Port to new Q_UNREACHABLE_RETURN()

This is a semantic patch using ClangTidyTransformator to convert
sequences of Q_UNREACHABLE() + return into Q_UNREACHABLE_RETURN(),
newly added to qtbase.

    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));

a.k.a qt-use-unreachable-return.

subStmt() and nextStmt() are non-standard matchers.

There was one false positive, suppressed it with NOLINTNEXTLINE.

It's not really a false positiive, 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.

Change-Id: I3855b2dc8523db1ea860f72ad9818738162495c6
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

2 files changed, 2 insertions, 4 deletions

diff --git a/src/qmldebug/qqmlprofilerevent.cpp b/src/qmldebug/qqmlprofilerevent.cpp
index 0cea64b41f..59e9eb4ebd 100644
--- a/src/qmldebug/qqmlprofilerevent.cpp
+++ b/src/qmldebug/qqmlprofilerevent.cpp
@@ -67,8 +67,7 @@ static inline Number readNumber(QDataStream &stream, qint8 type)
         return static_cast<Number>(value);
     }
     default:
-        Q_UNREACHABLE();
-        return 0;
+        Q_UNREACHABLE_RETURN(0);
     }
 }
 
diff --git a/src/qmldebug/qqmlprofilerevent_p.h b/src/qmldebug/qqmlprofilerevent_p.h
index 88aec820cf..9870e47897 100644
--- a/src/qmldebug/qqmlprofilerevent_p.h
+++ b/src/qmldebug/qqmlprofilerevent_p.h
@@ -175,8 +175,7 @@ QT_WARNING_POP
         case Inline8Bit:
             return QString::fromUtf8(m_data.internalChar, m_dataLength);
         default:
-            Q_UNREACHABLE();
-            return QString();
+            Q_UNREACHABLE_RETURN(QString());
         }
     }