This seems to happen in CONF=linux-x86_64-server-release, and only with older GCC, like on current RHELs.

Tools summary:
* C Compiler: Version 4.8.5 (at /usr/bin/gcc)
* C++ Compiler: Version 4.8.5 (at /usr/bin/g++)

=== Output from failing command(s) repeated here ===
* For target hotspot_variant-server_libjvm_objs_memnode.o:
/home/shade/jdk-jdk/src/hotspot/share/opto/memnode.cpp: In static member function 'static const TypePtr* MemNode::calculate_adr_type(const Type*, const TypePtr*)':
/home/shade/jdk-jdk/src/hotspot/share/opto/memnode.cpp:737:16: error: parameter 'cross_check' set but not used [-Werror=unused-but-set-parameter]
 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
                ^
At global scope:
cc1plus: error: unrecognized command line option "-Wno-cast-function-type" [-Werror]
cc1plus: error: unrecognized command line option "-Wno-misleading-indentation" [-Werror]
cc1plus: error: unrecognized command line option "-Wno-implicit-fallthrough" [-Werror]
cc1plus: error: unrecognized command line option "-Wno-int-in-bool-context" [-Werror]
cc1plus: all warnings being treated as errors

Accepting "extra" back fixes the build:

diff -r 0f882d53c204 make/hotspot/lib/CompileJvm.gmk
--- a/make/hotspot/lib/CompileJvm.gmk Wed Oct 23 12:21:32 2019 +0200
+++ b/make/hotspot/lib/CompileJvm.gmk Wed Oct 23 07:26:50 2019 -0400
@@ -78,7 +78,7 @@
 ################################################################################
 # Disabled warnings
 
-DISABLED_WARNINGS_gcc := parentheses comment unknown-pragmas address \
+DISABLED_WARNINGS_gcc := extra parentheses comment unknown-pragmas address \
     delete-non-virtual-dtor char-subscripts array-bounds int-in-bool-context \
     ignored-qualifiers missing-field-initializers implicit-fallthrough \
     empty-body strict-overflow sequence-point maybe-uninitialized \

...but maybe we should fix the code instead.