Address fallout from -Wsign-conversion work on Windows

[ngie-eign]

Some Windows users builds were broken after a0d60be. This change
addresses the lingering -Wsign-conversion issues with those platforms
by adding some missing static_cast calls as needed.

Signed-off-by: Enji Cooper [email protected]

[ngie-eign]

CC: @elcabesa, @elv-peter, @gennadiycivil. This fixes Cygwin compilation for sure and the one other Windows issue reported, but it doesn't necessarily fix all Windows issues. I will need more help chasing any remaining platform issues down, e.g., directions for setting up Visual Studio, MingW, etc, to reproduce the issues seen in the environment.

[elcabesa]

my setup is quite easy:

1. download mingw installer: https://sourceforge.net/projects/mingw-w64/files/latest/download
2. install it, ( i choosed 8.1.0, x86_64, posix, seh, 0)
3. download clang from their official page: http://releases.llvm.org/8.0.0/LLVM-8.0.0-win64.exe
   4)install it
4. create a batch file containing the following code and run it (please customize the paths ):

echo off
set PATH=F:\clang\LLVM\bin;F:\x86_64-8.1.0-posix-seh-rt_v6-rev0\mingw64\bin;%PATH%
"C:\WINDOWS\system32\cmd.exe"

now you have a console and you can run make :)
to use clang set those variables:

set CC=clang --target=x86_64-mingw32
set CXX=clang++ --target=x86_64-mingw32

to run make you have to type mingw32-make.

if you want to use cmake you have to install it. To create the makefiles from cmake on window you can use those instructions ( i created another batch):

set CC=clang --target=x86_64-mingw32
set CXX=clang++ --target=x86_64-mingw32
mkdir build
cd build 
cmake  -DCMAKE_BUILD_TYPE=Release -G "MinGW Makefiles" .. 
mingw32-make

[elcabesa]

your code still has some problems: one more implicit conversion:

[  1%] Building CXX object googletest-build/googletest/CMakeFiles/gtest.dir/src/gtest-all.obj
In file included from F:\vajolet22\build\googletest-src\googletest\src\gtest-all.cc:41:
F:/vajolet22/build/googletest-src/googletest\src/gtest.cc:1694:43: error: implicit conversion changes signedness: 'long'
      to 'DWORD' (aka 'unsigned long') [-Werror,-Wsign-conversion]
                                          hr,  // the error
                                          ^~
1 error generated.
mingw32-make[2]: *** [googletest-build\googletest\CMakeFiles\gtest.dir\build.make:63: googletest-build/googletest/CMakeFiles/gtest.dir/src/gtest-all.obj] Error 1
mingw32-make[1]: *** [CMakeFiles\Makefile2:105: googletest-build/googletest/CMakeFiles/gtest.dir/all] Error 2
mingw32-make: *** [Makefile:129: all] Error 2

[elcabesa]

you have to change gtest.cc:1694 to:
static_cast<DWORD>(hr), // the error

[elv-peter]

@ngie-eign This was the compile error I was getting (with the Emscripten toolchain as you can see):

cd /p/e/git/ws/elv-crypto/build/emscripten/googletest/googletest-build/googletest && /p/e/git/ws/elv-toolchain/dist/darwin-10.14/share/emsdk/emscripten/1.38.12/em++  -DELV_INCLUDE_EMSCRIPTEN_ @CMakeFiles/gtest.dir/includes_CXX.rsp -DNDEBUG -O2   -Wall -Wshadow -Werror -Wconversion -DGTEST_HAS_PTHREAD=1 -fexceptions -W -Wpointer-arith -Wreturn-type -Wcast-qual -Wwrite-strings -Wswitch -Wunused-parameter -Wcast-align -Wchar-subscripts -Winline -Wredundant-decls -Wall -Wextra -pedantic -Wno-unused-parameter -std=c++11 -o CMakeFiles/gtest.dir/src/gtest-all.cc.o -c /p/e/git/ws/elv-crypto/build/emscripten/googletest/googletest-src/googletest/src/gtest-all.cc
In file included from /p/e/git/ws/elv-crypto/build/emscripten/googletest/googletest-src/googletest/src/gtest-all.cc:41:
/p/e/git/ws/elv-crypto/build/emscripten/googletest/googletest-src/googletest/src/gtest.cc:1952:21: error: implicit conversion
      changes signedness: 'const wchar_t' to 'wint_t' (aka 'unsigned int') [-Werror,-Wsign-conversion]
    left = towlower(*lhs++);
           ~~~~~~~~ ^~~~~~
/p/e/git/ws/elv-crypto/build/emscripten/googletest/googletest-src/googletest/src/gtest.cc:1953:22: error: implicit conversion
      changes signedness: 'const wchar_t' to 'wint_t' (aka 'unsigned int') [-Werror,-Wsign-conversion]
    right = towlower(*rhs++);
            ~~~~~~~~ ^~~~~~
2 errors generated.

This fixes it:

left = towlower(static_cast<wint_t>(*lhs++));
right = towlower(static_cast<wint_t>(*rhs++));