Enable GCC16 compilation

Author: cost0much

common/autoconf/flags.m4

@@ -435,6 +435,20 @@ AC_DEFUN_ONCE([FLAGS_SETUP_COMPILER_FLAGS_FOR_JDK],
     $2CXXFLAGS_JDK="${$2CXXFLAGS_JDK} ${$2CXXSTD_CXXFLAG}"
     $2JVM_CFLAGS="${$2JVM_CFLAGS} ${$2CXXSTD_CXXFLAG}"
 
+    AC_MSG_CHECKING([if the default C dialect is pre-C23])
+    AC_LANG_PUSH([C])
+    AC_COMPILE_IFELSE([AC_LANG_SOURCE([[typedef int bool;]])],
+      [AC_MSG_RESULT([yes])
+        $2CSTD_CFLAG=""],
+      [AC_MSG_RESULT([no, pinning -std=gnu17])
+        $2CSTD_CFLAG="-std=gnu17"])
+    AC_LANG_POP([C])
+    $2CFLAGS_JDK="${$2CFLAGS_JDK} ${$2CSTD_CFLAG}"
+    m4_if([$2], [], [
+      LEGACY_HOST_CFLAGS="$LEGACY_HOST_CFLAGS ${CSTD_CFLAG}"
+      LEGACY_TARGET_CFLAGS="$LEGACY_TARGET_CFLAGS ${CSTD_CFLAG}"
+    ])
+
     AC_SUBST($2CXXSTD_CXXFLAG)
   fi
 

common/autoconf/generated-configure.sh

@@ -42873,6 +42873,40 @@ $as_echo "$supports" >&6; }
     CXXFLAGS_JDK="${CXXFLAGS_JDK} ${CXXSTD_CXXFLAG}"
     JVM_CFLAGS="${JVM_CFLAGS} ${CXXSTD_CXXFLAG}"
 
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking if the default C dialect is pre-C23" >&5
+$as_echo_n "checking if the default C dialect is pre-C23... " >&6; }
+    ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+typedef int bool;
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+        CSTD_CFLAG=""
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no, pinning -std=gnu17" >&5
+$as_echo "no, pinning -std=gnu17" >&6; }
+        CSTD_CFLAG="-std=gnu17"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+    ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+    CFLAGS_JDK="${CFLAGS_JDK} ${CSTD_CFLAG}"
+
+      LEGACY_HOST_CFLAGS="$LEGACY_HOST_CFLAGS ${CSTD_CFLAG}"
+      LEGACY_TARGET_CFLAGS="$LEGACY_TARGET_CFLAGS ${CSTD_CFLAG}"
+
+
 
   fi
 

hotspot/make/linux/makefiles/gcc.make

@@ -229,6 +229,12 @@ ifeq ($(USE_CLANG),)
     WARNINGS_ARE_ERRORS += -Wno-c++11-compat -Wno-switch -Wno-delete-non-virtual-dtor -Wno-uninitialized
     WARNINGS_ARE_ERRORS += -Wno-misleading-indentation -Wno-address
   endif
+  ifeq "$(shell expr \( $(CC_VER_MAJOR) \>= 16 \))" "1"
+    WARNINGS_ARE_ERRORS += -Wno-array-bounds -Wno-dangling-pointer -Wno-c++20-compat
+    ifeq ($(BUILDARCH), aarch64)
+      WARNINGS_ARE_ERRORS += -Wno-stringop-overflow
+    endif
+  endif
 
   # Since GCC 4.3, -Wconversion has changed its meanings to warn these implicit
   # conversions which might affect the values. Only enable it in earlier versions.