dist: Re-work how we describe the licence of Rust in our distributions

) add COPYRIGHT*.html files to the rustc binary distribution
) add contents of LICENSE folder to dist tarballs, because some of our in-tree licences will require that the license text is reproduced.
) The wording of COPYRIGHT is adjusted to not include license text (`reuse` ensures that it's in the LICENSE folder)
) A blanket copyright notice is added to LICENCE-MIT as required by the text.

The general approach is that the license statements are now compiled using a tool in CI (generate-copyright), and you get either:

* the source code (COPYRIGHT, LICENCE-APACHE, LICENCE-MIT, REUSE.toml and the LICENCES folder), or
* the compiled version (COPYRIGHT.html, COPYRIGHT-library.html and the LICENCES folder).

4 files changed, 54 insertions, 24 deletions

diff --git a/src/bootstrap/src/core/build_steps/dist.rs b/src/bootstrap/src/core/build_steps/dist.rs
index a636c4a9ef1..c26e0e250fb 100644
--- a/src/bootstrap/src/core/build_steps/dist.rs
+++ b/src/bootstrap/src/core/build_steps/dist.rs
@@ -503,14 +503,22 @@ impl Step for Rustc {
             // Debugger scripts
             builder.ensure(DebuggerScripts { sysroot: image.to_owned(), host });
 
-            // Misc license info
-            let cp = |file: &str| {
-                builder.install(&builder.src.join(file), &image.join("share/doc/rust"), 0o644);
+            // HTML copyright files
+            let file_list = builder.ensure(super::run::GenerateCopyright);
+            for file in file_list {
+                builder.install(&file, &image.join("share/doc/rust"), 0o644);
+            }
+
+            // README
+            builder.install(&builder.src.join("README.md"), &image.join("share/doc/rust"), 0o644);
+
+            // The REUSE-managed license files
+            let license = |path: &Path| {
+                builder.install(path, &image.join("share/doc/rust/licences"), 0o644);
             };
-            cp("COPYRIGHT");
-            cp("LICENSE-APACHE");
-            cp("LICENSE-MIT");
-            cp("README.md");
+            for entry in t!(std::fs::read_dir(builder.src.join("LICENSES"))).flatten() {
+                license(&entry.path());
+            }
         }
     }
 }
@@ -986,6 +994,7 @@ impl Step for PlainSourceTarball {
             "CONTRIBUTING.md",
             "README.md",
             "RELEASES.md",
+            "REUSE.toml",
             "configure",
             "x.py",
             "config.example.toml",
@@ -993,7 +1002,7 @@ impl Step for PlainSourceTarball {
             "Cargo.lock",
             ".gitmodules",
         ];
-        let src_dirs = ["src", "compiler", "library", "tests"];
+        let src_dirs = ["src", "compiler", "library", "tests", "LICENSES"];
 
         copy_src_dirs(builder, &builder.src, &src_dirs, &[], plain_dst_src);
 
diff --git a/src/bootstrap/src/core/build_steps/run.rs b/src/bootstrap/src/core/build_steps/run.rs
index c76504761be..0a6aea26359 100644
--- a/src/bootstrap/src/core/build_steps/run.rs
+++ b/src/bootstrap/src/core/build_steps/run.rs
@@ -196,7 +196,7 @@ impl Step for CollectLicenseMetadata {
 pub struct GenerateCopyright;
 
 impl Step for GenerateCopyright {
-    type Output = PathBuf;
+    type Output = Vec<PathBuf>;
     const ONLY_HOSTS: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
@@ -220,7 +220,7 @@ impl Step for GenerateCopyright {
         cmd.env("CARGO", &builder.initial_cargo);
         cmd.run(builder);
 
-        dest
+        vec![dest, dest_libstd]
     }
 }
 
diff --git a/src/tools/generate-copyright/templates/COPYRIGHT-library.html b/src/tools/generate-copyright/templates/COPYRIGHT-library.html
index 2c1eba741db..590a84dd931 100644
--- a/src/tools/generate-copyright/templates/COPYRIGHT-library.html
+++ b/src/tools/generate-copyright/templates/COPYRIGHT-library.html
@@ -8,20 +8,31 @@
 
 <h1>Copyright notices for The Rust Standard Library</h1>
 
-<p>This file describes the copyright and licensing information for the Rust
-Standard Library source code within The Rust Project git tree, and the
-third-party dependencies used when building the Rust Standard Library.</p>
-
 <h2>Table of Contents</h2>
 <ul>
+    <li><a href="#short-version">Short version for non-lawyers</a></li>
+    <li><a href="#longer-version">Longer version</a></li>
     <li><a href="#in-tree-files">In-tree files</a></li>
     <li><a href="#out-of-tree-dependencies">Out-of-tree dependencies</a></li>
 </ul>
 
+<h2 id="short-version">Short version for non-lawyers</h2>
+
+The Rust Standard Library is dual-licensed under Apache 2.0 and MIT terms.
+
+<h2 id="longer-version">Longer version</h2>
+
+<p>Copyrights in the Rust Standard Library are retained by their contributors. No copyright assignment is required to contribute to the Rust project.</p>
+
+<p>Some files include explicit copyright notices and/or license notices. For full authorship information, see the version control history or <a href="https://thanks.rust-lang.org">https://thanks.rust-lang.org</a>.</p>
+
+<p>Except as otherwise noted (below and/or in individual files), the Rust Standard Library is licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a> or the <a href="http://opensource.org/licenses/MIT">MIT</a> license, at your option.</p>
+
+<p>This file describes the copyright and licensing information for the source code within The Rust Project git tree related to the Rust Standard Library, and the third-party dependencies used when building the Rust Standard Library.</p>
+
 <h2 id="in-tree-files">In-tree files</h2>
 
-<p>The following licenses cover the in-tree source files that were used in this
-release:</p>
+<p>The following licenses cover the in-tree source files that were used in this release:</p>
 
 {{ in_tree|safe }}
 
diff --git a/src/tools/generate-copyright/templates/COPYRIGHT.html b/src/tools/generate-copyright/templates/COPYRIGHT.html
index ccb177a54d4..a0ed7bfb8d0 100644
--- a/src/tools/generate-copyright/templates/COPYRIGHT.html
+++ b/src/tools/generate-copyright/templates/COPYRIGHT.html
@@ -8,27 +8,37 @@
 
 <h1>Copyright notices for The Rust Toolchain</h1>
 
-<p>This file describes the copyright and licensing information for the source
-code within The Rust Project git tree, and the third-party dependencies used
-when building the Rust toolchain (including the Rust Standard Library).</p>
-
 <h2>Table of Contents</h2>
 <ul>
+    <li><a href="#short-version">Short version for non-lawyers</a></li>
+    <li><a href="#longer-version">Longer version</a></li>
     <li><a href="#in-tree-files">In-tree files</a></li>
     <li><a href="#out-of-tree-dependencies">Out-of-tree dependencies</a></li>
 </ul>
 
+<h2 id="short-version">Short version for non-lawyers</h2>
+
+The Rust Project is dual-licensed under Apache 2.0 and MIT terms.
+
+<h2 id="longer-version">Longer version</h2>
+
+<p>Copyrights in the Rust project are retained by their contributors. No copyright assignment is required to contribute to the Rust project.</p>
+
+<p>Some files include explicit copyright notices and/or license notices. For full authorship information, see the version control history or <a href="https://thanks.rust-lang.org">https://thanks.rust-lang.org</a>.</p>
+
+<p>Except as otherwise noted (below and/or in individual files), Rust is licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a> or the <a href="http://opensource.org/licenses/MIT">MIT</a> license, at your option.</p>
+
+<p>This file describes the copyright and licensing information for the source code within The Rust Project git tree, and the third-party dependencies used when building the Rust toolchain (including the Rust Standard Library).</p>
+
 <h2 id="in-tree-files">In-tree files</h2>
 
-<p>The following licenses cover the in-tree source files that were used in this
-release:</p>
+<p>The following licenses cover the in-tree source files that were used in this release:</p>
 
 {{ in_tree|safe }}
 
 <h2 id="out-of-tree-dependencies">Out-of-tree dependencies</h2>
 
-<p>The following licenses cover the out-of-tree crates that were used in this
-release:</p>
+<p>The following licenses cover the out-of-tree crates that were used in this release:</p>
 
 {% for (key, value) in dependencies %}
     <h3>📦 {{key.name}}-{{key.version}}</h3>