PATCH: merge CONVERT_EXPR and NOP_EXPR part 1/2

[Tom Tromey]

>>>>> "Tomas" == Tomas Bily <tbily@suse.cz> writes:

Tomas>  CONVERT_EXPR and NOP_EXPR have nearly same use in current gcc. 
Tomas>  This patch merge the diferences between CONVERT_EXPR and NOP_EXPR.

How about deleting FIXED_CONVERT_EXPR and FLOAT_EXPR as follow-up
patches?  :-)  IMO we really only need 2 conversion operators for
trees: one CONVERT_EXPR-like and one VIEW_CONVERT_EXPR-like.

Personally I'd prefer the resulting conversion operator to be named
"CONVERT_EXPR" rather than "NOP_EXPR", as I think the latter is less
clear.  But a global rename could be a follow-up I suppose.

Tomas>  Bootstraped and tested on x86_64-unknow-linux, i686-unknown-linux,
Tomas> ia64-unknow-linux. Ok ?

In addition to Richard's comments:

* Your tree.def change should simply delete CONVERT_EXPR rather than
comment it out.

* You did not update the documentation.

Finally, this should wait for stage 1.

Tom