Meaning-preserving SCC annotations (#15730)
This patch implements GHC Proposal #176
Before the change:
1 / 2 / 2 = 0.25
1 / {-# SCC "name" #-} 2 / 2 = 1.0
After the change:
1 / 2 / 2 = 0.25
1 / {-# SCC "name" #-} 2 / 2 = parse error
Fixes #15730 (closed)