[cfe-dev] A small proposal about TagType's and source ranges

[John McCall]

On Mar 12, 2011, at 11:28 AM, Abramo Bagnara wrote:

> Il 12/03/2011 20:10, John McCall ha scritto:
>> 
>> On Mar 12, 2011, at 8:54 AM, Abramo Bagnara wrote:
>> 
>>> 
>>> We are struggling to fix lack of proper source location range for
>>> TagType's due to missing setting of both source location for tag keyword
>>> and name.
>>> 
>>> We'd like to propose the following simplification of current approach to
>>> tag types and elaborated types storing:
>>> 
>>> Currently clang uses (only in C++) an ElaboratedType whenever the type
>>> has an explicit class/struct/union/enum keyword *or* a name qualifier.
>>> 
>>> We propose to use an ElaboratedType *only* whenever there is a name
>>> qualifier and to add to TagTypeLoc a (possibly invalid) tag keyword
>>> location (removing the one now available in ElaboratedTypeLoc).
>> 
>> How would we represent "struct A::B" in C++?
>> 
>> It's also important to distinguish between A and struct A in C++.  If we don't have an elaborated type node, what remembers this distinction?
> 
> On the syntactic side they can be distinguished in the TagTypeLoc using
> the validity of tag keyword location. On the semantic side they can be
> distinguished inheriting TagType from TypeWithKeyword.


Adding non-canonical state to TagType is not really acceptable;  it's really,
really nice right now that TagTypes are always canonical.

John.