Rollup merge of #57011 - QuietMisdreavus:static-root-path, r=GuillaumeGomez

rustdoc: add new CLI flag to load static files from a different location

This PR adds a new CLI flag to rustdoc, `--static-root-path`, which controls how rustdoc links pages to the CSS/JS/font static files bundled with the output. By default, these files are linked with a series of `../` which is calculated per-page to link it to the documentation root - i.e. a relative link to the directory given by `-o`. This is causing problems for docs.rs, because even though docs.rs has saved one copy of these files and is dispatching them dynamically, browsers have no way of knowing that these are the same files and can cache them. This can allow it to link these files as, for example, `/rustdoc.css` instead of `../../rustdoc.css`, creating a single location that the files are loaded from.

I made sure to only change links for the *static* files, those that don't change between crates. Files like the search index, aliases, the source files listing, etc, are still linked with relative links.

r? @GuillaumeGomez

cc @onur

1 files changed, 24 insertions, 0 deletions

diff --git a/src/test/rustdoc/static-root-path.rs b/src/test/rustdoc/static-root-path.rs
new file mode 100644
index 00000000000..7df3fee3365
--- /dev/null
+++ b/src/test/rustdoc/static-root-path.rs
@@ -0,0 +1,24 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// compile-flags:-Z unstable-options --static-root-path /cache/
+
+// @has static_root_path/struct.SomeStruct.html
+// @matches - '"/cache/main\.js"'
+// @!matches - '"\.\./main\.js"'
+// @matches - '"\.\./search-index\.js"'
+// @!matches - '"/cache/search-index\.js"'
+pub struct SomeStruct;
+
+// @has src/static_root_path/static-root-path.rs.html
+// @matches - '"/cache/source-script\.js"'
+// @!matches - '"\.\./\.\./source-script\.js"'
+// @matches - '"\.\./\.\./source-files.js"'
+// @!matches - '"/cache/source-files\.js"'