[Flang][OpenMP] Avoid default none errors for seq loop indices in par…

[kiranchandramohan]

…allel

[tblah]

@kiranchandramohan what more is needed to make this PR ready?

[llvmbot]

@llvm/pr-subscribers-flang-semantics

@llvm/pr-subscribers-flang-openmp

Author: Kiran Chandramohan (kiranchandramohan)

Changes

…allel

---

Full diff: https://github.com/llvm/llvm-project/pull/76258.diff

2 Files Affected:

• (modified) flang/lib/Semantics/resolve-directives.cpp (+5-1)
• (modified) flang/test/Semantics/OpenMP/resolve05.f90 (+13)

diff --git a/flang/lib/Semantics/resolve-directives.cpp b/flang/lib/Semantics/resolve-directives.cpp
index d7b13631ab4df0..b30b81cf90c951 100644
--- a/flang/lib/Semantics/resolve-directives.cpp
+++ b/flang/lib/Semantics/resolve-directives.cpp
@@ -1946,7 +1946,11 @@ void OmpAttributeVisitor::Post(const parser::Name &name) {
       if (Symbol * found{currScope().FindSymbol(name.source)}) {
         if (symbol != found) {
           name.symbol = found; // adjust the symbol within region
-        } else if (GetContext().defaultDSA == Symbol::Flag::OmpNone) {
+        } else if (GetContext().defaultDSA == Symbol::Flag::OmpNone &&
+            // Exclude indices of sequential loops that are privatised in
+            // the scope of the parallel region, and not in this scope.
+            // TODO: check whether this should be caught in IsObjectWithDSA
+            !symbol->test(Symbol::Flag::OmpPrivate)) {
           context_.Say(name.source,
               "The DEFAULT(NONE) clause requires that '%s' must be listed in "
               "a data-sharing attribute clause"_err_en_US,
diff --git a/flang/test/Semantics/OpenMP/resolve05.f90 b/flang/test/Semantics/OpenMP/resolve05.f90
index 00f4860302183d..c4cebb48ac5c2b 100644
--- a/flang/test/Semantics/OpenMP/resolve05.f90
+++ b/flang/test/Semantics/OpenMP/resolve05.f90
@@ -17,7 +17,20 @@ subroutine default_none()
   !$omp end parallel
 end subroutine default_none
 
+! Test that indices of sequential loops are privatised and hence do not error
+! for DEFAULT(NONE)
+subroutine default_none_seq_loop
+  integer :: i
+
+  !$omp parallel do default(none)
+  do i = 1, 10
+     do j = 1, 20
+    enddo
+  enddo
+end subroutine
+
 program mm
   call default_none()
+  call default_none_seq_loop()
   !TODO: private, firstprivate, shared
 end

[tblah]

LGTM, this does fix the bug. Thanks!