ocaml.ppwarning ignored in the toplevel

[vicuna]

Original bug ID: 7081
Reporter: @sliquister
Assigned to: @diml
Status: closed (set by @xavierleroy on 2017-02-16T14:18:16Z)
Resolution: fixed
Priority: normal
Severity: minor
Version: 4.02.3
Fixed in version: 4.03.0+dev / +beta1
Category: ~DO NOT USE (was: OCaml general)

Bug description

The toplevel ignores [@ocaml.ppwarning ".."], which is quite confusing.

Steps to reproduce

$ cat /tmp/a.ml
1 [@ppwarning "asd"];;
$ ocaml /tmp/a.ml
$ ocamlc /tmp/a.ml
File "/tmp/a.ml", line 1, characters 14-19:
Warning 22: asd

[vicuna]

Comment author: @sliquister

Presumably Typemod.type_toplevel_phrase should call Typetexp.emit_external_warnings.structure, like Typemod.type_implementation and Typemod.type_interface do.

[vicuna]

Comment author: @diml

Indeed, I committed the fix in trunk (87f92ab)

[vicuna]

Comment author: @diml

Thinking more about this, using an AST mapper here is not perfect as you can't disable the warning with [@@@ocaml.warning "-22"].

[vicuna]

Comment author: @alainfrisch

using an AST mapper here is not perfect as you can't disable the warning with [@@@ocaml.warning "-22"].

Indeed, and here is what the comment in the code says:

let emit_external_warnings =
  (* Note: this is run as a preliminary pass when type-checking an
     interface or implementation.  This allows to cover all kinds of
     attributes, but the drawback is that it doesn't take local
     configuration of warnings (with '@@warning'/'@@warnerror'
     attributes) into account.  We should rather check for
     'ppwarning' attributes during the actual type-checking, making
     sure to cover all contexts (easier and more ugly alternative:
     duplicate here the logic which control warnings locally). *)
...