[flang][msvc] Explicitly reference "this" inside closure. NFC.
The Microsoft compiler seems to have difficulties to decide between a const/non-const method of a captured object context in a closure. The error message is:
symbol.cpp(261): error C2668: 'Fortran::semantics::Symbol::detailsIf': ambiguous call to overloaded function symbol.h(535): note: could be 'const D *Fortran::semantics::Symbol::detailsIf<Fortran::semantics::DerivedTypeDetails>(void) const' symbol.h(534): note: or 'D *Fortran::semantics::Symbol::detailsIf<Fortran::semantics::DerivedTypeDetails>(void)' symbol.cpp(261): note: while trying to match the argument list '()'
Explicitly using the this-pointer resolves this problem.
This patch is part of the series to make flang compilable with MS Visual Studio http://lists.llvm.org/pipermail/flang-dev/2020-July/000448.html.
Reviewed By: DavidTruby
Differential Revision: https://reviews.llvm.org/D88052