Warnings are ignored because it's too hard or not possible to configure the compiler to only issue the warnings a particular developer finds useful and actionable.
Adding more warnings, especially for silly corner cases like the example we're discussing, is not the solution.
> Warnings are ignored because it's too hard or not possible to configure the compiler to only issue the warnings a particular developer finds useful and actionable.
That's why you don't do that based on the whims of an individual developer. Simply have a "no warnings" policy. Then the project decides what is enabled and what isn't.
A commit must not introduce warnings.
If a code change triggers a warning, it must be accompanied with a disabling of that diagnostic, which must then pass review so that it is peer approved.
If the warning cannot be disabled, the change must be reworked.
This "silly corner case" is not silly at all; it reveals a dangerous translation strategy in the compiler. The appropriate treatment isn't the issuance of a warning; rather, this translation strategy should be turned off unless explicitly requested by an exotic code generation option. (And then it can be applied without any warning.)
Adding more warnings, especially for silly corner cases like the example we're discussing, is not the solution.