为什么一元 * 运算符没有约束 "the operand shall not be a pointer to void"？
Why the unary * operator does not have a constraint "the operand shall not be a pointer to void"?
C2x，6.5.3.2 地址和间接运算符，约束，2：
The operand of the unary * operator shall have pointer type.
为什么没有约束“操作数不应是指向 void 的指针”？
虽然可以推导出：
C2x，6.5.3.2 地址和间接运算符，语义，4：
The unary * operator denotes indirection. If the operand points to a function, the result is a function designator; if it points to an object, the result is an lvalue designating the object.
C2x，6.3.2.1 左值、数组和函数指示符，1:
An lvalue is an expression (with an object type other than void) that potentially designates an object; ...
一个 可能 （虽然有点做作，我承认）添加 'suggested' 约束会破坏代码的情况是 & 和 * 运算符被连接起来。在这种情况下，a = &*p 等表达式，其中 p 是 void* 类型， 是 允许的。
来自 this Draft Standard，立即 在您第一次引用的部分之后（粗体强调我的）：
Semantics
3 The unary & operator yields the address of its
operand. If the operand has type ‘‘type’’, the result has type
‘‘pointer to type’’. If the operand is the result of a unary *
operator, neither that operator nor the & operator is evaluated
and the result is as if both were omitted, except that the
constraints on the operators still apply and the result is not an
lvalue. …
目前，我无法为 &* 组合（在 void* 或任何其他指针类型上）想到一个 use-case – 但它 可能出现在“auto-generated”and/or使用条件宏扩展的代码中。
C2x，6.5.3.2 地址和间接运算符，约束，2：
The operand of the unary * operator shall have pointer type.
为什么没有约束“操作数不应是指向 void 的指针”？
虽然可以推导出：
C2x，6.5.3.2 地址和间接运算符，语义，4：
The unary * operator denotes indirection. If the operand points to a function, the result is a function designator; if it points to an object, the result is an lvalue designating the object.
C2x，6.3.2.1 左值、数组和函数指示符，1:
An lvalue is an expression (with an object type other than void) that potentially designates an object; ...
一个 可能 （虽然有点做作，我承认）添加 'suggested' 约束会破坏代码的情况是 & 和 * 运算符被连接起来。在这种情况下，a = &*p 等表达式，其中 p 是 void* 类型， 是 允许的。
来自 this Draft Standard，立即 在您第一次引用的部分之后（粗体强调我的）：
Semantics
3 The unary&operator yields the address of its operand. If the operand has type ‘‘type’’, the result has type ‘‘pointer to type’’. If the operand is the result of a unary*operator, neither that operator nor the&operator is evaluated and the result is as if both were omitted, except that the constraints on the operators still apply and the result is not an lvalue. …
目前，我无法为 &* 组合（在 void* 或任何其他指针类型上）想到一个 use-case – 但它 可能出现在“auto-generated”and/or使用条件宏扩展的代码中。