In Problems I see errors from compilation (with gcc) and from Eclipse internal parsing. There are actually some errors from this parsing that do not show up in compilation. I do not care about fixing this parsing, but I would like these errors not to show up.
How can this be done?
The errors from internal parsing are shown by Eclipse CDT's CodAn (Code Analysis) component, which can be configured in Preferences | C/C++ | Code Analysis.
On that preference page, you can uncheck the category Syntax and Semantic Errors if you don't want to see CodAn errors, and the category Potential Programming Problems if you don't want to see CodAn warnings either.