Rule 10.6 An expression shall not be assigned to a wider type

[LordMordac]

The full rule title is:

The value of a composite expression shall not be assigned to an object with a wider essential type

I am having a lively debate with my scanner vendor about the quality of their scans. The following example code is generating the commented violation:
[code]
static inline uint32_t bit32 (uint32_t pos)
{
static const uint32_t mask = 31U;
static const uint32_t one = 1U;

// Event misra_c_2012_rule_10_6_violation: Assigning composite expression "1U