0004841: Cannot make callbacks from C code when using the -output-obj option under Mac OS X

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0004841

OCaml

OCaml general

public

2009-07-25 16:20

2009-09-13 18:50

Reporter

vouillon

Assigned To

xleroy

Priority

normal

Severity

major

Reproducibility

always

Status

closed

Resolution

fixed

Platform

Mac OS X

OS Version

Product Version

3.11.1

Target Version

Fixed in Version

3.11.2+dev

Summary

0004841: Cannot make callbacks from C code when using the -output-obj option under Mac OS X

Description

We use the -output-obj option when compiling the Mac OS UI of Unison. With Ocaml 3.11.1, we get the following error when linking the final binary:
  Undefined symbols:
     "_caml_apply2", referenced from:
         _caml_callback2_exn in libasmrun.a(i386.o)
     "_caml_apply3", referenced from:
         _caml_callback3_exn in libasmrun.a(i386.o)

Indeed, the symbols caml_apply2 and caml_apply3 are local:
    > nm u-b.o | grep apply2
    000024b0 t _caml_apply2
(File u-b.o is the result of linking the Ocaml code using the "-output-obj" option.)

Apparently, this is a consequence of using "private_extern" rather than "glob" (bug 0004960):
        .text
        .align 4
        .private_extern _caml_apply2
_caml_apply2:
        subl $12, %esp
        [...]

We have tried to use the "-keep_private_externs" of ld as a workaround: it is supposed to prevent the private external symbols from becoming local. But this does not seem to make any difference.

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Relationships

parent of	0004878	closed		Cannot make callbacks from C code when using the -output-obj option under Mac OS X (other solution of 0004841)
has duplicate	0004860	closed	xleroy	3.11.1 fails to link mixed C/Ocaml program which 3.11.0 can link on OS X

Notes
(0005078) xleroy (administrator) 2009-09-13 18:50	Fixed in 3.11 bugfix CVS branch (by not emitting .private_extern declarations if -output-obj is active). Will go in 3.11.2.

Issue History
Date Modified	Username	Field	Change
2009-07-25 16:20	vouillon	New Issue
2009-09-13 18:41	xleroy	Status	new => assigned
2009-09-13 18:41	xleroy	Assigned To	=> xleroy
2009-09-13 18:42	xleroy	Relationship added	has duplicate 0004860
2009-09-13 18:50	xleroy	Note Added: 0005078
2009-09-13 18:50	xleroy	Status	assigned => closed
2009-09-13 18:50	xleroy	Resolution	open => fixed
2009-09-13 18:50	xleroy	Fixed in Version	=> 3.11.2+dev
2010-04-18 15:00	xleroy	Relationship added	parent of 0004878