rust: add to_system_dependency

Move the logic for system dependencies outside Cargo.interpreter and
into the rust module, so that it can be reused by the workspace object.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/docs/markdown/Rust-module.md b/docs/markdown/Rust-module.md
index b1edb793c..37ba59d8e 100644
--- a/docs/markdown/Rust-module.md
+++ b/docs/markdown/Rust-module.md
@@ -172,6 +172,21 @@ Only a subset of [[shared_library]] keyword arguments are allowed:
 - link_with
 - override_options
 
+### to_system_dependency()
+
+*Since 1.11.0*
+
+```meson
+rustmod.to_system_dependency(dep[, name])
+```
+
+Create and return an internal dependency that wraps `dep` and
+defines `cfg(system_deps_have_NAME)`.  This is compatible with
+how the `system-deps` crate reports the availability of a system
+dependency to Rust code.
+
+If omitted, the name defaults to the name of the dependency.
+
 ### workspace()
 
 Basic usage: