https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94535
Bug ID: 94535
Summary: __LINE__ value changed for macro invocations spanning
multiple lines
Product: gcc
Version: 9.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: preprocessor
Assignee: unassigned at gcc dot gnu.org
Reporter: alisdairm at me dot com
Target Milestone: ---
Given the following simple program, the line that static_asserts changed from
gcc 8 to gcc 9 (and remains so for current trunk prior to 10's release):
#define LINE(DUMMY) __LINE__
constexpr int X = LINE(
wrap);
static_assert(X == 3); // gcc 8 and earlier, non-gcc compilers
static_assert(X == 4); // gcc 9 and 10
Note that every other compiler I have access to has the original gcc 8
behavior.
(tested widely with Godbolt compiler explorer, and on Solaris/AIX with native
compilers)
Unsurprisingly, this is breaking unit tests and other code similarly sensitive
to line numbers.
Godbolt link for quick testing: https://godbolt.org/z/LU--gC
