http://gcc.gnu.org/bugzilla/show_bug.cgi?id=7652
--- Comment #23 from Manuel López-Ibáñez <manu at gcc dot gnu.org> --- (In reply to Michael Chapman from comment #21) > Created attachment 32716 [details] > Proposed patch > > Patch to enable warnings (-Wswitch-fallthrough) when a switch case falls > through. Enabled by -Wall. Thanks! Patches need to be submitted to gcc-patc...@gcc.gnu.org with a Changelog after bootstrapping and regression testing. The patch is missing a testcase for the regression testsuite showing in which cases it should warn and in which cases it should not. First of all, you need to have a copyright assignment in place with the FSF. This is slightly annoying to do the first time, but you only have to do it once for all GNU projects. See: http://gcc.gnu.org/contribute.html About the patch: +int +c_stmt_ends_with_goto (tree t) This should return 'bool' +{ + if (TREE_CODE (t) == GOTO_EXPR) + return TRUE; + if (TREE_CODE (t) == BIND_EXPR) + return c_stmt_ends_with_goto (tsi_stmt (tsi_last (BIND_EXPR_BODY (t)))); + return FALSE; +} You can use 'true' and 'false' + +/* Handle -Wswitch-fallthrough */ +void +c_do_switch_fallthru_warnings (tree body) +{ + tree_stmt_iterator i; + tree previous_stmt = NULL; + tree previous_label = NULL; + tree stmts = BIND_EXPR_BODY (body); I think it would be worthwhile to add: if (!warn_switch_fallthrough) return; to avoid going through the loop if we are not going to warn anyway. +Wswitch-fallthrough +C ObjC C++ ObjC++ Var(warn_switch_fallthrough) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall) +Warn about switch cases which fall through to the next case + This says that the warning is available in C++, but I don't see any code in your patch that calls the new function from the C++ FE. It would be nice to have the same warning in C++. This will allow testing how noisy it is in GCC itself, for instance. But you (or someone else) could do that as a follow-up.
