https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71029
Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |FIXED Target Milestone|--- |11.0 --- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> --- Seems to have been fixed for GCC 11.1 with r11-5826: c-family: Fix hang with -Wsequence-point [PR98126] verify_sequence_points uses verify_tree to recursively walk the subexpressions of an expression, and while recursing, it also keeps lists of expressions found after/before a sequence point. For a large expression, the list can grow significantly. And merge_tlist is at least N(n^2): for a list of length n it will iterate n(n -1) times, and call candidate_equal_p each time, and that can recurse further. warn_for_collision also has to go through the whole list. With a large-enough expression, the compilation can easily get stuck here for 24 hours. This patch is a simple kludge: if we see that the expression is overly complex, don't even try.