RFC: Change what assert does on error

[Dennis]

On Tuesday, 8 July 2025 at 10:47:52 UTC, Richard (Rikki) Andrew 
Cattermole wrote:
> I've found where the compiler is implementing this, verified it.
>
> Its not nothrow specific.

Whether a function is nothrow affects whether a call expression 
'can throw'

https://github.com/dlang/dmd/blob/9610da2443ec4ed3aeed060783e07f76287ae397/compiler/src/dmd/canthrow.d#L131-L139

Which affects whether a statement 'can throw'

https://github.com/dlang/dmd/blob/9610da2443ec4ed3aeed060783e07f76287ae397/compiler/src/dmd/blockexit.d#L101C23-L101C31

And when a 'try' statement can only fall through or halt, then a 
(try A; finally B) gets transformed into (A; B). When the try 
statement 'can throw' this doesn't happen.

https://github.com/dlang/dmd/blob/9610da2443ec4ed3aeed060783e07f76287ae397/compiler/src/dmd/statementsem.d#L3421-L3432

Through that path, nothrow produceds better generated code, which 
you can easily verify by looking at assembler output of:

```D
void f();
void testA() {try {f();} finally {f();}}

void g() nothrow;
void testB() {try {g();} finally {g();}}
```

> Its Exception specific, not nothrow. Its subtle, but very 
> distinct difference.

I have no idea what this distinction is supposed to say, but 
"there is no nothrow specific optimizations taking place" is 
either false or pedantic about words.