[Bug ld/33180] New: LD cannot include symbol _pei386_runtime_relocator from AR archive

[pali at kernel dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=33180

            Bug ID: 33180
           Summary: LD cannot include symbol _pei386_runtime_relocator
                    from AR archive
           Product: binutils
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: pali at kernel dot org
  Target Milestone: ---

This issue could be related to bug #30343 but now it is without LTO involved.

For indirect usage of _pei386_runtime_relocator, LD cannot locate this symbol
in AR archive, but it can load it from ordinary object file.

Test reproducer:

First create simple library lib.dll with just one symbol "var":

$ cat lib.c 
int var = 47;
$ i686-w64-mingw32-gcc -c lib.c -o lib.o
$ i686-w64-mingw32-ld -shared -entry 0 -s lib.o -o lib.dll

Then create pseudo-reloc.a archive with dummy _pei386_runtime_relocator()
implementation and variable _pei386_runtime_relocator_ptr with pointer to that
function:

$ cat pseudo-reloc.c
void _pei386_runtime_relocator(void) {}
void (*_pei386_runtime_relocator_ptr)(void) = _pei386_runtime_relocator;
$ i686-w64-mingw32-gcc -c pseudo-reloc.c -o pseudo-reloc.o
$ rm -f pseudo-reloc.a; i686-w64-mingw32-ar rcs pseudo-reloc.a pseudo-reloc.o

And now the test case. Declare "var" variable without dllimport attribute (to
trigger usage of pseudo relocator) and specify tentative definition for
_pei386_runtime_relocator_ptr, and call it if is non-NULL. If pseudo-reloc is
linked then it provides non-tentative definition of
_pei386_runtime_relocator_ptr which should be used in the final variable.

$ cat test.c
extern int var;
void (*_pei386_runtime_relocator_ptr)(void);
__attribute__((used)) int mainCRTStartup(void)
{
  if (_pei386_runtime_relocator_ptr)
    _pei386_runtime_relocator_ptr();
  return var;
}

Compiling this code and linking everything together cause GNU LD linker error:

$ i686-w64-mingw32-gcc -c test.c -o test.o
$ i686-w64-mingw32-ld test.o lib.dll pseudo-reloc.a -o test.exe
i686-w64-mingw32-ld: test_exe_ertr000004.o:(.rdata+0x0): undefined reference to
`_pei386_runtime_relocator'

When pseudo-reloc.a is replaced by pseudo-reloc.o then there is no error and
GNU LD can find the _pei386_runtime_relocator symbol.

So it looks like that GNU LD is not able to locate the
_pei386_runtime_relocator symbol in AR archive pseudo-reloc.a but it is able to
locate it in object file pseudo-reloc.o.

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