Clarify requirements for the set_storage method
This specifies that the account which storage is to be modified MUST exist.
@@ -411,7 +411,7 @@ typedef bool (*evmc_account_exists_fn)(struct evmc_context* context, const evmc_
/**
* Get storage callback function.
*
- * This callback function is used by a VM to query the given contract storage entry.
+ * This callback function is used by a VM to query the given account storage entry.
*
* @param context The Host execution context.
* @param address The address of the account.
@@ -467,10 +467,13 @@ enum evmc_storage_status
/**
* Set storage callback function.
*
- * This callback function is used by an EVM to update the given contract storage entry.
+ * This callback function is used by a VM to update the given account storage entry.
+ * The VM MUST make sure that the account exists. This requirement is only a formality because
+ * VM implementations only modify storage of the account of the current execution context
+ * (i.e. referenced by evmc_message::destination).
*
* @param context The pointer to the Host execution context.
- * @param address The address of the contract.
+ * @param address The address of the account.
* @param key The index of the storage entry.
* @param value The value to be stored.
* @return The effect on the storage item.
