heuristics to determine when it's useful to desugar a type for display
to the user. Introduce two C++-specific heuristics:
- For a qualified type (like "foo::bar"), only produce a new
desugred type if desugaring the qualified type ("bar", in this
case) produces something interesting. For example, if "foo::bar"
refers to a class named "bar", don't desugar. However, if
"foo::bar" refers to a typedef of something else, desugar to that
something else. This gives some useful desugaring such as
"foo::bar (aka 'int')".
- Don't desugar class template specialization types like
"basic_string<char>" down to their underlying "class
basic_string<char, char_traits<char>, allocator<char>>, etc.";
it's better just to leave such types alone.
Update diagnostics.html with some discussion and examples of type
preservation in C++, showing qualified names and class template
specialization types.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@68207 91177308-0d34-0410-b5e6-96231b3b80d8
Chris Lattner
Douglas Gregor