[clang] [OpenACC] Implement 'cache' construct parsing (PR #74324)

[Erich Keane via cfe-commits]

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@@ -268,6 +270,71 @@ ExprResult Parser::ParseOpenACCRoutineName() {
   return getActions().CorrectDelayedTyposInExpr(Res);
 }
 
+void Parser::ParseOpenACCCacheVar() {
+  ExprResult ArrayName = ParseOpenACCIDExpression();
+  // FIXME: Pass this to Sema.
+  (void)ArrayName;
+
+  // If the expression is invalid, just continue parsing the brackets, there
+  // is likely other useful diagnostics we can emit inside of those.
+
+  BalancedDelimiterTracker SquareBrackets(*this, tok::l_square,
+                                          tok::annot_pragma_openacc_end);
+
+  // Square brackets are required, so error here, and try to recover by moving
+  // until the next comma, or the close paren/end of pragma.
+  if (SquareBrackets.expectAndConsume()) {
+    SkipUntil(tok::comma, tok::r_paren, tok::annot_pragma_openacc_end,
+              Parser::StopBeforeMatch);
+    return;
+  }
+
+  ExprResult Lower = getActions().CorrectDelayedTyposInExpr(ParseExpression());
+  // FIXME: Pass this to Sema.
+  (void)Lower;
+
+  // The 'length' expression is optional, as this could be a single array
+  // element. If there is no colon, we can treat it as that.
+  if (getCurToken().is(tok::colon)) {
+    ConsumeToken();
+    ExprResult Length =
+        getActions().CorrectDelayedTyposInExpr(ParseExpression());
+    // FIXME: Pass this to Sema.
+    (void)Length;
+  }
+
+  // Diagnose the square bracket being in the wrong place and continue.
+  SquareBrackets.consumeClose();
+}
+
+void Parser::ParseOpenACCCacheVarList() {
+  // If this is the end of the line, just return 'false' and count on the close
+  // paren diagnostic to catch the issue.
+  if (getCurToken().isAnnotation())
+    return;
+
+  // The VarList is an optional `readonly:` followed by a list of a variable
+  // specifications.  First, see if we have `readonly:`, else we back-out and
+  // treat it like the beginning of a reference to a potentially-existing
+  // `readonly` variable.
+  if (getPreprocessor().getSpelling(getCurToken()) == "readonly" &&
+      NextToken().is(tok::colon)) {
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erichkeane wrote:

I see!  I've been using it all over the place thanks to copying from the OMP implementation here.  I'll change it here, then do an RAC commit to fix up the rest of my uses

https://github.com/llvm/llvm-project/pull/74324