[Libguestfs] total warning-removal for daemon/

The warnings in daemon were aggravating and risky for development (too easy to miss new ones) so I spent some time last week and today working on removing them. The first patch gets us down to almost no warnings with the original -Wall setting. That was by far the hardest part. Once I'd done that, I enabled nearly all of gcc's warnings via gnulib's warnings and manywarnings modules and the code added to configure.ac in the final patch. I did it that way so that we can still bisect without compile failure, even when using the new --enable-gcc-warnings option. I.e., fix all warnings, *and then* add the code that turns on the new -W options along with -Werror. I suggest that developers always configure with --enable-gcc-warnings. The 2nd patch is self explanatory. 0003 adds some omitted "\n"-after ";" in emitted code. The remaining changes address new warnings exposed by using all of the new -W options. Among them, there were some real bugs. 0006 is a portability bug, at least. 0007 probably doesn't matter much in practice, but I looked because of a warning about ignored write return value. 0011 is definitely a bug. It was highlighted via the sign-vs-unsigned warning. 751 0001-adjust-const-pointers-to-avoid-warnings.patch 33 0002-python-avoid-_POSIX_C_SOURCE-redefinition-warning.patch 39 0003-generator.ml-emit-slightly-prettier-code.patch 50 0004-avoid-warning-about-old-style-no-param-function-defi.patch 39 0005-command.c-avoid-shadowing-a-global-function.patch 41 0006-guestfsd.c-don-t-perform-arithmetic-on-void-pointers.patch 42 0007-daemon-zero-don-t-ignore-write-and-close-errors.patch 41 0008-wc-blockdev-avoid-warnings-about-discarding-const-qu.patch 48 0009-sfdisk.c-fallocate.c-use-a-string-literal-as-format.patch 26 0010-daemon.h-avoid-warning-about-possible-noreturn-funct.patch 27 0011-guestfsd-don-t-ignore-failed-write-to-socket.patch 35 0012-xattr.c-avoid-warning-about-comparison-between-signe.patch 125 0013-daemon-enable-Werror-and-many-gcc-warnings-when-enab.patch $ diffstat 00* b/daemon/Makefile.am | 3 - b/daemon/augeas.c | 2 b/daemon/blockdev.c | 2 b/daemon/command.c | 12 ++-- b/daemon/configure.ac | 61 ++++++++++++++++++++++++ b/daemon/daemon.h | 6 +- b/daemon/debug.c | 2 b/daemon/df.c | 4 - b/daemon/fallocate.c | 2 b/daemon/guestfsd.c | 20 ++++---- b/daemon/lvm.c | 12 +--- b/daemon/m4/gnulib-cache.m4 | 5 +- b/daemon/proto.c | 3 - b/daemon/sfdisk.c | 10 ++-- b/daemon/sync.c | 3 - b/daemon/wc.c | 3 - b/daemon/xattr.c | 11 ++-- b/daemon/zero.c | 19 +++++-- b/fish/fish.c | 6 +- b/fish/fish.h | 6 +- b/src/generator.ml | 108 ++++++++++++++++++++++++-------------------- daemon/blockdev.c | 2 daemon/command.c | 9 +-- daemon/daemon.h | 3 - daemon/guestfsd.c | 7 +- daemon/sfdisk.c | 5 -- src/generator.ml | 12 ++-- 27 files changed, 206 insertions(+), 132 deletions(-)