Docs about proc_macros

sourcefrog · Sep 30, 2024 · 1a7c70d · 1a7c70d
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diff --git a/NEWS.md b/NEWS.md
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 ## Unreleased
 
+- New: Mutate `proc_macro` targets and functions.
+
 - Fixed: Avoid generating empty string elements in `ENCODED_RUSTFLAGS` when `--cap-lints` is set. In some situations these could cause a compiler error complaining about the empty argument.
 
 - New: `--profile` option allows selecting a Cargo profile. In particular, it's recommended that you can use `--profile=mutants` and configure a custom profile in your `Cargo.toml` to optimize the build for mutants, by turning off debug symbols.

diff --git a/book/src/SUMMARY.md b/book/src/SUMMARY.md
@@ -24,6 +24,7 @@
   - [Strict lints](lints.md)
 - [Generating mutants](mutants.md)
   - [Error values](error-values.md)
+  - [Macros](macros.md)
 - [Improving performance](performance.md)
   - [Parallelism](parallelism.md)
   - [Jobserver](jobserver.md)

diff --git a/book/src/macros.md b/book/src/macros.md
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+# Mutating code using macros
+
+cargo-mutants will mutate the contents of `#[proc_macro]` functions defined in the current crate, and run tests to see if those mutations are caught.
+
+cargo-mutants does not currently mutate calls to macros, or the expansion of a macro, or the definition of declarative `macro_rules` macros. As a result on code that is mostly produced by macro expansion it may not find many mutation opportunities.