[flang-commits] [PATCH] D145745: [flang][runtime] Catch infinite unlimited format repetition better

[Peter Klausler via Phabricator via flang-commits]

klausler created this revision.
klausler added a reviewer: vdonaldson.
klausler added a project: Flang.
Herald added subscribers: sunshaoce, jdoerfert.
Herald added a project: All.
klausler requested review of this revision.

The runtime check for infinite unlimited format repetition is missing
the case of implicit unlimited format repetition at the top level  
without finding the next data edit descriptor that corresponds with
a data list item.

Replace the check with a Boolean flag that detects unlimited   
repetition hitting a right parenthesis and restarting, and fail
when it happens the second time.


https://reviews.llvm.org/D145745

Files:
  flang/runtime/format-implementation.h


Index: flang/runtime/format-implementation.h
===================================================================
--- flang/runtime/format-implementation.h
+++ flang/runtime/format-implementation.h
@@ -212,7 +212,7 @@
 // format validator gauntlet.
 template <typename CONTEXT>
 int FormatControl<CONTEXT>::CueUpNextDataEdit(Context &context, bool stop) {
-  int unlimitedLoopCheck{-1};
+  bool hitUnlimitedLoopEnd{false};
   // Do repetitions remain on an unparenthesized data edit?
   while (height_ > 1 && format_[stack_[height_ - 1].start] != '(') {
     offset_ = stack_[height_ - 1].start;
@@ -267,7 +267,6 @@
       RUNTIME_CHECK(context, format_[stack_[height_].start] == '(');
       if (unlimited || height_ == 0) {
         stack_[height_].remaining = Iteration::unlimited;
-        unlimitedLoopCheck = offset_ - 1;
       } else if (repeat) {
         if (*repeat <= 0) {
           *repeat = 1; // error recovery
@@ -305,12 +304,13 @@
               restart);
           return 0;
         }
-        if (offset_ == unlimitedLoopCheck) {
+        if (hitUnlimitedLoopEnd) {
           ReportBadFormat(context,
               "Unlimited repetition in FORMAT lacks data edit descriptors",
               restart);
           return 0;
         }
+        hitUnlimitedLoopEnd = true;
         offset_ = restart;
       } else if (stack_[height_ - 1].remaining-- > 0) {
         offset_ = restart;


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