使用g++12/13编译BoringSSL失败，求解决办法

问题概述 #

在Debian测试版系统中，使用g++-12或更高版本编译BoringSSL时，会因gcc新的悬空指针检测警告（被当作错误处理）导致编译失败，g++-11及以下版本可正常编译。

编译报错信息 #

ninja: Entering directory `build/'
[459/751] Building C object crypto/CMakeFiles/crypto.dir/bytestring/cbb.c.o
FAILED: crypto/CMakeFiles/crypto.dir/bytestring/cbb.c.o 
/usr/bin/cc -DBORINGSSL_IMPLEMENTATION -Ipath/to/lib/boringssl/include -Werror -Wformat=2 -Wsign-compare -Wwrite-strings -Wvla -Wshadow -Wtype-limits -ggdb -Wall -fvisibility=hidden -fno-common -Wno-free-nonheap-object -Wimplicit-fallthrough -Wformat-signedness -Wmissing-prototypes -Wold-style-definition -Wstrict-prototypes -D_XOPEN_SOURCE=700 -O3 -DNDEBUG -std=gnu11 -MD -MT crypto/CMakeFiles/crypto.dir/bytestring/cbb.c.o -MF crypto/CMakeFiles/crypto.dir/bytestring/cbb.c.o.d -o crypto/CMakeFiles/crypto.dir/bytestring/cbb.c.o -c path/to/lib/boringssl/crypto/bytestring/cbb.c
In function ‘cbb_add_child’,
    inlined from ‘CBB_add_asn1’ at path/to/lib/boringssl/crypto/bytestring/cbb.c:361:10,
    inlined from ‘CBB_add_asn1’ at path/to/lib/boringssl/crypto/bytestring/cbb.c:342:5,
    inlined from ‘CBB_add_asn1_octet_string’ at path/to/lib/boringssl/crypto/bytestring/cbb.c:544:8:
path/to/lib/boringssl/crypto/bytestring/cbb.c:291:14: error: storing the address of local variable ‘child’ in ‘*cbb.child’ [-Werror=dangling-pointer=]
  291 |   cbb->child = out_child;
      |   ~~~~~~~~~~~^~~~~~~~~~~
path/to/lib/boringssl/crypto/bytestring/cbb.c: In function ‘CBB_add_asn1_octet_string’:
path/to/lib/boringssl/crypto/bytestring/cbb.c:543:7: note: ‘child’ declared here
  543 |   CBB child;
      |       ^~~~~
path/to/lib/boringssl/crypto/bytestring/cbb.c:542:36: note: ‘cbb’ declared here
  542 | int CBB_add_asn1_octet_string(CBB *cbb, const uint8_t *data, size_t data_len) {
      |                               ~~~~~^~~
In function ‘cbb_add_child’,
    inlined from ‘CBB_add_asn1’ at path/to/lib/boringssl/crypto/bytestring/cbb.c:361:10,
    inlined from ‘CBB_add_asn1’ at path/to/lib/boringssl/crypto/bytestring/cbb.c:342:5,
    inlined from ‘CBB_add_asn1_bool’ at path/to/lib/boringssl/crypto/bytestring/cbb.c:555:8:
path/to/lib/boringssl/crypto/bytestring/cbb.c:291:14: error: storing the address of local variable ‘child’ in ‘*cbb.child’ [-Werror=dangling-pointer=]
  291 |   cbb->child = out_child;
      |   ~~~~~~~~~~~^~~~~~~~~~~
path/to/lib/boringssl/crypto/bytestring/cbb.c: In function ‘CBB_add_asn1_bool’:
path/to/lib/boringssl/crypto/bytestring/cbb.c:554:7: note: ‘child’ declared here
  554 |   CBB child;
      |       ^~~~~
path/to/lib/boringssl/crypto/bytestring/cbb.c:553:28: note: ‘cbb’ declared here
  553 | int CBB_add_asn1_bool(CBB *cbb, int value) {
      |                       ~~~~~^~~
cc1: all warnings being treated as errors
[472/751] Building CXX object CMakeFiles/ssl_test.dir/ssl/ssl_test.cc.o
ninja: build stopped: subcommand failed.

原编译步骤 #

git clone https://github.com/google/boringssl.git
cd boringssl
cmake -DCMAKE_CXX_COMPILER=g++-12 -DCMAKE_BUILD_TYPE=Release -B build -GNinja
ninja -C build

解决方法 #

方法1：临时禁用悬空指针错误警告 #

该报错是gcc 12+过度内联分析导致的误判，BoringSSL代码本身不存在实际的悬空指针问题，可通过添加编译选项关闭该警告的错误触发：

修改cmake命令为：

cmake -DCMAKE_CXX_COMPILER=g++-12 -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_C_FLAGS="-Wno-error=dangling-pointer" \
  -DCMAKE_CXX_FLAGS="-Wno-error=dangling-pointer" \
  -B build -GNinja

之后执行编译：

ninja -C build

方法2：使用官方修复代码 #

官方已在内部bug追踪系统中记录该问题（编号650），确认是gcc新版本检测逻辑误判。可等待官方合并修复补丁，或自行拉取包含修复的分支编译。若需手动修复，可修改crypto/bytestring/cbb.c中的相关函数，添加__attribute__((noinline))阻止过度内联，避免编译器误判。

内容的提问来源于stack exchange，提问作者LeXav