[flang][OpenMP] Introduce variant argument, customize OmpArgument par… (#160372)

…sing

The DECLARE_VARIANT directive takes two names separated by a colon as an
argument: base-name:variant-name. Define OmpBaseVariantNames to
represent this, since no existing argument alternative matches it.

However, there is an issue. The syntax "name1:name2" can be the argument
to DECLARE_VARIANT (if both names are OmpObjects), but it can also be a
reduction-specifier if "name2" is a type. This conflict can only be
resolved once we know what the names are, which is after name resolution
has visited them. The problem is that name resolution has side-effects
that may be (practically) impossible to undo (e.g. creating new symbols,
emitting diagnostic messages).

To avoid this problem this PR makes the parsing of OmpArgument
directive- sensitive: when the directive is DECLARE_VARIANT, don't
attempt to parse a reduction-specifier, consider OmpBaseVariantNames
instead. Otherwise ignore OmpBaseVariantNames in favor of
reduction-specifier.

0 files changed, 0 insertions, 0 deletions