[cfe-dev] [Debug Info] Wrong column numbers come from macros

[Adrian Prantl via cfe-dev]

> On Feb 21, 2018, at 9:04 AM, David Blaikie <dblaikie at gmail.com> wrote:
> 
> Not sure I follow there, though, Adrian - the semantics don't dictate just how we could model this in a debugger.. (similarly how our diagnostics can provide more detail rather than modelling a macro expansion as though it was all written at the macro invocation point)
> 
> I think we've talked about using something like inlining to represent macro expansions, for example - to provide help with the debugging experience.

Something like this would certainly be doable, but I'm somewhat concerned that we wouldn't be able to reproduce a compilation from preprocessed source any more. I suppose we could extend #line with inline information to reflect the macro expansion, though.

-- adrian

> 
> On Wed, Feb 21, 2018 at 8:18 AM Adrian Prantl <aprantl at apple.com <mailto:aprantl at apple.com>> wrote:
> This is not even a limitation of DWARF but rather mandated by the C specification. The C language standard explicitly specifies that all code in a (multi-line) macro expansion shall behave as if it were on the same line as the macro invocation. I understand that it technically doesn't say anything about columns and perhaps we could do something for single-line macros there, but this is basically the root of the issue.
> 
> 
> -- adrian
> 
>> On Feb 21, 2018, at 8:00 AM, David Blaikie <dblaikie at gmail.com <mailto:dblaikie at gmail.com>> wrote:
>> 
>> I think it's a matter of this being the best of no great options available in DWARF, but I personally haven't given it a great deal of thought.
>> 
>> On Tue, Feb 20, 2018 at 10:34 PM Alex Denisov via cfe-dev <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
>> Hi,
>> 
>> I see an issue with debug info and macro. Here is an example:
>> 
>> #define f(x) x
>> ...
>> int a = f(b + c);
>>         ^
>> 
>> The debug information for each node in 'b + c' points to the 'f' (see the caret). I expect it to point to the actual source location.
>> 
>> I assume that is a known issue, but I could find neither explanation nor bug report.
>> Can somebody shed some light on the issue?
>> 
>> Cheers,
>> Alex.
>> 
>> _______________________________________________
>> cfe-dev mailing list
>> cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev <http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev>
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20180221/8574911d/attachment.html>