Auto merge of #146526 - jhpratt:rollup-afb1dgo, r=jhpratt

Rollup of 8 pull requests

Successful merges:

 - rust-lang/rust#113095 (Document `become` keyword)
 - rust-lang/rust#146159 (Some hygiene doc improvements)
 - rust-lang/rust#146171 (tidy: check that error messages don't start with a capitalized letter)
 - rust-lang/rust#146419 (Update the arm-* and aarch64-* platform docs.)
 - rust-lang/rust#146473 (Revert "Constify SystemTime methods")
 - rust-lang/rust#146506 (Fix small typo in check-cfg.md)
 - rust-lang/rust#146517 (fix Condvar::wait_timeout docs)
 - rust-lang/rust#146521 (document `core::ffi::VaArgSafe`)

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

19 files changed, 331 insertions, 41 deletions

diff --git a/src/doc/rustc/src/SUMMARY.md b/src/doc/rustc/src/SUMMARY.md
index 8e378e53e51..e4bf33dd8a0 100644
--- a/src/doc/rustc/src/SUMMARY.md
+++ b/src/doc/rustc/src/SUMMARY.md
@@ -48,6 +48,7 @@
     - [\*-apple-visionos](platform-support/apple-visionos.md)
     - [aarch64-nintendo-switch-freestanding](platform-support/aarch64-nintendo-switch-freestanding.md)
     - [aarch64-unknown-linux-musl](platform-support/aarch64-unknown-linux-musl.md)
+    - [aarch64-unknown-none*](platform-support/aarch64-unknown-none.md)
     - [aarch64_be-unknown-none-softfloat](platform-support/aarch64_be-unknown-none-softfloat.md)
     - [aarch64_be-unknown-linux-musl](platform-support/aarch64_be-unknown-linux-musl.md)
     - [amdgcn-amd-amdhsa](platform-support/amdgcn-amd-amdhsa.md)
@@ -55,7 +56,9 @@
     - [arm-none-eabi](platform-support/arm-none-eabi.md)
       - [armv4t-none-eabi](platform-support/armv4t-none-eabi.md)
       - [armv5te-none-eabi](platform-support/armv5te-none-eabi.md)
-      - [armv7r-none-eabi](platform-support/armv7r-none-eabi.md)
+      - [armv7a-none-eabi{,hf}](platform-support/armv7a-none-eabi.md)
+      - [armv7r-none-eabi{,hf}](platform-support/armv7r-none-eabi.md)
+      - [armebv7r-none-eabi{,hf}](platform-support/armebv7r-none-eabi.md)
       - [armv8r-none-eabihf](platform-support/armv8r-none-eabihf.md)
       - [thumbv6m-none-eabi](./platform-support/thumbv6m-none-eabi.md)
       - [thumbv7em-none-eabi\*](./platform-support/thumbv7em-none-eabi.md)
diff --git a/src/doc/rustc/src/check-cfg.md b/src/doc/rustc/src/check-cfg.md
index 00add2651ae..4caeaa106b4 100644
--- a/src/doc/rustc/src/check-cfg.md
+++ b/src/doc/rustc/src/check-cfg.md
@@ -134,7 +134,7 @@ As of `2025-01-02T`, the list of known names is as follows:
  - `unix`
  - `windows`
 
-> Starting with 1.85.0, the `test` cfg is consider to be a "userspace" config
+> Starting with 1.85.0, the `test` cfg is considered to be a "userspace" config
 > despite being also set by `rustc` and should be managed by the build system itself.
 
 Like with `values(any())`, well known names checking can be disabled by passing `cfg(any())`
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index 9ad9cb5b526..e5e46f72637 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -149,22 +149,22 @@ target | std | notes
 [`aarch64-apple-ios-sim`](platform-support/apple-ios.md) | ✓ | Apple iOS Simulator on ARM64
 [`aarch64-linux-android`](platform-support/android.md) | ✓ | ARM64 Android
 [`aarch64-unknown-fuchsia`](platform-support/fuchsia.md) | ✓ | ARM64 Fuchsia
-`aarch64-unknown-none` | * | Bare ARM64, hardfloat
-`aarch64-unknown-none-softfloat` | * | Bare ARM64, softfloat
+[`aarch64-unknown-none`](platform-support/aarch64-unknown-none.md) | * | Bare ARM64, hardfloat
+[`aarch64-unknown-none-softfloat`](platform-support/aarch64-unknown-none.md) | * | Bare ARM64, softfloat
 [`aarch64-unknown-uefi`](platform-support/unknown-uefi.md) | ? | ARM64 UEFI
 [`arm-linux-androideabi`](platform-support/android.md) | ✓ | Armv6 Android
 `arm-unknown-linux-musleabi` | ✓ | Armv6 Linux with musl 1.2.3
 `arm-unknown-linux-musleabihf` | ✓ | Armv6 Linux with musl 1.2.3, hardfloat
 [`arm64ec-pc-windows-msvc`](platform-support/arm64ec-pc-windows-msvc.md) | ✓ | Arm64EC Windows MSVC
-[`armebv7r-none-eabi`](platform-support/armv7r-none-eabi.md) | * | Bare Armv7-R, Big Endian
-[`armebv7r-none-eabihf`](platform-support/armv7r-none-eabi.md) | * | Bare Armv7-R, Big Endian, hardfloat
+[`armebv7r-none-eabi`](platform-support/armebv7r-none-eabi.md) | * | Bare Armv7-R, Big Endian
+[`armebv7r-none-eabihf`](platform-support/armebv7r-none-eabi.md) | * | Bare Armv7-R, Big Endian, hardfloat
 [`armv5te-unknown-linux-gnueabi`](platform-support/armv5te-unknown-linux-gnueabi.md) | ✓ | Armv5TE Linux (kernel 4.4+, glibc 2.23)
 `armv5te-unknown-linux-musleabi` | ✓ | Armv5TE Linux with musl 1.2.3
 [`armv7-linux-androideabi`](platform-support/android.md) | ✓ | Armv7-A Android
 `armv7-unknown-linux-gnueabi` | ✓ | Armv7-A Linux (kernel 4.15+, glibc 2.27)
 `armv7-unknown-linux-musleabi` | ✓ | Armv7-A Linux with musl 1.2.3
 `armv7-unknown-linux-musleabihf` | ✓ | Armv7-A Linux with musl 1.2.3, hardfloat
-[`armv7a-none-eabi`](platform-support/arm-none-eabi.md) | * | Bare Armv7-A
+[`armv7a-none-eabi`](platform-support/armv7a-none-eabi.md) | * | Bare Armv7-A
 [`armv7r-none-eabi`](platform-support/armv7r-none-eabi.md) | * | Bare Armv7-R
 [`armv7r-none-eabihf`](platform-support/armv7r-none-eabi.md) | * | Bare Armv7-R, hardfloat
 `i586-unknown-linux-gnu` | ✓ | 32-bit Linux (kernel 3.2+, glibc 2.17, original Pentium) [^x86_32-floats-x87]
diff --git a/src/doc/rustc/src/platform-support/aarch64-unknown-none.md b/src/doc/rustc/src/platform-support/aarch64-unknown-none.md
new file mode 100644
index 00000000000..7e18e8c157f
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/aarch64-unknown-none.md
@@ -0,0 +1,78 @@
+# `aarch64-unknown-none` and `aarch64-unknown-none-softfloat`
+
+* **Tier: 2**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
+
+Bare-metal targets for CPUs in the Armv8-A architecture family, running in AArch64 mode.
+
+For the AArch32 mode carried over from Armv7-A, see
+[`armv7a-none-eabi`](armv7a-none-eabi.md) instead.
+
+Processors in this family include the [Arm Cortex-A35, 53, 76, etc][aarch64-cpus].
+
+[aarch64-cpus]: https://en.wikipedia.org/wiki/Comparison_of_ARM_processors#ARMv8-A
+
+## Target maintainers
+
+[Rust Embedded Devices Working Group Arm Team]
+
+[Rust Embedded Devices Working Group Arm Team]: https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team
+
+## Target CPU and Target Feature options
+
+All AArch64 processors include an FPU. The difference between the `-none` and
+`-none-softfloat` targets is whether the FPU is used for passing function arguments.
+You may prefer the `-softfloat` target when writing a kernel or interfacing with
+pre-compiled binaries that use the soft-float ABI.
+
+When using the hardfloat targets, the minimum floating-point features assumed
+are those of the `fp-armv8`, which excludes NEON SIMD support. If your
+processor supports a different set of floating-point features than the default
+expectations of `fp-armv8`, then these should also be enabled or disabled as
+needed with `-C target-feature=(+/-)`. It is also possible to tell Rust (or
+LLVM) that you have a specific model of Arm processor, using the
+[`-Ctarget-cpu`][target-cpu] option. Doing so may change the default set of
+target-features enabled.
+
+[target-cpu]: https://doc.rust-lang.org/rustc/codegen-options/index.html#target-cpu
+[target-feature]: https://doc.rust-lang.org/rustc/codegen-options/index.html#target-feature
+
+## Requirements
+
+These targets are cross-compiled and use static linking.
+
+By default, the `lld` linker included with Rust will be used; however, you may
+want to use the GNU linker instead. This can be obtained for Windows/Mac/Linux
+from the [Arm Developer Website][arm-gnu-toolchain], or possibly from your OS's
+package manager. To use it, add the following to your `.cargo/config.toml`:
+
+```toml
+[target.aarch64-unknown-none]
+linker = "aarch64-none-elf-ld"
+```
+
+The GNU linker can also be used by specifying `aarch64-none-elf-gcc` as the
+linker. This is needed when using GCC's link time optimization.
+
+These targets don't provide a linker script, so you'll need to bring your own
+according to the specific device you are using. Pass
+`-Clink-arg=-Tyour_script.ld` as a rustc argument to make the linker use
+`your_script.ld` during linking.
+
+[arm-gnu-toolchain]: https://developer.arm.com/Tools%20and%20Software/GNU%20Toolchain
+
+## Cross-compilation toolchains and C code
+
+This target supports C code compiled with the `aarch64-none-elf` target
+triple and a suitable `-march` or `-mcpu` flag.
+
+## Start-up and Low-Level Code
+
+The [Rust Embedded Devices Working Group Arm Team] maintain the
+[`aarch64-cpu`] crate, which may be useful for writing bare-metal code using
+this target.
+
+The *TrustedFirmware* group also maintain [Rust crates for this
+target](https://github.com/ArmFirmwareCrates).
+
+[`aarch64-cpu`]: https://docs.rs/aarch64-cpu
diff --git a/src/doc/rustc/src/platform-support/arm-none-eabi.md b/src/doc/rustc/src/platform-support/arm-none-eabi.md
index 9732df4be7f..aaa80e42971 100644
--- a/src/doc/rustc/src/platform-support/arm-none-eabi.md
+++ b/src/doc/rustc/src/platform-support/arm-none-eabi.md
@@ -12,10 +12,10 @@ their own document.
 ### Tier 2 Target List
 
 - Arm A-Profile Architectures
-  - `armv7a-none-eabi`
+  - [`armv7a-none-eabi`](armv7a-none-eabi.md)
 - Arm R-Profile Architectures
   - [`armv7r-none-eabi` and `armv7r-none-eabihf`](armv7r-none-eabi.md)
-  - [`armebv7r-none-eabi` and `armebv7r-none-eabihf`](armv7r-none-eabi.md)
+  - [`armebv7r-none-eabi` and `armebv7r-none-eabihf`](armebv7r-none-eabi.md)
 - Arm M-Profile Architectures
   - [`thumbv6m-none-eabi`](thumbv6m-none-eabi.md)
   - [`thumbv7m-none-eabi`](thumbv7m-none-eabi.md)
@@ -28,7 +28,7 @@ their own document.
 ### Tier 3 Target List
 
 - Arm A-Profile Architectures
-  - `armv7a-none-eabihf`
+  - [`armv7a-none-eabihf`](armv7a-none-eabi.md)
 - Arm R-Profile Architectures
   - [`armv8r-none-eabihf`](armv8r-none-eabihf.md)
 - Arm M-Profile Architectures
diff --git a/src/doc/rustc/src/platform-support/armebv7r-none-eabi.md b/src/doc/rustc/src/platform-support/armebv7r-none-eabi.md
new file mode 100644
index 00000000000..3e90319c373
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/armebv7r-none-eabi.md
@@ -0,0 +1,55 @@
+# `armebv7r-none-eabi` and `armebv7r-none-eabihf`
+
+* **Tier: 2**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
+
+Bare-metal target for CPUs in the Armv7-R architecture family running in Big
+Endian mode. These processors support dual ARM/Thumb mode, with ARM mode as
+the default.
+
+**NOTE:** You should almost always prefer the [little-endian
+versions](armv7r-none-eabi.md) of these target. Big Endian Arm systems are
+highly unusual.
+
+Processors in this family include the [Arm Cortex-R4, 5, 7, and 8][cortex-r].
+
+See [`arm-none-eabi`](arm-none-eabi.md) for information applicable to all
+`arm-none-eabi` targets.
+
+[cortex-r]: https://en.wikipedia.org/wiki/ARM_Cortex-R
+
+## Target maintainers
+
+[@chrisnc](https://github.com/chrisnc)
+
+## Requirements
+
+Note that some variants of the Cortex-R have both big-endian instructions and
+data. This configuration is known as BE-32, while data-only big-endianness is
+known as BE-8. To build programs for BE-32 processors, the GNU linker must be
+used with the `-mbe32` option. See [ARM Cortex-R Series Programmer's Guide:
+Endianness][endianness] for more details about different endian modes.
+
+When using the hardfloat targets, the minimum floating-point features assumed
+are those of the `vfpv3-d16`, which includes single- and double-precision, with
+16 double-precision registers. This floating-point unit appears in Cortex-R4F
+and Cortex-R5F processors. See [VFP in the Cortex-R processors][vfp]
+for more details on the possible FPU variants.
+
+If your processor supports a different set of floating-point features than the
+default expectations of `vfpv3-d16`, then these should also be enabled or
+disabled as needed with `-C target-feature=(+/-)`.
+
+[endianness]: https://developer.arm.com/documentation/den0042/a/Coding-for-Cortex-R-Processors/Endianness
+
+[vfp]: https://developer.arm.com/documentation/den0042/a/Floating-Point/Floating-point-basics-and-the-IEEE-754-standard/VFP-in-the-Cortex-R-processors
+
+## Start-up and Low-Level Code
+
+The [Rust Embedded Devices Working Group Arm Team] maintain the [`cortex-ar`]
+and [`cortex-r-rt`] crates, which may be useful for writing bare-metal code
+using this target. Those crates include several examples which run in QEMU and
+build using these targets.
+
+[`cortex-ar`]: https://docs.rs/cortex-ar
+[`cortex-r-rt`]: https://docs.rs/cortex-r-rt
diff --git a/src/doc/rustc/src/platform-support/armv4t-none-eabi.md b/src/doc/rustc/src/platform-support/armv4t-none-eabi.md
index 56f919e2a12..c6d88762fb1 100644
--- a/src/doc/rustc/src/platform-support/armv4t-none-eabi.md
+++ b/src/doc/rustc/src/platform-support/armv4t-none-eabi.md
@@ -1,6 +1,7 @@
 # armv4t-none-eabi / thumbv4t-none-eabi
 
-Tier 3
+* **Tier:  3**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
 
 These two targets are part of the [`arm-none-eabi`](arm-none-eabi.md) target
 group, and all the information there applies.
diff --git a/src/doc/rustc/src/platform-support/armv5te-none-eabi.md b/src/doc/rustc/src/platform-support/armv5te-none-eabi.md
index 22287972b7e..e9f34d4ede8 100644
--- a/src/doc/rustc/src/platform-support/armv5te-none-eabi.md
+++ b/src/doc/rustc/src/platform-support/armv5te-none-eabi.md
@@ -1,6 +1,7 @@
 # `armv5te-none-eabi`
 
-**Tier: 3**
+* **Tier: 3**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
 
 Bare-metal target for any cpu in the Armv5TE architecture family, supporting
 ARM/Thumb code interworking (aka `A32`/`T32`), with `A32` code as the default code
diff --git a/src/doc/rustc/src/platform-support/armv7a-none-eabi.md b/src/doc/rustc/src/platform-support/armv7a-none-eabi.md
new file mode 100644
index 00000000000..3dadda86a5f
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/armv7a-none-eabi.md
@@ -0,0 +1,70 @@
+# `armv7a-none-eabi` and `armv7a-none-eabihf`
+
+* **Tier: 2** for `armv7a-none-eabi`
+* **Tier: 3** for `armv7a-none-eabihf`
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
+
+Bare-metal target for CPUs in the Armv7-A architecture family, supporting
+dual ARM/Thumb mode, with ARM mode as the default.
+
+Note, this is for processors running in AArch32 mode. For the AArch64 mode
+added in Armv8-A, see [`aarch64-unknown-none`](aarch64-unknown-none.md) instead.
+
+Processors in this family include the [Arm Cortex-A5, 8, 32, etc][cortex-a].
+
+See [`arm-none-eabi`](arm-none-eabi.md) for information applicable to all
+`arm-none-eabi` targets.
+
+[cortex-a]: https://en.wikipedia.org/wiki/ARM_Cortex-A
+
+## Target maintainers
+
+[Rust Embedded Devices Working Group Arm Team]
+
+[Rust Embedded Devices Working Group Arm Team]: https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team
+
+## Requirements
+
+Almost all Armv7-A processors include an FPU (a VFPv3 or a VFPv4). The
+difference between the `-eabi` and `-eabihf` targets is whether the FPU is
+used for passing function arguments. You may prefer the `-eabi` soft-float
+target when the processor does not have a floating point unit or the compiled
+code should not use the floating point unit.
+
+When using the hardfloat targets, the minimum floating-point features assumed
+are those of the VFPv3-D16, which includes single- and double-precision, with
+16 double-precision registers. This floating-point unit appears in Cortex-A8
+and Cortex-A9 processors. See [VFP in the Cortex-A processors][vfp] for more
+details on the possible FPU variants.
+
+If your processor supports a different set of floating-point features than the
+default expectations of VFPv3-D16, then these should also be enabled or
+disabled as needed with `-C target-feature=(+/-)`.
+
+In general, the following four combinations are possible:
+
+- VFPv3-D16, target feature `+vfp3` and `-d32`
+- VFPv3-D32, target feature `+vfp3` and `+d32`
+- VFPv4-D16, target feature `+vfp4` and `-d32`
+- VFPv4-D32, target feature `+vfp4` and `+d32`
+
+An Armv7-A processor may optionally include a NEON hardware unit which
+provides Single Instruction Multiple Data (SIMD) operations. The
+implementation of this unit implies VFPv3-D32. The target feature `+neon` may
+be added to inform the compiler about the availability of NEON.
+
+You can refer to the [arm-none-eabi](arm-none-eabi.md) documentation for a
+generic guide on target feature and target CPU specification and how to enable
+and disable them via `.cargo/config.toml` file.
+
+[vfp]: https://developer.arm.com/documentation/den0013/0400/Floating-Point/Floating-point-basics-and-the-IEEE-754-standard/ARM-VFP
+
+## Start-up and Low-Level Code
+
+The [Rust Embedded Devices Working Group Arm Team] maintain the [`cortex-ar`]
+and [`cortex-a-rt`] crates, which may be useful for writing bare-metal code
+using this target. The [`cortex-ar` repository](https://github.com/rust-embedded/cortex-ar)
+includes several examples which run in QEMU and build using these targets.
+
+[`cortex-ar`]: https://docs.rs/cortex-ar
+[`cortex-a-rt`]: https://docs.rs/cortex-a-rt
diff --git a/src/doc/rustc/src/platform-support/armv7r-none-eabi.md b/src/doc/rustc/src/platform-support/armv7r-none-eabi.md
index 88b2689dcf0..c1252b4a4bf 100644
--- a/src/doc/rustc/src/platform-support/armv7r-none-eabi.md
+++ b/src/doc/rustc/src/platform-support/armv7r-none-eabi.md
@@ -1,14 +1,13 @@
-# `arm(eb)?v7r-none-eabi(hf)?`
+# `armv7r-none-eabi` and `armv7r-none-eabihf`
 
-**Tier: 2**
+* **Tier: 2**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
 
 Bare-metal target for CPUs in the Armv7-R architecture family, supporting
 dual ARM/Thumb mode, with ARM mode as the default.
 
 Processors in this family include the [Arm Cortex-R4, 5, 7, and 8][cortex-r].
 
-The `eb` versions of this target generate code for big-endian processors.
-
 See [`arm-none-eabi`](arm-none-eabi.md) for information applicable to all
 `arm-none-eabi` targets.
 
@@ -17,15 +16,11 @@ See [`arm-none-eabi`](arm-none-eabi.md) for information applicable to all
 ## Target maintainers
 
 [@chrisnc](https://github.com/chrisnc)
+[Rust Embedded Devices Working Group Arm Team]
 
-## Requirements
+[Rust Embedded Devices Working Group Arm Team]: https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team
 
-When using the big-endian version of this target, note that some variants of
-the Cortex-R have both big-endian instructions and data. This configuration is
-known as BE-32, while data-only big-endianness is known as BE-8. To build
-programs for BE-32 processors, the GNU linker must be used with the `-mbe32`
-option. See [ARM Cortex-R Series Programmer's Guide: Endianness][endianness]
-for more details about different endian modes.
+## Requirements
 
 When using the hardfloat targets, the minimum floating-point features assumed
 are those of the `vfpv3-d16`, which includes single- and double-precision, with
@@ -41,7 +36,12 @@ disabled as needed with `-C target-feature=(+/-)`.
 
 [vfp]: https://developer.arm.com/documentation/den0042/a/Floating-Point/Floating-point-basics-and-the-IEEE-754-standard/VFP-in-the-Cortex-R-processors
 
-## Cross-compilation toolchains and C code
+## Start-up and Low-Level Code
+
+The [Rust Embedded Devices Working Group Arm Team] maintain the [`cortex-ar`]
+and [`cortex-r-rt`] crates, which may be useful for writing bare-metal code
+using this target. Those crates include several examples which run in QEMU and
+build using these targets.
 
-This target supports C code compiled with the `arm-none-eabi` target triple and
-`-march=armv7-r` or a suitable `-mcpu` flag.
+[`cortex-ar`]: https://docs.rs/cortex-ar
+[`cortex-r-rt`]: https://docs.rs/cortex-r-rt
diff --git a/src/doc/rustc/src/platform-support/armv8r-none-eabihf.md b/src/doc/rustc/src/platform-support/armv8r-none-eabihf.md
index 569d8802ebe..0d5a36c3ee2 100644
--- a/src/doc/rustc/src/platform-support/armv8r-none-eabihf.md
+++ b/src/doc/rustc/src/platform-support/armv8r-none-eabihf.md
@@ -1,6 +1,7 @@
 # `armv8r-none-eabihf`
 
-**Tier: 3**
+* **Tier: 3**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
 
 Bare-metal target for CPUs in the Armv8-R architecture family, supporting
 dual ARM/Thumb mode, with ARM mode as the default.
@@ -17,6 +18,9 @@ See [`arm-none-eabi`](arm-none-eabi.md) for information applicable to all
 ## Target maintainers
 
 [@chrisnc](https://github.com/chrisnc)
+[Rust Embedded Devices Working Group Arm Team]
+
+[Rust Embedded Devices Working Group Arm Team]: https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team
 
 ## Requirements
 
@@ -34,7 +38,14 @@ Technical Reference Manual for more details.
 
 [fpu]: https://developer.arm.com/documentation/100026/0104/Advanced-SIMD-and-floating-point-support/About-the-Advanced-SIMD-and-floating-point-support
 
-## Cross-compilation toolchains and C code
-
-This target supports C code compiled with the `arm-none-eabi` target triple and
-`-march=armv8-r` or a suitable `-mcpu` flag.
+### Table of supported CPUs for `armv8r-none-eabihf`
+
+| CPU         | FPU | Neon | Target CPU       | Target Features    |
+|:----------- | --- |:---- |:---------------- |:------------------ |
+| Any         | SP  | No   | None             | None               |
+| Cortex-R52  | SP  | No   | `cortex-r52`     | `-fp64,-d32,-neon` |
+| Cortex-R52  | DP  | No   | `cortex-r52`     | `-neon`            |
+| Cortex-R52  | DP  | Yes  | `cortex-r52`     | None               |
+| Cortex-R52+ | SP  | No   | `cortex-r52plus` | `-fp64,-d32,-neon` |
+| Cortex-R52+ | DP  | No   | `cortex-r52plus` | `-neon`            |
+| Cortex-R52+ | DP  | Yes  | `cortex-r52plus` | None               |
diff --git a/src/doc/rustc/src/platform-support/thumbv6m-none-eabi.md b/src/doc/rustc/src/platform-support/thumbv6m-none-eabi.md
index 746b8443547..d4bd0b0945a 100644
--- a/src/doc/rustc/src/platform-support/thumbv6m-none-eabi.md
+++ b/src/doc/rustc/src/platform-support/thumbv6m-none-eabi.md
@@ -1,6 +1,7 @@
 # `thumbv6m-none-eabi`
 
-**Tier: 2**
+* **Tier: 2**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
 
 Bare-metal target for CPUs in the [Armv6-M] architecture family, supporting a
 subset of the [T32 ISA][t32-isa].
@@ -26,7 +27,7 @@ only option because there is no FPU support in [Armv6-M].
 
 ## Target maintainers
 
-* [Rust Embedded Devices Working Group Arm Team](https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team)
+[Rust Embedded Devices Working Group Arm Team](https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team)
 
 ## Target CPU and Target Feature options
 
diff --git a/src/doc/rustc/src/platform-support/thumbv7em-none-eabi.md b/src/doc/rustc/src/platform-support/thumbv7em-none-eabi.md
index 12e28265678..98dcf9bd396 100644
--- a/src/doc/rustc/src/platform-support/thumbv7em-none-eabi.md
+++ b/src/doc/rustc/src/platform-support/thumbv7em-none-eabi.md
@@ -1,6 +1,7 @@
 # `thumbv7em-none-eabi` and `thumbv7em-none-eabihf`
 
-**Tier: 2**
+* **Tier: 2**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
 
 Bare-metal target for CPUs in the [Armv7E-M] architecture family, supporting a
 subset of the [T32 ISA][t32-isa].
@@ -21,7 +22,7 @@ See [`arm-none-eabi`](arm-none-eabi.md) for information applicable to all
 
 ## Target maintainers
 
-* [Rust Embedded Devices Working Group Arm Team](https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team)
+[Rust Embedded Devices Working Group Arm Team](https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team)
 
 ## Target CPU and Target Feature options
 
diff --git a/src/doc/rustc/src/platform-support/thumbv7m-none-eabi.md b/src/doc/rustc/src/platform-support/thumbv7m-none-eabi.md
index 03324b341d0..d8f3970c8bf 100644
--- a/src/doc/rustc/src/platform-support/thumbv7m-none-eabi.md
+++ b/src/doc/rustc/src/platform-support/thumbv7m-none-eabi.md
@@ -1,6 +1,7 @@
 # `thumbv7m-none-eabi`
 
-**Tier: 2**
+* **Tier: 2**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
 
 Bare-metal target for CPUs in the [Armv7-M] architecture family, supporting a
 subset of the [T32 ISA][t32-isa].
@@ -22,7 +23,7 @@ only option because there is no FPU support in [Armv7-M].
 
 ## Target maintainers
 
-* [Rust Embedded Devices Working Group Arm Team](https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team)
+[Rust Embedded Devices Working Group Arm Team](https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team)
 
 ## Target CPU and Target Feature options
 
diff --git a/src/doc/rustc/src/platform-support/thumbv8m.base-none-eabi.md b/src/doc/rustc/src/platform-support/thumbv8m.base-none-eabi.md
index 4a92e856466..b16d450275d 100644
--- a/src/doc/rustc/src/platform-support/thumbv8m.base-none-eabi.md
+++ b/src/doc/rustc/src/platform-support/thumbv8m.base-none-eabi.md
@@ -1,6 +1,7 @@
 # `thumbv8m.base-none-eabi`
 
-**Tier: 2**
+* **Tier: 2**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
 
 Bare-metal target for CPUs in the Baseline [Armv8-M] architecture family,
 supporting a subset of the [T32 ISA][t32-isa].
@@ -22,7 +23,7 @@ only option because there is no FPU support in [Armv8-M] Baseline.
 
 ## Target maintainers
 
-* [Rust Embedded Devices Working Group Arm Team](https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team)
+[Rust Embedded Devices Working Group Arm Team](https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team)
 
 ## Target CPU and Target Feature options
 
diff --git a/src/doc/rustc/src/platform-support/thumbv8m.main-none-eabi.md b/src/doc/rustc/src/platform-support/thumbv8m.main-none-eabi.md
index 9f85d08fa0a..a2d515d07ea 100644
--- a/src/doc/rustc/src/platform-support/thumbv8m.main-none-eabi.md
+++ b/src/doc/rustc/src/platform-support/thumbv8m.main-none-eabi.md
@@ -1,6 +1,7 @@
 # `thumbv8m.main-none-eabi` and `thumbv8m.main-none-eabihf`
 
-**Tier: 2**
+* **Tier: 2**
+* **Library Support:** core and alloc (bare-metal, `#![no_std]`)
 
 Bare-metal target for CPUs in the Mainline [Armv8-M] architecture family,
 supporting a subset of the [T32 ISA][t32-isa].
@@ -25,7 +26,7 @@ See [`arm-none-eabi`](arm-none-eabi.md) for information applicable to all
 
 ## Target maintainers
 
-* [Rust Embedded Devices Working Group Arm Team](https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team)
+[Rust Embedded Devices Working Group Arm Team](https://github.com/rust-embedded/wg?tab=readme-ov-file#the-arm-team)
 
 ## Target CPU and Target Feature options
 
diff --git a/src/tools/tidy/src/fluent_lowercase.rs b/src/tools/tidy/src/fluent_lowercase.rs
new file mode 100644
index 00000000000..13f0319909e
--- /dev/null
+++ b/src/tools/tidy/src/fluent_lowercase.rs
@@ -0,0 +1,64 @@
+//! Checks that the error messages start with a lowercased letter (except when allowed to).
+
+use std::path::Path;
+
+use fluent_syntax::ast::{Entry, Message, PatternElement};
+
+use crate::walk::{filter_dirs, walk};
+
+#[rustfmt::skip]
+const ALLOWED_CAPITALIZED_WORDS: &[&str] = &[
+    // tidy-alphabetical-start
+    "ABI",
+    "ABIs",
+    "ADT",
+    "C",
+    "CGU",
+    "Ferris",
+    "MIR",
+    "OK",
+    "Rust",
+    "VS", // VS Code
+    // tidy-alphabetical-end
+];
+
+fn filter_fluent(path: &Path) -> bool {
+    if let Some(ext) = path.extension() { ext.to_str() != Some("ftl") } else { true }
+}
+
+fn is_allowed_capitalized_word(msg: &str) -> bool {
+    ALLOWED_CAPITALIZED_WORDS.iter().any(|word| {
+        msg.strip_prefix(word)
+            .map(|tail| tail.chars().next().map(|c| c == '-' || c.is_whitespace()).unwrap_or(true))
+            .unwrap_or_default()
+    })
+}
+
+fn check_lowercase(filename: &str, contents: &str, bad: &mut bool) {
+    let (Ok(parse) | Err((parse, _))) = fluent_syntax::parser::parse(contents);
+
+    for entry in &parse.body {
+        if let Entry::Message(msg) = entry
+            && let Message { value: Some(pattern), .. } = msg
+            && let [first_pattern, ..] = &pattern.elements[..]
+            && let PatternElement::TextElement { value } = first_pattern
+            && value.chars().next().is_some_and(char::is_uppercase)
+            && !is_allowed_capitalized_word(value)
+        {
+            tidy_error!(
+                bad,
+                "{filename}: message `{value}` starts with an uppercase letter. Fix it or add it to `ALLOWED_CAPITALIZED_WORDS`"
+            );
+        }
+    }
+}
+
+pub fn check(path: &Path, bad: &mut bool) {
+    walk(
+        path,
+        |path, is_dir| filter_dirs(path) || (!is_dir && filter_fluent(path)),
+        &mut |ent, contents| {
+            check_lowercase(ent.path().to_str().unwrap(), contents, bad);
+        },
+    );
+}
diff --git a/src/tools/tidy/src/lib.rs b/src/tools/tidy/src/lib.rs
index 37713cbf75e..2a9c3963d2d 100644
--- a/src/tools/tidy/src/lib.rs
+++ b/src/tools/tidy/src/lib.rs
@@ -257,6 +257,7 @@ pub mod extra_checks;
 pub mod features;
 pub mod filenames;
 pub mod fluent_alphabetical;
+pub mod fluent_lowercase;
 pub mod fluent_period;
 mod fluent_used;
 pub mod gcc_submodule;
diff --git a/src/tools/tidy/src/main.rs b/src/tools/tidy/src/main.rs
index bfe30258915..f9e82341b7a 100644
--- a/src/tools/tidy/src/main.rs
+++ b/src/tools/tidy/src/main.rs
@@ -121,6 +121,7 @@ fn main() {
         check!(error_codes, &root_path, &[&compiler_path, &librustdoc_path], verbose, &ci_info);
         check!(fluent_alphabetical, &compiler_path, bless);
         check!(fluent_period, &compiler_path);
+        check!(fluent_lowercase, &compiler_path);
         check!(target_policy, &root_path);
         check!(gcc_submodule, &root_path, &compiler_path);