mstorsjo added inline comments.
================
Comment at: clang/test/Driver/cl-options.c:567
-// This test was super sneaky: "/Z7" means "line-tables", but "-gdwarf" occurs
-// later on the command line, so it should win. Interestingly the cc1 arguments
-// came out right, but had wrong semantics, because an invariant assumed by
-// CompilerInvocation was violated: it expects that at most one of {gdwarfN,
-// line-tables-only} appear. If you assume that, then you can safely use
-// Args.hasArg to test whether a boolean flag is present without caring
-// where it appeared. And for this test, it appeared to the left of -gdwarf
-// which made it "win". This test could not detect that bug.
+// If We specify both /Z7 and -gdwarf we should get dwarf, not codeview.
// RUN: %clang_cl /Z7 -gdwarf /c -### -- %s 2>&1 | FileCheck
-check-prefix=Z7_gdwarf %s
----------------
smeenai wrote:
> bogner wrote:
> > smeenai wrote:
> > > bogner wrote:
> > > > rnk wrote:
> > > > > I think Meta folks depend on a mode that emits both codeview and
> > > > > DWARF. +@smeenai
> > > > Hopefully if that's the case there's a better test somewhere than this
> > > > one that discusses in detail how `/Z7` is an alias for
> > > > `-gline-tables-only`, which hasn't been true since 2017.
> > > Thanks for the headers up :) We don't depend on that mode any more
> > > though, so no problems on our end.
> > Also note that this change does not affect what happens if we specify both
> > `-gcodeview` and `-gdwarf` together. That continues to pass both
> > `-gcodeview` and `-dwarf-version=...` to `clang -cc1`. However, I don't see
> > any tests that actually check that behaviour, so if that is a mode that's
> > useful to keep working we definitely have some gaps there.
> >
> > This change means that if you want to ask `-cc1` for dwarf *and* codeview
> > with `/Z7` or `/Zi`, you'll need to specify `-gdwarf` and `-gcodeview` now.
> > This matches how you would get both sets of options to render with `-g`,
> > which I think makes sense.
> Yeah, that sounds good. IIRC when we were using the joint codeview + DWARF
> mode it was with the gcc-style Clang driver and not clang-cl, and we passed
> `-gdwarf -gcodeview` or similar to enable it anyway. We don't need that
> anymore though; @mstorsjo would know if there's anything on the MinGW side
> that cares for it.
I'm not aware of mingw usecases of using both codeview and DWARF at the same
time - I've occasionally mentioned that I know some people do use that, but I
haven't actually guided anybody into doing it.
For mingw, as long as `-g -gcodeview` on the driver level generates codeview
(and not DWARF) like it used to, mingw should be fine.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D157794/new/
https://reviews.llvm.org/D157794
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