chore(CI): build ubuntu-26.04 with clang-21 and gcc-15 (#26883)

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
Co-authored-by: sudlud <sudlud@users.noreply.github.com>

.github/SECURITY.md

@@ -72,17 +72,16 @@ We support the following versions of dependencies.
 
 | CLang |       Status       |     Recommended      |
 | :---- | :----------------: | :------------------: |
-| 18    | :white_check_mark: | :large_blue_diamond: |
-| 15    | :white_check_mark: |                      |
-| 14 ≤  |    :red_circle:    |                      |
+| 21    | :white_check_mark: | :large_blue_diamond: |
+| 18    | :white_check_mark: |                      |
+| 17 ≤  |    :red_circle:    |                      |
 
 ### Supported GCC Versions:
 
 | GCC  |       Status       |     Recommended      |
 | :--- | :----------------: | :------------------: |
-| 14   | :white_check_mark: | :large_blue_diamond: |
-| 12   | :white_check_mark: |                      |
-| 11 ≤ |    :red_circle:    |                      |
+| 15   | :white_check_mark: | :large_blue_diamond: |
+| 14 ≤ |    :red_circle:    |                      |
 
 > [!NOTE]
 > We do **NOT** support any repacks that may or may not have been made based on AzerothCore. This is because they are usually based on older versions and there is no way to know what is in the precompiled binaries. Instead, you should compile your binaries from the AzerothCore source. To get started, read the [Installation Guide](https://www.azerothcore.org/wiki/installation).

.github/workflows/core-build-nopch.yml

@@ -35,14 +35,14 @@ jobs:
             compiler:
               CC: clang-18
               CXX: clang++-18
-          - os: ubuntu-24.04
-            compiler:
-              CC: gcc-14
-              CXX: g++-14
           - os: ubuntu-26.04
             compiler:
-              CC: clang-20
-              CXX: clang++-20
+              CC: gcc-15
+              CXX: g++-15
+          - os: ubuntu-26.04
+            compiler:
+              CC: clang-21
+              CXX: clang++-21
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.os }}-${{ matrix.compiler.CC }}-nopch
     if: github.repository == 'azerothcore/azerothcore-wotlk' && !github.event.pull_request.draft

.github/workflows/core-build-pch.yml

@@ -37,8 +37,8 @@ jobs:
               CXX: clang++-18
           - os: ubuntu-26.04
             compiler:
-              CC: clang-20
-              CXX: clang++-20
+              CC: clang-21
+              CXX: clang++-21
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.os }}-${{ matrix.compiler.CC }}-pch
     if: github.repository == 'azerothcore/azerothcore-wotlk' && !github.event.pull_request.draft

deps/jemalloc/Hotfix safety_check_set_abort prototype.diff

@@ -0,0 +1,13 @@
+diff --git a/deps/jemalloc/include/jemalloc/internal/safety_check.h b/deps/jemalloc/include/jemalloc/internal/safety_check.h
+index 53339ac12f..ec4b33699b 100644
+--- a/deps/jemalloc/include/jemalloc/internal/safety_check.h
++++ b/deps/jemalloc/include/jemalloc/internal/safety_check.h
+@@ -3,7 +3,7 @@
+ 
+ void safety_check_fail(const char *format, ...);
+ /* Can set to NULL for a default. */
+-void safety_check_set_abort(void (*abort_fn)());
++void safety_check_set_abort(void (*abort_fn)(const char *));
+ 
+ JEMALLOC_ALWAYS_INLINE void
+ safety_check_set_redzone(void *ptr, size_t usize, size_t bumped_usize) {

deps/jemalloc/include/jemalloc/internal/safety_check.h

@@ -3,7 +3,7 @@
 
 void safety_check_fail(const char *format, ...);
 /* Can set to NULL for a default. */
-void safety_check_set_abort(void (*abort_fn)());
+void safety_check_set_abort(void (*abort_fn)(const char *));
 
 JEMALLOC_ALWAYS_INLINE void
 safety_check_set_redzone(void *ptr, size_t usize, size_t bumped_usize) {

src/cmake/googletest-download.cmake

@@ -23,8 +23,13 @@ ExternalProject_Add(
         BINARY_DIR "@GOOGLETEST_DOWNLOAD_ROOT@/googletest-build"
         GIT_REPOSITORY
         https://github.com/google/googletest.git
+        # Pinned to a main-branch commit rather than a tag: gtest-printers.h
+        # converted char8_t/char16_t to char32_t implicitly, which clang-21
+        # rejects under -Werror (-Wcharacter-conversion). Upstream fixed it in
+        # fa8438ae, three weeks after v1.17.0 was cut, so no release carries it
+        # yet. Move back to a tag once one ships that commit.
         GIT_TAG
-        release-1.12.1
+        3940de91897160fea4815998e08d0fa3c2fb077e
         CONFIGURE_COMMAND ""
         BUILD_COMMAND ""
         INSTALL_COMMAND ""