https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98043
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:7482d5a3acb7a8a5564f5cddc4f9d2ebbaea75e4 commit r11-5829-g7482d5a3acb7a8a5564f5cddc4f9d2ebbaea75e4 Author: Marek Polacek <pola...@redhat.com> Date: Wed Dec 2 10:47:49 2020 -0500 c++: ICE with switch and scoped enum bit-fields [PR98043] In this testcase we are crashing trying to gimplify a switch, because the types of the switch condition and case constants have different TYPE_PRECISIONs. This started with my r5-3726 fix: SWITCH_STMT_TYPE is supposed to be the original type of the switch condition before any conversions, so in the C++ FE we need to use unlowered_expr_type to get the unlowered type of enum bit-fields. Normally, the switch type is subject to integral promotions, but here we have a scoped enum type and those don't promote: enum class B { A }; struct C { B c : 8; }; switch (x.c) // type B case B::A: // type int, will be converted to B Here TREE_TYPE is "signed char" but SWITCH_STMT_TYPE is "B". When gimplifying this in gimplify_switch_expr, the index type is "B" and we convert all the case values to "B" in preprocess_case_label_vec, but SWITCH_COND is of type "signed char": gimple_switch_index should be the (possibly promoted) type, not the original type, so we gimplify the "x.c" SWITCH_COND to a SSA_NAME of type "signed char". And then we crash because the precision of the index type doesn't match the precision of the case value type. I think it makes sense to do the following; at the end of pop_switch we've already issued the switch warnings, and since scoped enums don't promote, it should be okay to use the type of SWITCH_STMT_COND. The r5-3726 change was about giving warnings for enum bit-fields anyway. gcc/cp/ChangeLog: PR c++/98043 * decl.c (pop_switch): If SWITCH_STMT_TYPE is a scoped enum type, set it to the type of SWITCH_STMT_COND. gcc/testsuite/ChangeLog: PR c++/98043 * g++.dg/cpp0x/enum41.C: New test.
