Debugger: Add fallback when gdb.Value.cast() fails for typedefs

Fixes: QTCREATORBUG-18450
Change-Id: I9239beb7e1879a284e28a30579129fe487eb2dd2
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

share/qtcreator/debugger/gdbbridge.py

@@ -247,8 +247,14 @@ class Dumper(DumperBase):
             if targetType.code == gdb.TYPE_CODE_ARRAY:
                 val = self.Value(self)
             else:
-                # Cast may fail (e.g for arrays, see test for Bug5799)
-                val = self.fromNativeValue(nativeValue.cast(targetType))
+                try:
+                    # Cast may fail for arrays, for typedefs to __uint128_t with
+                    # gdb.error: That operation is not available on integers
+                    # of more than 8 bytes.
+                    # See test for Bug5799, QTCREATORBUG-18450.
+                    val = self.fromNativeValue(nativeValue.cast(targetType))
+                except:
+                    val = self.Value(self)
             #warn('CREATED TYPEDEF: %s' % val)
         else:
             val = self.Value(self)

tests/auto/debugger/tst_dumpers.cpp

@@ -5383,6 +5383,23 @@ void tst_Dumpers::dumper_data()
                + Check("s32s", "-2147483648", TypeDef("int", "@qint32"));
 
 
+    QTest::newRow("Int128")
+            << Data("#include <limits.h>\n",
+                    "using typedef_s128 = __int128_t;\n"
+                    "using typedef_u128 = __uint128_t;\n"
+                    "__int128_t s128 = 12;\n"
+                    "__uint128_t u128 = 12;\n"
+                    "typedef_s128 ts128 = 12;\n"
+                    "typedef_u128 tu128 = 12;\n"
+                    "unused(&u128, &s128, &tu128, &ts128);\n")
+                // Sic! The expected type is what gcc 8.2.0 records.
+               + GdbEngine
+               + Check("s128", "12", "__int128")
+               + Check("u128", "12", "__int128 unsigned")
+               + Check("ts128", "12", "typedef_s128")
+               + Check("tu128", "12", "typedef_u128") ;
+
+
     QTest::newRow("Float")
             << Data("#include <QFloat16>\n",
                     "qfloat16 f1 = 45.3f; unused(&f1);\n"