rust: build: add "make clippy", "make rustfmt", "make rustdoc"

Abstract common invocations of "cargo", that do not require copying
the generated bindgen file or setting up MESON_BUILD_ROOT.

In the future these could also do completely without cargo and invoke
the underlying programs directly.

Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

rust/meson.build

@@ -2,3 +2,25 @@ subdir('qemu-api-macros')
 subdir('qemu-api')
 
 subdir('hw')
+
+cargo = find_program('cargo', required: false)
+
+if cargo.found()
+  run_target('clippy',
+    command: [config_host['MESON'], 'devenv',
+              '--workdir', '@CURRENT_SOURCE_DIR@',
+              cargo, 'clippy', '--tests'],
+    depends: bindings_rs)
+
+  run_target('rustfmt',
+    command: [config_host['MESON'], 'devenv',
+              '--workdir', '@CURRENT_SOURCE_DIR@',
+              cargo, 'fmt'],
+    depends: bindings_rs)
+
+  run_target('rustdoc',
+    command: [config_host['MESON'], 'devenv',
+              '--workdir', '@CURRENT_SOURCE_DIR@',
+              cargo, 'doc', '--no-deps', '--document-private-items'],
+    depends: bindings_rs)
+endif

rust/qemu-api/README.md

@@ -5,13 +5,15 @@ This library exports helper Rust types, Rust macros and C FFI bindings for inter
 The C bindings can be generated with `bindgen`, using this build target:
 
 ```console
-$ ninja bindings.inc.rs
+$ make bindings.inc.rs
 ```
 
 ## Generate Rust documentation
 
-To generate docs for this crate, including private items:
+Common Cargo tasks can be performed from the QEMU build directory
 
-```sh
-pyvenv/bin/meson devenv -w ../rust cargo doc --no-deps --document-private-items
+```console
+$ make clippy
+$ make rustfmt
+$ make rustdoc
 ```

rust/qemu-api/build.rs

@@ -20,8 +20,13 @@ fn main() -> Result<()> {
     let file = Path::new(&file);
     if !Path::new(&file).exists() {
         panic!(concat!(
-            "No generated C bindings found! If you want to run `cargo`, start a subshell\n",
-            "with `meson devenv`, or point MESON_BUILD_ROOT to the top of the build tree."
+            "\n",
+            "    No generated C bindings found! Maybe you wanted one of\n",
+            "    `make clippy`, `make rustfmt`, `make rustdoc`?\n",
+            "\n",
+            "    For other uses of `cargo`, start a subshell with\n",
+            "    `pyvenv/bin/meson devenv`, or point MESON_BUILD_ROOT to\n",
+            "    the top of the build tree."
         ));
     }