cmtice added a comment.
Hmmm...I'm having upload issues.
================
Comment at: clang/lib/Driver/ToolChains/Clang.cpp:3250
// -gline-directives-only supported only for the DWARF debug info.
if (DWARFVersion == 0 && DebugInfoKind ==
codegenoptions::DebugDirectivesOnly)
DebugInfoKind = codegenoptions::NoDebugInfo;
----------------
dblaikie wrote:
> probinson wrote:
> > After setting DWARFVersion above, when nothing was requested, this looks
> > peculiar. Is `DWARFVersion == 0` a proxy for `-gcodeview` ?
> Yep, DWARFVersion shouldn't be set when none was requested - see discussion
> above between myself & @cmtice - that should leave this code fine/correct.
DWARFVersion is (will be) only set when the debug info kind is DWARF, i.e. when
EmitDwarf is True. I apologize for the confusion -- David Blaikie and I has
some misunderstandings about the original implementation intent. DWARFVersion
== 0 ought only to result in codeview being generated/used if the user
specified -g and codeview is the default debug format for the platform.
================
Comment at: clang/lib/Driver/ToolChains/Clang.cpp:6174
+ DwarfVersion = ParseDebugDefaultVersion(getToolChain(), Args);
+
if (DwarfVersion == 0)
----------------
dblaikie wrote:
> probinson wrote:
> > I have to say, this sequence is a whole lot easier to follow than what's up
> > in RenderDebugOptions. It would be nice if they were both so easy to
> > understand.
> >
> > Although it makes me wonder, does `-fdebug-default-version` go unclaimed
> > here if there's a `-gdwarf-2` on the command line?
> Once the "else if (DefaultDWARFVersion != 0)" clause is removed, and the
> ParseDebugDefaultVersion call is sunk down into the "if (EmitDwarf)" case -
> hopefully that'll simplify the RenderDebugOptions code enough to be
> reasonable?
>
> I think the complication there is that "-g" can imply CodeView if nothing
> explicitly requests DWARF & the target is windows, whereas there's no support
> for that kind of CV fallback here? So some of that might be inherent.
>
> & agreed - worth testing that -fdebug-default-version doesn't get a -Wunused
> warning if someone says "-fdebug-default-version 4 -gdwarf-2". @cmtice is
> that tested? You might be able to add -Werror to the existing test case's RUN
> lines to demonstrate that no such warnings are produced?
The thought is that if the user actually chose a specific dwarf version, e.g.
-gdwarf-2, then that value should override the general default, specified with
-fdebug-default-version (soon to be
-fdwarf-default-version).
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D69822/new/
https://reviews.llvm.org/D69822
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