build: + --clobber feature for .build/reconfigure script

copies reconfigure script to /tmp before
killing build directory.

share/xo-macros/xo-reconfigure.in

@@ -3,20 +3,35 @@
 # Generated by cmake - rerun to reconfigure
 
 dry_run_flag=false
+clobber=false
 testing=@ENABLE_TESTING@
 
+orig_path=@CMAKE_BINARY_DIR@/reconfigure
+self_path=$(cd $(dirname $0) && pwd)/$(basename $0)
+
 # Parse arguments
 while [[ $# -gt 0 ]]; do
     case "$1" in
         -n|--dry-run)
             dry_run_flag=true
             ;;
+        --print-source-dir)
+            echo @CMAKE_SOURCE_DIR@
+            exit 0
+            ;;
+        --print-build-dir)
+            echo @CMAKE_BINARY_DIR@
+            exit 0
+            ;;
         --enable-testing)
             testing=1
             ;;
         --disable-testing)
             testing=0
             ;;
+        --clobber)
+            clobber=true
+            ;;
         --)
             break;
             ;;
@@ -24,8 +39,14 @@ while [[ $# -gt 0 ]]; do
             echo "error: xo-reconfigure: unexpected argument [$1]"
             echo "usage: xo-reconfigure"
             echo "       xo-reconfigure [-n|--dry-run]"
+            echo "                      [--print-source-dir|--print-build-dir]"
+            echo "                      [--clobber]"
             echo "                      [--enable-testing|--disable-testing]"
             echo "                      -- CMAKE_ARGS"
+            echo ""
+            echo "1. clobber ignores --enable-testing/--disable-testing flags"
+            echo "   use to cleanse build directory when stale build artifacts"
+            echo "   are confusing cmake"
             exit 1
     esac
 
@@ -54,11 +75,54 @@ CMAKE_CMD=(
     "${@}"
 )
 
-if [[ ${dry_run_flag} = true ]]; then
-    # Print the command with proper quoting for copy-paste
-    printf '%q ' "${CMAKE_CMD[@]}" | sed -e 's: -D: \\\n    -D:g'
-    printf '\n'
+if [[ ${clobber} == true ]]; then
+    if [[ ${dry_run_flag} == true ]]; then
+        2>&1 echo "would clobber directory [@CMAKE_BINARY_DIR@], then run reconfigure:"
+        2>&1 echo
+    else
+        if [[ ${orig_path} == ${self_path} ]]; then
+            # must copy self out of doomed build directory before we clobber
+
+            # 1. rescue reconfigure script from build directory
+            tmpfile=$(mktemp /tmp/reconfigure-XXX)
+            cp ${self_path} ${tmpfile}
+
+            # 2. copy needs to be executable
+            chmod +x ${tmpfile}
+
+            # 2. run reconfigure from non-build directory
+            exec ${tmpfile} --clobber
+        else
+            # running outside build directory
+
+            2>&1 echo "removing build directory [@CMAKE_BINARY_DIR@]"
+            rm -rf @CMAKE_BINARY_DIR@
+
+            2>&1 echo "run cmake:"
+            2>&1 echo "${CMAKE_CMD[@]}"
+            2>&1 echo
+
+            # run reconfigure
+            "${CMAKE_CMD[@]}"
+
+            if [[ $(realpath ${self_path}) == /tmp/* ]]; then
+                # since we're in /tmp, delete ourselves as final step
+                rm -f ${self_path}
+            fi
+
+            # rehearse cmake command for visibility
+            2>&1 echo ""
+            2>&1 echo "cmake command was:"
+            2>&1 echo "${CMAKE_CMD[@]}"
+        fi
+    fi
 else
-    # Execute the command
-    "${CMAKE_CMD[@]}"
+    if [[ ${dry_run_flag} = true ]]; then
+        # Print the command with proper quoting for copy-paste
+        printf '%q ' "${CMAKE_CMD[@]}" | sed -e 's: -D: \\\n    -D:g'
+        printf '\n'
+    else
+        # Execute the command
+        "${CMAKE_CMD[@]}"
+    fi
 fi