error #20: identifier is undefined

stevenh

Guru 19995 points

Hello,

The compiler is generating an error #20: identifier is undefined error because it can't find a structure type definition (i.e typedef struct { }).

The compilation output in the console window shows the include file (that has the typedef struct ...) is being included. I have checked all path names thoughly and checked all relavent files and I am not able to find out why it can't find the typedef.

I am using compiler version 6.4.0. I have tried compiler versions (i.e. 6.1.0, and 6.3.0) with the same result.

What compiler command line options would help me discovery what is causing the issue.

Stephen

over 11 years ago

0 stevenh over 11 years ago

Guru 19995 points

Ok, I fixed the problem, but I am not sure why it was causing the problem.

The header file that has the typedef struct (call it header file #1) is included in another header file (call it header file #2). Also, header file #1 includes header file #2, which causes a recursive situation.

Each of the include files have an header guard, so why should this recursive situation be a problem.

Also, why can't the compiler warn about this kind of recursive situation?

Stephen

0 Archaeologist over 11 years ago in reply to stevenh

TI__Guru* 84225 points

In order to fully diagnose the problem, we would need to see the definitions in file #1 and file #2 which are mutually dependent.

Note that include header guards mean the file is effectively completely blank every time it is included past the first time, so it's not a cure-all for header file dependence order.

My guess is that you need a third header in your project which includes the truly common definitions, and then file #1 and file #2 can include that instead.

The TI compiler will only warn you about cases where you have infinite recursive inclusion. If you have a header file guard, you don't have infinite recursive inclusion.

0 George Mock over 11 years ago

TI__Guru**** 240575 points

stevenh said:
What compiler command line options would help me discovery what is causing the issue.

The option --gen_acp_raw is often useful in situations where preprocessing is causing confusion. It is documented in the compiler manual. I'm not sure which compiler you are using, so this links to all of them.

Thanks and regards,

-George

0 stevenh over 11 years ago in reply to Archaeologist

Guru 19995 points

Thanks.

Yes, a common header file would be better.

Stephen

0 stevenh over 11 years ago in reply to George Mock

Guru 19995 points

Thanks George.

I didn't see that option in the CCS compilier or advanced compilier options. Where is it located?

Stephen

0 George Mock over 11 years ago in reply to stevenh

TI__Guru**** 240575 points

Here's a screen shot from CCS 5.4. Hope this helps ...

-George

0 stevenh over 11 years ago in reply to George Mock

Guru 19995 points

Thanks.

0 Mikael Kengmegne Noubi over 8 years ago in reply to stevenh

Prodigy 20 points

Hi,

Stephen, I have unfortunately got the same problem... can you please tell me explicitly what you did with both header files...?

Mikael

0 Mikael Kengmegne Noubi over 8 years ago in reply to stevenh

Prodigy 20 points

have you just decouple the header...?

Mikael

0 stevenh over 8 years ago in reply to Mikael Kengmegne Noubi

Guru 19995 points

Hello Mikael,

I can't remember what I did to fix the problem. Maybe i moved the structure to a separate header file and then included that header file in the other two header files.

Stephen

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error #20: identifier is undefined