tree 7fba77fdab1630f41ff78c2c8f582f41c01c5ffd
parent 2a23247420094c8f576dd6ec30978fe418355336
author John Bowler <jbowler@acm.org> 1705341024 -0800
committer John Bowler <jbowler@acm.org> 1705341024 -0800

pngfix: del workround for GCC7.1 -Wstrict-overflow

Previously pngfix had been made warning-free in GCC7.1 by marking auto
variables (volatile).  This prevented the arithmetic optimizations which
caused warnings from GCC7.1 with higher values -Wstrict-overflow=<n>

GCC has moved on a lot since 7.1 and pngfix.c now compiles with just one
warning using -Wstrict-overflow=5.  The change includes a change to make
this go away by performing the rearrangement GCC was using in the code:

   i == ndigits-1

becomes:

   i+1 == ndigits

i is initialized to ndigits and has been decremented at least once so
this is fine.

Test, configure:

  CFLAGS="-Wall -Wextra -Wno-maybe-uninitialized -Wstrict-overflow=5" \
    ../configure --enable-werror
  make
  make cehck

Test, cmake:

  cmake ..
  make
  make test

Signed-off-by: John Bowler <jbowler@acm.org>