I saw -Werror=maybe-uninitialized compiler warnings when I tried to build OpenJDK with GCC 12 on Ubuntu 22.04 in AArch64 system.

This gcc warning seems to be a false alarm. As I checked the source code of "k_rem_pio2.c" file, array "fq" with elements from index 0 to "jz", has already been initialized as "fw" at line 290.

Note that: in my local test, x86-64 build with GCC12 on Ubuntu 22.04 passed.


Here is the configuration:
====================================================
A new configuration has been successfully created in
/tmp/jdk-test/build-release
using configure arguments '--with-boot-jdk=/tmp/test/openjdk/packages/boot-jdk/aarch64/jdk18 --with-debug-level=release --with-version-opt=git-d191e4751 --with-toolchain-type=gcc est=/tmp/test/openjdk/tools/googletest'.

Configuration summary:
* Name: /tmp/jdk-test/build-release
* Debug level: release
* HS debug level: product
* JVM variants: server
* JVM features: server: 'cds compiler1 compiler2 dtrace epsilongc g1gc jfr jni-check jvmci jvmti management parallelgc serialgc services shenandoahgc vm-structs zgc'
* OpenJDK target: OS: linux, CPU architecture: aarch64, address length: 64
* Version string: 20-internal-git-d191e4751 (20-internal)
* Source date: 1663194132 (2022-09-14T22:22:12Z)

Tools summary:
* Boot JDK: openjdk version "18-internal" 2022-03-22 OpenJDK Runtime Environment (build 18-internal+0-git-0f2113cee) OpenJDK 64-Bit Server VM (build 18-internal+0-git-0f2113cee, mixed ring) (at /tmp/test/openjdk/packages/boot-jdk/aarch64/jdk18)
* Toolchain: gcc (GNU Compiler Collection)
* C Compiler: Version 12.0.1 (at /usr/bin/gcc-12)
* C++ Compiler: Version 12.0.1 (at /usr/bin/g++-12)

Build performance summary:
* Build jobs: 224
* Memory limit: 257299 MB

Here is the error log
=== Output from failing command(s) repeated here ===
* For target support_native_java.base_libfdlibm_k_rem_pio2.o:
/tmp/jdk-test/jdk_src/src/java.base/share/native/libfdlibm/k_rem_pio2.c: In function '__j__kernel_rem_pio2':
/tmp/jdk-test/jdk_src/src/java.base/share/native/libfdlibm/k_rem_pio2.c:305:24: error: 'fq' may be used uninitialized [-Werror=maybe-uninitialized]
  305 | fw = fq[0]-fw;
      | ~~^~~
/tmp/jdk-test/jdk_src/src/java.base/share/native/libfdlibm/k_rem_pio2.c:183:27: note: 'fq' declared here
  183 | double z,fw,f[20],fq[20],q[20];
      | ^~
/tmp/jdk-test/jdk_src/src/java.base/share/native/libfdlibm/k_rem_pio2.c:305:24: error: 'fq' may be used uninitialized [-Werror=maybe-uninitialized]
  305 | fw = fq[0]-fw;
      | ~~^~~
/tmp/jdk-test/jdk_src/src/java.base/share/native/libfdlibm/k_rem_pio2.c:183:27: note: 'fq' declared here
  183 | double z,fw,f[20],fq[20],q[20];
      | ^~
cc1: all warnings being treated as errors

* All command lines available in /tmp/jdk-test/build-release/make-support/failure-logs.
=== End of repeated output ===