Avoid passing Linux-like flags on Windows distros

.evergreen/compile.sh

@@ -69,7 +69,6 @@ export CMAKE_BUILD_PARALLEL_LEVEL
 if command -V ccache 2>/dev/null; then
   export CMAKE_CXX_COMPILER_LAUNCHER=ccache
 
-
   # Allow reuse of ccache compilation results between different build directories.
   export CCACHE_BASEDIR CCACHE_NOHASHDIR
   CCACHE_BASEDIR="$(pwd)"
@@ -99,7 +98,7 @@ esac
 : "${cmake_examples_target:?}"
 
 # Create a VERSION_CURRENT file in the build directory to include in the dist tarball.
-python ./etc/calc_release_version.py > ./build/VERSION_CURRENT
+python ./etc/calc_release_version.py >./build/VERSION_CURRENT
 cd build
 
 cmake_flags=(
@@ -116,7 +115,7 @@ case "${OSTYPE:?}" in
 cygwin)
   case "${generator:-}" in
   *2015*) cmake_flags+=("-DBOOST_ROOT=C:/local/boost_1_60_0") ;;
-  *2017*|*2019*) cmake_flags+=("-DCMAKE_CXX_STANDARD=17") ;;
+  *2017* | *2019*) cmake_flags+=("-DCMAKE_CXX_STANDARD=17") ;;
   *)
     echo "missing explicit CMake Generator on Windows distro" 1>&2
     exit 1
@@ -147,7 +146,9 @@ cc_flags=()
 cxx_flags=()
 
 case "${OSTYPE:?}" in
-cygwin) ;;
+cygwin)
+  # Most compiler flags are not applicable to builds on Windows distros.
+  ;;
 darwin*)
   cc_flags+=("${cc_flags_init[@]}")
   cxx_flags+=("${cxx_flags_init[@]}" -stdlib=libc++)
@@ -162,35 +163,40 @@ linux*)
   ;;
 esac
 
-# Sanitizers overwrite the usual compiler flags.
-if [[ "${USE_SANITIZER_ASAN:-}" == "ON" ]]; then
-  cxx_flags=(
-    "${cxx_flags_init[@]}"
-    -D_GLIBCXX_USE_CXX11_ABI=0
-    -fsanitize=address
-    -O1 -g -fno-omit-frame-pointer
-  )
-fi
-if [[ "${USE_SANITIZER_UBSAN:-}" == "ON" ]]; then
-  cxx_flags=(
-    "${cxx_flags_init[@]}"
-    -D_GLIBCXX_USE_CXX11_ABI=0
-    -fsanitize=undefined
-    -fsanitize-blacklist="$(pwd)/../etc/ubsan.ignorelist"
-    -fno-sanitize-recover=undefined
-    -O1 -g -fno-omit-frame-pointer
-  )
-fi
-
-# Ignore warnings generated by core::optional in mnmlstc/core.
-if [[ "${OSTYPE:?}" == linux* && "${HOSTTYPE:?}" == powerpc64le ]]; then
-  cxx_flags+=(-Wno-error=maybe-uninitialized)
-fi
-
-# Ignore deprecation warnings when building on a release branch.
-if [ "$(echo "${branch_name:?}" | cut -f2 -d'/')" != "${branch_name:?}" ]; then
-  cc_flags+=(-Wno-deprecated-declarations)
-  cxx_flags+=(-Wno-deprecated-declarations)
+# Most compiler flags are not applicable to builds on Windows distros.
+if [[ "${OSTYPE:?}" != cygwin ]]; then
+  # Sanitizers overwrite the usual compiler flags.
+  if [[ "${USE_SANITIZER_ASAN:-}" == "ON" ]]; then
+    cxx_flags=(
+      "${cxx_flags_init[@]}"
+      -D_GLIBCXX_USE_CXX11_ABI=0
+      -fsanitize=address
+      -O1 -g -fno-omit-frame-pointer
+    )
+  fi
+
+  # Sanitizers overwrite the usual compiler flags.
+  if [[ "${USE_SANITIZER_UBSAN:-}" == "ON" ]]; then
+    cxx_flags=(
+      "${cxx_flags_init[@]}"
+      -D_GLIBCXX_USE_CXX11_ABI=0
+      -fsanitize=undefined
+      -fsanitize-blacklist="$(pwd)/../etc/ubsan.ignorelist"
+      -fno-sanitize-recover=undefined
+      -O1 -g -fno-omit-frame-pointer
+    )
+  fi
+
+  # Ignore warnings generated by core::optional in mnmlstc/core.
+  if [[ "${OSTYPE:?}" == linux* && "${HOSTTYPE:?}" == powerpc64le ]]; then
+    cxx_flags+=(-Wno-error=maybe-uninitialized)
+  fi
+
+  # Ignore deprecation warnings when building on a release branch.
+  if [[ "$(echo "${branch_name:?}" | cut -f2 -d'/')" != "${branch_name:?}" ]]; then
+    cc_flags+=(-Wno-deprecated-declarations)
+    cxx_flags+=(-Wno-deprecated-declarations)
+  fi
 fi
 
 if [[ "${#cc_flags[@]}" -gt 0 ]]; then