https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104994
Bug ID: 104994
Summary: extern thread_local declaration rejected in constexpr
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: hstong at ca dot ibm.com
Target Milestone: ---
GCC rejects block-scope extern declarations with the `thread_local` keyword in
constexpr bodies. The relevant wording (prior to removal by P2242
<https://wg21.link/p2242>) prohibits only definitions.
### SOURCE (<stdin>):
constexpr void f() {
extern thread_local int x;
}
### COMPILER INVOCATION:
g++ -fsyntax-only -std=c++20 -xc++ -
### ACTUAL OUTPUT:
<stdin>: In function 'constexpr void f()':
<stdin>:2:27: error: 'x' declared 'thread_local' in 'constexpr' function only
available with '-std=c++2b' or '-std=gnu++2b'
### EXPECTED OUTPUT:
Clean compile.
### COMPILER VERSION INFO (g++ -v):
Using built-in specs.
COLLECT_GCC=/opt/wandbox/gcc-head/bin/g++
COLLECT_LTO_WRAPPER=/opt/wandbox/gcc-head/libexec/gcc/x86_64-pc-linux-gnu/12.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../source/configure --prefix=/opt/wandbox/gcc-head
--enable-languages=c,c++ --disable-multilib --without-ppl --without-cloog-ppl
--enable-checking=release --disable-nls --enable-lto
LDFLAGS=-Wl,-rpath,/opt/wandbox/gcc-head/lib,-rpath,/opt/wandbox/gcc-head/lib64,-rpath,/opt/wandbox/gcc-head/lib32
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.0.1 20220319 (experimental) (GCC)
