From 6e2a775ef27158274af5097030ee093c9ff5021e Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Sun, 19 Jun 2022 16:45:11 +0930
Subject: [PATCH] common/param: support renaming options using
 "|<deprecatedname>".

This is *much* easier to do inside parsing than in the caller!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 common/param.c          | 20 +++++++++++++++-----
 common/param.h          |  5 ++++-
 common/test/run-param.c | 24 ++++++++++++++++++++++++
 3 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/common/param.c b/common/param.c
index 9326465c9..34c6682c5 100644
--- a/common/param.c
+++ b/common/param.c
@@ -1,6 +1,8 @@
 #include "config.h"
 #include <ccan/asort/asort.h>
+#include <ccan/mem/mem.h>
 #include <ccan/tal/str/str.h>
+#include <common/configdir.h>
 #include <common/json_command.h>
 #include <common/json_tok.h>
 #include <common/param.h>
@@ -106,9 +108,15 @@ static struct param *find_param(struct param *params, const char *start,
 	struct param *last = first + tal_count(params);
 
 	while (first != last) {
-		if (strncmp(first->name, start, n) == 0)
-			if (strlen(first->name) == n)
-				return first;
+		size_t arglen = strcspn(first->name, "|");
+		if (memeq(first->name, arglen, start, n))
+			return first;
+		if (deprecated_apis
+		    && first->name[arglen]
+		    && memeq(first->name + arglen + 1,
+			     strlen(first->name + arglen + 1),
+			     start, n))
+			return first;
 		first++;
 	}
 	return NULL;
@@ -237,12 +245,14 @@ static char *param_usage(const tal_t *ctx,
 {
 	char *usage = tal_strdup(ctx, "");
 	for (size_t i = 0; i < tal_count(params); i++) {
+		/* Don't print |deprecated part! */
+		int len = strcspn(params[i].name, "|");
 		if (i != 0)
 			tal_append_fmt(&usage, " ");
 		if (params[i].style == PARAM_REQUIRED)
-			tal_append_fmt(&usage, "%s", params[i].name);
+			tal_append_fmt(&usage, "%.*s", len, params[i].name);
 		else
-			tal_append_fmt(&usage, "[%s]", params[i].name);
+			tal_append_fmt(&usage, "[%.*s]", len, params[i].name);
 	}
 	return usage;
 }
diff --git a/common/param.h b/common/param.h
index dcaa9f25d..a127d85cf 100644
--- a/common/param.h
+++ b/common/param.h
@@ -19,7 +19,7 @@
  *
  * 	if (!param(cmd, buffer, params,
  * 		   p_req("cltv", json_tok_number, &cltv),
- * 		   p_opt("msatoshi", json_tok_u64, &msatoshi),
+ * 		   p_opt("amount_msat|msatoshi", json_tok_u64, &msatoshi),
  * 		   p_opt("note", json_tok_tok, &note),
  * 		   p_opt_def("expiry", json_tok_u64, &expiry, 3600),
  * 		   NULL))
@@ -76,6 +76,7 @@ enum param_style {
 
 /*
  * Add a required parameter.
+ * name can be <normal>|<deprecated> if it's been renamed.
  */
 #define p_req(name, cbx, arg)				     \
 	      name"",                                        \
@@ -89,6 +90,7 @@ enum param_style {
 
 /*
  * Add an optional parameter.  *arg is set to NULL if it isn't found.
+ * name can be <normal>|<deprecated> if it's been renamed.
  */
 #define p_opt(name, cbx, arg)                                   \
 	      name"",                                           \
@@ -103,6 +105,7 @@ enum param_style {
 
 /*
  * Add an optional parameter.  *arg is set to @def if it isn't found.
+ * name can be <normal>|<deprecated> if it's been renamed.
  */
 #define p_opt_def(name, cbx, arg, def)				    \
 		  name"",					    \
diff --git a/common/test/run-param.c b/common/test/run-param.c
index edda9895d..6577f5b29 100644
--- a/common/test/run-param.c
+++ b/common/test/run-param.c
@@ -34,6 +34,8 @@ struct command_result *command_fail(struct command *cmd,
 }
 
 /* AUTOGENERATED MOCKS START */
+/* Generated stub for deprecated_apis */
+bool deprecated_apis;
 /* Generated stub for fromwire_tlv */
 bool fromwire_tlv(const u8 **cursor UNNEEDED, size_t *max UNNEEDED,
 		  const struct tlv_record_type *types UNNEEDED, size_t num_types UNNEEDED,
@@ -457,6 +459,27 @@ static void sendpay(void)
 	assert(*msatoshi == 547);
 }
 
+static void deprecated_rename(void)
+{
+	struct json *j = json_parse(cmd, "{ 'u64': 42 }");
+	u64 *u64;
+
+	assert(param(cmd, j->buffer, j->toks,
+		     p_req("u64|old_u64", param_u64, &u64),
+		     NULL));
+	assert(*u64 == 42);
+
+	deprecated_apis = true;
+	j = json_parse(cmd, "{ 'old_u64': 42 }");
+	assert(param(cmd, j->buffer, j->toks,
+		     p_req("u64|old_u64", param_u64, &u64),
+		     NULL));
+	deprecated_apis = false;
+	assert(!param(cmd, j->buffer, j->toks,
+		      p_req("u64|old_u64", param_u64, &u64),
+		      NULL));
+}
+
 static void sendpay_nulltok(void)
 {
 	struct json *j = json_parse(cmd, "[ 'A', '123']");
@@ -632,6 +655,7 @@ int main(int argc, char *argv[])
 	advanced_fail();
 	param_tests();
 	usage();
+	deprecated_rename();
 
 	printf("run-params ok\n");
 	common_shutdown();