Narrowing conversion to bool warning in MSVC

When compiling this code:

enum B: bool { T = true };
struct A { bool member; };

void foo(const B b = T)
{
    A a{b}; // warning here
}

void bar()
{
    const B b = T;
    A a{b};
}

MSVC issues a warning in foo:

warning C4838: conversion from 'const B' to 'bool' requires a narrowing conversion

but compiles bar fine.

Here is a proof

Is it a compiler bug or intended behavior?