Eeschema: Append schematics clears out existing annotation

OBS this is actually present in 5.0.1 stable.
Should perhaps be fixed in stable as well

Workaround: create a temporary hierarchical sheet. Append the schematic there. Then copy from there and paste to another sheet.

@Frank, do you mean all of the other sheets in your schematic or all of the other sheets in the appended schematic?

In all my schematic, root and Subsheets

In the sheet where it was appended to and all its subsheets. But not the sheet in upper level. For example sheet hierarchy:

A
|__B
   |___C

where C is a hierarchical sheet inside B and B is inside A.

If I append a .sch file to B, the annotations in B and C are cleared, but not A.

If I understood Frank correctly he thinks that the annotations of the newly appended symbols should be cleared, not the annotations which were already in the current schematic, no matter what the hierarchy. I agree with that.

Thanks for the clarification @Eelik. And that is indeed exactly my points

@Frank, are B and C in @eelik's example in #5 part of the current project? If so, then it makes sense that the B and C references are cleared because all references in the appended schematic(s) are cleared not just the new reference paths. We would need to change the code to only clear the references of the appended reference paths which would be rather complex. We opted for the easy way out and cleared all reference paths which would cause the behavior you are seeing.

@Wayne
Yes I have B and C subsheets in my project. In my case I needed to append to A (rootsheet), which cleared all designator on my entire schematic.

just to be clear, the schematic I appended, was a single sheet with no subsheets.

to summarize I don't see why appended schematics should touch any preexisting schematic.

Lets make it even simpler. This whole thing also affects schematics without any hierarchical sheets in it. I made a quick screencast [1] of what happens if you append a sheet with one single symbol in it to another one with also one symbol in it. The expectation would be that the original symbol (J2) keeps its annotation and only the one from the source sheet (X1) should loose it.

It has also been reported on the forum [2]. In that case there is already an existing layout. Loosing the annotation means that the layout and schematic get out of sync.

I attached the projects i used to create the screencast.

[1]: https://youtu.be/LkXT06GrM5s
[2]: https://forum.kicad.info/t/appending-components-in-eeschema-resets-all-annotations/13917

I've attached a patch to fix this issue but I would like some further testing before I commit it. There was an ominous warning comment (eeschema/files_io.cpp lines 623-624) about clearing the annotation before the symbol links were updated but this doesn't make sense to me. Git blamed @Jeff for this comment so I'm curious as to why this is an issue since the symbol links shouldn't effect the annotation.

@Wayne, afraid I can't help much on the comment:

    // Clear all annotation in the imported schematic
       to prevent clashes with existing annotation.
    // Must be done after updating the symbol links as
       we need to know about multi-unit parts.

The first half predates me. I just moved it and added the second half about the clear needing to be done after updating the links.

@Wayne-

Your patch seems to work as advertised.

That said, the original comment was written in the fix to lp:1731760

I pushed my patch. If someone finds a corner case, I can fix it then.

Fixed in revision 07ebc4df14583cf6eefc93a143882922d1b71ad2
https://git.launchpad.net/kicad/patch/?id=07ebc4df14583cf6eefc93a143882922d1b71ad2

@Wayne Thanks for the fix! should this be added to stable as well?

@Frank, 5.0.2 has already been tagged and the packages are in the process of being built so this fix wont make it. I'm hoping we can get 5.1 release before FOSDEM so we wont have to create a 5.0.3 release.