[vcpkg] Clean up CMake build system (#10834)

There are quite a few changes to the CMake build system packaged up into
one set here:
* Added `toolsrc/cmake/utilities.cmake`, which contains the following:
  * `vcpkg_detect_compiler` -- get the name of the C++ compiler, as one
    of {gcc, clang, msvc}
  * `vcpkg_detect_standard_library` -- get the name of the standard
    library we're linking to, as one of {libstdc++, libc++, msvc-stl}
  * `vcpkg_detect_std_filesystem` -- figure out how to link and call
    into C++17's filesystem; whether one needs to link to `stdc++fs` or
    `c++fs`, and whether to use `<filesystem>` or
    `<experimental/filesystem>`.
* Added a `VCPKG_WARNINGS_AS_ERRORS`, split off from
  `VCPKG_DEVELOPMENT_WARNINGS`, which allows one to use the development
  warnings without passing -Werror
* Rename `DEFINE_DISABLE_METRICS` to `VCPKG_DISABLE_METRICS` -- the
  former will now print a deprecation message and set the latter.
* Now, print a deprecation message on `WERROR`; it doesn't do anything
  since the behavior it requested is now the default.
* Pass `-std=c++17` if the compiler allows it, instead of `-std=c++1z`
* Do some code movement
* Pass `USE_STD_FILESYSTEM` if possible, instead of only on minGW
  * Renamed to `VCPKG_USE_STD_FILESYSTEM`

Additionally, we now pass `/W4` in Debug mode on x86 in the Visual
Studio build system; this brings it in line with the CMake build system,
and the x64 Visual Studio build system.

And finally, we make some minor code changes to support compiling in
VCPKG_DEVELOPMENT_WARNINGS mode.

1 files changed, 8 insertions, 25 deletions

diff --git a/scripts/bootstrap.sh b/scripts/bootstrap.sh
index bf8de7897..7959c4465 100644
--- a/scripts/bootstrap.sh
+++ b/scripts/bootstrap.sh
@@ -199,11 +199,10 @@ fetchTool()
 
 selectCXX()
 {
-    __output=$1
-
     if [ "x$CXX" = "x" ]; then
-        CXX=g++
-        if which g++-9 >/dev/null 2>&1; then
+        if which g++ >/dev/null 2>&1; then
+            CXX=g++
+        elif which g++-9 >/dev/null 2>&1; then
             CXX=g++-9
         elif which g++-8 >/dev/null 2>&1; then
             CXX=g++-8
@@ -212,24 +211,8 @@ selectCXX()
         elif which g++-6 >/dev/null 2>&1; then
             CXX=g++-6
         fi
+        # If we can't find g++, allow CMake to do the look-up
     fi
-
-    gccversion="$("$CXX" -v 2>&1)"
-    gccversion="$(extractStringBetweenDelimiters "$gccversion" "gcc version " ".")"
-    if [ "$gccversion" -lt "6" ]; then
-        echo "CXX ($CXX) is too old; please install a newer compiler such as g++-7."
-        echo "On Ubuntu try the following:"
-        echo "  sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y"
-        echo "  sudo apt-get update -y"
-        echo "  sudo apt-get install g++-7 -y"
-        echo "On CentOS try the following:"
-        echo "  sudo yum install centos-release-scl"
-        echo "  sudo yum install devtoolset-7"
-        echo "  scl enable devtoolset-7 bash"
-        return 1
-    fi
-
-    eval $__output="'$CXX'"
 }
 
 # Preparation
@@ -246,10 +229,10 @@ if [ "$os" = "osx" ]; then
     if [ "$vcpkgAllowAppleClang" = "true" ] ; then
         CXX=clang++
     else
-        selectCXX CXX || exit 1
+        selectCXX
     fi
 else
-    selectCXX CXX || exit 1
+    selectCXX
 fi
 
 # Do the build
@@ -257,8 +240,8 @@ buildDir="$vcpkgRootDir/toolsrc/build.rel"
 rm -rf "$buildDir"
 mkdir -p "$buildDir"
 
-(cd "$buildDir" && CXX=$CXX "$cmakeExe" .. -DCMAKE_BUILD_TYPE=Release -G "Ninja" "-DCMAKE_MAKE_PROGRAM=$ninjaExe" "-DBUILD_TESTING=OFF" "-DVCPKG_DEVELOPMENT_WARNINGS=Off" "-DDEFINE_DISABLE_METRICS=$vcpkgDisableMetrics" "-DVCPKG_ALLOW_APPLE_CLANG=$vcpkgAllowAppleClang") || exit 1
-(cd "$buildDir" && "$cmakeExe" --build .) || exit 1
+("$cmakeExe" -B "$buildDir" -S toolsrc -DCMAKE_BUILD_TYPE=Release -G "Ninja" "-DCMAKE_MAKE_PROGRAM=$ninjaExe" "-DBUILD_TESTING=OFF" "-DVCPKG_DEVELOPMENT_WARNINGS=OFF" "-DVCPKG_WARNINGS_AS_ERRORS=OFF" "-DVCPKG_DISABLE_METRICS=$vcpkgDisableMetrics" "-DVCPKG_ALLOW_APPLE_CLANG=$vcpkgAllowAppleClang") || exit 1
+("$cmakeExe" --build "$buildDir") || exit 1
 
 rm -rf "$vcpkgRootDir/vcpkg"
 cp "$buildDir/vcpkg" "$vcpkgRootDir/"