@@ -133,10 +154,14 @@ pub(super) fn write_shared(
             SharedResource::ToolchainSpecific { basename: p },
             c,
             options.enable_minification,
+            &options.emit,
         )
     };
-    let write_toolchain =
+    let write_toolchain = |p: &_, c: &_| {
-        |p: &_, c: &_| cx.write_shared(SharedResource::ToolchainSpecific { basename: p }, c);
+        cx.write_shared(SharedResource::ToolchainSpecific { basename: p }, c, &options.emit)
+    };
+    let write_crate =
+        |p, c: &_| cx.write_shared(SharedResource::CrateSpecific { basename: p }, c, &options.emit);
 
     // Add all the static files. These may already exist, but we just
     // overwrite them anyway to make sure that they're fresh and up-to-date.
@@ -214,7 +239,7 @@ pub(super) fn write_shared(
     }
     write_minify("normalize.css", static_files::NORMALIZE_CSS)?;
     for (name, contents) in &*FILES_UNVERSIONED {
-        cx.write_shared(SharedResource::Unversioned { name }, contents)?;
+        cx.write_shared(SharedResource::Unversioned { name }, contents, &options.emit)?;
     }
 
     fn collect(path: &Path, krate: &str, key: &str) -> io::Result<(Vec<String>, Vec<String>)> {
@@ -354,7 +379,7 @@ pub(super) fn write_shared(
             "var N = null;var sourcesIndex = {{}};\n{}\ncreateSourceSidebar();\n",
             all_sources.join("\n")
         );
-        cx.write_shared(SharedResource::CrateSpecific { basename: "source-files.js" }, v)?;
+        write_crate("source-files.js", &v)?;
     }
 
     // Update the search index and crate list.
@@ -371,12 +396,12 @@ pub(super) fn write_shared(
         let mut v = String::from("var searchIndex = JSON.parse('{\\\n");
         v.push_str(&all_indexes.join(",\\\n"));
         v.push_str("\\\n}');\ninitSearch(searchIndex);");
-        cx.write_shared(SharedResource::CrateSpecific { basename: "search-index.js" }, v)?;
+        write_crate("search-index.js", &v)?;
     }
 
     let crate_list =
         format!("window.ALL_CRATES = [{}];", krates.iter().map(|k| format!("\"{}\"", k)).join(","));
-    cx.write_shared(SharedResource::CrateSpecific { basename: "crates.js" }, crate_list)?;
+    write_crate("crates.js", &crate_list)?;
 
     if options.enable_index_page {
         if let Some(index_page) = options.index_page.clone() {

src/librustdoc/lib.rs

@@ -527,6 +527,14 @@ fn opts() -> Vec<RustcOptGroup> {
         unstable("print", |o| {
             o.optmulti("", "print", "Rustdoc information to print on stdout", "[unversioned-files]")
         }),
+        unstable("emit", |o| {
+            o.optmulti(
+                "",
+                "emit",
+                "Comma separated list of types of output for rustdoc to emit",
+                "[unversioned-shared-resources,toolchain-shared-resources,crate-specific]",
+            )
+        }),
     ]
 }
 

src/test/run-make/emit-shared-files/Makefile

@@ -0,0 +1,32 @@
+-include ../../run-make-fulldeps/tools.mk
+
+CRATE_ONLY = $(TMPDIR)/crate-only
+TOOLCHAIN_ONLY = $(TMPDIR)/toolchain-only
+ALL_SHARED = $(TMPDIR)/all-shared
+
+all: crate-only toolchain-only all-shared
+
+crate-only:
+	$(RUSTDOC) -Z unstable-options --emit=crate-specific --output $(CRATE_ONLY) --resource-suffix=-xxx x.rs
+	[ -e $(CRATE_ONLY)/search-index-xxx.js ]
+	[ -e $(CRATE_ONLY)/settings.html ]
+	[ -e $(CRATE_ONLY)/x/all.html ]
+	[ -e $(CRATE_ONLY)/x/index.html ]
+	! [ -e $(CRATE_ONLY)/storage-xxx.js ]
+	! [ -e $(CRATE_ONLY)/SourceSerifPro-It.ttf.woff ]
+
+toolchain-only:
+	$(RUSTDOC) -Z unstable-options --emit=toolchain-shared-resources --output $(TOOLCHAIN_ONLY) --resource-suffix=-xxx x.rs
+	[ -e $(TOOLCHAIN_ONLY)/storage-xxx.js ]
+	! [ -e $(TOOLCHAIN_ONLY)/SourceSerifPro-It.ttf.woff ]
+	! [ -e $(TOOLCHAIN_ONLY)/search-index-xxx.js ]
+	! [ -e $(TOOLCHAIN_ONLY)/x/index.html ]
+
+all-shared:
+	$(RUSTDOC) -Z unstable-options --emit=toolchain-shared-resources,unversioned-shared-resources --output $(ALL_SHARED) --resource-suffix=-xxx x.rs
+	[ -e $(ALL_SHARED)/storage-xxx.js ]
+	[ -e $(ALL_SHARED)/SourceSerifPro-It.ttf.woff ]
+	! [ -e $(ALL_SHARED)/search-index-xxx.js ]
+	! [ -e $(ALL_SHARED)/settings.html ]
+	! [ -e $(ALL_SHARED)/x ]
+	! [ -e $(ALL_SHARED)/src ]

src/test/run-make/emit-shared-files/x.rs

@@ -0,0 +1 @@
+// nothing to see here