a short null dereference story

[Basile B.]

On Monday, 8 December 2025 at 02:58:48 UTC, Walter Bright wrote:
> On 12/5/2025 12:58 PM, Basile B. wrote:
>> So for D the equivalent would be to generate a check on each 
>> DotVarExp.
>
> ```d
> struct S { int a; }
>
> int main()
> {
>     S* s = null;
>     return s.a;
> }
> ```
>
> compile:
>
> [...]
>
> Program received signal SIGSEGV, Segmentation fault.
> D main () at ./test.d:8
> 8           return s.a;

Yes but the code instrumentation approach gives the opportunity 
to fix the invalid read without running in the debugger. Also 
note that the runtime error indicates the column. GDB is not that 
precise (DWARF attrib DW_AT_decl_column is never used), so for 
`x.s.a` you have to evaluate `x` then `s` to be sure.