[flang][runtime] Complete list-directed character input with DECIMAL='COMMA'

[klausler]

Summary

Most of the infrastructure for DECIMAL='COMMA' mode was in place
in the I/O runtime support library, but I dropped the ball for
list-directed character input, which has its own detection of
input separators. Finish the job.

flang/runtime/edit-input.cpp

if (IsNamelistName(io) || io.GetConnectionState().IsAtEOF()) {
     return false;
   }
   // Undelimited list-directed character input: stop at a value separator
   // or the end of the current record.  Subtlety: the "remaining" count
   // here is a dummy that's used to avoid the interpretation of separators
   // in NextInField.
   std::optional<int> remaining{length > 0 ? maxUTF8Bytes : 0};
   while (std::optional<char32_t> next{io.NextInField(remaining, edit)}) {
+    bool isSep{false};
     switch (*next) {
     case ' ':
     case '\t':
+    case '/':
+      isSep = true;
+      break;
     case ',':
+      isSep = !(edit.modes.editingFlags & decimalComma);
+      break;
     case ';':
-    case '/':
-      remaining = 0; // value separator: stop
+      isSep = !!(edit.modes.editingFlags & decimalComma);
       break;
     default:
+      break;
+    }
+    if (isSep) {
+      remaining = 0;
+    } else {
       *x++ = *next;
       remaining = --length > 0 ? maxUTF8Bytes : 0;
     }
   }
   std::fill_n(x, length, ' ');
   return true;
 }
 

flang/runtime/io-stmt.cpp

std::optional<char32_t> IoStatementState::NextInField(
   std::size_t byteCount{0};
   if (!remaining) { // Stream, list-directed, or NAMELIST
     if (auto next{GetCurrentChar(byteCount)}) {
       if (edit.IsListDirected()) {
         // list-directed or NAMELIST: check for separators
         switch (*next) {
         case ' ':
         case '\t':
-        case ';':
         case '/':
         case '(':
         case ')':
         case '\'':
         case '"':
         case '*':
         case '\n': // for stream access
           return std::nullopt;
         case ',':
-          if (edit.modes.editingFlags & decimalComma) {
-            break;
-          } else {
+          if (!(edit.modes.editingFlags & decimalComma)) {
+            return std::nullopt;
+          }
+        case ';':
+          if (edit.modes.editingFlags & decimalComma) {
             return std::nullopt;
           }
+          break;
         default:
           break;
         }
       }
       HandleRelativePosition(byteCount);
       GotChar(byteCount);
       return next;
     }