Add markdown lints to CI

.github/workflows/check.yml

@@ -230,6 +230,27 @@ jobs:
                 diff --unified=5 "cpp-overload-test/examples/$test_name.stderr" /tmp/"$test_name.stderr"
             done
 
+  markdown-lint:
+    name: 11. Lint Markdown files
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      - name: Run markdownlint-cli
+        uses: nosborn/github-action-markdown-cli@508d6cefd8f0cc99eab5d2d4685b1d5f470042c1 # v3.5.0
+        with:
+          files: "**.md"
+
+  markdown-style:
+    name: 12. Check Markdown style
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      - name: Run prettier on Markdown files
+        # The version available on macOS homebrew
+        run: npx --yes prettier@3.9.6 --check **/*.md
+
   all:
     name: All checks
     # Always run this job, even if earlier steps were skipped (or failed):
@@ -247,6 +268,8 @@ jobs:
       - diagnostics-rust
       - cpp-overload-test-ok
       - cpp-overload-test-fail
+      - markdown-lint
+      - markdown-style
     steps:
       - name: Fail if any other job failed
         # Every job status needs to be checked here, because `always()` stops failures from propagating automatically
@@ -262,3 +285,5 @@ jobs:
           [[ "${{ needs.diagnostics-rust.result }}" == "success" ]] || exit 1
           [[ "${{ needs.cpp-overload-test-ok.result }}" == "success" ]] || exit 1
           [[ "${{ needs.cpp-overload-test-fail.result }}" == "success" ]] || exit 1
+          [[ "${{ needs.markdown-lint.result }}" == "success" ]] || exit 1
+          [[ "${{ needs.markdown-style.result }}" == "success" ]] || exit 1

.markdownlint.yaml

@@ -0,0 +1,17 @@
+# MD013/line-length : Line length : https://github.com/DavidAnson/markdownlint/blob/v0.41.1/doc/md013.md
+MD013:
+  # Number of characters
+  line_length: 100
+  # Number of characters for headings
+  heading_line_length: 100
+  # Number of characters for code blocks
+  code_block_line_length: 100
+
+# MD033/no-inline-html : Inline HTML : https://github.com/DavidAnson/markdownlint/blob/v0.41.1/doc/md033.md
+MD033:
+  # Allowed elements
+  allowed_elements: [
+    "br",
+  ]
+  # Allowed elements in tables
+  table_allowed_elements: []

CONTRIBUTING.md

@@ -1,33 +1,33 @@
 # Contributing to a Rust Foundation Project
 
-Thank you for your interest in contributing to this Rust Foundation project. 
+Thank you for your interest in contributing to this Rust Foundation project.
 We are happy and excited to review and accept your pull requests.
 
 ## Before You Begin Contributing
 
 ### Licenses
 
-There is no Contributor License Agreement to sign to contribute this project. 
-Your contribution will be covered by the license(s) granted for this 
-repository, commonly MIT, Apache, and/or CC-BY, but could be a different 
-license. In other words, your contribution will be licensed to the Foundation 
-and all downstream users under those licenses. You can read more in the 
+There is no Contributor License Agreement to sign to contribute this project.
+Your contribution will be covered by the license(s) granted for this
+repository, commonly MIT, Apache, and/or CC-BY, but could be a different
+license. In other words, your contribution will be licensed to the Foundation
+and all downstream users under those licenses. You can read more in the
 Foundation's [intellectual property policy][ip-policy].
 
 ### Code of Conduct
 
-Please review and adhere to the [code of conduct](CODE_OF_CONDUCT.md) before 
+Please review and adhere to the [code of conduct](CODE_OF_CONDUCT.md) before
 contributing any pull requests.
 
 ## Contribution Process
 
 All submissions, including submissions by project members, require review. We
-use GitHub pull requests for this purpose. Consult [GitHub Help][pull-requests] 
+use GitHub pull requests for this purpose. Consult [GitHub Help][pull-requests]
 for more information on using pull requests.
 
 ### Issues
 
-Do you just want to file an issue for the project? Please do so in GitHub under 
+Do you just want to file an issue for the project? Please do so in GitHub under
 the `Issues` tab.
 
 [ip-policy]: https://foundation.rust-lang.org/policies/intellectual-property-policy/

README.md

@@ -1,17 +1,27 @@
 # Rust Function Overloading Macros
 
-This repository is a [Rust Foundation *experiment*](https://rustfoundation.org/media/experimenting-with-function-overloading-in-rust-why-it-matters/) in ergonomic function overloading in Rust.
+This repository is a [Rust Foundation *experiment*][experiment-blog] in ergonomic function
+overloading in Rust.
 
-The experiment uses macros to improve the ergonomics of the [`splat` Rust language experiment](https://github.com/rust-lang/rust/issues/153629).
-Technical details for the current stage of the experiment can be found [on the Inside Rust blog](https://blog.rust-lang.org/inside-rust/2026/08/19/overloading-experiment/).
+The experiment uses macros to improve the ergonomics of the
+[`splat` Rust language experiment][splat-tracking]. Technical details for the current stage of the
+experiment can be found [on the Inside Rust blog][technical-blog].
 
 Most of this code requires a recent nightly Rust compiler.
 
+[experiment-blog]: https://rustfoundation.org/media/experimenting-with-function-overloading-in-rust-why-it-matters/
+[splat-tracking]: https://github.com/rust-lang/rust/issues/153629
+[technical-blog]: https://blog.rust-lang.org/inside-rust/2026/08/19/overloading-experiment/
+
 ## Experimental Outcomes
 
-Some outcomes of this experiment are summarised in the [C++ overloads in Rust](https://github.com/rustfoundation/overloading-macros/blob/main/cpp-overloads-in-rust.md) document & compatibility table.
+Some outcomes of this experiment are summarised in the [C++ overloads in Rust][cpp-overloads-rust]
+document & compatibility table.
+
+These outcomes are based on the current state of the experimental compiler feature and overloading
+macro: they are not Rust language design decisions.
 
-These outcomes are based on the current state of the experimental compiler feature and overloading macro: they are not Rust language design decisions.
+[cpp-overloads-rust]: https://github.com/rustfoundation/overloading-macros/blob/main/cpp-overloads-in-rust.md
 
 ## Macro Setup
 
@@ -22,7 +32,8 @@ Add this `overloading-macros` crate as a dependency.
 rustup update nightly
 cd your-project-name
 rustup override set nightly
-cargo add overloading-macros ||  cargo add --git https://github.com/rustfoundation/overloading-macros overloading-macros
+cargo add overloading-macros || \
+    cargo add --git https://github.com/rustfoundation/overloading-macros overloading-macros
 ```
 
 Then use the macro to add overloading to your functions or methods.

cpp-overload-test/README.md

@@ -1,7 +1,8 @@
 This code is automatically run in CI:
 
 - Submodules of `lib.rs` are expected to succeed. They are named after each C++ class.
-- Examples are expected to fail, with output in the corresponding `.stderr` file, also named after C++ classes.
+- Examples are expected to fail, with output in the corresponding `.stderr` file, also named after
+  C++ classes.
 
 Sometimes the C++ code extracted by `cpp_build` will become outdated, and you will get errors like: