[flang] C774: Defined operator/assignment may not have NOPASS

Original-commit: flang-compiler/f18@6bfa3d3568
Reviewed-on: https://github.com/flang-compiler/f18/pull/872
Tree-same-pre-rewrite: false

flang/lib/semantics/check-declarations.cc

@@ -518,7 +518,9 @@ static bool ConflictsWithIntrinsicOperator(
 bool CheckHelper::CheckDefinedOperator(const SourceName &opName,
     const GenericKind &kind, const Symbol &specific, const Procedure &proc) {
   std::optional<parser::MessageFixedText> msg;
-  if (!proc.functionResult.has_value()) {
+  if (specific.attrs().test(Attr::NOPASS)) {  // C774
+    msg = "%s procedure '%s' may not have NOPASS attribute"_err_en_US;
+  } else if (!proc.functionResult.has_value()) {
     msg = "%s procedure '%s' must be a function"_err_en_US;
   } else if (proc.functionResult->IsAssumedLengthCharacter()) {
     msg = "%s function '%s' may not have assumed-length CHARACTER(*)"
@@ -608,7 +610,10 @@ bool CheckHelper::CheckDefinedOperatorArg(const SourceName &opName,
 bool CheckHelper::CheckDefinedAssignment(
     const Symbol &specific, const Procedure &proc) {
   std::optional<parser::MessageFixedText> msg;
-  if (!proc.IsSubroutine()) {
+  if (specific.attrs().test(Attr::NOPASS)) {  // C774
+    msg = "Defined assignment procedure '%s' may not have"
+          " NOPASS attribute"_err_en_US;
+  } else if (!proc.IsSubroutine()) {
     msg = "Defined assignment procedure '%s' must be a subroutine"_err_en_US;
   } else if (proc.dummyArguments.size() != 2) {
     msg = "Defined assignment subroutine '%s' must have"

flang/test/semantics/resolve63.f90

@@ -220,6 +220,12 @@ module m6
     procedure, pass(y) :: p2 => f2
     generic :: operator(+) => p2
   end type
+  type :: t3
+  contains
+    procedure, nopass :: p1 => f1
+    !ERROR: OPERATOR(+) procedure 'p1' may not have NOPASS attribute
+    generic :: operator(+) => p1
+  end type
 contains
   integer function f1(x, y)
     class(t1), intent(in) :: x

flang/test/semantics/resolve65.f90

@@ -30,6 +30,12 @@ module m1
     generic :: assignment(=) => assign_t, assign_t2, assign_t3, assign_t4
     procedure :: assign_t4
   end type
+  type :: t2
+  contains
+    procedure, nopass :: assign_t
+    !ERROR: Defined assignment procedure 'assign_t' may not have NOPASS attribute
+    generic :: assignment(=) => assign_t
+  end type
 contains
   subroutine assign_t(x, y)
     class(t), intent(out) :: x