[OpenACC] Implement Sema work for OpenACC Clauses

Now that we have AST nodes for OpenACC Clauses, this patch adds their
creation to Sema and makes the Parser call all the required functions.
This also redoes TreeTransform to work with the clauses/make sure they
are transformed.

Much of this is NFC, since there is no clause we can test this behavior
with.  However, there IS one noticable change; we are now no longer
diagnosing that a clause is 'not implemented' unless it there was no
errors parsing its parameters.  This is because it cleans up how we
create and diagnose clauses.

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -12252,6 +12252,8 @@ def warn_acc_clause_unimplemented
 def err_acc_construct_appertainment
     : Error<"OpenACC construct '%0' cannot be used here; it can only "
             "be used in a statement context">;
+def err_acc_clause_appertainment
+    : Error<"OpenACC '%1' clause not valid on '%0' directive">;
 def err_acc_branch_in_out_compute_construct
     : Error<"invalid %select{branch|return|throw}0 %select{out of|into}1 "
             "OpenACC Compute Construct">;

clang/include/clang/Parse/Parser.h

@@ -41,6 +41,7 @@ namespace clang {
   class InMessageExpressionRAIIObject;
   class PoisonSEHIdentifiersRAIIObject;
   class OMPClause;
+  class OpenACCClause;
   class ObjCTypeParamList;
   struct OMPTraitProperty;
   struct OMPTraitSelector;
@@ -3594,11 +3595,26 @@ class Parser : public CodeCompletionHandler {
     OpenACCDirectiveKind DirKind;
     SourceLocation StartLoc;
     SourceLocation EndLoc;
-    // TODO OpenACC: Add Clause list here once we have a type for that.
+    SmallVector<OpenACCClause *> Clauses;
     // TODO OpenACC: As we implement support for the Atomic, Routine, Cache, and
     // Wait constructs, we likely want to put that information in here as well.
   };
 
+  /// Represents the 'error' state of parsing an OpenACC Clause, and stores
+  /// whether we can continue parsing, or should give up on the directive.
+  enum class OpenACCParseCanContinue { Cannot = 0, Can = 1 };
+
+  /// A type to represent the state of parsing an OpenACC Clause. Situations
+  /// that result in an OpenACCClause pointer are a success and can continue
+  /// parsing, however some other situations can also continue.
+  /// FIXME: This is better represented as a std::expected when we get C++23.
+  using OpenACCClauseParseResult =
+      llvm::PointerIntPair<OpenACCClause *, 1, OpenACCParseCanContinue>;
+
+  OpenACCClauseParseResult OpenACCCanContinue();
+  OpenACCClauseParseResult OpenACCCannotContinue();
+  OpenACCClauseParseResult OpenACCSuccess(OpenACCClause *Clause);
+
   /// Parses the OpenACC directive (the entire pragma) including the clause
   /// list, but does not produce the main AST node.
   OpenACCDirectiveParseInfo ParseOpenACCDirective();
@@ -3613,12 +3629,18 @@ class Parser : public CodeCompletionHandler {
   bool ParseOpenACCClauseVarList(OpenACCClauseKind Kind);
   /// Parses any parameters for an OpenACC Clause, including required/optional
   /// parens.
-  bool ParseOpenACCClauseParams(OpenACCDirectiveKind DirKind,
-                                OpenACCClauseKind Kind);
-  /// Parses a single clause in a clause-list for OpenACC.
-  bool ParseOpenACCClause(OpenACCDirectiveKind DirKind);
+  OpenACCClauseParseResult
+  ParseOpenACCClauseParams(ArrayRef<const OpenACCClause *> ExistingClauses,
+                           OpenACCDirectiveKind DirKind, OpenACCClauseKind Kind,
+                           SourceLocation ClauseLoc);
+  /// Parses a single clause in a clause-list for OpenACC. Returns nullptr on
+  /// error.
+  OpenACCClauseParseResult
+  ParseOpenACCClause(ArrayRef<const OpenACCClause *> ExistingClauses,
+                     OpenACCDirectiveKind DirKind);
   /// Parses the clause-list for an OpenACC directive.
-  void ParseOpenACCClauseList(OpenACCDirectiveKind DirKind);
+  SmallVector<OpenACCClause *>
+  ParseOpenACCClauseList(OpenACCDirectiveKind DirKind);
   bool ParseOpenACCWaitArgument();
   /// Parses the clause of the 'bind' argument, which can be a string literal or
   /// an ID expression.

clang/include/clang/Sema/SemaOpenACC.h

@@ -28,6 +28,37 @@ class Sema;
 
 class SemaOpenACC {
 public:
+  /// A type to represent all the data for an OpenACC Clause that has been
+  /// parsed, but not yet created/semantically analyzed. This is effectively a
+  /// discriminated union on the 'Clause Kind', with all of the individual
+  /// clause details stored in a std::variant.
+  class OpenACCParsedClause {
+    OpenACCDirectiveKind DirKind;
+    OpenACCClauseKind ClauseKind;
+    SourceRange ClauseRange;
+    SourceLocation LParenLoc;
+
+    // TODO OpenACC: Add variant here to store details of individual clauses.
+
+  public:
+    OpenACCParsedClause(OpenACCDirectiveKind DirKind,
+                        OpenACCClauseKind ClauseKind, SourceLocation BeginLoc)
+        : DirKind(DirKind), ClauseKind(ClauseKind), ClauseRange(BeginLoc, {}) {}
+
+    OpenACCDirectiveKind getDirectiveKind() const { return DirKind; }
+
+    OpenACCClauseKind getClauseKind() const { return ClauseKind; }
+
+    SourceLocation getBeginLoc() const { return ClauseRange.getBegin(); }
+
+    SourceLocation getLParenLoc() const { return LParenLoc; }
+
+    SourceLocation getEndLoc() const { return ClauseRange.getEnd(); }
+
+    void setLParenLoc(SourceLocation EndLoc) { LParenLoc = EndLoc; }
+    void setEndLoc(SourceLocation EndLoc) { ClauseRange.setEnd(EndLoc); }
+  };
+
   SemaOpenACC(Sema &S);
 
   ASTContext &getASTContext() const;
@@ -37,7 +68,8 @@ class SemaOpenACC {
   Sema &SemaRef;
 
   /// Called after parsing an OpenACC Clause so that it can be checked.
-  bool ActOnClause(OpenACCClauseKind ClauseKind, SourceLocation StartLoc);
+  OpenACCClause *ActOnClause(ArrayRef<const OpenACCClause *> ExistingClauses,
+                             OpenACCParsedClause &Clause);
 
   /// Called after the construct has been parsed, but clauses haven't been
   /// parsed.  This allows us to diagnose not-implemented, as well as set up any
@@ -63,7 +95,10 @@ class SemaOpenACC {
   /// declaration group or associated statement.
   StmtResult ActOnEndStmtDirective(OpenACCDirectiveKind K,
                                    SourceLocation StartLoc,
-                                   SourceLocation EndLoc, StmtResult AssocStmt);
+                                   SourceLocation EndLoc,
+                                   MutableArrayRef<OpenACCClause *> Clauses,
+                                   StmtResult AssocStmt);
+
   /// Called after the directive has been completely parsed, including the
   /// declaration group or associated statement.
   DeclGroupRef ActOnEndDeclDirective();