Fix warnings new in xcode 9

sources/iTermProfilePreferencesBaseViewController.m

@@ -109,7 +109,7 @@
                               key:(NSString *)key
                              type:(PreferenceInfoType)type
                    settingChanged:(void (^)(id))settingChanged
-                           update:(BOOL (^)())update {
+                           update:(BOOL (^)(void))update {
     assert(self.delegate);
     return [super defineControl:control
                             key:key

sources/iTermRateLimitedUpdate.h

@@ -16,7 +16,7 @@
 - (void)invalidate;
 // Performs the block immediately, or perhaps after up to minimumInterval time.
-- (void)performRateLimitedBlock:(void (^)())block;
+- (void)performRateLimitedBlock:(void (^)(void))block;
 // A target/action version of the above.
 - (void)performRateLimitedSelector:(SEL)selector

sources/iTermRateLimitedUpdate.m

@@ -12,7 +12,7 @@
 @implementation iTermRateLimitedUpdate {
     // While nonnil, block will not be performed.
     NSTimer *_timer;
-    void (^_block)();
+    void (^_block)(void);
 }
 - (void)invalidate {
@@ -21,7 +21,7 @@
     _block = nil;
 }
-- (void)performRateLimitedBlock:(void (^)())block {
+- (void)performRateLimitedBlock:(void (^)(void))block {
     if (_timer == nil) {
         block();
         _timer = [NSTimer scheduledWeakTimerWithTimeInterval:self.minimumInterval
@@ -50,7 +50,7 @@
 - (void)performBlockIfNeeded:(NSTimer *)timer {
     _timer = nil;
     if (_block != nil) {
-        void (^block)() = _block;
+        void (^block)(void) = _block;
         _block = nil;
         block();
     }

sources/iTermRemotePreferences.m

@@ -111,7 +111,7 @@
             alert.informativeText = [NSString stringWithFormat:@"HTTP request failed: %@",
                                      [error localizedDescription] ?: @"unknown error"];
             [alert runModal];
-            return NO;
+            return nil;
         }
         // Write it to disk
@@ -125,7 +125,7 @@
             alert.informativeText = [NSString stringWithFormat:@"Error on file %@: %@", tempFile,
                                      [error localizedDescription]];
             [alert runModal];
-            return NO;
+            return nil;
         }
         remotePrefs = [NSDictionary dictionaryWithContentsOfFile:tempFile];

sources/iTermSemanticHistoryController.m

@@ -424,12 +424,12 @@ NSString *const kSemanticHistoryWorkingDirectorySubstitutionKey = @"semanticHist
 - (NSString *)bundleIdForDefaultAppForURL:(NSURL *)fileUrl {
     NSURL *appUrl = [[NSWorkspace sharedWorkspace] URLForApplicationToOpenURL:fileUrl];
     if (!appUrl) {
-        return NO;
+        return nil;
     }
     NSBundle *appBundle = [NSBundle bundleWithURL:appUrl];
     if (!appBundle) {
-        return NO;
+        return nil;
     }
     return [appBundle bundleIdentifier];
 }

sources/iTermTextExtractor.m

@@ -548,7 +548,7 @@ const NSInteger kLongMaximumWordLength = 100000;
 // Make characterAt: much faster when called with the same line number over and over again. Assumes
 // the line buffer won't be mutated while it's running.
-- (void)performBlockWithLineCache:(void (^)())block {
+- (void)performBlockWithLineCache:(void (^)(void))block {
     assert(!_shouldCacheLines);
     _shouldCacheLines = YES;
     block();

sources/iTermTipCardViewController.h

@@ -63,7 +63,7 @@
               originalCardFrame:(NSRect)originalCardFrame
              postAnimationFrame:(NSRect)postAnimationFrame
                  superviewWidth:(CGFloat)superviewWidth
-                          block:(void (^)())block;
+                          block:(void (^)(void))block;
 // Make two buttons share a row. Currently, this assumes a row has either 1 or
 // 2 buttons, and both titles must be for existing buttons.

sources/iTermTipCardViewController.m

@@ -452,7 +452,7 @@ static const CGFloat kMarginBetweenTitleAndBody = 8;
               originalCardFrame:(NSRect)originalCardFrame
              postAnimationFrame:(NSRect)postAnimationFrame
                  superviewWidth:(CGFloat)superviewWidth
-                          block:(void (^)())block {
+                          block:(void (^)(void))block {
     [CATransaction begin];
     [self retain];
     [CATransaction setCompletionBlock:^{

sources/iTermWarning.h

@@ -140,7 +140,7 @@ typedef void(^iTermWarningActionBlock)(iTermWarningSelection);
 @property(nonatomic, copy) NSString *cancelLabel;
 // If set then a "help" button is added to the alert box and this block is invoked when it is clicked.
-@property(nonatomic, copy) void (^showHelpBlock)();
+@property(nonatomic, copy) void (^showHelpBlock)(void);
 // Modally show the alert. Returns the selection.
 - (iTermWarningSelection)runModal;