add a CPP program field to Settings file (decouple CPP program and C compiler choice)

the tight coupling in a vanilla GHC between the choice of c compiler and CPP program (for the normal user, with or without cabal-install managing the build) is a huge source of support problems for GHC on OS X right now. Additionally, even if everyone started having cpphs or something similar installed on their computers tomorrow, we have no way of bundling it with GHC so that it will be called by default for any Haskell CPP needs.

accordingly, maybe it'd be worth adding a cpp program field to settings? i'm aware of -pgmP and how cabal can use it (or I can), but normal ghc packages and naive end users don't twiddle that.

also its been said a number of times recently that GHC should have its own preprocessor, and if so, we need to bake in machinery to be able to distribute a program distinct from the C compiler for that role

Trac metadata

Trac field	Value
Version	7.7
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

changed milestone to %7.10.1

changed weight to 5

added Tfeature request Trac import labels

mentioned in issue #8683 (closed)

Trac metadata

Trac field	Value
Related	→ #8683 (closed)

closed

removed milestone

Duplicate of #8683 (closed).

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedDuplicate
Component	Compiler → Build System

The new Hadrian build system has been merged. Relabeling the tickets concerning the legacy make build system to prevent confusion.

Trac metadata

Trac field	Value
Component	Build System → Build System (make)

added Pnormal label