JSON parser: always accept both name variants, flag controls which we generate.

* JSON parser: always accept both name variants, flag controls which we generate.

My previous commit was based on wrong information about the
proto3 JSON spec.  It turns out we need to accept both field
name formats all the time, and a runtime flag should control
which we generate.

* Documented the preserve_proto_fieldnames option.

* Fix bugs in PR.

1 files changed, 6 insertions, 5 deletions

diff --git a/upb/json/parser.c b/upb/json/parser.c
index e1a334d..1662f1a 100644
--- a/upb/json/parser.c
+++ b/upb/json/parser.c
@@ -1527,7 +1527,7 @@ _again:
 #line 1270 "upb/json/parser.rl"
 
   if (p != pe) {
-    upb_status_seterrf(&parser->status, "Parse error at %s\n", p);
+    upb_status_seterrf(&parser->status, "Parse error at '%.*s'\n", p, pe - p);
     upb_env_reporterror(parser->env, &parser->status);
   } else {
     capture_suspend(parser, &p);
@@ -1628,6 +1628,7 @@ static void add_jsonname_table(upb_json_parsermethod *m, const upb_msgdef* md) {
       upb_msg_field_next(&i)) {
     const upb_fielddef *f = upb_msg_iter_field(&i);
 
+    /* Add an entry for the JSON name. */
     size_t field_len = upb_fielddef_getjsonname(f, buf, len);
     if (field_len > len) {
       size_t len2;
@@ -1638,10 +1639,10 @@ static void add_jsonname_table(upb_json_parsermethod *m, const upb_msgdef* md) {
     }
     upb_strtable_insert(t, buf, upb_value_constptr(f));
 
-    if (getenv("UPB_JSON_ACCEPT_LEGACY_FIELD_NAMES")) {
-      /* Temporary code to help people migrate if they were depending on the
-       * old, non-proto3-json-compliant field names.  In this case we
-       * recognize both old names and new names. */
+    if (strcmp(buf, upb_fielddef_name(f)) != 0) {
+      /* Since the JSON name is different from the regular field name, add an
+       * entry for the raw name (compliant proto3 JSON parsers must accept
+       * both). */
       upb_strtable_insert(t, upb_fielddef_name(f), upb_value_constptr(f));
     }