Auto merge of #129647 - tgross35:rollup-jume49s, r=tgross35

Rollup of 9 pull requests

Successful merges:

 - #126985 (Implement `-Z embed-source` (DWARFv5 source code embedding extension))
 - #127922 (Add unsafe to extern blocks in style guide)
 - #128731 (simd_shuffle intrinsic: allow argument to be passed as vector)
 - #128935 (More work on `zstd` compression)
 - #128942 (miri weak memory emulation: put previous value into initial store buffer)
 - #129418 (rustc: Simplify getting sysroot library directory)
 - #129490 (Add Trusty OS as tier 3 target)
 - #129536 (Add `f16` and `f128` inline ASM support for `aarch64`)
 - #129559 (float types: document NaN bit pattern guarantees)

r? `@ghost`
`@rustbot` modify labels: rollup

5 files changed, 68 insertions, 2 deletions

diff --git a/src/doc/rustc/src/SUMMARY.md b/src/doc/rustc/src/SUMMARY.md
index 4e34e2667cf..b3a74a7716b 100644
--- a/src/doc/rustc/src/SUMMARY.md
+++ b/src/doc/rustc/src/SUMMARY.md
@@ -49,6 +49,7 @@
     - [aarch64-unknown-teeos](platform-support/aarch64-unknown-teeos.md)
     - [\*-espidf](platform-support/esp-idf.md)
     - [\*-unknown-fuchsia](platform-support/fuchsia.md)
+    - [\*-unknown-trusty](platform-support/trusty.md)
     - [\*-kmc-solid_\*](platform-support/kmc-solid.md)
     - [csky-unknown-linux-gnuabiv2\*](platform-support/csky-unknown-linux-gnuabiv2.md)
     - [hexagon-unknown-linux-musl](platform-support/hexagon-unknown-linux-musl.md)
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index dd478e9df37..0d79e5f4114 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -264,6 +264,7 @@ target | std | host | notes
 [`aarch64-unknown-netbsd`](platform-support/netbsd.md) | ✓ | ✓ | ARM64 NetBSD
 [`aarch64-unknown-openbsd`](platform-support/openbsd.md) | ✓ | ✓ | ARM64 OpenBSD
 [`aarch64-unknown-redox`](platform-support/redox.md) | ✓ |  | ARM64 Redox OS
+[`aarch64-unknown-trusty`](platform-support/trusty.md) | ? |  |
 `aarch64-uwp-windows-msvc` | ✓ |  |
 [`aarch64-wrs-vxworks`](platform-support/vxworks.md) | ✓ |  | ARM64 VxWorks OS
 `aarch64_be-unknown-linux-gnu_ilp32` | ✓ | ✓ | ARM64 Linux (big-endian, ILP32 ABI)
@@ -283,6 +284,7 @@ target | std | host | notes
 [`armv7-unknown-linux-uclibceabihf`](platform-support/armv7-unknown-linux-uclibceabihf.md) | ✓ | ? | Armv7-A Linux with uClibc, hardfloat
 `armv7-unknown-freebsd` | ✓ | ✓ | Armv7-A FreeBSD
 [`armv7-unknown-netbsd-eabihf`](platform-support/netbsd.md) | ✓ | ✓ | Armv7-A NetBSD w/hard-float
+[`armv7-unknown-trusty`](platform-support/trusty.md) | ? |  |
 [`armv7-wrs-vxworks-eabihf`](platform-support/vxworks.md) | ✓ |  | Armv7-A for VxWorks
 [`armv7a-kmc-solid_asp3-eabi`](platform-support/kmc-solid.md) | ✓ |  | ARM SOLID with TOPPERS/ASP3
 [`armv7a-kmc-solid_asp3-eabihf`](platform-support/kmc-solid.md) | ✓ |  | ARM SOLID with TOPPERS/ASP3, hardfloat
diff --git a/src/doc/rustc/src/platform-support/trusty.md b/src/doc/rustc/src/platform-support/trusty.md
new file mode 100644
index 00000000000..dec3b96ff64
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/trusty.md
@@ -0,0 +1,51 @@
+# `aarch64-unknown-trusty` and `armv7-unknown-trusty`
+
+**Tier: 3**
+
+[Trusty] is a secure Operating System that provides a Trusted Execution
+Environment (TEE) for Android.
+
+## Target maintainers
+
+- Nicole LeGare (@randomPoison)
+- Stephen Crane (@rinon)
+- As a fallback trusty-dev-team@google.com can be contacted
+
+## Requirements
+
+These targets are cross-compiled. They have no special requirements for the host.
+
+Support for the standard library is work-in-progress. It is expected that
+they will support alloc with the default allocator, and partially support std.
+
+Trusty uses the ELF file format.
+
+## Building the target
+
+The targets can be built by enabling them for a `rustc` build, for example:
+
+```toml
+[build]
+build-stage = 1
+target = ["aarch64-unknown-trusty", "armv7-unknown-trusty"]
+```
+
+## Building Rust programs
+
+There is currently no supported way to build a Trusty app with Cargo. You can
+follow the [Trusty build instructions] to build the Trusty kernel along with any
+Rust apps that are setup in the project.
+
+## Testing
+
+See the [Trusty build instructions] for information on how to build Rust code
+within the main Trusty project. The main project also includes infrastructure
+for testing Rust applications within a QEMU emulator.
+
+## Cross-compilation toolchains and C code
+
+See the [Trusty build instructions] for information on how C code is built
+within Trusty.
+
+[Trusty]: https://source.android.com/docs/security/features/trusty
+[Trusty build instructions]: https://source.android.com/docs/security/features/trusty/download-and-build
diff --git a/src/doc/style-guide/src/items.md b/src/doc/style-guide/src/items.md
index 8e1b1d80fb6..5ea8b6cd542 100644
--- a/src/doc/style-guide/src/items.md
+++ b/src/doc/style-guide/src/items.md
@@ -449,8 +449,8 @@ entries, format it across multiple lines as with a type alias.
 ## extern items
 
 When writing extern items (such as `extern "C" fn`), always specify the ABI.
-For example, write `extern "C" fn foo ...`, not `extern fn foo ...`, or
-`extern "C" { ... }`.
+For example, write `extern "C" fn foo ...` or `unsafe extern "C" { ...}`
+and avoid `extern fn foo ...` and `unsafe extern { ... }`.
 
 ## Imports (`use` statements)
 
diff --git a/src/doc/unstable-book/src/compiler-flags/embed-source.md b/src/doc/unstable-book/src/compiler-flags/embed-source.md
new file mode 100644
index 00000000000..01a11e37797
--- /dev/null
+++ b/src/doc/unstable-book/src/compiler-flags/embed-source.md
@@ -0,0 +1,12 @@
+# `embed-source`
+
+This flag controls whether the compiler embeds the program source code text into
+the object debug information section. It takes one of the following values:
+
+* `y`, `yes`, `on` or `true`: put source code in debug info.
+* `n`, `no`, `off`, `false` or no value: omit source code from debug info (the default).
+
+This flag is ignored in configurations that don't emit DWARF debug information
+and is ignored on non-LLVM backends. `-Z embed-source` requires DWARFv5. Use
+`-Z dwarf-version=5` to control the compiler's DWARF target version and `-g` to
+enable debug info generation.