[project @ 2002-02-07 12:51:47 by simonpj]

[project @ 2002-02-07 12:51:47 by simonpj]
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	Slurp in a few more instance decls with ghc --make
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ghc --make wasn't slurping in quite enough instance decls.
The relevant comment is in RnIfaces; the new part is marked.
George Russel's Uniform showed this up.

We slurp in an instance decl from the gated instance pool iff

	all its gates are either in the gates of the module,
	or are a previously-loaded tycon or class.

The latter constraint is because there might have been an instance
decl slurped in during an earlier compilation, like this:

	instance Foo a => Baz (Maybe a) where ...

In the module being compiled we might need (Baz (Maybe T)), where T
is defined in this module, and hence we need (Foo T).  So @Foo@ becomes
a gate.  But there's no way to 'see' that.

NEW:  More generally, types might be involved as well:
NEW:  	instance Foo2 T a => Baz2 a where ...
NEW:
NEW: Now we must treat T as a gate too, as well as Foo.  So the solution
NEW: we adopt is:
NEW:
NEW: 	we simply treat all previously-loaded
NEW: 	tycons and classes as gates.
NEW:
NEW: This gloss only affects ghc --make and ghc --interactive.