create a .cargo/config so intellij uses the same target dir as cmake (#…

…173)

rust/.gitignore

@@ -1 +1,2 @@
 Cargo.lock
+.cargo/

rust/CMakeLists.txt

@@ -1,5 +1,12 @@
 file(WRITE CMAKE_BINARY_DIR "${CMAKE_BINARY_DIR}\n")
 
+execute_process(
+    COMMAND /usr/bin/env "CMAKE_BINARY_DIR=${CMAKE_BINARY_DIR}" "/bin/bash" "${CMAKE_CURRENT_LIST_DIR}/scripts/setup.sh"
+    WORKING_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}"
+    RESULT_VARIABLE CARGO_RESULT
+    OUTPUT_VARIABLE CARGO_CONFIG_OUT
+    ERROR_VARIABLE CARGO_CONFIG_OUT)
+
 if(HAVE_RUST)
     add_subdirectory(ccommon_rs)
 endif()

rust/scripts/setup.sh

@@ -0,0 +1,35 @@
+#!/bin/bash
+
+# utility script run by cmake for writing a .cargo/config that points
+# to the common 'target' directory under the CMAKE_BINARY_DIR. This
+# allows automated tools (such as the intellij rust plugin or vcode
+# rust integration) to share output and avoid recompiling between
+# the command line and the IDE.
+#
+# it is assumed that this script is run with the CWD being the
+# place where the .cargo dir should be created.
+
+set -euo pipefail
+IFS=$'\n\t'
+
+die() { echo "fatal: $*" >&2; exit 1; }
+
+if [[ -z "${CMAKE_BINARY_DIR:-}" ]]; then
+  die "CMAKE_BINARY_DIR must be set!"
+fi
+
+mkdir -p .cargo
+
+cleanup() {
+  [[ -n "${TEMPFILE:-}" ]] && rm -rf "$TEMPFILE"
+}
+trap cleanup EXIT
+
+TEMPFILE="$(mktemp '.cargo/config.XXXXXXXX')" || die "could not create tempfile"
+
+cat > "$TEMPFILE" <<EOS
+[build]
+target-dir = "${CMAKE_BINARY_DIR}/target"
+EOS
+
+mv "$TEMPFILE" .cargo/config