在C++14标准(C++98/11也一样)中，在Annex C Compatibility里有这么一条：

Change: Converting void* to a pointer-to-object type requires casting

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char a[10];
void* b=a;
void foo() {
  char* c=b;
}

ISO C will accept this usage of pointer to void being assigned to a pointer to object type. C ++ will not.

但是为什么operator new()会返回void*且不用显式转换为T*就能赋值给T*呢？