Debugger: Paddle back on the (non-)auto detection of Qt versions

It looks like there are Qt-using scenarios without easy way to have
the right Qt version in the kit,

Among the frequent cases where we need to distinguish Qt versions in
the dumpers are the Qt5/6 container layout differences which can in
some cases be detected from the currently dumped value. Use that now
as the primary distinction and fall back to the previous expensive
peeking only if that is needed. This also postpones any Qt version
related activity until a real Qt type is encountered, i.e. does not
impact non-Qt scenarios.

Task-number: QTCREATORBUG-31033
Change-Id: I67b6e34c42994ad9f6e8ec8698b430b55327cf0c
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: David Schulz <david.schulz@qt.io>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

share/qtcreator/debugger/gdbbridge.py

@@ -874,6 +874,36 @@ class Dumper(DumperBase):
         except:
             return '0x%x' % address
 
+    def qtVersionString(self):
+        try:
+            return str(gdb.lookup_symbol('qVersion')[0].value()())
+        except:
+            pass
+        try:
+            ns = self.qtNamespace()
+            return str(gdb.parse_and_eval("((const char*(*)())'%sqVersion')()" % ns))
+        except:
+            pass
+        return None
+
+    def extractQtVersion(self):
+        try:
+            # Only available with Qt 5.3+
+            return int(str(gdb.parse_and_eval('((void**)&qtHookData)[2]')), 16)
+        except:
+            pass
+
+        try:
+            version = self.qtVersionString()
+            (major, minor, patch) = version[version.find('"') + 1:version.rfind('"')].split('.')
+            qtversion = 0x10000 * int(major) + 0x100 * int(minor) + int(patch)
+            self.qtVersion = lambda: qtversion
+            return qtversion
+        except:
+            # Use fallback until we have a better answer.
+            return None
+
+
     def createSpecialBreakpoints(self, args):
         self.specialBreakpoints = []