[OpenACC] Fix assert when parsing 'bind' clause

I'd  misunderstood how the ParseStringLiteralExpression function worked,
  so I assumed it would catch non-string literals, however it instead
  asserted.  This patch now checks for that case and diagnoses.

Fixes: #139346

Author: erichkeane

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -1469,7 +1469,8 @@ def err_acc_expected_reduction_operator
 def err_acc_invalid_reduction_operator
     : Error<"invalid reduction operator,  expected '+', '*', 'max', 'min', "
             "'&', '|', '^', '&&', or '||'">;
-def err_acc_incorrect_bind_arg : Error<"expected identifier or string literal">;
+def err_acc_incorrect_bind_arg
+    : Error<"expected identifier or string literal in OpenACC 'bind' clause">;
 def err_acc_modifier
     : Error<"%enum_select<ACCModifier>{%Unknown{unknown}|%Duplicate{duplicate}}"
             "0 modifier %1 in OpenACC modifier-list on '%2' clause">;

clang/lib/Parse/ParseOpenACC.cpp

@@ -1429,6 +1429,11 @@ Parser::ParseOpenACCBindClauseArgument() {
     return II;
   }
 
+  if (!tok::isStringLiteral(getCurToken().getKind())) {
+    Diag(getCurToken(), diag::err_acc_incorrect_bind_arg);
+    return std::monostate{};
+  }
+
   ExprResult Res =
       getActions().CorrectDelayedTyposInExpr(ParseStringLiteralExpression(
           /*AllowUserDefinedLiteral=*/false, /*Unevaluated=*/true));

clang/test/ParserOpenACC/parse-clauses.c

@@ -1345,9 +1345,15 @@ void bar();
 #pragma acc routine seq bind
 void BCP1();
 
-  // expected-error@+1{{expected identifier or string literal}}
+  // expected-error@+1{{expected identifier or string literal in OpenACC 'bind' clause}}
 #pragma acc routine(BCP1) seq bind()
 
+  // expected-error@+1{{expected identifier or string literal in OpenACC 'bind' clause}}
+#pragma acc routine(BCP1) seq bind(1)
+
+  // expected-error@+1{{expected identifier or string literal in OpenACC 'bind' clause}}
+#pragma acc routine(BCP1) gang bind(0xF)
+
 // expected-error@+1{{expected function or lambda declaration for 'routine' construct}}
 #pragma acc routine seq bind("ReductionClauseParsing")