https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102496
Bug ID: 102496
Summary: [11 regression] extern __thread declaration in
function scope produces a non-TLS reference
Product: gcc
Version: 11.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jlegg at feralinteractive dot com
Target Milestone: ---
A variable declaration inside a function body qualified with extern and
__thread appears to ignore the __thread qualification when compiling c++.
For example:
Contents of test1.cc:
extern __thread int thing;
__thread int thing = 0;
Contents of test2.cc:
int main()
{
extern __thread int thing;
return thing;
}
When invoking g++ 11.2.0 with arguments test1.cc test2.cc, I get the following
output:
/usr/local/bin/ld: thing: TLS definition in /tmp/ccXxZiSY.o section
.tbss mismatches non-TLS reference in /tmp/ccYXyoSR.o
/usr/local/bin/ld: /tmp/ccYXyoSR.o: error adding symbols: bad value
collect2: error: ld returned 1 exit status
If the example code was instead in files with a .c extension and compiled with
gcc (as opposed to g++) 11.2.0, it does not produce an error. I also could not
reproduce the error with g++ 10.2.0.
The options I used when configuring GCC are: --prefix=/usr
--program-suffix=-11.2 --libexecdir=/usr/lib
--with-gxx-include-dir=/usr/include/c++/11.2 --libdir=/usr/lib
--with-tune=generic --enable-checking=release --disable-multilib
--enable-languages=c,c++ --build=x86_64-linux-gnu --target=x86_64-linux-gnu
--enable-linker-build-id --enable-version-specific-runtime-libs
It is possible to work around the issue by moving or copying the variable
declaration to namespace scope.
