错误：“int__atomic_compare_exchange(Params1)”的定义使内置声明“bool__atomic_compare_exchange(Params2)”成为歧义。

Question

我试图在Ubuntu 20.0.4 LTS上构建Berkley Db 4.8.30

这就是我迄今为止所做的：

wget http://download.oracle.com/berkeley-db/db-4.8.30.zip
unzip db-4.8.30.zip
cd db-4.8.30
cd build_unix/
../dist/configure --prefix=/usr/local --enable-cxx
make
make install

在编译过程中，我得到了错误消息：

错误：“int __atomic_compare_exchange(db_atomic_t*，atomic_value_t，atomic_value_t)”的定义将内置声明“bool__atomic_compare_exchange”(长时间无符号int，易失符号int*，int，int)定义为歧义。

编译标志为我的平台正确设置。以下是代码的相关部分：

原子h(截断)

#if defined(DB_WIN32)
typedef DWORD   atomic_value_t;
#else
typedef int32_t  atomic_value_t;
#endif
/*
 * Windows CE has strange issues using the Interlocked APIs with variables
 * stored in shared memory. It seems like the page needs to have been written
 * prior to the API working as expected. Work around this by allocating an
 * additional 32-bit value that can be harmlessly written for each value
 * used in Interlocked instructions.
 */
#if defined(DB_WINCE)
typedef struct {
    volatile atomic_value_t value;
    volatile atomic_value_t dummy;
} db_atomic_t;
#else
typedef struct {
    volatile atomic_value_t value;
} db_atomic_t;
#endif


#define atomic_compare_exchange(env, p, o, n)   \
    __atomic_compare_exchange((p), (o), (n))



/*
 * x86/gcc Compare exchange for shared latches. i486+
 *  Returns 1 for success, 0 for failure
 *
 * GCC 4.1+ has an equivalent  __sync_bool_compare_and_swap() as well as
 * __sync_val_compare_and_swap() which returns the value read from *dest
 * http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
 * which configure could be changed to use.
 */
static inline int __atomic_compare_exchange(
    db_atomic_t *p, atomic_value_t oldval, atomic_value_t newval)
{
    atomic_value_t was;

    if (p->value != oldval) /* check without expensive cache line locking */
        return 0;
    __asm__ __volatile__("lock; cmpxchgl %1, (%2);"
        :"=a"(was)
        :"r"(newval), "r"(p), "a"(oldval)
        :"memory", "cc");
    return (was == oldval);
}

我想我需要设置一个实用程序来忽略类型的安全检查.但不太确定。如何解决此编译错误？

Answer 1

功能

bool __atomic_compare_exchange(long unsigned int, volatile void*, void*, void*, int, int)

是一个内置的用于原子操作的GCC编译器函数.详见此处：

https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html

功能

int __atomic_compare_exchange(db_atomic_t*, atomic_value_t, atomic_value_t)

似乎是Berkley 4.8.30的一个函数，这会造成冲突。没有两个函数可以有相同的名称。

下面的链接是可以应用于解决问题的修补程序(包括补丁说明)的链接：

https://gist.github.com/danieldk/5700533