From c685b57bf27d3ddecd83ab77e1973d36dff755b4 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Mon, 12 Mar 2018 17:16:21 -0500
Subject: [PATCH 01/20] add page to the Rustdoc Book about unstable features

---
 src/doc/rustdoc/src/SUMMARY.md           |  1 +
 src/doc/rustdoc/src/unstable-features.md | 10 ++++++++++
 2 files changed, 11 insertions(+)
 create mode 100644 src/doc/rustdoc/src/unstable-features.md

diff --git a/src/doc/rustdoc/src/SUMMARY.md b/src/doc/rustdoc/src/SUMMARY.md
index 6315cb81a8495..46528187c1175 100644
--- a/src/doc/rustdoc/src/SUMMARY.md
+++ b/src/doc/rustdoc/src/SUMMARY.md
@@ -5,3 +5,4 @@
 - [The `#[doc]` attribute](the-doc-attribute.md)
 - [Documentation tests](documentation-tests.md)
 - [Passes](passes.md)
+- [Unstable features](unstable-features.md)
diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
new file mode 100644
index 0000000000000..35380cdf069ed
--- /dev/null
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -0,0 +1,10 @@
+# Unstable features
+
+Rustdoc is under active developement, and like the Rust compiler, some features are only available
+on the nightly releases. Some of these are new and need some more testing before they're able to get
+released to the world at large, and some of them are tied to features in the Rust compiler that are
+themselves unstable. Several features here require a matching `#![feature(...)]` attribute to
+enable, and thus are more fully documented in the [Unstable Book]. Those sections will link over
+there as necessary.
+
+[Unstable Book]: ../unstable-book/

From 373b2cdcd13788249e27d7f06f5c36f37bc8684e Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Mon, 12 Mar 2018 17:26:20 -0500
Subject: [PATCH 02/20] talk about error numbers for compile_fail doctests

---
 src/doc/rustdoc/src/unstable-features.md | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 35380cdf069ed..8dbd0aa9a9a1f 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -8,3 +8,26 @@ enable, and thus are more fully documented in the [Unstable Book]. Those section
 there as necessary.
 
 [Unstable Book]: ../unstable-book/
+
+## Error numbers for `compile-fail` doctests
+
+As detailed in [the chapter on documentation tests][doctest-attributes], you can add a
+`compile_fail` attribute to a doctest to state that the test should fail to compile. However, on
+nightly, you can optionally add an error number to state that a doctest should emit a specific error
+number:
+
+[doctest-attributes]: documentation-tests.html#attributes
+
+``````markdown
+```compile_fail,E0044
+extern { fn some_func<T>(x: T); }
+```
+``````
+
+This is used by the error index to ensure that the samples that correspond to a given error number
+properly emit that error code. However, these error codes aren't guaranteed to be the only thing
+that a piece of code emits from version to version, so this in unlikely to be stabilized in the
+future.
+
+Attempting to use these error numbers on stable will result in the code sample being interpreted as
+plain text.

From 30adb53f46628fa37042543359a269221350b6d7 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Tue, 13 Mar 2018 17:00:51 -0500
Subject: [PATCH 03/20] talk about intra-links

---
 src/doc/rustdoc/src/unstable-features.md | 45 ++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 8dbd0aa9a9a1f..08cceff0e701f 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -31,3 +31,48 @@ future.
 
 Attempting to use these error numbers on stable will result in the code sample being interpreted as
 plain text.
+
+## Linking to items by type
+
+As designed in [RFC 1946], Rustdoc can parse paths to items when you use them as links. To resolve
+these type names, it uses the items currently in-scope, either by declaration or by `use` statement.
+For modules, the "active scope" depends on whether the documentation is written outside the module
+(as `///` comments on the `mod` statement) or inside the module (at `//!` comments inside the file
+or block). For all other items, it uses the enclosing module's scope.
+
+[RFC 1946]: https://github.com/rust-lang/rfcs/pull/1946
+
+For example, in the following code:
+
+```rust
+/// Does the thing.
+pub fn do_the_thing(_: SomeType) {
+	println!("Let's do the thing!");
+}
+
+/// Token you use to [`do_the_thing`].
+pub struct SomeType;
+```
+
+The link to ``[`do_the_thing`]`` in `SomeType`'s docs will properly link to the page for `fn
+do_the_thing`. Note that here, rustdoc will insert the link target for you, but manually writing the
+target out also works:
+
+```rust
+pub mod some_module {
+	/// Token you use to do the thing.
+	pub struct SomeStruct;
+}
+
+/// Does the thing. Requires one [`SomeStruct`] for the thing to work.
+///
+/// [`SomeStruct`]: some_module::SomeStruct
+pub fn do_the_thing(_: some_module::SomeStruct) {
+	println!("Let's do the thing!");
+}
+```
+
+For more details, check out [the RFC][RFC 1946], and see [the tracking issue][43466] for more
+information about what parts of the feature are available.
+
+[43466]: https://github.com/rust-lang/rust/issues/43466

From 0f96e145fbe8c635e7a58fb17c8c46bc4e42d454 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Wed, 14 Mar 2018 15:32:25 -0500
Subject: [PATCH 04/20] talk about doc(cfg)

---
 src/doc/rustdoc/src/unstable-features.md | 52 ++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 08cceff0e701f..245d53e8b7964 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -76,3 +76,55 @@ For more details, check out [the RFC][RFC 1946], and see [the tracking issue][43
 information about what parts of the feature are available.
 
 [43466]: https://github.com/rust-lang/rust/issues/43466
+
+## Documenting platform-/feature-specific information
+
+Because of the way Rustdoc documents a crate, the documentation it creates is specific to the target
+rustc compiles for. Anything that's specific to any other target is dropped via `#[cfg]` attribute
+processing early in the compilation process. However, Rustdoc has a trick up its sleeve to handle
+platform-specific code if it *does* receive it.
+
+Because Rustdoc doesn't need to fully compile a crate to binary, it replaces function bodies with
+`loop {}` to prevent having to process more than necessary. This means that any code within a
+function that requires platform-specific pieces is ignored. Combined with a special attribute,
+`#[doc(cfg(...))]`, you can tell Rustdoc exactly which platform something is supposed to run on,
+ensuring that doctests are only run on the appropriate platforms.
+
+The `#[doc(cfg(...))]` attribute has another effect: When Rustdoc renders documentation for that
+item, it will be accompanied by a banner explaining that the item is only available on certain
+platforms.
+
+As mentioned earlier, getting the items to Rustdoc requires some extra preparation. The standard
+library adds a `--cfg dox` flag to every Rustdoc command, but the same thing can be accomplished by
+adding a feature to your Cargo.toml and adding `--feature dox` (or whatever you choose to name the
+feature) to your `cargo doc` calls.
+
+Either way, once you create an environment for the documentation, you can start to augment your
+`#[cfg]` attributes to allow both the target platform *and* the documentation configuration to leave
+the item in. For example, `#[cfg(any(windows, feature = "dox"))]` will preserve the item either on
+Windows or during the documentation process. Then, adding a new attribute `#[doc(cfg(windows))]`
+will tell Rustdoc that the item is supposed to be used on Windows. For example:
+
+```rust
+#![feature(doc_cfg)]
+
+/// Token struct that can only be used on Windows.
+#[cfg(any(windows, feature = "dox"))]
+#[doc(cfg(windows))]
+pub struct WindowsToken;
+
+/// Token struct that can only be used on Unix.
+#[cfg(any(unix, feature = "dox"))]
+#[doc(cfg(unix))]
+pub struct UnixToken;
+```
+
+In this sample, the tokens will only appear on their respective platforms, but they will both appear
+in documentation.
+
+`#[doc(cfg(...))]` was introduced to be used by the standard library and is currently controlled by
+a feature gate. For more information, see [its chapter in the Unstable Book][unstable-doc-cfg] and
+[its tracking issue][issue-doc-cfg].
+
+[unstable-doc-cfg]: ../unstable-book/language-features/doc-cfg.html
+[issue-doc-cfg]: https://github.com/rust-lang/rust/issues/43781

From 23a1da4d637648ae37090f88be695de3a63cd507 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Wed, 14 Mar 2018 16:06:53 -0500
Subject: [PATCH 05/20] talk about doc(spotlight)

---
 src/doc/rustdoc/src/unstable-features.md | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 245d53e8b7964..1670223952441 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -128,3 +128,23 @@ a feature gate. For more information, see [its chapter in the Unstable Book][uns
 
 [unstable-doc-cfg]: ../unstable-book/language-features/doc-cfg.html
 [issue-doc-cfg]: https://github.com/rust-lang/rust/issues/43781
+
+## Adding your trait to the "Important Traits" dialog
+
+Rustdoc keeps a list of a few traits that are believed to be "fundamental" to a given type when
+implemented on it. These traits are intended to be the primary interface for their types, and are
+often the only thing available to be documented on their types. For this reason, Rustdoc will track
+when a given type implements one of these traits and call special attention to it when a function
+returns one of these types. This is the "Important Traits" dialog, visible as a circle-i button next
+to the function, which, when clicked, shows the dialog.
+
+In the standard library, the traits that qualify for inclusion are `Iterator`, `io::Read`, and
+`io::Write`. However, rather than being implemented as a hard-coded list, these traits have a
+special marker attribute on them: `#[doc(spotlight)]`. This means that you could apply this
+attribute to your own trait to include it in the "Important Traits" dialog in documentation.
+
+The `#[doc(spotlight)]` attribute is controlled by a feature gate. For more information, see [its
+chapter in the Unstable Book][unstable-spotlight] and [its tracking issue][issue-spotlight].
+
+[unstable-spotlight]: ../unstable-book/language-features/doc-spotlight.html
+[issue-spotlight]: https://github.com/rust-lang/rust/issues/45040

From 82bd146d60425c3cd0c99892742f1454f5eb8191 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Wed, 14 Mar 2018 16:40:28 -0500
Subject: [PATCH 06/20] talk about doc(masked)

---
 src/doc/rustdoc/src/unstable-features.md | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 1670223952441..9f0476d4eef70 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -148,3 +148,23 @@ chapter in the Unstable Book][unstable-spotlight] and [its tracking issue][issue
 
 [unstable-spotlight]: ../unstable-book/language-features/doc-spotlight.html
 [issue-spotlight]: https://github.com/rust-lang/rust/issues/45040
+
+## Exclude certain dependencies from documentation
+
+The standard library uses several dependencies which, in turn, use several types and traits from the
+standard library. In addition, there are several compiler-internal crates that are not considered to
+be part of the official standard library, and thus would be a distraction to include in
+documentation. It's not enough to exclude their crate documentation, since information about trait
+implementations appears on the pages for both the type and the trait, which can be in different
+crates!
+
+To prevent internal types from being included in documentation, the standard library adds an
+attribute to their `extern crate` declarations: `#[doc(masked)]`. This causes Rustdoc to "mask out"
+types from these crates when building lists of trait implementations.
+
+The `#[doc(masked)]` attribute is intended to be used internally, and is governed by a feature gate.
+For more information, see [its chapter in the Unstable Book][unstable-masked] and [its tracking
+issue][issue-masked].
+
+[unstable-masked]: ../unstable-book/language-features/doc-masked.html
+[issue-masked]: https://github.com/rust-lang/rust/issues/44027

From 067553d5a1d867c7f8404153ce37a4008489b82a Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Wed, 14 Mar 2018 17:13:52 -0500
Subject: [PATCH 07/20] talk about doc(include)

---
 src/doc/rustdoc/src/unstable-features.md | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 9f0476d4eef70..62112fbf293c0 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -162,9 +162,25 @@ To prevent internal types from being included in documentation, the standard lib
 attribute to their `extern crate` declarations: `#[doc(masked)]`. This causes Rustdoc to "mask out"
 types from these crates when building lists of trait implementations.
 
-The `#[doc(masked)]` attribute is intended to be used internally, and is governed by a feature gate.
-For more information, see [its chapter in the Unstable Book][unstable-masked] and [its tracking
-issue][issue-masked].
+The `#[doc(masked)]` attribute is intended to be used internally, and is controlled by a feature
+gate.  For more information, see [its chapter in the Unstable Book][unstable-masked] and [its
+tracking issue][issue-masked].
 
 [unstable-masked]: ../unstable-book/language-features/doc-masked.html
 [issue-masked]: https://github.com/rust-lang/rust/issues/44027
+
+## Include external files as API documentation
+
+As designed in [RFC 1990], Rustdoc can read an external file to use as a type's documentation. This
+is useful if certain documentation is so long that it would break the flow of reading the source.
+Instead of writing it all inline, writing `#[doc(include = "sometype.md")]` (where `sometype.md` is
+a file adjacent to the `lib.rs` for the crate) will ask Rustdoc to instead read that file and use it
+as if it were written inline.
+
+[RFC 1990]: https://github.com/rust-lang/rfcs/pull/1990
+
+`#[doc(include = "...")]` is currently controlled by a feature gate. For more information, see [its
+chapter in the Unstable Book][unstable-include] and [its tracking issue][issue-include].
+
+[unstable-include]: ../unstable-book/language-features/external-doc.html
+[issue-include]: https://github.com/rust-lang/rust/issues/44732

From 3d90b4d73880f7f7146a31544ac414e85014ca6f Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Wed, 14 Mar 2018 17:22:15 -0500
Subject: [PATCH 08/20] add headings to categorize the features

---
 src/doc/rustdoc/src/unstable-features.md | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 62112fbf293c0..5f9978c61b6e4 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -9,7 +9,14 @@ there as necessary.
 
 [Unstable Book]: ../unstable-book/
 
-## Error numbers for `compile-fail` doctests
+## Nightly-gated functionality
+
+These features just require a nightly build to operate. Unlike the other features on this page,
+these don't need to be "turned on" with a command-line flag or a `#![feature(...)]` attribute in
+your crate. This can give them some subtle fallback modes when used on a stable release, so be
+careful!
+
+### Error numbers for `compile-fail` doctests
 
 As detailed in [the chapter on documentation tests][doctest-attributes], you can add a
 `compile_fail` attribute to a doctest to state that the test should fail to compile. However, on
@@ -32,7 +39,7 @@ future.
 Attempting to use these error numbers on stable will result in the code sample being interpreted as
 plain text.
 
-## Linking to items by type
+### Linking to items by type
 
 As designed in [RFC 1946], Rustdoc can parse paths to items when you use them as links. To resolve
 these type names, it uses the items currently in-scope, either by declaration or by `use` statement.
@@ -77,7 +84,12 @@ information about what parts of the feature are available.
 
 [43466]: https://github.com/rust-lang/rust/issues/43466
 
-## Documenting platform-/feature-specific information
+## Extensions to the `#[doc]` attribute
+
+These features operate by extending the `#[doc]` attribute, and thus can be caught by the compiler
+and enabled with a `#![feature(...)]` attribute in your crate.
+
+### Documenting platform-/feature-specific information
 
 Because of the way Rustdoc documents a crate, the documentation it creates is specific to the target
 rustc compiles for. Anything that's specific to any other target is dropped via `#[cfg]` attribute
@@ -129,7 +141,7 @@ a feature gate. For more information, see [its chapter in the Unstable Book][uns
 [unstable-doc-cfg]: ../unstable-book/language-features/doc-cfg.html
 [issue-doc-cfg]: https://github.com/rust-lang/rust/issues/43781
 
-## Adding your trait to the "Important Traits" dialog
+### Adding your trait to the "Important Traits" dialog
 
 Rustdoc keeps a list of a few traits that are believed to be "fundamental" to a given type when
 implemented on it. These traits are intended to be the primary interface for their types, and are
@@ -149,7 +161,7 @@ chapter in the Unstable Book][unstable-spotlight] and [its tracking issue][issue
 [unstable-spotlight]: ../unstable-book/language-features/doc-spotlight.html
 [issue-spotlight]: https://github.com/rust-lang/rust/issues/45040
 
-## Exclude certain dependencies from documentation
+### Exclude certain dependencies from documentation
 
 The standard library uses several dependencies which, in turn, use several types and traits from the
 standard library. In addition, there are several compiler-internal crates that are not considered to
@@ -169,7 +181,7 @@ tracking issue][issue-masked].
 [unstable-masked]: ../unstable-book/language-features/doc-masked.html
 [issue-masked]: https://github.com/rust-lang/rust/issues/44027
 
-## Include external files as API documentation
+### Include external files as API documentation
 
 As designed in [RFC 1990], Rustdoc can read an external file to use as a type's documentation. This
 is useful if certain documentation is so long that it would break the flow of reading the source.

From c24a58c87c41f17e341cb165f990ef2fd5ec3cb5 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Thu, 15 Mar 2018 09:29:54 -0500
Subject: [PATCH 09/20] fix link

---
 src/doc/rustdoc/src/unstable-features.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 5f9978c61b6e4..243d607376783 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -7,7 +7,7 @@ themselves unstable. Several features here require a matching `#![feature(...)]`
 enable, and thus are more fully documented in the [Unstable Book]. Those sections will link over
 there as necessary.
 
-[Unstable Book]: ../unstable-book/
+[Unstable Book]: ../unstable-book/index.html
 
 ## Nightly-gated functionality
 

From 43ed37711e98585178cc291283b9b3345448f311 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Thu, 15 Mar 2018 09:33:57 -0500
Subject: [PATCH 10/20] add new section about CLI flags

---
 src/doc/rustdoc/src/unstable-features.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 243d607376783..837a55f371fb5 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -196,3 +196,10 @@ chapter in the Unstable Book][unstable-include] and [its tracking issue][issue-i
 
 [unstable-include]: ../unstable-book/language-features/external-doc.html
 [issue-include]: https://github.com/rust-lang/rust/issues/44732
+
+## Unstable command-line arguments
+
+These features are enabled by passing a command-line flag to Rustdoc, but the flags in question are
+themselves marked as unstable. To use any of these options, pass `-Z unstable-options` as well as
+the flag in question to Rustdoc on the command-line. To do this from Cargo, you can either use the
+`RUSTDOCFLAGS` environment variable or the `cargo rustdoc` command.

From bb328237fc68fcc9c0495b283da74f8ec361b371 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Thu, 15 Mar 2018 12:47:26 -0500
Subject: [PATCH 11/20] talk about --markdown-(before|after)-content

---
 src/doc/rustdoc/src/unstable-features.md | 28 ++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 837a55f371fb5..873aebfc77779 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -203,3 +203,31 @@ These features are enabled by passing a command-line flag to Rustdoc, but the fl
 themselves marked as unstable. To use any of these options, pass `-Z unstable-options` as well as
 the flag in question to Rustdoc on the command-line. To do this from Cargo, you can either use the
 `RUSTDOCFLAGS` environment variable or the `cargo rustdoc` command.
+
+### `--markdown-before-content`: include rendered Markdown before the content
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -Z unstable-options --markdown-before-content extra.md
+$ rustdoc README.md -Z unstable-options --markdown-before-content extra.md
+```
+
+Just like `--html-before-content`, this allows you to insert extra content inside the `<body>` tag
+but before the other content `rustdoc` would normally produce in the rendered documentation.
+However, instead of directly inserting the file verbatim, `rustdoc` will pass the files through a
+Markdown renderer before inserting the result into the file.
+
+### `--markdown-after-content`: include rendered Markdown after the content
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -Z unstable-options --markdown-after-content extra.md
+$ rustdoc README.md -Z unstable-options --markdown-after-content extra.md
+```
+
+Just like `--html-after-content`, this allows you to insert extra content before the `</body>` tag
+but after the other content `rustdoc` would normally produce in the rendered documentation.
+However, instead of directly inserting the file verbatim, `rustdoc` will pass the files through a
+Markdown renderer before inserting the result into the file.

From 5d8443aeb1bf441897efddfc1246377f0d51149d Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Thu, 15 Mar 2018 14:44:17 -0500
Subject: [PATCH 12/20] talk about --playground-url

---
 src/doc/rustdoc/src/unstable-features.md | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 873aebfc77779..9cb5760ec3797 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -231,3 +231,26 @@ Just like `--html-after-content`, this allows you to insert extra content before
 but after the other content `rustdoc` would normally produce in the rendered documentation.
 However, instead of directly inserting the file verbatim, `rustdoc` will pass the files through a
 Markdown renderer before inserting the result into the file.
+
+### `--playground-url`: control the location of the playground
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -Z unstable-options --playground-url https://play.rust-lang.org/
+```
+
+When rendering a crate's docs, this flag gives the base URL of the Rust Playground, to use for
+generating `Run` buttons. Unlike `--markdown-playground-url`, this argument works for standalone
+Markdown files *and* Rust crates. This works the same way as adding `#![doc(html_playground_url =
+"url")]` to your crate root, as mentioned in [the chapter about the `#[doc]`
+attribute][doc-playground]. Please be aware that the official Rust Playground at
+https://play.rust-lang.org does not have every crate available, so if your examples require your
+crate, make sure the playground you provide has your crate available.
+
+[doc-playground]: the-doc-attribute.html#html_playground_url
+
+If both `--playground-url` and `--markdown-playground-url` are present when rendering a standalone
+Markdown file, the URL given to `--markdown-playground-url` will take precedence. If both
+`--playground-url` and `#![doc(html_playground_url = "url")]` are present when rendering crate docs,
+the attribute will take precedence.

From f9d38451382017a6cd053e25011e4c096d545d17 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Fri, 16 Mar 2018 13:38:06 -0500
Subject: [PATCH 13/20] talk about --crate-version

---
 src/doc/rustdoc/src/unstable-features.md | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 9cb5760ec3797..867e4585d9c1e 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -254,3 +254,15 @@ If both `--playground-url` and `--markdown-playground-url` are present when rend
 Markdown file, the URL given to `--markdown-playground-url` will take precedence. If both
 `--playground-url` and `#![doc(html_playground_url = "url")]` are present when rendering crate docs,
 the attribute will take precedence.
+
+### `--crate-version`: control the crate version
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -Z unstable-options --crate-version 1.3.37
+```
+
+When `rustdoc` receives this flag, it will print an extra "Version (version)" into the sidebar of
+the crate root's docs. You can use this flag to differentiate between different versions of your
+library's documentation.

From 33ed787b495477f2cc859b275a1deb6dc1a396a0 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Fri, 16 Mar 2018 13:46:10 -0500
Subject: [PATCH 14/20] talk about --linker

---
 src/doc/rustdoc/src/unstable-features.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 867e4585d9c1e..870d77895fd6e 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -266,3 +266,16 @@ $ rustdoc src/lib.rs -Z unstable-options --crate-version 1.3.37
 When `rustdoc` receives this flag, it will print an extra "Version (version)" into the sidebar of
 the crate root's docs. You can use this flag to differentiate between different versions of your
 library's documentation.
+
+### `--linker`: control the linker used for documentation tests
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc --test src/lib.rs -Z unstable-options --linker foo
+$ rustdoc --test README.md -Z unstable-options --linker foo
+```
+
+When `rustdoc` runs your documentation tests, it needs to compile and link the tests as executables
+before running them. This flag can be used to change the linker used on these executables. It's
+equivalent to passing `-C linker=foo` to `rustc`.

From cc4f97e88354bea5d07c3ae762ac0466e5c9888c Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Fri, 16 Mar 2018 14:30:56 -0500
Subject: [PATCH 15/20] talk about --sort-modules-by-appearance

---
 src/doc/rustdoc/src/unstable-features.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 870d77895fd6e..80b59166503fa 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -279,3 +279,16 @@ $ rustdoc --test README.md -Z unstable-options --linker foo
 When `rustdoc` runs your documentation tests, it needs to compile and link the tests as executables
 before running them. This flag can be used to change the linker used on these executables. It's
 equivalent to passing `-C linker=foo` to `rustc`.
+
+### `--sort-modules-by-appearance`: control how items on module pages are sorted
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -Z unstable-options --sort-modules-by-appearance
+```
+
+Ordinarily, when `rustdoc` prints items in module pages, it will sort them alphabetically (taking
+some consideration for their stability, and names that end in a number). Giving this flag to
+`rustdoc` will disable this sorting and instead make it print the items in the order they appear in
+the source.

From 6b2906018f93a9813392056da4c3de855d92f619 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Fri, 16 Mar 2018 14:41:51 -0500
Subject: [PATCH 16/20] talk about --themes and --theme-checker

---
 src/doc/rustdoc/src/unstable-features.md | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 80b59166503fa..3ebc2fa466cb6 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -292,3 +292,27 @@ Ordinarily, when `rustdoc` prints items in module pages, it will sort them alpha
 some consideration for their stability, and names that end in a number). Giving this flag to
 `rustdoc` will disable this sorting and instead make it print the items in the order they appear in
 the source.
+
+### `--themes`: provide additional themes
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -Z unstable-options --themes theme.css
+```
+
+Giving this flag to `rustdoc` will make it copy your theme into the generated crate docs and enable
+it in the theme selector. Note that `rustdoc` will reject your theme file if it doesn't style
+everything the "main" theme does. See `--theme-checker` below for details.
+
+### `--theme-checker`: verify theme CSS for validity
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc -Z unstable-options --theme-checker theme.css
+```
+
+Before including your theme in crate docs, `rustdoc` will compare all the CSS rules it contains
+against the "main" theme included by default. Using this flag will allow you to see which rules are
+missing if `rustdoc` rejects your theme.

From b5ab5ceb4b2aa733366ed9453c0e714d6f0cd9f0 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Fri, 16 Mar 2018 15:06:36 -0500
Subject: [PATCH 17/20] talk about --resource-suffix

---
 src/doc/rustdoc/src/unstable-features.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 3ebc2fa466cb6..93489f89626fe 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -316,3 +316,16 @@ $ rustdoc -Z unstable-options --theme-checker theme.css
 Before including your theme in crate docs, `rustdoc` will compare all the CSS rules it contains
 against the "main" theme included by default. Using this flag will allow you to see which rules are
 missing if `rustdoc` rejects your theme.
+
+### `--resource-suffix`: modifying the name of CSS/JavaScript in crate docs
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -Z unstable-options --resource-suffix suf
+```
+
+When rendering docs, `rustdoc` creates several CSS and JavaScript files as part of the output. Since
+all these files are linked from every page, changing where they are can be cumbersome if you need to
+specially cache them. This flag will rename all these files in the output to include the suffix in
+the filename. For example, `main.css` would become `main-suf.css` with the above command.

From 5e93394d321823ec2f54e130150791ab95b6f755 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Tue, 20 Mar 2018 11:18:42 -0500
Subject: [PATCH 18/20] talk about --display-warnings

---
 src/doc/rustdoc/src/unstable-features.md | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 93489f89626fe..6a786c1985142 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -329,3 +329,19 @@ When rendering docs, `rustdoc` creates several CSS and JavaScript files as part
 all these files are linked from every page, changing where they are can be cumbersome if you need to
 specially cache them. This flag will rename all these files in the output to include the suffix in
 the filename. For example, `main.css` would become `main-suf.css` with the above command.
+
+### `--display-warnings`: display warnings when documenting or running documentation tests
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -Z unstable-options --display-warnings
+$ rustdoc --test src/lib.rs -Z unstable-options --display-warnings
+```
+
+The intent behind this flag is to allow the user to see warnings that occur within their library or
+their documentation tests, which are usually suppressed. However, [due to a
+bug][issue-display-warnings], this flag doesn't 100% work as intended. See the linked issue for
+details.
+
+[issue-display-warnings]: https://github.com/rust-lang/rust/issues/41574

From 83e9f395d17afc95d259febe8d675084f1baf497 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Tue, 20 Mar 2018 11:23:48 -0500
Subject: [PATCH 19/20] talk about force-unstable-if-unmarked

---
 src/doc/rustdoc/src/unstable-features.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 6a786c1985142..ac69cc1007d80 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -345,3 +345,16 @@ bug][issue-display-warnings], this flag doesn't 100% work as intended. See the l
 details.
 
 [issue-display-warnings]: https://github.com/rust-lang/rust/issues/41574
+
+### `-Z force-unstable-if-unmarked`
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -Z force-unstable-if-unmarked
+```
+
+This is an internal flag intended for the standard library and compiler that applies an
+`#[unstable]` attribute to any dependent crate that doesn't have another stability attribute. This
+allows `rustdoc` to be able to generate documentation for the compiler crates and the standard
+library, as an equivalent command-line argument is provided to `rustc` when building those crates.

From b996f9d60fdb1db6bd870fc7f600be4c7660f3a2 Mon Sep 17 00:00:00 2001
From: QuietMisdreavus <grey@quietmisdreavus.net>
Date: Wed, 21 Mar 2018 09:52:18 -0500
Subject: [PATCH 20/20] review comments

---
 src/doc/rustdoc/src/unstable-features.md | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index ac69cc1007d80..16356c20c7069 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -33,7 +33,7 @@ extern { fn some_func<T>(x: T); }
 
 This is used by the error index to ensure that the samples that correspond to a given error number
 properly emit that error code. However, these error codes aren't guaranteed to be the only thing
-that a piece of code emits from version to version, so this in unlikely to be stabilized in the
+that a piece of code emits from version to version, so this is unlikely to be stabilized in the
 future.
 
 Attempting to use these error numbers on stable will result in the code sample being interpreted as
@@ -134,9 +134,9 @@ pub struct UnixToken;
 In this sample, the tokens will only appear on their respective platforms, but they will both appear
 in documentation.
 
-`#[doc(cfg(...))]` was introduced to be used by the standard library and is currently controlled by
-a feature gate. For more information, see [its chapter in the Unstable Book][unstable-doc-cfg] and
-[its tracking issue][issue-doc-cfg].
+`#[doc(cfg(...))]` was introduced to be used by the standard library and currently requires the
+`#![feature(doc_cfg)]` feature gate. For more information, see [its chapter in the Unstable
+Book][unstable-doc-cfg] and [its tracking issue][issue-doc-cfg].
 
 [unstable-doc-cfg]: ../unstable-book/language-features/doc-cfg.html
 [issue-doc-cfg]: https://github.com/rust-lang/rust/issues/43781
@@ -155,8 +155,9 @@ In the standard library, the traits that qualify for inclusion are `Iterator`, `
 special marker attribute on them: `#[doc(spotlight)]`. This means that you could apply this
 attribute to your own trait to include it in the "Important Traits" dialog in documentation.
 
-The `#[doc(spotlight)]` attribute is controlled by a feature gate. For more information, see [its
-chapter in the Unstable Book][unstable-spotlight] and [its tracking issue][issue-spotlight].
+The `#[doc(spotlight)]` attribute currently requires the `#![feature(doc_spotlight)]` feature gate.
+For more information, see [its chapter in the Unstable Book][unstable-spotlight] and [its tracking
+issue][issue-spotlight].
 
 [unstable-spotlight]: ../unstable-book/language-features/doc-spotlight.html
 [issue-spotlight]: https://github.com/rust-lang/rust/issues/45040
@@ -174,9 +175,9 @@ To prevent internal types from being included in documentation, the standard lib
 attribute to their `extern crate` declarations: `#[doc(masked)]`. This causes Rustdoc to "mask out"
 types from these crates when building lists of trait implementations.
 
-The `#[doc(masked)]` attribute is intended to be used internally, and is controlled by a feature
-gate.  For more information, see [its chapter in the Unstable Book][unstable-masked] and [its
-tracking issue][issue-masked].
+The `#[doc(masked)]` attribute is intended to be used internally, and requires the
+`#![feature(doc_masked)]` feature gate.  For more information, see [its chapter in the Unstable
+Book][unstable-masked] and [its tracking issue][issue-masked].
 
 [unstable-masked]: ../unstable-book/language-features/doc-masked.html
 [issue-masked]: https://github.com/rust-lang/rust/issues/44027
@@ -191,8 +192,9 @@ as if it were written inline.
 
 [RFC 1990]: https://github.com/rust-lang/rfcs/pull/1990
 
-`#[doc(include = "...")]` is currently controlled by a feature gate. For more information, see [its
-chapter in the Unstable Book][unstable-include] and [its tracking issue][issue-include].
+`#[doc(include = "...")]` currently requires the `#![feature(external_doc)]` feature gate. For more
+information, see [its chapter in the Unstable Book][unstable-include] and [its tracking
+issue][issue-include].
 
 [unstable-include]: ../unstable-book/language-features/external-doc.html
 [issue-include]: https://github.com/rust-lang/rust/issues/44732