Eclipse CDT indexer does not know C++11 containers

Question

I configured a C++11 project in Eclipse CDT to use gcc-4.7. It is not the default compiler on my system, which does not support C++11. In order for compilation to work, I need to pass the flag -std=c++11 and also include the following header path: /usr/local/Cellar/gcc/4.7.2/gcc/include/c++/4.7.2

Whenever I use C++11 container types like std::unordered_set or std::unordered_map, the CDT indexer complains: Symbol unordered_set could not be resolved. How can I tell the indexer to resolve these symbols correctly?

This is how I have configured my indexer:

enter image description here

As far as I understand the settings, the indexer is supposed to use the compiler settings from the currently active build configuration. Compilation works fine, so why doesn't indexing, too?

selyunin · Answer 1 · 2016-12-15T09:28:47.650

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Setting up **__GXX_EXPERIMENTAL_CXX0X__** does not help in my case (Jul 2014, Eclipse Kepler 20130919, Ubuntu 12.04).

To fix C++11 syntax highlighting go to:

Project Properties --> C/C++ General --> Paths and Symbols --> Symbols --> GNU C++

and overwrite the symbol (i.e. add new symbol):

__cplusplus

with value

201103L

UPDATED: If you use newer version of Eclispe (as of 2016) and still experience the same problem, try value (as pointed by jose.diego):

201402L

Make sure that indexer is enabled in Project settings (C/C++ general --> Indexer)

Then reindex (Project --> C/C++ Index --> Rebuild)

if the problem still persist reindex once again. It should work now.

edited Dec 15 '16 at 09:28

answered Jul 08 '14 at 08:44

selyunin

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Although it works with plain helloworlds, it doesn't work with makefile project. Any suggestions? – nitrocaster Jul 26 '14 at 21:49
solved it for me too, setting up __GXX_EXPERIMENTAL_CXX0X__ didn't work for me either – tschale Feb 06 '15 at 16:43
@nitrocaster see http://stackoverflow.com/a/24628885/52074 which I tested and it works for makefile projects too. – Trevor Boyd Smith Apr 01 '15 at 15:11
Worked for me too. Only added a __cplusplus symbol with value 201103L. I don't need to do the enabling indexer step. Previously, setting up GXX_EXPERIMENTAL_CXX0X didn't work for me either – linbianxiaocao Jul 19 '15 at 16:43
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setting __cplusplus to 201402L was the only thing that solved my issue in Eclipse Mars2 – thinlizzy Apr 09 '16 at 16:47
Works for Neon too – xvan Aug 02 '16 at 16:01
None of these settings are working for me. Neon / g++ 5.4.0 -- I suspect the g++ version is more relevant than the Eclipse version. – Periata Breatta Nov 29 '16 at 08:56

Galik · Answer 2 · 2014-07-08T12:10:20.400

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I solved this problem recently after some lucky googling.

Click on your project and right-click->Properties

Select "C/C++ General -> Processor Include Paths, Macros etc..."

Select the "Providers" tab

Deselect everything except "CDT User Setting Entries" and "CDT GCC Built-in Compiler Settings"

Click on "CDT GCC Built-in Compiler Settings"

Deselect "Use global provider shared between projects"

Edit the box at the bottom labeled "Command to get compiler specs"

Insert into the command -std=c++11 so it looks something like this:

${COMMAND} -std=c++11 -E -P -v -dD "${INPUTS}"

Click Apply and Okay.

enter image description here

That worked for me. You probably need to re-index the project.

edited Jul 08 '14 at 12:10

answered Jul 08 '14 at 09:57

Galik

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re - "probably need to re-index": my tests show "you must re-index" – Trevor Boyd Smith Apr 01 '15 at 15:09
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I tested this with makefile projects and this solution works. – Trevor Boyd Smith Apr 01 '15 at 15:10
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It was suffice for me to simple move `GCC Built-int Compiller Settings` to the very top of this list – Vasilly.Prokopyev Jun 26 '15 at 22:34
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You can also set this as workspace configuration, so C++11 will be enabled in all your new projects. – Alessandro Pezzato Jul 21 '15 at 12:48
@Vasilly.Prokopyev thanks! In fact, just disabling "contributed pathentry containers" in that list did the trick for me. – Nickolay Nov 15 '15 at 22:57
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Really thanks, only working list of steps that really works – Payne Nov 04 '17 at 17:51
As of today, doesn't work with `-std=c++2x` but works a treat with `-std=c++17` – Blair Houghton Apr 14 '18 at 15:35
@BlairHoughton That is down to the version of the compiler you are using. It doesn't have anything to do with eclipse itself. Also I think the switch will be `-std=c++2a`. – Galik Apr 14 '18 at 15:38

score 35 · Accepted Answer · edited Oct 31 '13 at 03:54

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As described in this forum post:

http://www.eclipse.org/forums/index.php/mv/msg/282618/

right-click the project and go to "Properties" C/C++ General -> Paths and Symbols -> Symbols -> GNU C++.
Click "Add..." and paste __GXX_EXPERIMENTAL_CXX0X__ into "Name" and leave "Value" blank. Hit Apply, do whatever it asks you to do, then hit OK.

edited Oct 31 '13 at 03:54

Etherealone

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answered Jun 16 '13 at 11:08

user2485710

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This answer was correct was older release. But going ahead (with newer versions of Eclipse) @selyuni's answer works. Trying the answer which was once a correct solution is only a waste of time. Maybe SOF can change the policy to put more upvoted answers on top than just the correct answer. :-) – Coder Feb 18 '18 at 17:59
@VikasGoel: Does this depend on the Eclipse version, or on the compiler/library version, or both? – einpoklum Apr 07 '18 at 22:27
@einpoklum - only Eclipse version – Coder Apr 09 '18 at 19:56

score 9 · Answer 4 · edited Dec 14 '16 at 17:15

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Or go to:

C/C++ Build->Discovery Options->GCC C++ Compiler
add your flags to the Compiler invocation arguments. like -std=c++11 -m32
Clear discovered entrys now: click on Clear
rebuild the project

After that ALL symbols will be updated with correct values and the indexer should work as intended

edited Dec 14 '16 at 17:15

Danh

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answered Jun 16 '13 at 17:17

user1283078

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This resolved the problem for me. Note that on Eclipse Kepler it is preferences -> C/C++ -> Build -> Settings -> Discovery Tab. It is also mentioned on the eclipse community forums here: http://www.eclipse.org/forums/index.php/mv/msg/373462/909018/#msg_909018 . Really unintuitive and hard to find! – UmaN Aug 24 '13 at 15:56
the m32 was just to show that you can add any arguments you like. windows headers for example have significant differences between 32 and 64 bit. So if building a 32bit app on a compiler that uses 64bit mode by default you add -m32 so the indexer is aware of that and parses the correct headers – user1283078 Nov 07 '13 at 13:50
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The discovery tab seems to be gone in eclipse mars. – stu Feb 11 '16 at 15:10
Discovery Options has been deprecated and no longer appears in the menus. [Eclipse help documents it here.](https://help.eclipse.org/luna/index.jsp?topic=%2Forg.eclipse.cdt.doc.user%2Freference%2Fcdt_u_prop_build_discovery.htm) – Blair Houghton Apr 14 '18 at 15:41

score 6 · Answer 5 · answered Jun 28 '14 at 21:59

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The workaround for me, with a project that uses an external builder, was to define the symbol:

__cplusplus

with the value:

201403

in the project's: Paths and Symbols -> Symbols/GNU C++.

This worked in eclipse Kepler CDT Version: 8.3.0.201402142303.

answered Jun 28 '14 at 21:59

Afilu

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Worked for me (using a custom Makefile). – Canella Sep 23 '14 at 20:46

score 3 · Answer 6 · edited Apr 08 '17 at 02:11

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See this guide:

C/C++ Build->Settings->GCC C++ Compiler->Dialect
Choose "ISO C++11 (-std=c++0x)" in "language standard"
Apply and OK
Rebuild the project and it works:)

edited Apr 08 '17 at 02:11

Fabio says Reinstate Monica

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answered Apr 08 '17 at 01:46

Yojiaku

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caot · Answer 7 · 2018-06-26T14:05:15.047

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The follows works in Eclipse C/C++ Oxygen.2 with gcc-5.5.0

Eclipse Properties->C/C++ Build->Settings->GCC C++ Compiler->Dialect->Other dialect flags: -std=c++17

Don't pick up anything in the Language standard dropdown list.

edited Jun 26 '18 at 14:05

answered Jun 25 '18 at 16:51

caot

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q0987 · Answer 8 · 2019-01-28T20:54:14.713

The following configuration helps me to fix the issue indicated in the original question.

Environment: Eclipse(Oxygen.3a Release (4.7.3a)), Cygwin64. In case you have a different version of Cygwin, you can find similar directories as follows.

Step 1: Make sure you have the following two directories:

   C:\cygwin64\lib\gcc\x86_64-pc-cygwin\7.4.0\include
   C:\cygwin64\lib\gcc\x86_64-pc-cygwin\7.4.0\include\c++

If you don't see the above two directories, please launch your Cygwin setup program and install gcc-core, gcc-g++ and libgcc1.

Step 2: Copy the directory C:\cygwin64\lib\gcc\x86_64-pc-cygwin\7.4.0\include to C:\cygwin64\usr if you don't see above two include directories.

Step 3: Go to Project Property->C/C++ General->Paths and Symbols Make sure you can see the following two paths are listed

   C:\cygwin64\usr\include
   C:\cygwin64\usr\include\c++

Step 4: Property->C/C++ Build/Settings/ Choose Cygwin PE Parser

Step 5: Property->C/C++ Build/Tool Chain Editor Choose Cygwin GCC

Step 6: Property->C/C++ General/Indexer Choose Enable indexer

Step 7: Project->C/C++ Index->Rebuild

Now your eclipse should be able to see the C++11 types.

Eclipse CDT indexer does not know C++11 containers

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