[flang][OpenMP] Use new modifier infrastructure for MAP/FROM/TO clauses

This removes the specialized parsers and helper classes for these clauses,
namely ConcatSeparated, MapModifiers, and MotionModifiers. Map and the
motion clauses are now handled in the same way as all other clauses with
modifiers, with one exception: the commas separating their modifiers are
optional. This syntax is deprecated in OpenMP 5.2.

Implement version checks for modifiers: for a given modifier on a given
clause, check if that modifier is allowed on this clause in the specified
OpenMP version. This replaced several individual checks.

Add a testcase for handling map modifiers in a different order, and for
diagnosing an ultimate modifier out of position.

Author: kparzysz

flang/include/flang/Parser/dump-parse-tree.h

@@ -476,6 +476,11 @@ class ParseTreeDumper {
   NODE(parser, NullInit)
   NODE(parser, ObjectDecl)
   NODE(parser, OldParameterStmt)
+  NODE(parser, OmpMapper)
+  NODE(parser, OmpMapType)
+  NODE_ENUM(OmpMapType, Value)
+  NODE(parser, OmpMapTypeModifier)
+  NODE_ENUM(OmpMapTypeModifier, Value)
   NODE(parser, OmpIteratorSpecifier)
   NODE(parser, OmpIterator)
   NODE(parser, OmpAffinityClause)
@@ -536,7 +541,9 @@ class ParseTreeDumper {
   NODE(parser, OmpEndLoopDirective)
   NODE(parser, OmpEndSectionsDirective)
   NODE(parser, OmpFromClause)
-  NODE_ENUM(OmpFromClause, Expectation)
+  NODE(OmpFromClause, Modifier)
+  NODE(parser, OmpExpectation)
+  NODE_ENUM(OmpExpectation, Value)
   NODE(parser, OmpIfClause)
   NODE_ENUM(OmpIfClause, DirectiveNameModifier)
   NODE_ENUM(OmpLastprivateClause, LastprivateModifier)
@@ -548,9 +555,7 @@ class ParseTreeDumper {
   NODE_ENUM(OmpLinearModifier, Value)
   NODE(parser, OmpLoopDirective)
   NODE(parser, OmpMapClause)
-  NODE(parser, OmpMapperIdentifier)
-  NODE_ENUM(OmpMapClause, TypeModifier)
-  NODE_ENUM(OmpMapClause, Type)
+  NODE(OmpMapClause, Modifier)
   static std::string GetNodeName(const llvm::omp::Clause &x) {
     return llvm::Twine(
         "llvm::omp::Clause = ", llvm::omp::getOpenMPClauseName(x))
@@ -601,8 +606,7 @@ class ParseTreeDumper {
   NODE(parser, OmpSectionsDirective)
   NODE(parser, OmpSimpleStandaloneDirective)
   NODE(parser, OmpToClause)
-  // No NODE_ENUM for OmpToClause::Expectation, because it's an alias
-  // for OmpFromClause::Expectation.
+  NODE(OmpToClause, Modifier)
   NODE(parser, Only)
   NODE(parser, OpenACCAtomicConstruct)
   NODE(parser, OpenACCBlockConstruct)

flang/include/flang/Parser/parse-tree.h

@@ -3502,6 +3502,21 @@ struct OmpDependenceType {
   WRAPPER_CLASS_BOILERPLATE(OmpDependenceType, Value);
 };
 
+// Ref: [5.1:205-209], [5.2:166-168]
+//
+// motion-modifier ->
+//    PRESENT |                                     // since 5.0, until 5.0
+//    mapper | iterator
+// expectation ->
+//    PRESENT                                       // since 5.1
+//
+// The PRESENT value was a part of motion-modifier in 5.1, and became a
+// value of expectation in 5.2.
+struct OmpExpectation {
+  ENUM_CLASS(Value, Present);
+  WRAPPER_CLASS_BOILERPLATE(OmpExpectation, Value);
+};
+
 // Ref: [5.0:47-49], [5.1:49-51], [5.2:67-69]
 //
 // iterator-modifier ->
@@ -3519,6 +3534,24 @@ struct OmpLinearModifier {
   WRAPPER_CLASS_BOILERPLATE(OmpLinearModifier, Value);
 };
 
+// [5.0:176-180], [5.1:205-210], [5.2:149-150]
+//
+// mapper ->
+//    identifier                                    // since 4.5
+struct OmpMapper {
+  WRAPPER_CLASS_BOILERPLATE(OmpMapper, Name);
+};
+
+struct OmpMapType {
+  ENUM_CLASS(Value, Alloc, Delete, From, Release, To, Tofrom);
+  WRAPPER_CLASS_BOILERPLATE(OmpMapType, Value);
+};
+
+struct OmpMapTypeModifier {
+  ENUM_CLASS(Value, Always, Close, Present, Ompx_Hold)
+  WRAPPER_CLASS_BOILERPLATE(OmpMapTypeModifier, Value);
+};
+
 // Ref: [4.5:56-63], [5.0:101-109], [5.1:126-133], [5.2:252-254]
 //
 // modifier ->
@@ -3723,15 +3756,9 @@ struct OmpDeviceTypeClause {
 //  motion-modifier ->
 //    PRESENT | mapper-modifier | iterator-modifier
 struct OmpFromClause {
-  ENUM_CLASS(Expectation, Present);
   TUPLE_CLASS_BOILERPLATE(OmpFromClause);
-
-  // As in the case of MAP, modifiers are parsed as lists, even if they
-  // are unique. These restrictions will be checked in semantic checks.
-  std::tuple<std::optional<std::list<Expectation>>,
-      std::optional<std::list<OmpIterator>>, OmpObjectList,
-      bool> // were the modifiers comma-separated?
-      t;
+  MODIFIER_BOILERPLATE(OmpExpectation, OmpIterator, OmpMapper);
+  std::tuple<MODIFIERS(), OmpObjectList, bool> t;
 };
 
 // OMP 5.2 12.6.1 grainsize-clause -> grainsize ([prescriptiveness :] value)
@@ -3794,8 +3821,6 @@ struct OmpLinearClause {
   std::variant<WithModifier, WithoutModifier> u;
 };
 
-WRAPPER_CLASS(OmpMapperIdentifier, std::optional<Name>);
-
 // 2.15.5.1 map ->
 //    MAP ([MAPPER(mapper-identifier)] [[map-type-modifier-list [,]]
 //    [iterator-modifier [,]] map-type : ]
@@ -3804,21 +3829,9 @@ WRAPPER_CLASS(OmpMapperIdentifier, std::optional<Name>);
 // map-type-modifier -> ALWAYS | CLOSE | PRESENT | OMPX_HOLD
 // map-type -> TO | FROM | TOFROM | ALLOC | RELEASE | DELETE
 struct OmpMapClause {
-  ENUM_CLASS(TypeModifier, Always, Close, Present, Ompx_Hold);
-  ENUM_CLASS(Type, To, From, Tofrom, Alloc, Release, Delete)
   TUPLE_CLASS_BOILERPLATE(OmpMapClause);
-
-  // All modifiers are parsed into optional lists, even if they are unique.
-  // The checks for satisfying those constraints are deferred to semantics.
-  // In OpenMP 5.2 the non-comma syntax has been deprecated: keep the
-  // information about separator presence to emit a diagnostic if needed.
-  std::tuple<OmpMapperIdentifier, // Mapper name
-      std::optional<std::list<TypeModifier>>,
-      std::optional<std::list<OmpIterator>>, // unique
-      std::optional<std::list<Type>>, // unique
-      OmpObjectList,
-      bool> // were the modifiers comma-separated?
-      t;
+  MODIFIER_BOILERPLATE(OmpMapTypeModifier, OmpMapper, OmpIterator, OmpMapType);
+  std::tuple<MODIFIERS(), OmpObjectList, bool> t;
 };
 
 // Ref: [5.0:101-109], [5.1:126-134], [5.2:233-234]
@@ -3877,15 +3890,9 @@ struct OmpScheduleClause {
 //  motion-modifier ->
 //    PRESENT | mapper-modifier | iterator-modifier
 struct OmpToClause {
-  using Expectation = OmpFromClause::Expectation;
   TUPLE_CLASS_BOILERPLATE(OmpToClause);
-
-  // As in the case of MAP, modifiers are parsed as lists, even if they
-  // are unique. These restrictions will be checked in semantic checks.
-  std::tuple<std::optional<std::list<Expectation>>,
-      std::optional<std::list<OmpIterator>>, OmpObjectList,
-      bool> // were the modifiers comma-separated?
-      t;
+  MODIFIER_BOILERPLATE(OmpExpectation, OmpIterator, OmpMapper);
+  std::tuple<MODIFIERS(), OmpObjectList, bool> t;
 };
 
 // OMP 5.2 12.6.2 num_tasks-clause -> num_tasks ([prescriptiveness :] value)