[flang-commits] [flang] [flang] Add semantics support for Fortran 2023 conditional arguments (F2023 R1526-R1528) (PR #195345)

[via flang-commits]

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@@ -1392,6 +1397,88 @@ static void CheckProcedureArg(evaluate::ActualArgument &arg,
   }
 }
 
+// F2023 C1540-C1543, C1545: Check conditional argument against dummy data
+// object
+static void CheckConditionalArg(
+    const evaluate::ActualArgument::ConditionalArg &condArg,
+    const characteristics::DummyDataObject &object,
+    const std::string &dummyName, parser::ContextualMessages &messages) {
+  // C1540: .NIL. shall not appear if dummy is not optional
+  if (condArg.HasNilConsequent() &&
+      !object.attrs.test(characteristics::DummyDataObject::Attr::Optional)) {
+    messages.Say(
+        ".NIL. in conditional argument associated with non-optional %s"_err_en_US,
+        dummyName);
+  }
+  // Check a single consequent for C1541, C1543, C1542
+  auto checkOneConsequent{[&](const evaluate::ActualArgument::ConditionalArg::
+                                  Consequent &cons) {
+    if (!cons) {
+      return;
+    }
+    const auto &consExpr{cons->value()};
+    // C1541: INTENT(OUT/INOUT) requires variable
+    if ((object.intent == common::Intent::Out ||
+            object.intent == common::Intent::InOut) &&
+        !evaluate::IsVariable(consExpr)) {
+      messages.Say(
+          "Each consequent-arg in conditional argument associated with INTENT(%s) %s must be a variable"_err_en_US,
+          object.intent == common::Intent::Out ? "OUT" : "IN OUT", dummyName);
+    }
+    // C1543: assumed-rank consequent-arg requires assumed-rank dummy
+    if (semantics::IsAssumedRank(consExpr) &&
+        !object.type.attrs().test(
+            characteristics::TypeAndShape::Attr::AssumedRank)) {
+      messages.Say(
+          "Assumed-rank consequent-arg in conditional argument may only be associated with assumed-rank %s"_err_en_US,
+          dummyName);
+    }
+    // C1542: coarray attribute
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jeanPerier wrote:

Can you add a comment here that the allocatable/pointer part of the requirement are checked via `checkOneExpr` called bellow on each non NIL consequent?

https://github.com/llvm/llvm-project/pull/195345