structured logging is great, but logging fails with variables ?

Oh, that’s interesting. Consider this tiny program:

#include <string>
#include <os/log.h>

void example(std::string& str)
{
    os_log_info(OS_LOG_DEFAULT, "'%s'", str.c_str());
    os_log_info(OS_LOG_DEFAULT, "'%{public}s'", str.c_str());
}

int main(int argc, const char * argv[]) {
    std::string s = "Hello Cruel World!";
    example(s);
    return 0;
}

The first log entry comes out as '' whereas the second is 'Hello Cruel World!'.

This relates to a key system log feature: the ability to selective log private info. By default a string is considered private, and thus you need to annotate it with {public} to have it show up in the log. Console renders a private string as <private>, but it seems that Xcode missed that memo.

This is very misleading and I encourage you to file a bug against Xcode. Please post your bug number, just for the record.

Oh, and this has nothing to do with C++ per se. The same problem affects C and probably Objective-C as well. It doesn’t affect Swift, probably because Swift interacts with the system log in a very different way than the C-based languages.

ps If you’re interesting in the system log, check out Your Friend the System Log.

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Ah yes. That makes a lot more sense. I did finally discover the privacy tag in the documentation, but you’re right it’s pretty misleading not to see that <private> marker. I’ll file a report as soon as I can.

By the way, is there no way to set the default to public? I just wanted to replace 100s of printfs with os_log to take advantage of the new Xcode 15 console features.

I was going to do a hack solution in which I preprocessed strings and replaced %s with %{public}s,

#define MY_LOG(fmt_, …) \
os_log_info(OS_LOG_DEFAULT, gen_public_fmt(fmt_), __VA_ARGS__)

but os_log asserts on non-constant format strings.

is there no way to set the default to public?

The system log has a huge number of configuration options. Again, I’m gonna point you to Your Friend the System Log for the links to the actual documentation.

The best approach to use depends on a bunch of factors: your platform; if it’s macOS, whether you’re building a command-line tool or an app; and so on. However, just as one specific example, if you’re targeting macOS and install a configuration profile with a com.apple.system.logging payload containing this:

<key>Subsystems</key>
<dict>
    <key>com.example.apple-samplecode.Test731121</key>
    <dict>
        <key>DEFAULT-OPTIONS</key>
        <dict>
            <key>Enable-Private-Data</key>
            <true/>
        </dict>
    </dict>
</dict>

that overrides the private nature of any log entries in the com.example.apple-samplecode.Test731121 subsystem. I ran a quick test of that today and that does seem to resolve the issue with Xcode 15 beta that brought you here.

If you’re targeting iOS, or a macOS app or appex, you should be able to do the same thing with the OSLogPreferences property in your Info.plist.

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

The bug report information is here: FB12279185 (os_log fails to display <private> in Xcode 15's console when an argument is private and instead displays nothing, which is misleading)

How would I set all logging public? The docs suggest that I have to set every subsystem and category to be public. Maybe I want the default logger to be public or several or all of them.

How would I set all logging public?

See Recording Private Data in the System Log.

IMPORTANT Pay heed to the warning that I just added to that post.

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Thanks.

By the way, I noticed: -jumping to a file and line number doesn’t seem to work in C/C++ — only Swift and Objective C(++). -structured logging doesn’t seem to give me any metadata at all when hovering over the console output when I build for iPadOS/iOS — only macOS seems to work.

jumping to a file and line number doesn’t seem to work in C/C++

That’s seems eminently bugworthy.

structured logging doesn’t seem to give me any metadata at all … when I build for iPadOS/iOS

How are you testing this?

I tried Xcode 15b1 as follows:

• With its iOS 17 simulator. This worked as I’d expect.

• With an iOS 16 beta device. This didn’t work; I saw old school non-structured log output.

That suggests that this requires iOS 17 beta. I could confirm that by testing with the iOS 16 simulator and an iOS 17 beta device, but I’m unable to run either of those tests at this exact moment.

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—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Ah I guess the iPasOS version needs to be 17. For the C/C++, I assumed the issue had something to do with a dependency on the objc runtime or something, which would explain why the click to jump wasn’t working. —or maybe the compiler’s confused by all of my cross-language craziness. :) I’ll double-check.

@eskimo I've submitted another bug report regarding the missing line jumping outside of swift: FB12340549