Mac/Cocoa/QtCreator: problem using objective C "boxed expression"

crystalidea

Hello!

I have Qt Creator 3.6 + XCode 5. Accessing array object using brackets syntax doesn't work! (though it should work starting from Xcode 4.5)

Example:

#if __has_feature(objc_boxed_expressions)
NSArray *array = @[@"value1", @"value2"];
id object = array[1];
#endif

Result: error: initializing 'id' with an expression of incompatible type 'NSArray'
id object = array[1];
^ ~~~~~~~~

Anyone has a solution? Thank you.

SGaist

Hi,

Where did you put that code ? How did you integrate it in your project ?

crystalidea

Hi, sgaist!

The .mm file is added into the .pro file via macx { OBJECTIVE_SOURCES += ...}
Trying to compile piece of code from Sparkle:

#import "SUOperatingSystem.h"

@implementation SUOperatingSystem

+ (NSOperatingSystemVersion)operatingSystemVersion
{
#if __MAC_OS_X_VERSION_MIN_REQUIRED < 101000
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wselector"
    if (![NSProcessInfo instancesRespondToSelector:@selector(operatingSystemVersion)])
#pragma clang diagnostic pop
    {
        NSOperatingSystemVersion version = { 0, 0, 0 };
        NSURL *coreServices = [[NSFileManager defaultManager] URLForDirectory:NSCoreServiceDirectory inDomain:NSSystemDomainMask appropriateForURL:nil create:NO error:nil];
        NSArray *components = [[NSDictionary dictionaryWithContentsOfURL:[coreServices URLByAppendingPathComponent:@"SystemVersion.plist"]][@"ProductVersion"] componentsSeparatedByString:@"."]; // **PROBLEM!**
        version.majorVersion = components.count > 0 ? [components[0] integerValue] : 0; // **PROBLEM!**
        version.minorVersion = components.count > 1 ? [components[1] integerValue] : 0; // **PROBLEM!**
        version.patchVersion = components.count > 2 ? [components[2] integerValue] : 0; // **PROBLEM!**
        return version;
    }
#endif
    return [[NSProcessInfo processInfo] operatingSystemVersion];
}

@end

SGaist

Are you looking for the information you can get from QSysInfo ?

crystalidea

I'd really love to know why I can't write such a simple code:

#if __has_feature(objc_boxed_expressions)
NSArray *array = @[@"value1", @"value2"];
id object = array[1];
#endif

Because I'm going to compile more .mm files in the project. It's strange and now a matter of honor to discover what's going on.

SGaist

Tested that one in a simple main.mm file, no problem except the warning about unused object variable.

crystalidea

Sure it's a valid code. Something is wrong with compiler/IDE setup I guess.

SGaist

Did you try to build a minimal dummy project with it ?

crystalidea

Yes, created the following test.mm file

void f()
{
    #if __has_feature(objc_boxed_expressions)
    NSArray *array = @[@"value1", @"value2"];
    id object = array[1];
    #endif
}

22:59:40: Running steps for project untitled...
22:59:40: Configuration unchanged, skipping qmake step.
22:59:40: Starting: "/usr/bin/make" 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -c -pipe -arch i386 -g -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk -mmacosx-version-min=10.7 -Wall -W -DQT_QML_DEBUG -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -I../untitled -I. -I/usr/local/Qt-5.5.1/lib/QtWidgets.framework/Headers -I/usr/local/Qt-5.5.1/lib/QtGui.framework/Headers -I/usr/local/Qt-5.5.1/lib/QtCore.framework/Headers -I. -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/System/Library/Frameworks/OpenGL.framework/Headers -I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/System/Library/Frameworks/AGL.framework/Headers -I. -I/usr/local/Qt-5.5.1/mkspecs/macx-clang-32 -F/usr/local/Qt-5.5.1/lib ../untitled/test.mm -o test.o
../untitled/test.mm:4:5: error: unknown type name 'NSArray'
    NSArray *array = @[@"value1", @"value2"];
    ^
../untitled/test.mm:4:22: error: NSArray must be available to use Objective-C array literals
    NSArray *array = @[@"value1", @"value2"];
                     ^
2 errors generated.
make: *** [test.o] Error 1
22:59:40: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project untitled (kit: Desktop)
When executing step "Make"
22:59:40: Elapsed time: 00:00.

Clang version:

Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)
Target: x86_64-apple-darwin15.3.0
Thread model: posix

SGaist

Are you linking against the Cocoa framework ?

crystalidea

Not sure if it's a problem of linker. (compiler?) here's the .pro file, added the framework line, no success

#-------------------------------------------------
#
# Project created by QtCreator 2016-02-01T22:56:54
#
#-------------------------------------------------

QT       += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = untitled
TEMPLATE = app
SOURCES += main.cpp\
        mainwindow.cpp
HEADERS  += mainwindow.h
FORMS    += mainwindow.ui
OBJECTIVE_SOURCES += \
    test.mm

LIBS += -framework Cocoa

PS.
Also added the line
#import <Foundation/Foundation.h>

To remove "NSArray must be available to use Objective-C array literals" error