Is Circular Dependency a bug or a feature?

I am porting some modern, usually Linux based, libraries to an archaic OS that does not have Autotools or Cmake. I've noticed a tendency to tolerate circular dependency that is detrimental to my link process.

A module A uses a function from module B and module B is using a function from module A. Apparently, Autotools know how to resolve this without warnings. I have to do a two pass linking.

My question is, is that a correct way to program in C? Is Circular Dependency a bug or a feature?

Thank you
ZA

Function prototypes (function declarations) in a .h file included in both module .c files. A good book on the C programming language will explain this and other features you need to know especially when working with old C code.

That is not normally called a Circular Dependency.
And, using headers in C and C++ to prototype functions is a great feature of C and C++.

Tim S.

But in linkage time, especially doing static link, this causes the link to fail and I need to run a two ass link
ZA

Quote:

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Originally Posted by zatlas1

A module A uses a function from module B and module B is using a function from module A. Apparently, Autotools know how to resolve this without warnings. I have to do a two pass linking.

My question is, is that a correct way to program in C? Is Circular Dependency a bug or a feature?

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It's something you should avoid if possible, but is sometimes necessary. It's not strictly a C issue, it's a linker issue, but C allows mutal dependencies for functions.

A case where it is necessary is if you are doing recursive descent parsing. The function parse_expression() will call the function parse_factor(), and "(expression)" is allowed as a factor. So parse_factor() has to call parse_expression().

What Compiler/Linker are you using?

Some linkers can list the libraries more than once to avoid the errors.
Others have a set of linker option that tells the linker to go though the library list more than once.
I forget which options GCC uses; might be both or neither.

Example library listed more than once.

Code:

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-llibA -llibB -llibA

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Tim S.

Quote:

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Originally Posted by stahta01

What Compiler/Linker are you using?

Some linkers can list the libraries more than once to avoid the errors.
Others have a set of linker option that tells the linker to go though the library list more than once.
I forget which options GCC uses; might be both or neither.
...
Tim S.

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Did I say an archaic OS...

classic z/OS on IBM z Series.

ZA

Quote:

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Originally Posted by zatlas1

Did I say an archaic OS...

classic z/OS on IBM z Series.

ZA

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Maybe gcc for z/OS?

Quote:

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Originally Posted by Sir Galahad

Maybe gcc for z/OS?

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Not a choice for a few reasons. I am using IBM C/C++ compiler for better or worse.
ZA

Quote:

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Originally Posted by zatlas1

I am porting some modern, usually Linux based, libraries to an archaic OS that does not have Autotools or Cmake. I've noticed a tendency to tolerate circular dependency that is detrimental to my link process.
ZA

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Sorry for going off-topic from your question, but I'd really like to know what you're using in place of autotools and cmake on that system. Are you just using standard GNU make or a similar make tool? Have you looked at CDetect? I've used it with make on AIX.

As far as circular dependencies with libraries (like with pkg-config requiring glib which requires pkg-config), I try to avoid these situations whenever possible. For instance, I replaced pkg-config with pkgconf which has no circular dependencies.