[flang] Fix subtle type naming bug in module file output (#108892)
A derived type specification in semantics holds both its source name
(for location purposes) and its ultimate derived type symbol. But for
correct module file generation of a structure constructor using that
derived type spec, the original symbol may be needed so that USE
association can be exposed.
Save both the original symbol and its ultimate symbol in the
DerivedTypeSpec, and collect the right one when traversing expressions
(specifically for handling initialization in module files).
Fixes https://github.com/llvm/llvm-project/issues/108827.
llvm-project
b0bdc7fc - [flang] Fix subtle type naming bug in module file output (#108892)
