Debugger: Prepend '*'s for autodereferenced pointers

If automatic dereferencing of pointers is enabled, the
"Value" and "Type" columns for pointers hold the values for
the dereferenced pointers.

In order to have a consistent behavior for the "Name" column
as well, prepend '*'s to indicate that the variable/expression
has actually been dereferenced.
Add parantheses around the original expression if it doesn't
match a simple regex for variable names, to avoid that the
leading '*' changes the meaning of the expression
(so e.g. a dereferenced 'somepointer + 1' is displayed
as  '*(somepointer + 1)' rather than '*somepointer + 1').

This introduces a new 'autoderefcount' field to propagate the
information how many levels of dereferencing have taken
place from the Python to the C++ side, which is then
used to add the leading '*'s for the display name.

Fixes: QTCREATORBUG-20907
Change-Id: Ia9a41cb42e25ba72a6d980a765dbe2b454deb8c8
Reviewed-by: hjk <hjk@qt.io>

share/qtcreator/debugger/dumper.py

@@ -1312,6 +1312,11 @@ class DumperBase():
         savedCurrentChildType = self.currentChildType
         self.currentChildType = innerType.name
         derefValue.name = '*'
+        derefValue.autoDerefCount = value.autoDerefCount + 1
+
+        if derefValue.type.code != TypeCode.Pointer:
+            self.putField('autoderefcount', '{}'.format(derefValue.autoDerefCount))
+
         self.putItem(derefValue)
         self.currentChildType = savedCurrentChildType
 
@@ -2920,6 +2925,7 @@ class DumperBase():
             self.targetValue = None  # For references.
             self.isBaseClass = None
             self.nativeValue = None
+            self.autoDerefCount = 0
 
         def copy(self):
             val = self.dumper.Value(self.dumper)

src/plugins/debugger/watchdata.cpp

@@ -115,6 +115,7 @@ WatchItem::WatchItem() :
     wantsChildren(false),
     valueEnabled(true),
     valueEditable(true),
+    autoDerefCount(0),
     outdated(false)
 {
 }
@@ -388,6 +389,14 @@ void WatchItem::parseHelper(const GdbMi &input, bool maySort)
     else if (mi.data() == "false")
         valueEditable = false;
 
+    mi = input["autoderefcount"];
+    if (mi.isValid()) {
+        bool ok = false;
+        uint derefCount = mi.data().toUInt(&ok);
+        if (ok)
+            autoDerefCount = derefCount;
+    }
+
     mi = input["numchild"]; // GDB/MI
     if (mi.isValid())
         setHasChildren(mi.toInt() > 0);

src/plugins/debugger/watchdata.h

@@ -99,6 +99,7 @@ public:
     bool            wantsChildren;
     bool            valueEnabled;  // Value will be enabled or not
     bool            valueEditable; // Value will be editable
+    uint            autoDerefCount; // number of levels of automatic dereferencing that has taken place (for pointer types)
     bool            outdated;      // \internal item is to be removed.
     double          time = 0;      // Time used on the dumper side to produce this item
 

src/plugins/debugger/watchhandler.cpp

@@ -869,6 +869,19 @@ static QString displayName(const WatchItem *item)
     else
         result = watchModel(item)->removeNamespaces(item->name);
 
+    // prepend '*'s to indicate where autodereferencing has taken place
+    if (item->autoDerefCount > 0) {
+        // add parentheses for everything except simple variable names (e.g. pointer arithmetics,...)
+        QRegularExpression variableNameRegex("^[a-zA-Z0-9_]+$");
+        bool addParanthesis = !variableNameRegex.match(result).hasMatch();
+        if (addParanthesis)
+            result = "(" + result;
+        for (uint i = 0; i < item->autoDerefCount; i++)
+            result = "*" + result;
+        if (addParanthesis)
+            result += ")";
+    }
+
     // Simplify names that refer to base classes.
     if (result.startsWith('[')) {
         result = simplifyType(result);