Fixes so the compiler can infer msg_send! return types

Currently, due to a quirk in Rust's type inference interacting with the
structure of the msg_send! macro, a () return type will be inferred when
the compiler cannot otherwise determine the return type. This behavior
is expected to change, and in the future could resolve to a ! return
type, which results in undefined behavior.

Linting has previously been added for this in rust-lang/rust#39216, but
it did not catch these cases due to SSheldon/rust-objc#62. An upcoming
version of objc will be fixed to stop hiding these errors, at which
point they will become compile errors.

This change fixes these errors and allows cocoa to compile with the
fixed version of objc.

cocoa/src/appkit.rs

@@ -549,7 +549,7 @@ pub trait NSPasteboard: Sized {
 
 impl NSPasteboard for id {
     unsafe fn releaseGlobally(self) {
-        msg_send![self, releaseGlobally];
+        msg_send![self, releaseGlobally]
     }
 
     unsafe fn clearContents(self) -> NSInteger {
@@ -1547,11 +1547,11 @@ impl NSWindow for id {
     }
 
     unsafe fn setTabbingMode_(self, tabbingMode: NSWindowTabbingMode) {
-        msg_send![self, setTabbingMode: tabbingMode];
+        msg_send![self, setTabbingMode: tabbingMode]
     }
 
     unsafe fn addTabbedWindow_ordered_(self, window: id, ordering_mode: NSWindowOrderingMode) {
-        msg_send![self, addTabbedWindow:window ordered: ordering_mode];
+        msg_send![self, addTabbedWindow:window ordered: ordering_mode]
     }
 
     unsafe fn toggleTabBar_(self, sender: id) {
@@ -2977,7 +2977,7 @@ impl NSButton for id {
         msg_send![self, initWithFrame:frameRect]
     }
     unsafe fn setBezelStyle_(self, style: NSBezelStyle) {
-        msg_send![self, setBezelStyle:style];
+        msg_send![self, setBezelStyle:style]
     }
     unsafe fn setTitle_(self, title: id /* (NSString*) */) {
         msg_send![self, setTitle:title]
@@ -2990,7 +2990,7 @@ impl NSButton for id {
     }
 
     unsafe fn setAction_(self, selector: objc::runtime::Sel /* (Instance method *) */) {
-        msg_send![self, setAction:selector];
+        msg_send![self, setAction:selector]
     }
 }
 
@@ -3589,10 +3589,10 @@ impl NSTextField for id {
         msg_send![self, initWithFrame:frameRect]
     }
     unsafe fn setEditable_(self, editable: BOOL) {
-        msg_send![self, setEditable:editable];
+        msg_send![self, setEditable:editable]
     }
     unsafe fn setStringValue_(self, label: id) {
-        msg_send![self, setStringValue:label];
+        msg_send![self, setStringValue:label]
     }
 }
 

cocoa/src/quartzcore.rs

@@ -889,7 +889,7 @@ impl CALayer {
     #[inline]
     pub fn set_should_rasterize(&self, flag: bool) {
         unsafe {
-            msg_send![self.id(), setShouldRasterize:(flag as BOOL)];
+            msg_send![self.id(), setShouldRasterize:(flag as BOOL)]
         }
     }
 
@@ -1459,7 +1459,7 @@ impl CARenderer {
                 Some(ref layer) => layer.id(),
                 None => nil,
             };
-            msg_send![self.id(), setLayer:layer];
+            msg_send![self.id(), setLayer:layer]
         }
     }
 

cocoa/tests/foundation.rs

@@ -100,7 +100,7 @@ mod foundation {
                 let mut_components: id = msg_send![components, mutableCopy];
                 let mut iter = mut_components.iter();
                 iter.next();
-                msg_send![mut_components, removeObjectAtIndex:1];
+                let () = msg_send![mut_components, removeObjectAtIndex:1];
                 iter.next();
             }
         }