Detect C functions that can be declared with static linkage

[mptre]

Currently limited to C as I assume the anonymous namespace should be favored for C++.

[chrchr-github]

clang-tidy has misc-use-internal-linkage: https://clang.llvm.org/extra/clang-tidy/checks/misc/use-internal-linkage.html
Not sure if we should attempt to duplicate that functionality.

[mptre]

On Mon, Dec 23, 2024 at 12:45:45AM -0800, chrchr-github wrote: clang-tidy has `misc-use-internal-linkage`: https://clang.llvm.org/extra/clang-tidy/checks/misc/use-internal-linkage.html Not sure if we should attempt to duplicate that functionality.

Although, clang-tidy is less effective as it cannot detect functions used in a single TU while it's prototype resides in a header file.

[firewave]

There is also the compiler warning -Wmissing-prototypes.

[firewave]

There is also the reverse case to be detected - prototypes which do not have an implementation - see https://trac.cppcheck.net/ticket/10670.

[danmar]

Although, clang-tidy is less effective as it cannot detect functions used in a single TU while it's prototype resides in a header file.

It makes sense to me I think we should have this. Please finish it. 👍

There is also the compiler warning -Wmissing-prototypes.

That does not warn when there is a prototype but the function is only used in 1 TU.

[mptre]

The failing tests have been resolved by now. Anything else that needs to be addressed before this can be merged?