This is a testcase (a space before a backslash or after a newline, and two pairs of quotes (or no quotes at all), are important):
"hello," \ "world" In GCC 4.5.0 20091015, preprocessor produces this: # 1 "<stdin>" # 1 "<built-in>" # 1 "<command-line>" # 1 "<stdin>" "hello," "world" whereas older GCC versions give this: # 1 "<stdin>" # 1 "<built-in>" # 1 "<command-line>" # 1 "<stdin>" "hello," "world" Such a new behavior seems to be in contradiction with what the documentation says: "the backslash is removed and the following line is joined with the current one." -- Summary: Continued lines are not merged into one long line Product: gcc Version: 4.5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: preprocessor AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: d dot g dot gorbachev at gmail dot com GCC build triplet: i686-pc-linux-gnu GCC host triplet: i686-pc-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41748