Extend "extension<LanguageFeature>()" to incorporate an explanatory
message better than the current generic "nonstandard usage:".
Differential Revision: https://reviews.llvm.org/D122035
Like in D87961, msvc has difficulties deducing the template argument. The error message is:
```
expr-parsers.cpp(383): error C2672: 'applyLambda': no matching overloaded function found
```
Explicitly pass the first template argument to help it.
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/D88001
Msvc has trouble defining a struct/class and defining a constexpr symbol in the same declarator. It reports the following error:
```
basic-parsers.h(809): error C2131: expression did not evaluate to a constant
basic-parsers.h(809): note: failure was caused by call of undefined function or one not declared 'constexpr'
basic-parsers.h(809): note: see usage of 'Fortran::parser::OkParser::OkParser'
```
Fix the msvc compilation by splitting the two definitions into two separate declarators.
This patch is part of the series to [[ http://lists.llvm.org/pipermail/flang-dev/2020-July/000448.html | make flang compilable with MS Visual Studio ]].
Reviewed By: DavidTruby, klausler
Differential Revision: https://reviews.llvm.org/D85937
Peter Klausler