Eclipse "invalid project path: duplicate path entries"

I have a cplusplus project that is built using a makefile, eclipse constantly warns about "invalid project path: duplicate path entries", but I cannot figure out what the hell it wants me to do. I wowould like to disable this warning and continue with my life.

My application compiles and runs fine, with not a single warning before t this one. Being a conscientious developer I am keen to fix this problem so I have the warm fuzzies only a clean build can bring.

Solution

1. Open the project properties | C/C ++ build | discovery options.
2. Click the button by clear discovered entries now.
3. Rebuild.

It is seems to be a new feature in CDT. I have had this "invalid project path: duplicate path entries" problem for years, and this is apparently the newly provided solution.

Before doing this there were duplicate paths under C/C ++ General | paths and symbols | des tab. I cocould not get rid of these. they only appear when show built-in values is checked, so they are apparently generated somehow. after doing the above
They were replaced with a set that did not have duplicates. the only difference is that the same settings appeared under Assembly, gnu c, and gnu c ++. previusly they were different sets. the ones for assembly were empty, for example.

So far the problem has not returned.