Function type builders missing parameter bounds information

[dtarditi]

BuildFunctionType in lib\Sema\SemaType.h and RebuildFunctionProtoType in lib\Sema\TreeTransform.h are missing parameter bounds information as an argument. From what I can tell, BuildFunctionType is invoked along the C++ template instantiation path and along the tree transform path by RebuildFunctionProtoType. For Checked C, this could lead to parameter bounds information being dropped when the tree transformation routines are invoked on function prototypes.

The construction of function prototypes for the common C/C++ path does not invoke BuildFunctionType, so this issue does not affect the usual path for constructing prototypes.

We already have an issue about figuring out how to test tree transformations (issue #6), so I'm not sure how we'd test this fix if we made it.

Postponing this issue for now.

[dtarditi]

Bounds information is carried by the FunctionType::ExtProtoInfo struct that is passed as an argument to these functions. The information is not missing. However, we are lacking code to transform parameter and return bounds information in the struct. I've opened issue #370 to track that.