With the recent patches to the ASTImporter that improve template type importing
(D87444), most of the import-std-module tests can now finally import the
type of the STL container they are testing. This patch removes most of the casts
that were added to simplify types to something the ASTImporter can import
(for example, std::vector<int>::size_type was casted to `size_t` until now).
Also adds the missing tests that require referencing the container type (for
example simply printing the whole container) as here we couldn't use a casting
workaround.
The only casts that remain are in the forward_list tests that reference
the iterator and the stack test. Both tests are still failing to import the
respective container type correctly (or crash while trying to import).
This adds support for substituting std::pair instantiations with enabled
import-std-module.
With the fixes in parent revisions we can currently substitute a single pair
(however, a result that returns a second pair currently causes LLDB to crash
while importing the second template instantiation).
Reviewed By: aprantl
Differential Revision: https://reviews.llvm.org/D85141
Raphael Isemann