Missing warnings for UB float to unsigned cast

[Alcaro]

// Type your code here, or load an example.
unsigned line() { return -1.0; }
unsigned square() { return static_cast<unsigned>(-1.0); }
unsigned cube() { return (unsigned)-1.0; }
unsigned tesseract() { double num = -1.0; return num; }

Expected: All four compile to a single ret with -O2 (https://godbolt.org/z/h4vfe77qn), so I would quite like to see four warnings.
Actual: Only the first one warns.

edit: added one with static_cast because Someone™ on ms-stl discord doesn't like C casts

[firewave]

Using -Weverything you also get a -Wfloat-conversion warning for the last one: https://godbolt.org/z/fE8dn6z8s

Using an explicit conversions in the two other cases tells the compiler not to warn.

So I think everything works as expected.

[AaronBallman]

So I think everything works as expected.

Agreed; the explicit cast is a signal to the compiler to silence the diagnostic. The reason -Wfloat-conversion is not enabled by default is to reduce false positives (reducing the false positives so it could be enabled by default would require dataflow analysis which is expensive and better suited for the static analyzer than the compiler). The -Wliteral-conversion diagnostic can be on by default because we know the value of the literal without any sort of analysis.

Closing the issue as this is behaving by design.