feat(shell): add alias to function helpers

These can be useful to convert aliases to shell functions, which can
help resolve shell completion issues in some situations.

zshrc

@@ -107,6 +107,74 @@ setup-completions() {
   fi
 }
 
+# Convert a bash/zsh alias to a function. It prints the unalias command and the
+# function definition, meaning the output needs to be evaluated to take effect.
+#
+# Arguments:
+#   $1: The alias to convert. Should be a single line like "alias ll='ls -alF'"
+#       or "ll='ls -alF'".
+#
+# Example:
+#   alias brew="op plugin run -- brew"
+#   convert_alias_to_function "$(alias brew)"
+#
+# This will print:
+#   unalias brew
+#   brew() {
+#     op plugin run -- brew "$@"
+#   }
+convert-alias-source-to-function-source() {
+  local line="$1"
+
+  # Remove Bash's "alias " prefix if present.
+  line=${line#alias }
+
+  # Extract the alias name and the raw command.
+  local alias_name="$(echo "$line" | cut -d'=' -f1)"
+  local raw_command="$(echo "$line" | cut -d'=' -f2)"
+
+  # Evaluate the raw command to ensure we get the correct command, with any
+  # quotes or shell escape characters handled correctly.
+  local command
+  eval "command=$raw_command"
+
+  # Abort if the command is empty.
+  if [ -z "$command" ]; then
+    echo "Error: Empty command for alias $alias_name" >&2
+    return 1
+  fi
+
+  # Print the unalias command and the function definition.
+  echo -e "unalias ${alias_name}"
+  echo -e "${alias_name}() {\n  ${command} \"\$@\"\n}"
+}
+
+# Convert a bash/zsh alias to a function. It replaces the alias with a function
+# definition in the current shell that has the same behavior as the alias.
+#
+# Arguments:
+#   $1: The alias to convert. Should be the name of the alias.
+#
+# Example:
+#   alias brew="op plugin run -- brew"
+#   convert-alias-to-function brew
+#
+# This will replace the alias "brew" with a function that has the same behavior.
+convert-alias-to-function() {
+  local alias_name="$1"
+
+  # Get the alias source.
+  local alias_source="$(alias "$alias_name")"
+
+  # Abort if the alias does not exist.
+  if [ -z "$alias_source" ]; then
+    echo "Error: Alias $alias_name does not exist" >&2
+    return 1
+  fi
+
+  eval "$(convert-alias-source-to-function-source "$alias_source")"
+}
+
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