 //===----------------------------------------------------------------------===//
 
 #if os(OSX) || os(iOS) || os(watchOS) || os(tvOS)
-public let SIG_DFL: sig_t? = nil
-public let SIG_IGN = unsafeBitCast(1, sig_t.self)
-public let SIG_ERR = unsafeBitCast(-1, sig_t.self)
-public let SIG_HOLD = unsafeBitCast(5, sig_t.self)
+public var SIG_DFL: sig_t? { return nil }
+public var SIG_IGN: sig_t { return unsafeBitCast(1, sig_t.self) }
+public var SIG_ERR: sig_t { return unsafeBitCast(-1, sig_t.self) }
+public var SIG_HOLD: sig_t { return unsafeBitCast(5, sig_t.self) }
+#else
+internal var _ignore = _UnsupportedPlatformError()
 #endif
 

  return _swift_Darwin_openat(fd, path, oflag, mode)
}


public let	S_IFMT   = mode_t(0o170000)
public let	S_IFIFO  = mode_t(0o010000)
public let	S_IFCHR  = mode_t(0o020000)
public let	S_IFDIR  = mode_t(0o040000)
public let	S_IFBLK  = mode_t(0o060000)
public let	S_IFREG  = mode_t(0o100000)
public let	S_IFLNK  = mode_t(0o120000)
public let	S_IFSOCK = mode_t(0o140000)
public let	S_IFWHT  = mode_t(0o160000)

public let	S_IRWXU  = mode_t(0o000700)
public let	S_IRUSR  = mode_t(0o000400)
public let	S_IWUSR  = mode_t(0o000200)
public let	S_IXUSR  = mode_t(0o000100)

public let	S_IRWXG  = mode_t(0o000070)
public let	S_IRGRP  = mode_t(0o000040)
public let	S_IWGRP  = mode_t(0o000020)
public let	S_IXGRP  = mode_t(0o000010)

public let	S_IRWXO  = mode_t(0o000007)
public let	S_IROTH  = mode_t(0o000004)
public let	S_IWOTH  = mode_t(0o000002)
public let	S_IXOTH  = mode_t(0o000001)

public let	S_ISUID  = mode_t(0o004000)
public let	S_ISGID  = mode_t(0o002000)
public let	S_ISVTX  = mode_t(0o001000)

public let	S_ISTXT  = S_ISVTX
public let	S_IREAD  = S_IRUSR
public let	S_IWRITE = S_IWUSR
public let	S_IEXEC  = S_IXUSR


//===----------------------------------------------------------------------===//
// unistd.h

//===----------------------------------------------------------------------===//
// MacTypes.h
//===----------------------------------------------------------------------===//

public var noErr: OSStatus { return 0 }

/// The `Boolean` type declared in MacTypes.h and used throughout Core
/// Foundation.
