Description Raphael Zulliger 2014-01-15 01:12:06 EST

Created attachment 238990 [details]
Eclipse plugin that implements a resource filter to reproduce this bug

Resource specific toolchain settings removed with (CDT)configuration specific resource filter

How to reproduce:
  * Create an Eclipse-Plugin, implementing a resource filter (extension point 'org.eclipse.core.resources.filterMatchers'). That filter should "filter certain resources (i.e. a .cpp or a folder) depending on the active configuration"
  * Create a C/C++ project that contains a resource that get's filtered out for a certain configuration
  * Set file specific toolchain settings for that file that'll be filtered out for a certain configuration (e.g. set a compiler directive for that file)
  * Switch the configuration so that the file with the specific toolchain settings will be filtered out (means: is not visible in the Project Explorer anymore)
  * (maybe manually start a refresh on the project level to actually cause the resources to disappear - this may be worth filing another bug?)
  * Switch back to the previous configuration (in which the file re-appears)
  * (maybe manually start a refresh on the project level to actually cause the resources to disappear - this may be worth filing another bug?)

=> BUG: The resource specific settings have been removed!

In order to make it easier to reproduce the problem, I attached:
  * An Eclipse plugin implementing such a filter
  * A CDT project containing a "filtered resource (1 .c file an 1 folder) with resource specific settings"

Root cause: The code that causes the resource specific settings to be removed is located in org.eclipse.cdt.internal.core.settings.model.ResourceChangeHandler.RcMoveHandler.done(). That code intentionally removes all file specific settings for resources that got (re)moved. It does this for all configurations of a project. In other words: That piece of code assumes that all configurations of a project are using the same resources - which is not necessarily the case, as shown with the use case of a custom resource filters.

Other side-effects: Beside removing file specific settings, this also causes changes in the .cproject file whenever changin the active configuration...

Fixes I can think of:
  a) Remove resource specific settings only for "*removed* resources" if the resource is not filtered out
  b) Remove resource specific settings only for "*removed* resources" if the resource doesn't exist on the file system anymore
  c) Remove resource specific settings only for the active configuration (instead of "all configurations)

Personally, I prefer a) or b). I could push a patch to gerrit, once we've decided how to fix the issue.

Probably relevant/similar bugs: 311189, 317783 and 348569.