Add proper support for weak symbols to the runtime linker

Currently weak symbols support is only partially supported by the runtime linker. The current support is mostly there to provide COMDAT support.

In #11223 (closed) this support has been extended but there is still some work needed to finish weak symbols support.

Also there needs some investigation into how this support should look like. E.g. are we only supporting linking weak symbols in C or do we want to support it in Haskell as well.

Trac metadata

Trac field	Value
Version	8.1
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Runtime System (Linker)
Test case
Differential revisions
BlockedBy
Related	#11223 (closed)
Blocking
CC
Operating system
Architecture

mentioned in issue #3333 (closed)

changed milestone to %8.2.1

changed weight to 5

added RTS Tfeature request Trac import linking labels

Some test have already been defined in testsuite\tests\rts\T11223\all.T but they may need to be modified slightly.

Previous discussion in #3333 (closed).

Trac metadata

Trac field	Value
Test case	- → ghci/linking/T3333, rts/T11223/T11223_weak*
Related	#11223 (closed) → #3333 (closed), #11223 (closed)

Did something happen here already? I can't remember.

not since #11223 (closed) that I'm aware of.

added broken test label

added Pnormal label

marked this issue as related to #11223 (closed)

marked this issue as related to #5197