[flang][runtime] Fix formatted input of NAN(...) (#149606)

Formatted real input is allowed to have parenthesized information after
"NAN". We don't interpret the contents, but we should at least scan the
information correctly.

Fixes https://github.com/llvm/llvm-project/issues/149533 and
https://github.com/llvm/llvm-project/issues/150035.

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

@@ -375,21 +375,37 @@ static RT_API_ATTRS ScannedRealInput ScanRealInput(
         Put(*next);
       }
     }
-    if (next && *next == '(') { // NaN(...)
-      Put('(');
-      int depth{1};
-      while (true) {
-        next = io.NextInField(remaining, edit);
-        if (depth == 0) {
-          break;
-        } else if (!next) {
-          return {}; // error
-        } else if (*next == '(') {
-          ++depth;
-        } else if (*next == ')') {
-          --depth;
+    if (first == 'N' && (!next || *next == '(') &&
+        remaining.value_or(1) > 0) { // NaN(...)?
+      std::size_t byteCount{0};
+      if (!next) { // NextInField won't return '(' for list-directed
+        next = io.GetCurrentChar(byteCount);
+      }
+      if (next && *next == '(') {
+        int depth{1};
+        while (true) {
+          if (*next >= 'a' && *next <= 'z') {
+            *next = *next - 'a' + 'A';
+          }
+          Put(*next);
+          io.HandleRelativePosition(byteCount);
+          io.GotChar(byteCount);
+          if (remaining) {
+            *remaining -= byteCount;
+          }
+          if (depth == 0) {
+            break; // done
+          }
+          next = io.GetCurrentChar(byteCount);
+          if (!next || remaining.value_or(1) < 1) {
+            return {}; // error
+          } else if (*next == '(') {
+            ++depth;
+          } else if (*next == ')') {
+            --depth;
+          }
         }
-        Put(*next);
+        next = io.NextInField(remaining, edit);
       }
     }
   } else if (first == radixPointChar || (first >= '0' && first <= '9') ||

flang-rt/unittests/Runtime/NumericalFormatTest.cpp

@@ -964,6 +964,7 @@ TEST(IOApiTests, EditDoubleInputValues) {
       {"(RU,E9.1)", " 1.0E-325", 0x1, 0},
       {"(E9.1)", "-1.0E-325", 0x8000000000000000, 0},
       {"(RD,E9.1)", "-1.0E-325", 0x8000000000000001, 0},
+      {"(F7.0))", "+NaN(q)", 0x7ff8000000000000, 0},
   };
   for (auto const &[format, data, want, iostat] : testCases) {
     auto cookie{IONAME(BeginInternalFormattedInput)(