Tidy jsonpull call sites flagged in review

- geojson.cpp and attribute.cpp passed key_pool::pool() and
  set_attribute_accum() a c_str() from a std::string, forcing a needless
  reconstruction (and truncating at an embedded NUL). Both overloads take
  std::string, so pass it directly. The geojson.cpp one is the hottest
  loop in the program.
- Replace the hand-maintained counters beside range-for loops in
  attribute.cpp, main.cpp and tile-join.cpp with indexed loops, since the
  index is only wanted for error messages.
- parse_json_args took json_pull_ptr by value and then copied it, costing
  two refcount bumps per construction. Move it.
- Assert that the parser is still attached where geojson.cpp reads
  geometry->parser->line. Only json_read results reach it today, but
  json_read_tree and json_disconnect now clear every parser pointer, so a
  detached tree would null-deref there instead of tripping an assert.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017KNxyHKasyWrWcvre2yK4r

attribute.cpp

@@ -55,8 +55,9 @@ void set_attribute_accum(std::unordered_map<std::string, attribute_op> &attribut
 			exit(EXIT_JSON);
 		}
 
-		size_t i = 0;
-		for (const auto &e : o->entries()) {
+		for (size_t i = 0; i < o->entries().size(); i++) {
+			const auto &e = o->entries()[i];
+
 			if (e.key->type != JSON_STRING) {
 				fprintf(stderr, "%s: -E%s: key %zu not a string\n", *argv, arg, i);
 				exit(EXIT_JSON);
@@ -66,8 +67,7 @@ void set_attribute_accum(std::unordered_map<std::string, attribute_op> &attribut
 				exit(EXIT_JSON);
 			}
 
-			set_attribute_accum(attribute_accum, e.key->string().c_str(), e.value->string().c_str());
-			i++;
+			set_attribute_accum(attribute_accum, e.key->string(), e.value->string());
 		}
 
 		return;

geojson.cpp

@@ -188,7 +188,7 @@ int serialize_geojson_feature(struct serialization_state *sst, json_object *geom
 			if (e.key->type == JSON_STRING) {
 				serial_val sv = stringify_value(e.value.get(), sst->fname, sst->line, feature);
 
-				full_keys.emplace_back(key_pool.pool(e.key->string().c_str()));
+				full_keys.emplace_back(key_pool.pool(e.key->string()));
 				values.push_back(std::move(sv));
 			}
 		}
@@ -238,6 +238,10 @@ struct json_serialize_action : json_feature_action {
 	std::string layername;
 
 	int add_feature(json_object *geometry, bool geometrycollection, json_object *properties, json_object *id, json_object *tippecanoe, json_object *feature) {
+		// This only ever receives json_read results from geojson-loop, whose
+		// parser is still attached. json_read_tree / json_disconnect clear
+		// every parser pointer, so a detached tree would null-deref here.
+		assert(geometry->parser != nullptr);
 		sst->line = geometry->parser->line;
 		if (geometrycollection) {
 			int ret = 1;

geojson.hpp

@@ -17,7 +17,7 @@ struct parse_json_args {
 	struct serialization_state *sst;
 
 	parse_json_args(json_pull_ptr jp1, int layer1, std::string *layername1, struct serialization_state *sst1)
-	    : jp(jp1), layer(layer1), layername(layername1), sst(sst1) {
+	    : jp(std::move(jp1)), layer(layer1), layername(layername1), sst(sst1) {
 	}
 };
 

main.cpp

@@ -2896,8 +2896,9 @@ void set_attribute_value(const char *arg) {
 			exit(EXIT_JSON);
 		}
 
-		size_t i = 0;
-		for (const auto &e : o->entries()) {
+		for (size_t i = 0; i < o->entries().size(); i++) {
+			const auto &e = o->entries()[i];
+
 			if (e.key->type != JSON_STRING) {
 				fprintf(stderr, "%s: --set-attribute %s: key %zu not a string\n", *av, arg, i);
 				exit(EXIT_JSON);
@@ -2905,7 +2906,6 @@ void set_attribute_value(const char *arg) {
 
 			serial_val val = stringify_value(e.value.get(), "json", 1, o.get());
 			set_attributes.emplace(e.key->string(), val);
-			i++;
 		}
 
 		return;

tile-join.cpp

@@ -973,8 +973,9 @@ void handle_strategies(const unsigned char *s, std::vector<strategy> *st) {
 		for (size_t i = 0; i < o->array().size(); i++) {
 			const json_object_ptr &h = o->array()[i];
 			if (h->type == JSON_HASH) {
-				size_t j = 0;
-				for (const auto &kv : h->entries()) {
+				for (size_t j = 0; j < h->entries().size(); j++) {
+					const auto &kv = h->entries()[j];
+
 					if (kv.key->type != JSON_STRING) {
 						fprintf(stderr, "Key %zu of %zu is not a string: %s\n", j, i, s);
 					} else if (kv.value->type != JSON_NUMBER) {
@@ -1005,7 +1006,6 @@ void handle_strategies(const unsigned char *s, std::vector<strategy> *st) {
 							(*st)[i].feature_count += kv.value->number();
 						}
 					}
-					j++;
 				}
 			} else {
 				fprintf(stderr, "Element %zu is not a hash: %s\n", i, s);