[PATCH] D146101: [clang-format] Add DesignatedInitializerIndentWidth option.

[Jon Phillips via Phabricator via cfe-commits]

jp4a50 added inline comments.


================
Comment at: clang/lib/Format/ContinuationIndenter.cpp:1665-1669
+      const auto DesignatedInitializerIndentWidth =
+          Style.DesignatedInitializerIndentWidth < 0
+              ? Style.ContinuationIndentWidth
+              : Style.DesignatedInitializerIndentWidth;
+      NewIndent = CurrentState.LastSpace + DesignatedInitializerIndentWidth;
----------------
HazardyKnusperkeks wrote:
> owenpan wrote:
> > jp4a50 wrote:
> > > HazardyKnusperkeks wrote:
> > > > owenpan wrote:
> > > > > jp4a50 wrote:
> > > > > > owenpan wrote:
> > > > > > > owenpan wrote:
> > > > > > > > Using -1 to mean `ContinuationIndentWidth` is unnecessary and somewhat confusing IMO.
> > > > > > > Please disregard my comment above.
> > > > > > Just to make sure we are on the same page, does this mean that you are happy with the approach of using `-1` as a default value to indicate that `ContinuationIndentWidth` should be used?
> > > > > > 
> > > > > > I did initially consider using `std::optional<unsigned>` and using empty optional to indicate that `ContinuationIndentWidth` should be used but I saw that `PPIndentWidth` was using `-1` to default to using `IndentWidth` so I followed that precedent.
> > > > > Yep! I would prefer the `optional`, but as you pointed out, we already got `PPIndentWidth`using `-1`.
> > > > From the C++ side I totally agree. One could use `value_or()`, which would make the code much more readable.
> > > > And just because `PPIndentWidth` is using -1 is no reason to repeat that, we could just as easily change `PPIndentWidht` to an optional.
> > > > 
> > > > But how would it look in yaml?
> > > In YAML we wouldn't need to support empty optional being *explicitly* specified - it would just be the default.
> > > 
> > > So specifying `DesignatedInitializerIndentWidth: 4` would set the `std::optional<unsigned>` to `4` but if `DesignatedInitializerIndentWidth` was omitted from the YAML then the optional would simply not be set during parsing.
> > > 
> > > Of course, if we were to change `PPIndentWidth` to work that way too, it would technically be a breaking change because users may have *explicitly* specified `-1` in their YAML.
> > > And just because `PPIndentWidth` is using -1 is no reason to repeat that, we could just as easily change `PPIndentWidht` to an optional.
> > 
> > We would have to deal with backward compatibility to avoid regressions though.
> > In YAML we wouldn't need to support empty optional being *explicitly* specified - it would just be the default.
> > 
> > So specifying `DesignatedInitializerIndentWidth: 4` would set the `std::optional<unsigned>` to `4` but if `DesignatedInitializerIndentWidth` was omitted from the YAML then the optional would simply not be set during parsing.
> > 
> > Of course, if we were to change `PPIndentWidth` to work that way too, it would technically be a breaking change because users may have *explicitly* specified `-1` in their YAML.
> 
> You need an explicit entry, because you need to be able to write the empty optional on `--dump-config`.
> > In YAML we wouldn't need to support empty optional being *explicitly* specified - it would just be the default.
> > 
> > So specifying `DesignatedInitializerIndentWidth: 4` would set the `std::optional<unsigned>` to `4` but if `DesignatedInitializerIndentWidth` was omitted from the YAML then the optional would simply not be set during parsing.
> > 
> > Of course, if we were to change `PPIndentWidth` to work that way too, it would technically be a breaking change because users may have *explicitly* specified `-1` in their YAML.
> 
> You need an explicit entry, because you need to be able to write the empty optional on `--dump-config`.

It looks like the YAML IO logic just does the right thing (TM) with `std::optional`s. When calling `IO.mapOptional()` on output, it simply doesn't write the key out if the value is an empty optional. So I don't think this is an issue.

As @owenpan says, though, there is still the issue of backward compatibility with `PPIndentWidth`.

I don't feel strongly about which way to go so I'll leave it to you two to decide!


Repository:
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  https://reviews.llvm.org/D146101/new/

https://reviews.llvm.org/D146101