binutils: dlltool DATA exports incompatible with auto-import

[Yaakov (Cygwin/X)]

GNOME Evolution contains several interdependent libraries, so on 
Cygwin/MinGW the build creates artificial import libraries with dlltool 
from .def files.  While trying to build 2.28 I came across a possible 
incompatibility between the implib generated by dlltool and auto-import 
linkage:

$ gcc -shared -Wl,--out-implib,libtest.dll.a -o cygtest.dll libtest.c
Creating library file: libtest.dll.a

$ nm libtest.dll.a | grep -v ' [bdit] '

d000003.o:
00000000 I _cygtest_dll_iname

d000000.o:
00000000 I __head_cygtest_dll
          U _cygtest_dll_iname

d000002.o:
          U __head_cygtest_dll
00000000 I __imp__test_func
00000000 T _test_func

d000001.o:
          U __head_cygtest_dll
00000000 I __imp__test_data
00000000 I __nm__test_data

$ gcc -o test.exe test.c libtest.dll.a

# now let's try with dlltool
$ dlltool --dllname cygtest.dll --input-def libtest.def --output-lib 
libtest.dll.a

$ nm libtest.dll.a | grep -v ' [bdit] '

deobt.o:
00000000 I __libtest_dll_a_iname

deobh.o:
00000000 I __head_libtest_dll_a
          U __libtest_dll_a_iname

deobs00001.o:
          U __head_libtest_dll_a
00000000 I __imp__test_func
00000000 T _test_func

deobs00000.o:
          U __head_libtest_dll_a
00000000 I __imp__test_data
# Note no __nm__test_data auto-import here

$ gcc -o test.exe test.c libtest.dll.a
fu000001.o:(.idata$2+0xc): undefined reference to `_libtest_dll_a_iname'
nmth000000.o:(.idata$4+0x0): undefined reference to `__nm__test_data'
collect2: ld returned 1 exit status


Yaakov
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