[Bug c++/14936] New: -fdata-sections + uninitialized template data objects = spurious link errors

[zack at gcc dot gnu dot org]

Consider the following code fragment:

  template <typename T> struct S { static int i; };
  template <typename T> int S<T>::i;
  int j = S<double>::i;

When compiled normally, the variable S<double>::i is emitted as 

        .comm   _ZN1SIdE1iE,4,4

which is fine.  When compiled with -fdata-sections on an ELF target, however,
the same symbol is emitted in its own .bss subsection, like this:

        .globl _ZN1SIdE1iE
        .section        .bss._ZN1SIdE1iE,"aw",@nobits
        .align 4
        .type   _ZN1SIdE1iE,@object
        .size   _ZN1SIdE1iE,4
_ZN1SIdE1iE:
        .zero   4

This causes a multiple-definition error from the linker if two source files
instantiate S<double> and are compiled with -fdata-sections.  A linkonce section
should be used instead, as is done if S<T>::i is initialized.

-- 
           Summary: -fdata-sections + uninitialized template data objects =
                    spurious link errors
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: zack at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14936