Hi!
The testcase below has a useless break; that causes a bogus -Wreturn-type
warning. The C++ FE already has code to avoid adding a BREAK_STMT
after a return or similar sequence that is known not to return.
The following patch extends block_may_fallthrough to also return false
for SWITCH_STMTs that can't fall through.
Those are ones with non-empty body where the whole body can't fallthrough,
additionally they need to have a default: case label (or cover the whole
range of values, but that is not what this patch can compute, that would
be too big duplication of the gimplification processing) and no BREAK_STMT.
For the default: case label we need to look in all SWITCH_BODY children
except for nested SWITCH_STMTs, for BREAK_STMTs also not in
{FOR,DO,WHILE}_BODY.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2017-11-24 Jakub Jelinek <jakub@redhat.com>
PR sanitizer/81275
* cp-objcp-common.c (struct find_default_and_break_s): New type.
(find_default_and_break): New function.
(cxx_block_may_fallthru): Return false for SWITCH_STMT which
contains no BREAK_STMTs and contains a default: CASE_LABEL_EXPR.
* g++.dg/warn/pr81275.C: New test.