Async completion support

dotfiles/zshrc.d/completions.zsh

@@ -0,0 +1,13 @@
+# Build some completions if they don't exist
+# We run in the background to reduce shell startup time
+{
+  COMPDIR=${HOME}/.zshrc.completions
+  function missing_comp() {
+    test ! -f "$COMPDIR/$1"
+  }
+
+  have_command rustup && {
+    missing_comp _rustup && rustup completions zsh > $COMPDIR/_rustup
+    missing_comp _cargo && rustup completions zsh cargo > $COMPDIR/_cargo
+  } || true
+} &>/dev/null &!