Resolve semicolon_if_nothing_returned lints in generated code

    warning: consider adding a `;` to the last statement for consistent formatting
      --> tests/ffi/module.rs:62:17
       |
    62 |                 __c_take_trivial_ref(d as *const D as *const ::cxx::core::ffi::c_void)
       |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `__c_take_trivial_ref(d as *const D as *const ::cxx::core::ffi::c_void);`
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned
       = note: `-W clippy::semicolon-if-nothing-returned` implied by `-W clippy::pedantic`
       = help: to override `-W clippy::pedantic` add `#[allow(clippy::semicolon_if_nothing_returned)]`

    warning: consider adding a `;` to the last statement for consistent formatting
      --> tests/ffi/module.rs:71:17
       |
    71 |                 __c_take_trivial_mut_ref(d as *mut D as *mut ::cxx::core::ffi::c_void)
       |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `__c_take_trivial_mut_ref(d as *mut D as *mut ::cxx::core::ffi::c_void);`
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

    warning: consider adding a `;` to the last statement for consistent formatting
      --> tests/ffi/module.rs:80:17
       |
    80 | /                 __c_take_trivial_pin_ref(
    81 | |                     ::cxx::core::pin::Pin::into_inner_unchecked(d) as *const D
    82 | |                         as *const ::cxx::core::ffi::c_void,
    83 | |                 )
       | |_________________^
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned
    help: add a `;` here
       |
    83 |                 __c_take_trivial_pin_ref(
    84 |                     ::cxx::core::pin::Pin::into_inner_unchecked(d) as *const D
    85 |                         as *const ::cxx::core::ffi::c_void,
    86 ~                 );
       |

    warning: consider adding a `;` to the last statement for consistent formatting
      --> tests/ffi/module.rs:92:17
       |
    92 | /                 __c_take_trivial_pin_mut_ref(
    93 | |                     ::cxx::core::pin::Pin::into_inner_unchecked(d) as *mut D
    94 | |                         as *mut ::cxx::core::ffi::c_void,
    95 | |                 )
       | |_________________^
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned
    help: add a `;` here
       |
    95 |                 __c_take_trivial_pin_mut_ref(
    96 |                     ::cxx::core::pin::Pin::into_inner_unchecked(d) as *mut D
    97 |                         as *mut ::cxx::core::ffi::c_void,
    98 ~                 );
       |

    warning: consider adding a `;` to the last statement for consistent formatting
       --> tests/ffi/module.rs:125:17
        |
    125 |                 __c_take_trivial(d.as_mut_ptr())
        |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `__c_take_trivial(d.as_mut_ptr());`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

    warning: consider adding a `;` to the last statement for consistent formatting
       --> tests/ffi/module.rs:141:17
        |
    141 |                 __c_take_trivial_ns_ref(g as *const G as *const ::cxx::core::ffi::c_void)
        |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `__c_take_trivial_ns_ref(g as *const G as *const ::cxx::core::ffi::c_void);`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

    warning: consider adding a `;` to the last statement for consistent formatting
       --> tests/ffi/module.rs:151:17
        |
    151 |                 __c_take_trivial_ns(g.as_mut_ptr())
        |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `__c_take_trivial_ns(g.as_mut_ptr());`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

    warning: consider adding a `;` to the last statement for consistent formatting
       --> tests/ffi/module.rs:167:17
        |
    167 |                 __c_take_opaque_ref(e as *const E as *const ::cxx::core::ffi::c_void)
        |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `__c_take_opaque_ref(e as *const E as *const ::cxx::core::ffi::c_void);`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

    warning: consider adding a `;` to the last statement for consistent formatting
       --> tests/ffi/module.rs:203:17
        |
    203 |                 __c_take_opaque_ns_ref(e as *const F as *const ::cxx::core::ffi::c_void)
        |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `__c_take_opaque_ns_ref(e as *const F as *const ::cxx::core::ffi::c_void);`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

    warning: consider adding a `;` to the last statement for consistent formatting
       --> tests/ffi/module.rs:296:17
        |
    296 |                 __ns_c_take_trivial(d.as_mut_ptr())
        |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `__ns_c_take_trivial(d.as_mut_ptr());`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#semicolon_if_nothing_returned

Author: dtolnay

macro/src/expand.rs

@@ -721,8 +721,10 @@ fn expand_cxx_function_shim(efn: &ExternFn, types: &Types) -> TokenStream {
         if efn.throws {
             expr = quote_spanned!(span=> ::cxx::core::result::Result::Ok(#expr));
         }
-    } else {
+    } else if efn.throws {
         expr = call;
+    } else {
+        expr = quote! { #call; };
     }
     let dispatch = quote_spanned!(span=> unsafe { #setup #expr });
     let visibility = efn.visibility;