Debugger: Add debugging helper for std::tuple

Add debugging helper for std::tuple and add
a corresponding dumper test for it.

With this in place, the std::tuple variable and its elements
in the "tuple.cpp" sample program from QTCREATORBUG-25865 are
shown as expected on both, Linux (libstdc++) with GDB or LLDB and with
an MSVC build with CDB on Windows.

A debugging helper for libc++ had already been added in commit
34ff9c97e6.

Task-number: QTCREATORBUG-25865
Change-Id: I24b3d36b5daa26fd4fcb073c4df79015dfe752fc
Reviewed-by: hjk <hjk@qt.io>

share/qtcreator/debugger/stdtypes.py

@@ -697,6 +697,36 @@ def qdump__std__pair(d, value):
     d.putValue('(%s, %s)' % (key, value))
 
 
+def qdumpHelper_get_tuple_elements(d, tuple, value_typename, value_member):
+    """
+    Helper method that returns the elements of a tuple.
+    """
+    elems = []
+    other_members = []
+    for member in tuple.members(True):
+        if not member.type.templateArguments():
+            continue
+        if member.type.name.startswith(value_typename):
+            elems.append(member[value_member])
+        else:
+            other_members.append(member)
+    for member in other_members:
+        sub_elems = qdumpHelper_get_tuple_elements(d, member, value_typename, value_member)
+        elems = elems + sub_elems
+    return elems
+
+
+def qdump__std__tuple(d, value):
+    if d.isMsvcTarget():
+        elems = qdumpHelper_get_tuple_elements(d, value, "std::_Tuple_val", "_Val")
+    else:
+        elems = qdumpHelper_get_tuple_elements(d, value, "std::_Head_base", "_M_head_impl")
+    d.putItemCount(len(elems))
+    with Children(d):
+        for elem in elems:
+            d.putSubItem(0, elem)
+
+
 def qform__std__unordered_map():
     return [DisplayFormat.CompactMap]
 

tests/auto/debugger/tst_dumpers.cpp

@@ -5348,6 +5348,18 @@ void tst_Dumpers::dumper_data()
                + Check("v.0", "[0]", "\"foo\"", "std::string");
 
 
+    QTest::newRow("StdTuple")
+            << Data("#include <string>\n",
+
+                    "std::tuple<int, std::string, int> tuple = std::make_tuple(123, std::string(\"hello\"), 456);\n",
+
+                    "&tuple")
+
+               + Check("tuple.0", "[0]", "123", "int")
+               + Check("tuple.1", "[1]", "\"hello\"", "std::string")
+               + Check("tuple.2", "[2]", "456", "int");
+
+
     QTest::newRow("StdValArray")
             << Data("#include <valarray>\n"
                     "#include <list>\n",