@matloob Could you please include a short rationale for the backport, in accordance with https://golang.org/wiki/MinorReleases?

Including the rationale from the original change. go/types and go/packages (through the go/types dependency) will have a race in 1.12 without this fix.

The race in go/packages reported in #31749 was fixed at tip, but is still an issue for Go 1.13 and earlier, and is showing up in the go/packages race failure reported in #36605.

That race is caused by a race in go/types which in turn is caused by go/constant.Float64Val() calling Rat.Float64 in math/big, which has a race reported in #34919 , and subsequently fixed in tip.

Fixing this race in go/types on Go 1.13 and earlier requires backporting CL 201205 to those releases. (Alternatively, we could fix the race by adding a workaround in go/constant or go/types, but that would be more work). I'm not sure if fixing this is worth a backport but we might as well have the discussion. If we decide not to go with the backport, we'll have to accept a race in go/packages and disable some of its tests in race mode in Go 1.13 and earlier.

Go 1.14 has been released, so there will not be more Go 1.12.x releases per the release policy. I'll close this issue so that it doesn't get in the way when searching for other issues in CherryPickCandidate state.