of a dependency. `--library-path` provides directories to search in, `--extern`
instead lets you specify exactly which dependency is located where.
+## `-C`/`--codegen`: pass codegen options to rustc
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs -C target_feature=+avx
+$ rustdoc src/lib.rs --codegen target_feature=+avx
+
+$ rustdoc --test src/lib.rs -C target_feature=+avx
+$ rustdoc --test src/lib.rs --codegen target_feature=+avx
+
+$ rustdoc --test README.md -C target_feature=+avx
+$ rustdoc --test README.md --codegen target_feature=+avx
+```
+
+When rustdoc generates documentation, looks for documentation tests, or executes documentation
+tests, it needs to compile some rust code, at least part-way. This flag allows you to tell rustdoc
+to provide some extra codegen options to rustc when it runs these compilations. Most of the time,
+these options won't affect a regular documentation run, but if something depends on target features
+to be enabled, or documentation tests need to use some additional options, this flag allows you to
+affect that.
+
+The arguments to this flag are the same as those for the `-C` flag on rustc. Run `rustc -C help` to
+get the full list.
+
## `--passes`: add more rustdoc passes
Using this flag looks like this:
An argument of "list" will print a list of possible "rustdoc passes", and other
arguments will be the name of which passes to run in addition to the defaults.
-For more details on passes, see [the chapter on them](passes.html).
+For more details on passes, see [the chapter on them](passes.md).
See also `--no-defaults`.
removes those defaults, allowing you to use `--passes` to specify
exactly which passes you want.
-For more details on passes, see [the chapter on them](passes.html).
+For more details on passes, see [the chapter on them](passes.md).
See also `--passes`.
```
This flag will run your code examples as tests. For more, see [the chapter
-on documentation tests](documentation-tests.html).
+on documentation tests](documentation-tests.md).
See also `--test-args`.
```
This flag will pass options to the test runner when running documentation tests.
-For more, see [the chapter on documentation tests](documentation-tests.html).
+For more, see [the chapter on documentation tests](documentation-tests.md).
See also `--test`.
Similar to `rustc --sysroot`, this lets you change the sysroot `rustdoc` uses
when compiling your code.
+
+### `--edition`: control the edition of docs and doctests
+
+Using this flag looks like this:
+
+```bash
+$ rustdoc src/lib.rs --edition 2018
+$ rustdoc --test src/lib.rs --edition 2018
+```
+
+This flag allows rustdoc to treat your rust code as the given edition. It will compile doctests with
+the given edition as well. As with `rustc`, the default edition that `rustdoc` will use is `2015`
+(the first edition).
+