https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94535
--- Comment #2 from Alisdair Meredith <alisdairm at me dot com> --- Thanks for the speedy response, really appreciated! I believe this is well-defined behavior, but can accept that the value of __LINE__ may be unspecified - I do struggle with pre-processor wording. There is no multiline "macro function" here, there is an invocation of a macro, and the invocation spans multiple lines. Our actual use case looks more like: INVOKE_MACRO(ARG1, ARG2, ARG3); Where the line-wraps are forced by coding convention and line-length limits. This is not a control-line that defined a macro, so I believe the token sequence is taken after discarding irrelevant whitespace. The issue is whether __LINE__ should correspond to the line with the opening paren, the closing paren, or one of the lines in-between. Until gcc9, AFAICT, all compilers agreed on the line with the opening paren. Even if it is unspecified behavior (so free to choose) it would be helpful to preserve a compatibility with past gcc compilers, and all other tested compilers, unless there is a strong reason to want the change. If there were more compiler divergence on the issue, I would be less concerned.