Re: PVS-Studio Warning

[Roberto Ierusalimschy <roberto@...>]

> I am compiling Lua 5.1.5 using Visual Studio with PVS-Studio plugin.
> He is complaining about the use of fs pointer in the function close_func
> (lparser.c:358)
> 
> The fs pointer is used before it was verified against nullptr.
> 
>   lparser.cpp
>  358 FuncState *fs = ls->fs;
>      Proto *f = fs->f;
>      removevars(ls, 0);
>      luaK_ret(fs, 0, 0);  /* final return */
>      luaM_reallocvector(L, f->code, f->sizecode, fs->pc, Instruction);
>      ...
>  378 if (fs) anchor_token(ls);
> 
> I am not sure. But maybe anchor_token will always be reached.
> The if is useless.

Sure it is:

  ls->fs = fs->prev;        <<< would crash if fs == NULL
  /* last token read was anchored in defunct function; must reanchor it */
  if (fs) anchor_token(ls);

Probably the test should be 'if (ls->fs)', but it does not seem to
be necessary anyway.

Thank you for the report.

-- Roberto