Eclipse complains: "Invalid overload of 'endl'" - but code does compile

Question

I've written an operator<< for my templated class:

template<class T>
std::ostream& operator<<(std::ostream &strm, const MyClass<T> &obj)

and when I write

cout << myClassInstance << endl;

this compiles and runs, but my Eclipse CDT says:

Invalid overload of 'endl'

Why does it tell me that?

(I use Eclipse CDT Kepler on Win7 64bit with Cygwin gcc)

This probably would be an indexing problem. Try rebuilding the index and check your index settings under `Window` →　`Preferences` → `C/C++` → `Indexer` — Jesse Good, Jul 16 '13 at 10:58
@JesseGood: Settings seem fine, and re-indexing doesn't help. — einpoklum, Jul 16 '13 at 11:00
There is not enough information to give any more assistance. — Jesse Good, Jul 16 '13 at 11:04
@PlasmaHH: But that doesn't 'entitle' it to mark an error; at most a warning... — einpoklum, Jul 16 '13 at 13:07
@einpoklum: You can always ignore it. If your argument was valid, then it should never mention anything as an error since it could be wrong... — PlasmaHH, Jul 16 '13 at 13:23
I get the same error when compiling C++ code in Eclipse using MinGW's compiler. However when I compile it at console with MinGW's C++ compiler (4.8.1) I get no error. So it should be about indexing as Jesse Good said. — phoad, Oct 20 '13 at 03:36
I can only reproduce this in CDT 9 by having an unrelated syntax error higher up in the code. In my case, I had tried to call an auto variable I intended to be an integer as if it were a method. — hoodaticus, Jul 26 '17 at 15:06

score 14 · Answer 1 · edited Oct 20 '13 at 11:52

The problem is (as I understand) with the Code Analysis tool of Eclipse.

If you like, you can avoid this message by completely disabling the check for invalid overloads:

Open Preferences Window (from main menu Window\Preferences)
Go to C/C++ -> Code Analysis
At the right pane see "Syntax and Semantic Errors" | "Invalid Overload"
Un-check the check-box
Press OK

Then you will see that the error is disappeared.

However it might skip the real errors and it might be better to let it stay checked but use "Customize Selected" button to change its severity level.

I have changed it to "WARNING" instead of "ERROR".

As @plasmaHH said, I think Eclipse could not parse the C++ correctly in this scenario.

frmdstryr · Answer 2 · 2013-09-17T00:43:39.073

13

I was getting this error as well.

//print the value
cout << rt->element << endl;

A simple change to:

//print the value
cout << rt->element;
cout << endl;

removed the error for me. New to C++, but it seems like you also need to overload << for myClassInstance. If you want to use the original method.

edited Sep 17 '13 at 00:43

answered Sep 17 '13 at 00:29

frmdstryr

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Correct, element's class would need to overload `operator<<()`. – Brandlingo Jan 28 '14 at 15:59

score 12 · Accepted Answer · answered Feb 16 '14 at 03:39

12

This is indeed a bug with Eclipse CDT (more specifically Eclipse's Code Analysis tool CODAN). There is bug report and it has been fixed and should be available from CDT 8.3.0 which is due February 2014.

answered Feb 16 '14 at 03:39

iNFINITEi

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I'm running CDT 8.4 and am still seeing this problem. – MrMas Aug 08 '14 at 16:08
1

Same problem in 8.4.0.201406111759 – Yaroslav Bulatov Aug 31 '14 at 20:52
1

Same issue in 8.5, extremely annoying. – vsoftco Nov 07 '14 at 03:49
4

Still there in 2017! – Rexcirus Jun 20 '17 at 14:21
1

Almost in 2018 and still... :( – waas1919 Sep 14 '17 at 11:12
Still seeing the same in Version: 2021-12 (4.22.0). – sancho.s ReinstateMonicaCellio Jan 31 '22 at 13:06

score 2 · Answer 4 · edited Jun 08 '18 at 10:27

2

You can try to add the comment // @suppress("Invalid overload") as in the following line:

cout << "SOME TEXT" << endl; // @suppress("Invalid overload")

This will suppress that problem, keeping still the capability to detect other possible invalid overloads somewhere in the code.

Btw, if you click on the bug on the left side of the editor, Eclipse will do that for you. (Eclipse: Oxygen).

edited Jun 08 '18 at 10:27

Suraj Rao

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answered Jun 08 '18 at 10:26

dsenic2000

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Nice info! It is not useful for my collaborative projects though, since it somewhat taints the code for those who don't use Eclipse. – sancho.s ReinstateMonicaCellio Jan 31 '22 at 13:07

score 1 · Answer 5 · answered Jul 07 '16 at 13:59

I know this is an old question, but I encountered a similar issue with Eclipse Neon ( v4.6.0 ) on Ubuntu 16.04 LTS

My code was:

stringstream l_Buffer;
l_Buffer << "test" << endl;
const char* l_Temp = l_Buffer.str().c_str();

eclipse reported 3 errors:

Invalid overload of 'endl'
Method 'c_str' could not be resolved
Method 'str' could not be resolved

I tried a bunch of stuff, rebuilding the index, messing around with the Code Analysis tool (configuring it the same way as my build), and writing std::endl... All to no avail.

The thing that fixed all three errors in my case was by replacing

stringstream l_Buffer;

with:

basic_stringstream<char> l_Buffer;

Note: Ctrl + Clicking stringstream leads you to its typedef definition in iosfwd.h which is:

/// Class for @c char mixed input and output memory streams.
typedef basic_stringstream<char>    stringstream;

Make this into a new question please (and link to this one in the writeup). — einpoklum, Jul 07 '16 at 15:09

score 0 · Answer 6 · answered Oct 30 '14 at 10:21

even though it's an old question, for future visitors, the thing made the error go away for me was simply use fully qualified cout and endl:

std::cout << thing << std::endl

Not sure why Eclipse complains there, as it compiles and runs fine without namespaces in that particular place in code.

score 0 · Answer 7 · answered Oct 30 '14 at 10:41

0

try putting std::endl instead of endl or overload within your class as a member:

template<class T>
MyClass<T>& operator<<( std::ostream&(*f)(std::ostream&) ) {
  std::cout << f;
  return *this;
}

answered Oct 30 '14 at 10:41

Dr. Debasish Jana

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I wasn't asking for advice on avoiding the message, but for an explanation of why this is happening... – einpoklum Oct 31 '14 at 14:39

score 0 · Answer 8 · answered Jul 04 '15 at 08:55

This keeps happening to me when I upgrade the eclipse. It has all the strange error of Member declaration not found, invalid overload of endl, Invalid arguments .... Now I figured out that it is the info in the workspace and old projects were not up-to-date for the new CDT codan.

For someone has the same problem after upgrading the eclipse or copying workspaces to new platform. It is actually very easy to solve: Project->C/C++ index->Rebuild. After it is done, all strange errors will go away.

Eclipse complains: "Invalid overload of 'endl'" - but code does compile

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