CODEWITHSUNDEEP
command-line-interfaceshared-librariesposixcc
jagprog5
jagprog5

Reputation: 131

Are popular c compilers (gcc, clang, etc) not POSIX compliant?

Background

POSIX

The POSIX standard specifies what interface system utilities must have (amongst other things). For example, POSIX says that a conforming system must have a c compiler, and that it must use -I to include headers, etc.

Motivation

I created a lib which interfaces with C compilers, and I want to ensure that it will work with any c compiler, or at least those that are POSIX compliant.

Question

The POSIX standard says:

-G
    Create a shared library or create object files suitable for inclusion in such a shared library. Compilations shall be performed in a manner suitable for the creation of shared libraries (for example, by producing position-independent code). 
    ...

man gcc (v11) says:

       -G num
           Put definitions of externally-visible data in a small data section if that data is no bigger than
           num bytes.  The default value of num is 4 for any ARC configuration, or 8 when we have double
           load/store operations.

These two definitions for -G, unless I'm misunderstanding something, are entirely different.

What's going on here? Is gcc not POSIX compliant? Similarly for clang, which doesn't document a -G option, is clang also not POSIX compliant?

What's a POSIX compliant invocation for creating a shared object that also works with common c compilers?

Upvotes: 0

Views: 46

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