Add a template for target-specific documentation

Author: joshtriplett

src/doc/rustc/src/SUMMARY.md

@@ -13,6 +13,7 @@
 - [JSON Output](json.md)
 - [Tests](tests/index.md)
 - [Platform Support](platform-support.md)
+    - [Template for target-specific documentation](platform-support/TEMPLATE.md)
     - [aarch64-apple-ios-sim](platform-support/aarch64-apple-ios-sim.md)
     - [\*-kmc-solid_\*](platform-support/kmc-solid.md)
 - [Target Tier Policy](target-tier-policy.md)

src/doc/rustc/src/platform-support/TEMPLATE.md

@@ -0,0 +1,52 @@
+# `target-name-here`
+
+**Tier: 3**
+
+One-sentence description of the target (e.g. CPU, OS)
+
+## Target maintainers
+
+- Some Person, `[email protected]`, https://github.com/...
+
+## Requirements
+
+Does the target support host tools, or only cross-compilation? Does the target
+support std, or alloc (either with a default allocator, or if the user supplies
+an allocator)?
+
+Document the expectations of binaries built for the target. Do they assume
+specific minimum features beyond the baseline of the CPU/environment/etc? What
+version of the OS or environment do they expect?
+
+Are there notable `#[target_feature(...)]` or `-C target-feature=` values that
+programs may wish to use?
+
+What calling convention does `extern "C"` use on the target?
+
+What format do binaries use by default? ELF, PE, something else?
+
+## Building the target
+
+If Rust doesn't build the target by default, how can users build it? Can users
+just add it to the `target` list in `config.toml`?
+
+## Building Rust programs
+
+Rust does not yet ship pre-compiled artifacts for this target. To compile for
+this target, you will either need to build Rust with the target enabled (see
+"Building the target" above), or build your own copy of `core` by using
+`build-std` or similar.
+
+## Testing
+
+Does the target support running binaries, or do binaries have varying
+expectations that prevent having a standard way to run them? If users can run
+binaries, can they do so in some common emulator, or do they need native
+hardware? Does the target support running the Rust testsuite?
+
+## Cross-compilation toolchains and C code
+
+Does the target support C code? If so, what toolchain target should users use
+to build compatible C code? (This may match the target triple, or it may be a
+toolchain for a different target triple, potentially with specific options or
+caveats.)

src/doc/rustc/src/target-tier-policy.md

@@ -74,8 +74,9 @@ For a list of all supported targets and their corresponding tiers ("tier 3",
 Several parts of this policy require providing target-specific documentation.
 Such documentation should typically appear in a subdirectory of the
 platform-support section of this rustc manual, with a link from the target's
-entry in [platform support](platform-support.md). See other documentation in
-that directory for examples.
+entry in [platform support](platform-support.md). Use
+[TEMPLATE.md](platform-support/TEMPLATE.md) as a base, and see other
+documentation in that directory for examples.
 
 Note that a target must have already received approval for the next lower tier,
 and spent a reasonable amount of time at that tier, before making a proposal