From fc7676769251a27cbbc6d40d68f04bfe38511a5b Mon Sep 17 00:00:00 2001 From: Marc Mutz Date: Thu, 22 Sep 2022 11:39:44 +0200 Subject: Long live Q_UNREACHABLE_RETURN()! This is a combination of Q_UNREACHABLE() with a return statement. ATM, the return statement is unconditionally included. If we notice that some compilers warn about return after __builtin_unreachable(), then we can map Q_UNREACHABLE_RETURN(...) to Q_UNREACHABLE() without having to touch all the code that uses explicit Q_UNREACHABLE() + return. The fact that Boost has BOOST_UNREACHABLE_RETURN() indicates that there are compilers that complain about a lack of return after Q_UNREACHABLE (we know that MSVC, ICC, and GHS are among them), as well as compilers that complained about a return being present (Coverity). Take this opportunity to properly adapt to Coverity, by leaving out the return statement on this compiler. Apply the macro around the code base, using a clang-tidy transformer rule: const std::string unr = "unr", val = "val", ret = "ret"; auto makeUnreachableReturn = cat("Q_UNREACHABLE_RETURN(", ifBound(val, cat(node(val)), cat("")), ")"); auto ignoringSwitchCases = [](auto stmt) { return anyOf(stmt, switchCase(subStmt(stmt))); }; makeRule( stmt(ignoringSwitchCases(stmt(isExpandedFromMacro("Q_UNREACHABLE")).bind(unr)), nextStmt(returnStmt(optionally(hasReturnValue(expr().bind(val)))).bind(ret))), {changeTo(node(unr), cat(makeUnreachableReturn, ";")), // TODO: why is the ; lost w/o this? changeTo(node(ret), cat(""))}, cat("use ", makeUnreachableReturn)) ); where nextStmt() is copied from some upstream clang-tidy check's private implementation and subStmt() is a private matcher that gives access to SwitchCase's SubStmt. A.k.a. qt-use-unreachable-return. There were some false positives, suppressed them with NOLINTNEXTLINE. They're not really false positiives, it's just that Clang sees the world in one way and if conditonal compilation (#if) differs for other compilers, Clang doesn't know better. This is an artifact of matching two consecutive statements. I haven't figured out how to remove the empty line left by the deletion of the return statement, if it, indeed, was on a separate line, so post-processed the patch to remove all the lines matching ^\+ *$ from the diff: git commit -am meep git reset --hard HEAD^ git diff HEAD..HEAD@{1} | sed '/^\+ *$/d' | recountdiff - | patch -p1 [ChangeLog][QtCore][QtAssert] Added Q_UNREACHABLE_RETURN() macro. Change-Id: I9782939f16091c964f25b7826e1c0dbd13a71305 Reviewed-by: Marc Mutz Reviewed-by: Thiago Macieira --- .../platforminputcontexts/compose/qcomposeplatforminputcontext.cpp | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'src/plugins/platforminputcontexts') diff --git a/src/plugins/platforminputcontexts/compose/qcomposeplatforminputcontext.cpp b/src/plugins/platforminputcontexts/compose/qcomposeplatforminputcontext.cpp index 7e66e5fae8..3e74189076 100644 --- a/src/plugins/platforminputcontexts/compose/qcomposeplatforminputcontext.cpp +++ b/src/plugins/platforminputcontexts/compose/qcomposeplatforminputcontext.cpp @@ -108,8 +108,7 @@ bool QComposeInputContext::filterEvent(const QEvent *event) case XKB_COMPOSE_NOTHING: return false; default: - Q_UNREACHABLE(); - return false; + Q_UNREACHABLE_RETURN(false); } } -- cgit v1.2.3