[flang][runtime] Allow some list-directed child output to advance (llvm#166847)

List-directed child input is allowed to advance to new records in some
circumstances, and list-directed output should be as well so that e.g.
NAMELIST output via a defined WRITE(FORMATTED) generic doesn't get
truncated by FORT_FMT_RECL.

Fixes llvm#166804.

Author: klausler

flang-rt/include/flang-rt/runtime/io-stmt.h

@@ -730,8 +730,7 @@ class ChildListIoStatementState : public ChildIoStatementState<DIR>,
   RT_API_ATTRS bool AdvanceRecord(int = 1);
   RT_API_ATTRS int EndIoStatement();
   RT_API_ATTRS bool CanAdvance() {
-    return DIR == Direction::Input &&
-        (canAdvance_ || this->mutableModes().inNamelist);
+    return canAdvance_ || this->mutableModes().inNamelist;
   }
 
 private:

flang-rt/lib/runtime/edit-output.cpp

@@ -175,9 +175,10 @@ bool RT_API_ATTRS EditIntegerOutput(IoStatementState &io, const DataEdit &edit,
   }
   if (edit.IsListDirected()) {
     int total{std::max(leadingSpaces, 1) + subTotal};
-    if (io.GetConnectionState().NeedAdvance(static_cast<std::size_t>(total)) &&
-        !io.AdvanceRecord()) {
-      return false;
+    if (io.GetConnectionState().NeedAdvance(static_cast<std::size_t>(total))) {
+      if (!io.AdvanceRecord()) {
+        return false;
+      }
     }
     leadingSpaces = 1;
   } else if (!edit.width) {

flang-rt/lib/runtime/io-stmt.cpp

@@ -1109,20 +1109,20 @@ ChildListIoStatementState<DIR>::ChildListIoStatementState(
     ChildIo &child, const char *sourceFile, int sourceLine)
     : ChildIoStatementState<DIR>{child, sourceFile, sourceLine} {
 #if !defined(RT_DEVICE_AVOID_RECURSION)
-  if constexpr (DIR == Direction::Input) {
-    if (const auto *listInput{child.parent()
-                .get_if<ListDirectedStatementState<Direction::Input>>()}) {
-      this->set_eatComma(listInput->eatComma());
-      this->namelistGroup_ = listInput->namelistGroup();
-      if (auto *childListInput{child.parent()
-                  .get_if<ChildListIoStatementState<Direction::Input>>()}) {
-        // Child list input whose parent is child list input: can advance
-        // if the parent can.
-        this->canAdvance_ = childListInput->CanAdvance();
-      } else {
-        // Child list input of top-level list input: can advance.
-        this->canAdvance_ = true;
-      }
+  if (const auto *listParent{
+          child.parent().get_if<ListDirectedStatementState<DIR>>()}) {
+    if constexpr (DIR == Direction::Input) {
+      this->set_eatComma(listParent->eatComma());
+      this->namelistGroup_ = listParent->namelistGroup();
+    }
+    if (auto *childListParent{
+            child.parent().get_if<ChildListIoStatementState<DIR>>()}) {
+      // Child list I/O whose parent is child list I/O: can advance
+      // if the parent can.
+      this->canAdvance_ = childListParent->CanAdvance();
+    } else {
+      // Child list I/O of top-level list I/O: can advance.
+      this->canAdvance_ = true;
     }
   }
 #else