[PATCH] D156565: Diagnose use of VLAs in C++ by default

[Nathan Chancellor via Phabricator via cfe-commits]

nathanchance added a comment.

Is it expected that this introduces a warning for C code, as the commit message and tests appear to only affect C++? A trivial example from the Linux kernel:

https://elixir.bootlin.com/linux/v6.5.8/source/tools/lib/bpf/btf_dump.c#L1678

  #include <stddef.h>
  #include <stdio.h>
  #include <string.h>
  
  void foo(char *orig_name, char **cached_name, size_t dup_cnt)
  {
          const size_t max_len = 256;
          char new_name[max_len];
  
          snprintf(new_name, max_len, "%s___%zu", orig_name, dup_cnt);
          *cached_name = strdup(new_name);
  }



  $ clang -std=gnu89 -Wall -fsyntax-only test.c
  test.c:8:16: warning: variable length arrays are a C99 feature [-Wvla-extension]
      8 |         char new_name[max_len];
        |                       ^~~~~~~
  1 warning generated.


Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D156565