No easy way to add cost-centre to top-levels

As far as I can see from the user manual (I also tried placing some SCCs), there's no way to easily add cost-centres to top-level definitions. We can do things like:

f x y z = ...
=>
f = {-# SCC f #-} \x y z -> ...

but it becomes too much work once we have "equations" style definitions like

head [] = {-# SCC head #-} Nothing
head (x : _) = {-# SCC head #-} Just x

Also, where clauses work differently after the transformations. Example:

f x y z = ...
  where <can use x and y here>
=>
f = {-# SCC f #-} \x y z -> ...
  where <can't use x and y here>

So it gets annoying real quick. It'd be really great if we could just add {-# SCC ... #-} just like {-# INLINE ... #-} pragmas.

Any ideas/opinions?

Looking at the code, it seems like -fprof-auto and similar flags are adding ticks to FunBind.fun_tick. We could do the same with this new SCC pragma.

Trac metadata

Trac field	Value
Version	8.0.1
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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