'strncpy' output truncated warning with gcc 10

[babelouest]

While trying to build liboauth2 for Debian unstable with gcc 10, I have the following compiling error:

In function 'oauth2_strndup',
    inlined from 'oauth2_strdup' at src/util.c:545:9:
src/util.c:535:2: error: 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length [-Werror=stringop-truncation]
  535 |  strncpy(dst, src, len);
      |  ^~~~~~~~~~~~~~~~~~~~~~
src/util.c: In function 'oauth2_strdup':
src/util.c:545:35: note: length computed here
  545 |  return oauth2_strndup(src, src ? strlen(src) : 0);
      |                                   ^~~~~~~~~~~
In function 'oauth2_strndup',
    inlined from 'oauth2_strdup' at src/util.c:545:9,
    inlined from '_oauth2_stradd4' at src/util.c:555:9:
src/util.c:535:2: error: 'strncpy' destination unchanged after copying no bytes [-Werror=stringop-truncation]
  535 |  strncpy(dst, src, len);
      |  ^~~~~~~~~~~~~~~~~~~~~~
In function 'oauth2_strndup',
    inlined from 'oauth2_strdup' at src/util.c:545:9,
    inlined from 'oauth2_nv_list2s' at src/util.c:611:14:
src/util.c:535:2: error: 'strncpy' output truncated before terminating nul copying 1 byte from a string of the same length [-Werror=stringop-truncation]
  535 |  strncpy(dst, src, len);
      |  ^~~~~~~~~~~~~~~~~~~~~~

A quick workaround is to replace strncpy with memcpy on src/util.c:545 or to disable the warning just for this case:

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wstringop-truncation"
    strncpy(dst, src, len);
#pragma GCC diagnostic pop

[babelouest]

Closed by #13