OpenGL bool uniform?

§ 4.1 Basic Types
The OpenGL Shading Language supports the following basic data types, grouped as follows:

• bool a conditional type, taking on values of true or false
• bvec2 a two-component Boolean vector
• bvec3 a three-component Boolean vector
• bvec4 a four-component Boolean vector

…

§ 4.1.2 Booleans To make conditional execution of code easier to express, the type bool is supported. There is no expectation that hardware directly supports variables of this type. (…)

As for setting:

§ 2.2.1 (…) When state values are specified using a different parameter type than the actual type of that state, data conversions are
performed as follows:

• When the type of internal state is boolean, zero integer or floating-point values are converted to FALSE and non-zero values are converted to TRUE.