fix: DC table initializers put port 443 into ipv6 field, add -Werror CI

The struct dc_address gained an ipv6[16] field between ipv4 and port,
but the positional initializers { 1, 0, 443 } were not updated — 443
went into ipv6[0] (unsigned char, truncated to 187) instead of port.
Switch to designated initializers (.dc_id, .port) to prevent this
class of bug.

Add a build-werror CI job that compiles with -Werror to catch compiler
warnings before they reach releases. The main Makefile keeps -Wall
without -Werror so end-user builds aren't broken by compiler differences.

Author: dvershinin

.github/workflows/test.yml

@@ -11,6 +11,21 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
+  # Fast compile-only check: ensures no compiler warnings slip through.
+  # The main build uses -Wall but not -Werror, so warnings don't fail the
+  # build for end users on different compiler versions. This CI job adds
+  # -Werror to catch regressions like the dc-table overflow in v3.5.3.
+  build-werror:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install dependencies
+      run: |
+        sudo apt-get update
+        sudo apt-get install -y build-essential libssl-dev zlib1g-dev
+    - name: Build with -Werror
+      run: make clean && make -j$(nproc) EXTRA_CFLAGS="-Werror"
+
   test:
     runs-on: ubuntu-latest
     steps:

mtproto/mtproto-dc-table.c

@@ -30,17 +30,17 @@
  */
 
 static const struct dc_address production_dcs[] = {
-  { 1, 0, 443 },  /* 149.154.175.50  */
-  { 2, 0, 443 },  /* 149.154.167.51  */
-  { 3, 0, 443 },  /* 149.154.175.100 */
-  { 4, 0, 443 },  /* 149.154.167.91  */
-  { 5, 0, 443 },  /* 91.108.56.100   */
+  { .dc_id = 1, .port = 443 },  /* 149.154.175.50  */
+  { .dc_id = 2, .port = 443 },  /* 149.154.167.51  */
+  { .dc_id = 3, .port = 443 },  /* 149.154.175.100 */
+  { .dc_id = 4, .port = 443 },  /* 149.154.167.91  */
+  { .dc_id = 5, .port = 443 },  /* 91.108.56.100   */
 };
 
 static const struct dc_address test_dcs[] = {
-  { 1, 0, 443 },  /* 149.154.175.10  */
-  { 2, 0, 443 },  /* 149.154.167.40  */
-  { 3, 0, 443 },  /* 149.154.175.117 */
+  { .dc_id = 1, .port = 443 },  /* 149.154.175.10  */
+  { .dc_id = 2, .port = 443 },  /* 149.154.167.40  */
+  { .dc_id = 3, .port = 443 },  /* 149.154.175.117 */
 };
 
 static int dc_table_initialized;