Support cross compilation to non-windows targets

Don't have --host/$HOST imply targeting Windows, but actually inspect
the target triple where necessary.

build-lldb-mi.sh

@@ -89,10 +89,21 @@ fi
 if [ -n "$HOST" ]; then
     BUILDDIR=$BUILDDIR-$HOST
 
-    CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_SYSTEM_NAME=Windows"
     CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_C_COMPILER=$HOST-gcc"
     CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_CXX_COMPILER=$HOST-g++"
-    CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_RC_COMPILER=$HOST-windres"
+    case $HOST in
+    *-mingw32)
+        CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_SYSTEM_NAME=Windows"
+        CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_RC_COMPILER=$HOST-windres"
+        ;;
+    *-linux*)
+        CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_SYSTEM_NAME=Linux"
+        ;;
+    *)
+        echo "Unrecognized host $HOST"
+        exit 1
+        ;;
+    esac
 
     CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_FIND_ROOT_PATH=$LLVM_DIR"
     CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_FIND_ROOT_PATH_MODE_PROGRAM=NEVER"

build-llvm.sh

@@ -122,16 +122,19 @@ fi
 
 [ -z "$CHECKOUT_ONLY" ] || exit 0
 
-case $(uname) in
-MINGW*)
-    TARGET_WINDOWS=1
-    ;;
-*)
-    if [ -n "$HOST" ]; then
+if [ -n "$HOST" ]; then
+    case $HOST in
+    *-mingw32)
         TARGET_WINDOWS=1
-    fi
-    ;;
-esac
+        ;;
+    esac
+else
+    case $(uname) in
+    MINGW*)
+        TARGET_WINDOWS=1
+        ;;
+    esac
+fi
 
 if command -v ninja >/dev/null; then
     CMAKE_GENERATOR="Ninja"
@@ -153,10 +156,21 @@ fi
 CMAKEFLAGS="$LLVM_CMAKEFLAGS"
 
 if [ -n "$HOST" ]; then
-    CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_SYSTEM_NAME=Windows"
     CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_C_COMPILER=$HOST-gcc"
     CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_CXX_COMPILER=$HOST-g++"
-    CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_RC_COMPILER=$HOST-windres"
+    case $HOST in
+    *-mingw32)
+        CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_SYSTEM_NAME=Windows"
+        CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_RC_COMPILER=$HOST-windres"
+        ;;
+    *-linux*)
+        CMAKEFLAGS="$CMAKEFLAGS -DCMAKE_SYSTEM_NAME=Linux"
+        ;;
+    *)
+        echo "Unrecognized host $HOST"
+        exit 1
+        ;;
+    esac
 
     native=""
     for dir in llvm-project/llvm/build/bin llvm-project/llvm/build-asserts/bin; do
@@ -185,7 +199,7 @@ if [ -n "$HOST" ]; then
 
     BUILDDIR=$BUILDDIR-$HOST
 
-    if [ -n "$WITH_PYTHON" ]; then
+    if [ -n "$WITH_PYTHON" ] && [ -n "$TARGET_WINDOWS" ]; then
         # The python3-config script requires executing with bash. It outputs
         # an extra trailing space, which the extra 'echo' layer gets rid of.
         EXT_SUFFIX="$(echo $(bash $PREFIX/python/bin/python3-config --extension-suffix))"

build-mingw-w64-tools.sh

@@ -62,7 +62,11 @@ fi
 if [ -n "$HOST" ]; then
     CONFIGFLAGS="$CONFIGFLAGS --host=$HOST"
     CROSS_NAME=-$HOST
-    EXEEXT=.exe
+    case $HOST in
+    *-mingw32)
+        EXEEXT=.exe
+        ;;
+    esac
 else
     case $(uname) in
     MINGW*)

install-wrappers.sh

@@ -44,14 +44,18 @@ if [ -n "$HOST" ] && [ -z "$CC" ]; then
 fi
 : ${CC:=cc}
 
-case $(uname) in
-MINGW*)
-    EXEEXT=.exe
-    ;;
-esac
-
 if [ -n "$HOST" ]; then
-    EXEEXT=.exe
+    case $HOST in
+    *-mingw32)
+        EXEEXT=.exe
+        ;;
+    esac
+else
+    case $(uname) in
+    MINGW*)
+        EXEEXT=.exe
+        ;;
+    esac
 fi
 
 if [ -n "$MACOS_REDIST" ]; then
@@ -70,7 +74,7 @@ fi
 
 mkdir -p "$PREFIX/bin"
 cp wrappers/*-wrapper.sh "$PREFIX/bin"
-if [ -n "$HOST" ]; then
+if [ -n "$HOST" ] && [ -n "$EXEEXT" ]; then
     # TODO: If building natively on msys, pick up the default HOST value from there.
     WRAPPER_FLAGS="$WRAPPER_FLAGS -DDEFAULT_TARGET=\"$HOST\""
     for i in wrappers/*-wrapper.sh; do
@@ -94,7 +98,7 @@ for arch in $ARCHS; do
             ln -sf clang-target-wrapper$CTW_SUFFIX $arch-w64-$target_os-$exec$CTW_LINK_SUFFIX
         done
         for exec in addr2line ar ranlib nm objcopy readelf size strings strip llvm-ar llvm-ranlib; do
-            if [ -n "$HOST" ]; then
+            if [ -n "$EXEEXT" ]; then
                 link_target=llvm-wrapper
             else
                 case $exec in