CLANG10 interesting warning !

[Domingo Alvarez Duarte]

Hello !

When compiling with CLANG10 we get this warning:

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 clang -DHAVE_CONFIG_H -I. -I.. -I. -I./amd -I./api -I./bflib 
-I./colamd -I./draft -I./env -I./intopt -I./minisat -I./misc -I./mpl 
-I./npp -I./proxy -I./simplex -I./zlib -g -O3 -march=native -DNEBUG 
-DWITH_SPLAYTREE -flto 
-I/home/mingo/local/clang-10/lib/clang/10.0.0/include 
-I/home/mingo/local/clang-10/include -I/home/mingo/local/include -MT 
libglpk_la-spxprim.lo -MD -MP -MF .deps/libglpk_la-spxprim.Tpo -c 
simplex/spxprim.c  -fPIC -DPIC -o .libs/libglpk_la-spxprim.o
simplex/spxprim.c:1526:7: warning: add explicit braces to avoid dangling 
else [-Wdangling-else]
      else
      ^
1 warning generated.

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And looking at the code it's not clear the intention of the stack of 
"if" statements accumulated by previous bug fixes:

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#if 1 /* 23/VI-2017 */
      /* dual solution may be invalidated due to long step */
      if (csa->d_st)   ////!!!!!! it seems that this "if" should have 
braces !!!!!!!
#endif
#if 0 /* 11/VI-2017 */
      if (spx_update_d(lp, d, csa->p, csa->q, trow, tcol) <= 1e-9)
#else
      if (spx_update_d_s(lp, d, csa->p, csa->q, &csa->trow, &csa->tcol)
         <= 1e-9)
#endif
      {  /* successful updating */
         csa->d_st = 2;
         if (csa->phase == 1)
         {  /* adjust reduced cost of xN[q] in adjacent basis, since
             * its penalty coefficient changes (see below) */
            d[csa->q] -= c[head[csa->p]];
         }
      }
      else
      {  /* new reduced costs are inaccurate */
         csa->d_st = 0;
      }
      if (csa->phase == 1)
      {  /* xB[p] leaves the basis replacing xN[q], so set its penalty
          * coefficient to zero */
         c[head[csa->p]] = 0.0;
      }
      /* update steepest edge weights for adjacent basis, if used */

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Cheers !