Added gcc12 (#30388)

templates/tools/dockerfile/test/cxx_gcc_12_x64/Dockerfile.template

@@ -14,7 +14,7 @@
   # See the License for the specific language governing permissions and
   # limitations under the License.
   
-  FROM gcc:11
+  FROM gcc:12
   
   RUN apt-get update && apt-get install -y curl git time wget zip && apt-get clean
   <%include file="../../run_tests_python_deps.include"/>

tools/dockerfile/test/cxx_gcc_12_x64/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM gcc:11
+FROM gcc:12
 
 RUN apt-get update && apt-get install -y curl git time wget zip && apt-get clean
 #====================

tools/run_tests/run_tests.py

@@ -485,8 +485,8 @@ class CLanguage(object):
             return ('debian11_openssl102', [
                 "-DgRPC_SSL_PROVIDER=package",
             ])
-        elif compiler == 'gcc11':
-            return ('gcc_11', [])
+        elif compiler == 'gcc12':
+            return ('gcc_12', ["-DCMAKE_CXX_STANDARD=20"])
         elif compiler == 'gcc_musl':
             return ('alpine', [])
         elif compiler == 'clang6':
@@ -1496,7 +1496,7 @@ argp.add_argument(
         'gcc6',
         'gcc10.2',
         'gcc10.2_openssl102',
-        'gcc11',
+        'gcc12',
         'gcc_musl',
         'clang6',
         'clang13',

tools/run_tests/run_tests_matrix.py

@@ -300,7 +300,7 @@ def _create_portability_test_jobs(extra_args=[],
 
     # portability C and C++ on x64
     for compiler in [
-            'gcc6', 'gcc10.2_openssl102', 'gcc11', 'gcc_musl', 'clang6',
+            'gcc6', 'gcc10.2_openssl102', 'gcc12', 'gcc_musl', 'clang6',
             'clang13'
     ]:
         test_jobs += _generate_jobs(languages=['c', 'c++'],