Add forward declaration to fix compilation without ssl (#4794)

and add build checks with different configurations

.semaphore/semaphore.yml

@@ -114,6 +114,12 @@ blocks:
         commands:
           - '[[ -z $DOCKERHUB_APIKEY ]] || docker login --username $DOCKERHUB_USER --password $DOCKERHUB_APIKEY'
       jobs:
+        - name: 'Build configuration checks'
+          commands:
+            - wget -O rapidjson-dev.deb https://launchpad.net/ubuntu/+archive/primary/+files/rapidjson-dev_1.1.0+dfsg2-3_all.deb
+            - sudo dpkg -i rapidjson-dev.deb
+            - python3 -m pip install -U pip
+            - ./packaging/tools/build-configurations-checks.sh
         - name: 'Build and integration tests'
           commands:
             - wget -O rapidjson-dev.deb https://launchpad.net/ubuntu/+archive/primary/+files/rapidjson-dev_1.1.0+dfsg2-3_all.deb

packaging/tools/build-configurations-checks.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+set -e
+# Disable all flags to make sure it
+# compiles correctly in all cases
+./configure --install-deps --disable-ssl --disable-gssapi \
+--disable-curl --disable-zlib \
+--disable-zstd --disable-lz4-ext --disable-regex-ext \
+--disable-c11threads --disable-syslog
+make -j
+make -j -C tests run_local_quick

src/rdkafka_op.h

@@ -39,6 +39,7 @@
 typedef struct rd_kafka_q_s rd_kafka_q_t;
 typedef struct rd_kafka_toppar_s rd_kafka_toppar_t;
 typedef struct rd_kafka_op_s rd_kafka_op_t;
+typedef struct rd_kafka_broker_s rd_kafka_broker_t;
 
 /* One-off reply queue + reply version.
  * All APIs that take a rd_kafka_replyq_t makes a copy of the

tests/0133-ssl_keys.c

@@ -105,6 +105,21 @@ static void do_test_ssl_keys(const char *type, rd_bool_t correct_password) {
 
 
 int main_0133_ssl_keys(int argc, char **argv) {
+        rd_kafka_conf_t *conf;
+        char errstr[512];
+        rd_kafka_conf_res_t res;
+
+        test_conf_init(&conf, NULL, 10);
+
+        /* Check that we're linked/built with OpenSSL 3.x */
+        res = rd_kafka_conf_set(conf, "ssl.providers", "a,b", errstr,
+                                sizeof(errstr));
+        rd_kafka_conf_destroy(conf);
+        if (res == RD_KAFKA_CONF_INVALID) {
+                TEST_SKIP("%s\n", errstr);
+                return 0;
+        }
+
         do_test_ssl_keys("PKCS12", rd_true);
         do_test_ssl_keys("PKCS12", rd_false);
         do_test_ssl_keys("PEM", rd_true);