[flang-commits] [flang] [Flang][OpenMP] Add Semantics support for Nested OpenMPLoopConstructs (PR #145917)

[David Spickett via flang-commits]

DavidSpickett wrote:

> In this one case I wrapped the following "if" in "if (nextIt != block.end())" and that fixed the problem.

On Windows on Arm, the following hack passes all tests and hammering the specific tests produced no failures:
```
diff --git a/flang/lib/Semantics/canonicalize-omp.cpp b/flang/lib/Semantics/canonicalize-omp.cpp
index 1edcb376596b..f33d161d6870 100644
--- a/flang/lib/Semantics/canonicalize-omp.cpp
+++ b/flang/lib/Semantics/canonicalize-omp.cpp
@@ -151,12 +151,14 @@ private:
               std::move(*doCons);
           nextIt = block.erase(nextIt);
           // try to match OmpEndLoopDirective
+          if (nextIt != block.end()) {
           if (auto *endDir{
                   GetConstructIf<parser::OmpEndLoopDirective>(*nextIt)}) {
             std::get<std::optional<parser::OmpEndLoopDirective>>(x.t) =
                 std::move(*endDir);
             nextIt = block.erase(nextIt);
           }
+          }
         } else {
           messages_.Say(dir.source,
               "DO loop after the %s directive must have loop control"_err_en_US,
```

https://github.com/llvm/llvm-project/pull/145917