[compiler-hacking] Use of opam-compiler-conf: install packages

[Jeremy Yallop]

On 4 April 2016 at 13:45, Olivier Nicole
<olivier.nicole at ensta-paristech.fr> wrote:
> On 04/04/2016 07:36 AM, Jeremy Yallop wrote:
>> Is your OPAM package list up-to-date?  Recent versions of Core (e.g.
>> 113.33.00) should meet the version constraints for modified trunk
>> compilers:
>>
>>    https://github.com/ocaml/opam-repository/blob/master/packages/core/core.113.33.00/opam#L29
>>
>> Whether they'll actually build is another question, of course.
>
> Thank you, I just needed to do an `opam update`. But now the ppx-tools
> and sexplibs packages fail to build, and I'm quite sure it is not due to
> my changes in translcore.ml (I merely changed a condition to `true` so
> that records are always updated fieldwise). For example, the build of
> ppx_tools fails with:
>
>     File "src/gen/common.ml", line 73, characters 24-34:
>     Error: This expression has type Types.constructor_arguments
>            but an expression was expected of type Types.type_expr list
>
> Am I missing something or did my changes really break the package?

It's quite likely that the released versions of ppx-tools and sexplib
don't compile with OCaml trunk.  Packages that depend on compiler-libs
tend to break whenever there's a significant change to a module such
as Parsetree or Types.