MaskRay added inline comments.
================ Comment at: clang/test/Driver/darwin-version.c:217 // RUN: FileCheck --check-prefix=CHECK-VERSION-TNO-OSV1 %s -// CHECK-VERSION-TNO-OSV1: overriding '-mmacos-version-min=10.6' option with '-target x86_64-apple-macos10.11.2' +// CHECK-VERSION-TNO-OSV1: overriding '-mmacos-version-min=10.6' option with '-target x86_64-apple-macos10.11.2' [-Woverriding-t-option] ---------------- aaron.ballman wrote: > hans wrote: > > MaskRay wrote: > > > dblaikie wrote: > > > > MaskRay wrote: > > > > > dexonsmith wrote: > > > > > > MaskRay wrote: > > > > > > > dexonsmith wrote: > > > > > > > > MaskRay wrote: > > > > > > > > > hans wrote: > > > > > > > > > > MaskRay wrote: > > > > > > > > > > > hans wrote: > > > > > > > > > > > > dexonsmith wrote: > > > > > > > > > > > > > MaskRay wrote: > > > > > > > > > > > > > > dexonsmith wrote: > > > > > > > > > > > > > > > Why would we want to use the old name here? An > > > > > > > > > > > > > > > alias seems strictly better to me. > > > > > > > > > > > > > > Making `overriding-t-option` an alias for > > > > > > > > > > > > > > `overriding-option` would make > > > > > > > > > > > > > > `-Wno-overriding-t-option` applies to future > > > > > > > > > > > > > > overriding option diagnostics, which is exactly > > > > > > > > > > > > > > what I want to avoid. > > > > > > > > > > > > > > > > > > > > > > > > > > > I understand that you don't want `-t-` to apply to > > > > > > > > > > > > > work on future overriding option diagnostics, but I > > > > > > > > > > > > > think the platform divergence you're adding here is > > > > > > > > > > > > > worse. > > > > > > > > > > > > > > > > > > > > > > > > > > Having a few Darwin-specific options use > > > > > > > > > > > > > `-Woverriding-t-option` (and everything else use > > > > > > > > > > > > > `-Woverriding-option`) as the canonical spelling is > > > > > > > > > > > > > hard to reason about for maintainers, and for users. > > > > > > > > > > > > > > > > > > > > > > > > > > And might not users on other platforms have > > > > > > > > > > > > > `-Woverriding-t-option` hardcoded in build settings? > > > > > > > > > > > > > (So @dblaikie's argument that we shouldn't > > > > > > > > > > > > > arbitrarily make things hard for users would apply to > > > > > > > > > > > > > all options?) > > > > > > > > > > > > > > > > > > > > > > > > > > IMO, if we're not comfortable removing > > > > > > > > > > > > > `-Woverriding-t-option` entirely, then it should live > > > > > > > > > > > > > on as an alias (easy to reason about), not as > > > > > > > > > > > > > canonical-in-special-cases (hard to reason about). > > > > > > > > > > > > > IMO, if we're not comfortable removing > > > > > > > > > > > > > -Woverriding-t-option entirely, then it should live > > > > > > > > > > > > > on as an alias (easy to reason about), not as > > > > > > > > > > > > > canonical-in-special-cases (hard to reason about). > > > > > > > > > > > > > > > > > > > > > > > > +1 if we can't drop the old spelling, an alias seems > > > > > > > > > > > > like the best option. > > > > > > > > > > > Making `overriding-t-option` an alias for > > > > > > > > > > > `overriding-option`, as I mentioned, will make > > > > > > > > > > > `-Wno-overriding-t-option` affect new overriding-options > > > > > > > > > > > uses. This is exactly what I want to avoid. > > > > > > > > > > > > > > > > > > > > > > I know there are some `-Wno-overriding-t-option` uses. > > > > > > > > > > > Honestly, they are far fewer than other diagnostics we > > > > > > > > > > > are introducing or changing in Clang. I can understand > > > > > > > > > > > the argument "make -Werror users easier for this specific > > > > > > > > > > > diagnostic" (but `-Werror` will complain about other new > > > > > > > > > > > diagnostics), but do we really want to in the Darwin > > > > > > > > > > > case? I think no. They can remove the version from the > > > > > > > > > > > target triple like > > > > > > > > > > > https://github.com/facebook/ocamlrep/blame/abc14b8aafcc6746ec37bf7bf0de24bfc58d63a0/prelude/apple/apple_target_sdk_version.bzl#L50 > > > > > > > > > > > or make the version part consistent with > > > > > > > > > > > `-m.*os-version-min`. > > > > > > > > > > > > > > > > > > > > > > This change may force these users to re-think how they > > > > > > > > > > > should fix their build. I apology to these users, but I > > > > > > > > > > > don't feel that adding an alias is really necessary. > > > > > > > > > > > Making overriding-t-option an alias for > > > > > > > > > > > overriding-option, as I mentioned, will make > > > > > > > > > > > -Wno-overriding-t-option affect new overriding-options > > > > > > > > > > > uses. This is exactly what I want to avoid. > > > > > > > > > > > > > > > > > > > > Is keeping them separate actually important, though? > > > > > > > > > > -Wno-overriding-option has the same issue in that case, > > > > > > > > > > that using the flag will also affect any new > > > > > > > > > > overriding-options uses, and I don't think that's a problem. > > > > > > > > > `-Wno-overriding-option` is properly named, so affecting new > > > > > > > > > overriding-options uses looks fine to me. > > > > > > > > > `-Wno-overriding-t-option` is awkward, and making it affect > > > > > > > > > new uses makes me nervous. > > > > > > > > > > > > > > > > > > The gist of my previous comment is whether the uses cases > > > > > > > > > really justify a tiny bit of tech bit in clang and I think > > > > > > > > > the answer is no. > > > > > > > > > > > > > > > > > > This change is not about changing a semantic warning that has > > > > > > > > > mixed opinions, e.g. `-Wbitwise-op-parentheses` (many > > > > > > > > > consider it not justified). > > > > > > > > > The gist of my previous comment is whether the uses cases > > > > > > > > > really justify a tiny bit of tech bit in clang and I think > > > > > > > > > the answer is no. > > > > > > > > > > > > > > > > > > > > > > > > > I think we agree that we should add the minimal technical debt > > > > > > > > to clang. > > > > > > > > > > > > > > > > This patch is harder-to-reason about, and thus bigger IMO, > > > > > > > > technical debt than adding an alias would be. > > > > > > > Honestly when people asked whether we need back compatibility for > > > > > > > `-Werror` uses. I disagree with the idea after considering the > > > > > > > number of uses and legitimate uses. I've well summarized them > > > > > > > up-thread. > > > > > > > > > > > > > > Making overriding-option a super set of overriding-t-option is > > > > > > > IMHO the only solution to make -Wno-overriding-t-option not > > > > > > > affect other uses, which is what I strive to achieve. > > > > > > > > > > > > > > If `-Woverriding-t-option` looks strange for the Darwin > > > > > > > diagnostic and we really want to work around such `-Werror` users > > > > > > > (I disagree as I mentioned), we could rename it to something like > > > > > > > `-Woverriding-darwin-option` or something else, and add > > > > > > > `-Woverriding-t-option` as an alias. Then the diagnostic becomes: > > > > > > > > > > > > > > > overriding '-mmacos-version-min=10.6' option with '-target > > > > > > > > x86_64-apple-macos10.11.2' [-Woverriding-darwin-option] > > > > > > > > > > > > > > This would still achieve my goal of not making > > > > > > > `overriding-t-option` affect `overriding-option`. > > > > > > > > > > > > > > My most honest thinking is that we don't need any of the > > > > > > > `overriding-t-option` tech debt. The users need to migrate. It's > > > > > > > some work and I apologize to these users, but I don't think these > > > > > > > uses are anything close to reasonable that justifies any debt on > > > > > > > the clang side. > > > > > > > Making overriding-option a super set of overriding-t-option is > > > > > > > IMHO the only solution to make -Wno-overriding-t-option not > > > > > > > affect other uses, which is what I strive to achieve. > > > > > > > > > > > > > > > > > > > It's not clear why this specific piece matters. It seems moot to > > > > > > me. Any current users of overriding-t-option will blindly switch to > > > > > > the new spelling and, in effect, their old uses of > > > > > > `-Woverriding-t-option` [sic] will affect new instances of > > > > > > overriding-option. > > > > > > > > > > > > Stepping back, here's what I think the effects of the three choices > > > > > > are. > > > > > > > > > > > > With ToT: > > > > > > - Current users of overriding-t-option will need to migrate to > > > > > > overriding-option. Whatever their reasons for having > > > > > > overriding-t-option, existing uses will blindly migrate to > > > > > > overriding-option, and thus blindly affect all future > > > > > > overriding-option diagnostics. > > > > > > - Diagnostics will report as `-Woverriding-option`. Anyone seeing a > > > > > > new diagnostic will use the new spelling. > > > > > > - Maintainers don't have to think about overriding-t-option > > > > > > anymore, except for supporting user migration. > > > > > > > > > > > > With an alias: > > > > > > - Current users of overriding-t-option will not need to migrate to > > > > > > overriding-option. Just like ToT, their existing uses will blindly > > > > > > affect all overriding-option diagnostics. > > > > > > - Diagnostics will report as `-Woverriding-option`. Anyone seeing a > > > > > > new diagnostic will use the new spelling. > > > > > > - Maintainers don't have to think about overriding-t-option > > > > > > anymore; it'll be clear that it's just an old spelling. > > > > > > > > > > > > With this patch: > > > > > > - Some current users of overriding-t-option will need to migrate to > > > > > > overriding-option; others will not. > > > > > > - Some diagnostics will report as `-Woverriding-option`, others as > > > > > > `-Woverriding-t-option`, so new users hitting the latter will > > > > > > continue to add the old spelling to build settings. > > > > > > - The difference between which are canonically "t" (or not) is an > > > > > > accident of history and will be hard to reason about. > > > > > > - Maintainers who overriding-t-option will be tempted to clean it > > > > > > up, and need to dig up this thread to understand why it's like > > > > > > this, or land a change and hit the same problems. > > > > > > > > > > > > Do you agree with these effects? If not, what part have I got > > > > > > wrong? Or have I missed another important effect? > > > > > > > > > > > > If you agree that I have the effects correct, then I'm still > > > > > > confused as to how this patch would be easier to maintain or better > > > > > > for users than an alias. > > > > > > > > > > > > Note that my personal stake in this is low. My only current > > > > > > involvement in LLVM is volunteering my time as a reviewer. If those > > > > > > with users (e.g., @dblaikie or @aaron.ballman, who added > > > > > > post-commit review to https://reviews.llvm.org/D158137) agree with > > > > > > you that this patch is the right way forward, I'm happy to let it > > > > > > go through. > > > > > Thanks for taking time to write the summary. I agree with the > > > > > analysis and sorry that this discussion has taken your valuable time. > > > > > > > > > > > If you agree that I have the effects correct, then I'm still > > > > > > confused as to how this patch would be easier to maintain or better > > > > > > for users than an alias. > > > > > > > > > > This patch wasn't created with a good motivation. It was for > > > > > discussion when people raised compatibility concern (valid) that I > > > > > don't agree with, considering the scope of affected users and how > > > > > reasonable the `-Wno-overriding-t-option` use is. > > > > > > > > > > I do not want `-Wno-overriding-t-option` (even it is hidden) to > > > > > affect good uses while an alias. I think I am happy with an alias > > > > > that will be removed, say one year. > > > > > Note that my personal stake in this is low. My only current > > > > > involvement in LLVM is volunteering my time as a reviewer. If those > > > > > with users (e.g., @dblaikie or @aaron.ballman, who added post-commit > > > > > review to https://reviews.llvm.org/D158137) agree with you that this > > > > > patch is the right way forward, I'm happy to let it go through. > > > > > > > > (really appreciate your work, @dexonsmith, btw - both having historic > > > > context, and any help out with review load, etc, is really valuable) > > > > > > > > Yeah, I'd rather see this as an alias. I don't feel like it's worth > > > > removing later, though. I don't think it's substantial technical debt > > > > to keep an old alias around. It doesn't add significant friction to the > > > > project that I can think of. > > > (I was expecting more reasoning than "it's substantial technical debt, so > > > we take it".) > > > > > > I have performed a survey on existing `Wno-overriding-t-option` uses. > > > Only some Darwin use cases like > > > https://github.com/oldzhu/4dotnet/blob/master/package/dotnetcore/dotnetruntime/modified/configurecompiler.cmake.v6.0.2#L404 > > > requires some thoughts. It may be on the boundary of the scale that I'd > > > consider a workaround. Hence one of my previous comments said: > > > > > > > If -Woverriding-t-option looks strange for the Darwin diagnostic and we > > > > really want to work around such -Werror users (I disagree as I > > > > mentioned), we could rename it to something like > > > > -Woverriding-darwin-option or something else, and add > > > > -Woverriding-t-option as an alias. Then the diagnostic becomes: > > > > > > If we rename `warn_drv_overriding_t_option` below and clarify the > > > comment, I think the concern of new uses adopting > > > `warn_drv_overriding_t_option` (to-be-renamed) will be very low. > > > ``` > > > // Don't use warn_drv_overriding_t_option for new diagnostics. > > > def warn_drv_overriding_t_option : Warning< > > > "overriding '%0' option with '%1'">, > > > InGroup<OverridingTOption>; > > > def warn_drv_overriding_option : Warning< > > > "overriding '%0' option with '%1'">, > > > InGroup<OverridingOption>; > > > ``` > > > > > > Essentially, we split the `overriding-option` group and make the Darwin > > > use its own group. > > > > > > > With this patch: > > > > > > > > * Some current users of overriding-t-option will need to migrate to > > > > overriding-option; others will not. > > > > > > Yes. > > > > > > > * Some diagnostics will report as -Woverriding-option, others as > > > > -Woverriding-t-option, so new users hitting the latter will continue to > > > > add the old spelling to build settings. > > > > > > Yes. > > > > > > > The difference between which are canonically "t" (or not) is an > > > > accident of history and will be hard to reason about. > > > > > > If we add `-Wno-overriding-darwin-option` as the canonical spelling, this > > > concern can be addressed. > > > > > > > * Maintainers who overriding-t-option will be tempted to clean it up, > > > > and need to dig up this thread to understand why it's like this, or > > > > land a change and hit the same problems. > > > > > > Yes. > > > I do not want -Wno-overriding-t-option (even it is hidden) to affect good > > > uses while an alias. > > > > This seems to be the core of the disagreement. Could you expand on why this > > is important? > > Note that my personal stake in this is low. My only current involvement in > > LLVM is volunteering my time as a reviewer. If those with users (e.g., > > @dblaikie or @aaron.ballman, who added post-commit review to > > https://reviews.llvm.org/D158137) agree with you that this patch is the > > right way forward, I'm happy to let it go through. > > Assuming the analysis from @dexonsmith is accurate (thank you, that was a > really handy summary!), I think going with an alias is a good tradeoff > between maintenance burden and user experience, but I'd also like to > understand this point better: > > > I do not want -Wno-overriding-t-option (even it is hidden) to affect good > > uses while an alias. > > If we eventually get rid of the alias, then I can see why this would be a > problem (particularly for `-Werror` users), but... I don't imagine a need to > get rid of the alias. At most, I think we'd want to remove any mention of the > alias from documentation, etc and so over time search engines will "forget" > about it and so users won't organically run into the `-t-` alias. >> I do not want -Wno-overriding-t-option (even it is hidden) to affect good >> uses while an alias. > > This seems to be the core of the disagreement. Could you expand on why this > is important? > I think going with an alias is a good tradeoff between maintenance burden > and user experience, but I'd also like to understand this point better: This thought comes from my view of previous discussions regarding improved diagnostics break `-Werror` users. Frankly, I believe there are numerous other diagnostics that are hundred-time more disruptive than what we are currently observing as a relatively minor disturbance. Thus, I am having difficulty comprehending the rationale behind wanting to maintain this workaround indefinitely. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D158301/new/ https://reviews.llvm.org/D158301 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
