[lld] [llvm] [Symbolizer] Support for Missing Line Numbers. (PR #82240)

[via llvm-commits]

bd1976bris wrote:

> > I noticed that for the `--print-source-context-lines` for line zero addresses without `--skip-line-zero` you currently get very confusing output where the lines around line zero are displayed:
> 
> I think that is the default behaviour --print-source-context-lines will display the source lines around the queried address even when that address has no line number.
> 
> > ```
> > >llvm-symbolizer.exe 0x0000000000000156 --obj=main.elf --print-source-context-lines=3
> > f3
> > main.c:0:0
> > 1  : static int gvar1 = 0;
> > 2  : static int gvar2 = 0;
> > 3  : static int gvar3 = 0;
> > ```
> > 
> > 
> >     
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> >       
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> > I think that ideally it would be better not to display the context lines for line zero addresses. It might also be nice to emit a warning recommending trying a different address or using `--skip-line-zero`.
> 
> This would require making a change in the default functionality of `--print-source-context-lines`. Ideally, with/without `--skip-line-zero` `--print-source-context-lines` should output source context lines by default for any queried address(even it has line zero.).

Right I think that this is an enhancement that is separate to this PR. I have filed: https://github.com/llvm/llvm-project/issues/92403.

https://github.com/llvm/llvm-project/pull/82240