[Bug c/63344] New: [5 Regression] Linux (makeallyes config) compilation error: error: apic_numachip causes a section type conflict with numachip_system

[mliska at suse dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63344

            Bug ID: 63344
           Summary: [5 Regression] Linux (makeallyes config) compilation
                    error: error: apic_numachip causes a section type
                    conflict with numachip_system
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mliska at suse dot cz
                CC: hubicka at ucw dot cz

During testing of latest compiler, I've encountered an error in Linux kernel:
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/tree/arch/x86/kernel/apic/apic_numachip.c?id=refs/tags/next-20140923

arch/x86/kernel/apic/apic_numachip.c:33:12: error: numachip_system causes a
section type conflict with apic_numachip
 static int numachip_system __read_mostly;
            ^
arch/x86/kernel/apic/apic_numachip.c:205:26: note: 'apic_numachip' was declared
here
 static const struct apic apic_numachip __refconst = {

There's a testcase reduced by creduce:
$ cat testcase.ii

struct apic {
  int *name
} numachip_system __attribute__((__section__(".data..read_mostly")));
static const struct apic apic_numachip
    __attribute__((__section__(".data..read_mostly")));
static const struct apic apic_numachip
    __attribute__((__section__(""))) = {.name = ""};

$ gcc testcase.i -S
/home/marxin/Programming/testcases/kernel_numa/testcase.i:6:26: error:
apic_numachip causes a section type conflict with numachip_system

The problem started with: r211363

Older gcc produces:
/home/marxin/Programming/testcases/kernel_numa/testcase.i:3:1: warning: no
semicolon at end of struct or union [enabled by default]
 } numachip_system __attribute__((__section__(".data..read_mostly")));
 ^
/home/marxin/Programming/testcases/kernel_numa/testcase.i:7:5: warning:
initialization from incompatible pointer type [enabled by default]
     __attribute__((__section__(""))) = {.name = ""};
     ^
/home/marxin/Programming/testcases/kernel_numa/testcase.i:7:5: warning: (near
initialization for ‘apic_numachip.name’) [enabled by default]

I am not familiar with section attribute magic, but it looks like a regression.

Thank you,
Martin