Re: Bad-sounding schur.cc compilation warnings.

[Daniel J Sebald]

On 05/02/2016 12:59 PM, Daniel J Sebald wrote:
> I saw the following warnings during compilation.  They look kind of
> troublesome:
>
> /home/sebald/octave/octave/octave/liboctave/numeric/schur.cc: In member
> function 'octave_idx_type schur<T>::init(const T&, const string&, bool)
> [with T = Matrix; octave_idx_type = int; std::string =
> std::basic_string<char>]':
> /home/sebald/octave/octave/octave/liboctave/numeric/schur.cc:176:19:
> warning: variable 'selector' might be clobbered by 'longjmp' or 'vfork'
> [-Wclobbered]
>     double_selector selector = 0;

Hmm, very strange construct.  double_selector is a function type:

typedef octave_idx_type (*double_selector) (const double&, const double&);

so I can see why the complaint pertains to long-jumping and forking.  I 
don't quite understand the issue though.  The intention is to select the 
function that will be run for selecting:

  double_selector selector = 0;
  if (ord_char == 'A' || ord_char == 'a')
    selector = select_ana<double>;
  else if (ord_char == 'D' || ord_char == 'd')
    selector = select_dig<double>;
  else
    selector = 0;

(Note that the "double_selector selector = 0;" and third case "selector 
= 0" is redundant.)  The prototype has two input variables, but the 
template assigned to it has just <double>, but that doesn't seem like a 
program flow issue.  Does the type-definition for the (*double_selector) 
need a "long" specification somehow?

Dan