[GitHub] [incubator-nuttx] gustavonihei edited a comment on pull request #4124: add #undef for some libc function

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gustavonihei edited a comment on pull request #4124:
URL: https://github.com/apache/incubator-nuttx/pull/4124#issuecomment-879100326


   > --wrap is a gcc specific feature, even clang doesn't support yet:
   > https://stackoverflow.com/questions/31476632/what-is-the-equivalent-of-gnus-wrap-linker-flag-in-os-x-linker
   > And then violate https://github.com/apache/incubator-nuttx/blob/master/INVIOLABLES.md:
   
   Good point. I was unaware that LLVM's Linker did not implement it.
   
   @xiaoxiang781216 Have you considered renaming the standard functions as `nx_<function>` (e.g. `nx_malloc`) and defining `<function>` as a weak symbol when `CONFIG_MM_DEBUG` is enabled? Then the weak `malloc` by default only calls `nx_malloc` and any available checkers could simply provide a `malloc` implementation. Something like:
   ```c
   #ifdef CONFIG_MM_DEBUG
   weak_function FAR void *malloc(size_t size)
   {
     return nx_malloc(size);
   }
   
   FAR void *nx_malloc(size_t size)
   #else
   FAR void *malloc(size_t size)
   {
     /* Default implementation */
   }
   #endif
   ```
   
   This approach would have the advantage of being explicit of what this is intending to achieve, but at the cost of performing this mass renaming of target functions.
   That was I was referring to when I said that we wouldn't need to rely on the preprocessor.


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