Clang: Provide tooltips

This includes also the query data for the help system (F1) for an
identifier under cursor.

Regressions (libclang changes necessary):
 - Function signatures do not contain default values.
 - Aliases are not resolved for/at:
   - template types
   - qualified name of a type

Fixes/Improvements:
 - Resolve "auto"
 - On a template type, show also the template parameter.
 - For a typedef like
     typedef long long superlong;
   the tooltip was "long long superlong", which was confusing.
   Now, "long long" is shown.

New:
 - Show first or \brief paragraph of a documentation comment.
 - Show size of a class at definition.
 - Show size of a field member in class definition.

Task-number: QTCREATORBUG-11259
Change-Id: Ie1a07930d0e882015d07dc43e35bb81a685cdeb8
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/tools/clangbackend/source/cursor.h

@@ -67,6 +67,7 @@ public:
     bool isFunctionLike() const;
     bool isConstructorOrDestructor() const;
     bool isTemplateLike() const;
+    bool isAnyTypeAlias() const;
     bool hasFinalFunctionAttribute() const;
     bool hasFinalClassAttribute() const;
     bool isUnexposed() const;
@@ -81,6 +82,10 @@ public:
 
     Type type() const;
     Type nonPointerTupe() const;
+    Type enumType() const;
+
+    long long enumConstantValue() const;
+    unsigned long long enumConstantUnsignedValue() const;
 
     SourceLocation sourceLocation() const;
     CXSourceLocation cxSourceLocation() const;
@@ -92,17 +97,19 @@ public:
 
     Cursor definition() const;
     Cursor canonical() const;
-    Cursor alias() const;
     Cursor referenced() const;
     Cursor semanticParent() const;
     Cursor lexicalParent() const;
     Cursor functionBaseDeclaration() const;
     Cursor functionBase() const;
+    Type resultType() const;
     Cursor argument(int index) const;
     unsigned overloadedDeclarationsCount() const;
     Cursor overloadedDeclaration(unsigned index) const;
     Cursor specializedCursorTemplate() const;
 
+    CXFile includedFile() const;
+
     void collectOutputArgumentRangesTo(
             std::vector<CXSourceRange> &outputArgumentRanges) const;
     std::vector<CXSourceRange> outputArgumentRanges() const;
@@ -112,6 +119,8 @@ public:
     template <class VisitorCallback>
     void visit(VisitorCallback visitorCallback) const;
 
+    CXCursor cx() const;
+
 private:
     CXCursor cxCursor;
 };