It is important to have testing jobs that build the project with both
-Werror and -O2 to keep the code clean. -O2 is needed, because some
compiler warnings are available only after extra analyzing passes that
are disabled with lesser optimization levels.

The first attempt to add -Werror for release testing jobs was made in
da505ee7 ('Add -Werror for CI (1.10
part)'), but it mistakely doesn't enable -O2 for RelWithDebInfoWError
build. It is possible to fix it in this way:

 | --- a/cmake/compiler.cmake
 | +++ b/cmake/compiler.cmake
 | @@ -113,10 +113,14 @@ set (CMAKE_C_FLAGS_DEBUG
 |      "${CMAKE_C_FLAGS_DEBUG} ${CC_DEBUG_OPT} -O0")
 |  set (CMAKE_C_FLAGS_RELWITHDEBINFO
 |      "${CMAKE_C_FLAGS_RELWITHDEBINFO} ${CC_DEBUG_OPT} -O2")
 | +set (CMAKE_C_FLAGS_RELWITHDEBINFOWERROR
 | +    "${CMAKE_C_FLAGS_RELWITHDEBINFOWERROR} ${CC_DEBUG_OPT} -O2")
 |  set (CMAKE_CXX_FLAGS_DEBUG
 |      "${CMAKE_CXX_FLAGS_DEBUG} ${CC_DEBUG_OPT} -O0")
 |  set (CMAKE_CXX_FLAGS_RELWITHDEBINFO
 |      "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} ${CC_DEBUG_OPT} -O2")
 | +set (CMAKE_CXX_FLAGS_RELWITHDEBINFOWERROR
 | +    "${CMAKE_CXX_FLAGS_RELWITHDEBINFOWERROR} ${CC_DEBUG_OPT} -O2")
 |
 |  unset(CC_DEBUG_OPT)

However I think that a build type (and so `tarantool --version`) should
not show whether -Werror was passed or not. So I have added
ENABLE_WERROR CMake option for that. It can be set like so:

 | cmake . -DCMAKE_BUILD_TYPE=RelWithDebInfo -DENABLE_WERROR=ON

Enabled the option in testing Travis-CI jobs with the RelWithDebInfo
build type. Deploy jobs don't include it as before.

Fixed all -Wmaybe-uninitialized and -Wunused-result warnings. A few
notes about the fixes:

* net.box does not validate received data in general, so I don't add a
  check for autoincrement IDs too. Set the ID to INT64_MIN, because this
  value is less probably will appear here in a normal case and so is the
  best one to signal a user that something probably going wrongly.
* xrow_decode_*() functions could read uninitialized data from
  row->body[0].iov_base in xrow_on_decode_err() when printing a hex code
  for a row. It could be possible when the received msgpack was empty
  (row->bodycnt == 0), but there were expected keys (key_map != 0).
* getcwd() is marked with __attribute__((__warn_unused_result__)) in
  glibc, but the buffer filled by this call is not used anywhere and so
  just removed.
* Vinyl -Wmaybe-uninitialized warnings are false positive ones.

Added comments and quotes into .travis.yml to ease reading. Removed
"test" word from the CentOS 6 job name, because we don't run tests on
this distro (disabled in the RPM spec).

Fixes #4178.

Fixed Mojave Mac build with setting MACOSX_DEPLOYMENT_TARGET environment
variable for LuaJIT's Makefile. This variable specifies the minimum
version of OS X on which the target binaries are to be deployed.

The reason why we need to set MACOSX_DEPLOYMENT_TARGET to at least 10.6
is that 10.4 SDK (which is set by default in LuaJIT's Makefile) is not
longer included in Mac OS X Mojave 10.14.

See also https://github.com/LuaJIT/LuaJIT/issues/484

We already set -Wl,-macosx_version_min,10.6 (-macosx_version_min and
MACOSX_DEPLOYMENT_TARGET are synonymous), but it affects only a linker.
We possibly should remove -macosx_version_min, because it superseded by
MACOSX_DEPLOYMENT_TARGET, but it should be done with verification that
the original problem really fixed by the new way to set a deployment
target. This is not part of this patch.

Removed virtualenv usage in CI for OS X (so pip just installs packages
into a system), because OS X Mojave 10.14 does not offer virtualenv by
default.

Fixed #3797

The build time error is confusing for users. The patch makes the error
explicit and moves it to the cmake stage.

Follow up of #3070.

LLVM changes the API in the compiler-rt commit [1]. According to the
date of the commit it is between clang-3.9.0 and clang-3.9.1.

[1]: https://github.com/llvm-mirror/compiler-rt/commit/0b95585616bd28fc0b738289bcc5f7887d7c304e

Fixes #3070.

FreeBSD 10.4 has no libdl.so.

Fixes #3750.

Added -DENABLE_LTO=ON/OFF cmake option, OFF by default.

LTO speeds up cpu-intensive workloads by up to 20% (see [1] and [2]).

Requirements to enable LTO:

- cmake >= 3.9;
- Linux: ld.bfd / ld.gold from binutils >= 2.31 (or later 2.30)
  (gold >= 1.15);
- Mac OS: xcode >= 8 (earlier versions are not tested).

The requirement of the recent ld version is due to bug with exporting
symbols from dynamic list when LTO is enabled, see [3].

Note: -Wlto-type-mismatch on GCC (enabled by default with -flto) gives
namy warnings. Filed [4] to investigate it.

Note: LuaJIT will be compiled w/o LTO despite the option set, filed [5].

[1]: https://github.com/tarantool/tarantool/wiki/performance-research
[2]: https://gist.github.com/Khatskevich/31a2da6ab46ce903120e7a03d65966db
[3]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84901
[4]: https://github.com/tarantool/tarantool/issues/3742
[5]: https://github.com/tarantool/tarantool/issues/3743

Closes #3117

f

Added MAKE_BUILD_TYPE=RelWithDebInfoWError option, which means enabling
-DNDEBUG=1, -O2 and -Wall -Wextra -Werror. This ensures we have clean
release build without warnings.

Fixed found -Wunused-variable and -Wunused-parameter warnings.

Part of #3238.

The problem is that clang does not support -Wno-cast-function-type flag.
It is the regression from 8c538963.

Follow up of #3685.
Fixes #3701.

Since addition of -fopenmp to compiler also means
addition of -lgomp to the link stage, pass -fno-openmp
to the linking stage in case of static build. In that
case OMP functions are statically linked into libmisc.

Also, emit error if trying to perform static build using
clang.

A possibility to build tarantool with included library dependencies.
Use the flag -DBUILD_STATIC=ON to build statically against curl, readline,
ncurses, icu and z.
Use the flag -DOPENSSL_USE_STATIC_LIBS=ON to build with static
openssl

Changes:
  * Add FindOpenSSL.cmake because some distributions do not support the use of
  openssl static libraries.
  * Find libssl before curl because of build dependency.
  * Catch all bundled libraries API and export then it in case of static
  build.
  * Rename crc32 internal functions to avoid a name clash with linked libraries.

Notes:
  * Bundled libyaml is not properly exported, use the system one.
  * Dockerfile to build static with docker is included

Fixes #3445

Fixing build under FreeBSD:
Undefined symbol "iconv_open"
Add compile time build check with FindICONV.cmake
and a wrapper to import relevant symbol names with include file.

Closes #3441

No more `include/yaml.h` and `lib/libyaml_static.a` installs.

closes gh-3547

If curl does not have SSL support, don't panic, honor CURL_FIND_REQUIRED
variable, and panic only if it's set.

Correct the grammar in the error message.

On MAC several old curl versions don't support SSL by default.
Try to check it and print error message if so.

Close #3065

Fast ucol_strcollUTF8 function was introduced in ICU 50. In older
ICU versions we have to use slower ucol_strcollIter with properly
initialized UTF8 iterators.

Fix #2820

The option is '-DENABLE_BUNDLED_ZSTD' and defaults to ON.

There are two goals of making this conditional, both related to building
Tarantool on Gentoo Linux from an ebuild:

* Avoid bundled ZStd building issue w/o pay to investivage it.
* Allow user to choose between system and bundled library.

Apple's version of libcurl is outdated and buggy.
Use libcurl from homebrew by default.

Closes #2772

Speed up zstd as much as possible.

Update zstd submodule to v1.3.1 version.

The fallthrough attribute with a null statement serves as a fallthrough
statement. It hints to the compiler that a statement that falls through
to another case label, or user-defined label in a switch statement is
intentional and thus the -Wimplicit-fallthrough warning must not trigger.
The fallthrough attribute may appear at most once in each attribute list,
and may not be mixed with other attributes. It can only be used in a switch
statement (the compiler will issue an error otherwise), after a preceding
statement and before a logically succeeding case label, or user-defined
label.

https://developers.redhat.com/blog/2017/03/10/wimplicit-fallthrough-in-gcc-7/

getopt_long() is available on all supported platforms.
Get rid of legacy gopt and use getopt_long().

Incompatible changes:

 * `tarantool --version --no-such-option` printed
    "unrecognized option '--no-such-option'", now it displays version.
    `tarantool --no-such-option --version` still prints an error message.

Needed for #1265

Add an option to enable LuaJIT's GC64 mode and enable this option
by default on OS X.

Closes #2643

LuaJIT has some configuration flags which can be switched via
-DLUAJIT_USE_OPTION defines, e.g. USE_ASAN or USE_VALGRIND.
Before this patch these definitions were added by CMake to XCFLAGS
variable and passed to LuaJIT's Makefile. However, some of these
flags also affect the content of lj_xxx.h internal header files,
which were included by Tarantool (see utils.c) and compiled WITHOUT
proper flags. This situation might lead to inconsistent ABI between
compiled libluajit.a and Tarantool.

This patch adds all LUAJIT_USE_XXX defines to CMake's COMPILE_FLAGS
in order to enable these flags globally, then parses COMPILE_FLAGS
and adds them to LuaJIT's XCFLAGS.

Needed for #2643

Add missing #include <trivia/config.h>

Fixes #2635

Remove libbfd from dependencies and use libunwind for stack traces.

Closes #2103

Now module.h is autogenerated automatically on `make all`
if one or more source header files have changed.

Closes #2481

Now open MP sort is used for any size of an array.
For small arrays it's an overkill and even can cause overhead
due to thread pool creation.

Invoke open MP sort only for big arrays and use old good
single-thread qsort for small arrays.

Fix #2431

In context of #2312
See #1906

* Supress warnings in third-party code.
* Fix false-positive "variable may be used uninitialized in this function"
* Add MAYBE_UNUSED to variables used only for assertions
* Fix compilation on GCC 6.3.0 20170205
* Fix compilation on GCC 7.0.1 20170316
* Fix compilation on Clang 5.0.0-svn294894-1

Add missing -isysroot flag for LuaJIT on macOS.

Fixes #2091

* Move platform-specific defines to tt_pthread.h
* Set sched.coro.stack only with ENABLE_ASAN

Please note that pthread_getattr_np() + pthread_attr_destroy()
combination is totaly broken on Glibc 2.12 (RHELL 6.x).

Fixes #2085

Sophia was an experimental storage engine in 1.6.x.
Please use 'vinyl' engine in Tarantool 1.7 instead.

Closes #2040