[flang-commits] [flang] [Flang][OpenMP] Reject substring and section-component in affinity (PR #184424)

[via flang-commits]

https://github.com/chichunchen updated https://github.com/llvm/llvm-project/pull/184424

>From ea4522a9c356f4383043edb437202bdaf9d582c4 Mon Sep 17 00:00:00 2001
From: "Chi Chun, Chen" <chichun.chen at hpe.com>
Date: Tue, 3 Mar 2026 13:01:37 -0600
Subject: [PATCH] [Flang][OpenMP] Reject invalid AFFINITY locators in semantics

Add semantic checks for OpenMP AFFINITY clauses to reject
substring designators and structure components, including
iterator forms.
---
 flang/lib/Semantics/check-omp-structure.cpp   | 30 +++++++++-
 .../Semantics/OpenMP/affinity-invalid.f90     | 57 +++++++++++++++++++
 2 files changed, 86 insertions(+), 1 deletion(-)
 create mode 100644 flang/test/Semantics/OpenMP/affinity-invalid.f90

diff --git a/flang/lib/Semantics/check-omp-structure.cpp b/flang/lib/Semantics/check-omp-structure.cpp
index 89f1cdb5213cb..964c106e77992 100644
--- a/flang/lib/Semantics/check-omp-structure.cpp
+++ b/flang/lib/Semantics/check-omp-structure.cpp
@@ -5684,12 +5684,40 @@ void OmpStructureChecker::Leave(const parser::OpenMPInvalidDirective &x) {
     RequiresPositiveParameter(llvm::omp::Clause::Y, c.v); \
   }
 
+void OmpStructureChecker::Enter(const parser::OmpClause::Affinity &x) {
+  CheckAllowedClause(llvm::omp::Clause::OMPC_affinity);
+
+  auto &modifiers{OmpGetModifiers(x.v)};
+  if (auto *iter{OmpGetUniqueModifier<parser::OmpIterator>(modifiers)})
+    CheckIteratorModifier(*iter);
+
+  const auto &objects{std::get<parser::OmpObjectList>(x.v.t)};
+  for (const parser::OmpObject &object : objects.v) {
+    if (const parser::Designator *designator{
+            omp::GetDesignatorFromObj(object)}) {
+      if (std::holds_alternative<parser::Substring>(designator->u)) {
+        context_.Say(designator->source,
+            "Substrings are not allowed on AFFINITY clause"_err_en_US);
+        continue;
+      }
+
+      // OpenMP 5.2 3.2.1, unless otherwise specified, a variable
+      // that is part of another variable as a structure element cannot be a
+      // locator list item. AFFINITY does not provide an exception for
+      // structure components.
+      if (parser::Unwrap<parser::StructureComponent>(object)) {
+        context_.Say(designator->source,
+            "Structure components are not allowed in an AFFINITY clause"_err_en_US);
+      }
+    }
+  }
+}
+
 // Following clauses do not have a separate node in parse-tree.h.
 CHECK_SIMPLE_CLAUSE(Absent, OMPC_absent)
 CHECK_SIMPLE_CLAUSE(AcqRel, OMPC_acq_rel)
 CHECK_SIMPLE_CLAUSE(Acquire, OMPC_acquire)
 CHECK_SIMPLE_CLAUSE(AdjustArgs, OMPC_adjust_args)
-CHECK_SIMPLE_CLAUSE(Affinity, OMPC_affinity)
 CHECK_SIMPLE_CLAUSE(AppendArgs, OMPC_append_args)
 CHECK_SIMPLE_CLAUSE(Apply, OMPC_apply)
 CHECK_SIMPLE_CLAUSE(Bind, OMPC_bind)
diff --git a/flang/test/Semantics/OpenMP/affinity-invalid.f90 b/flang/test/Semantics/OpenMP/affinity-invalid.f90
new file mode 100644
index 0000000000000..4d79f61bbefb2
--- /dev/null
+++ b/flang/test/Semantics/OpenMP/affinity-invalid.f90
@@ -0,0 +1,57 @@
+! RUN: %python %S/../test_errors.py %s %flang -fopenmp -fopenmp-version=52
+
+subroutine affinity_substring()
+  character(len=7) :: a(8)
+  !ERROR: Substrings are not allowed on AFFINITY clause
+  !$omp task affinity(a(2)(2:4))
+    a(1) = "abcdefg"
+  !$omp end task
+end subroutine
+
+subroutine affinity_iterator_substring(n)
+  integer, intent(in) :: n
+  integer :: i
+  character(len=7) :: a(n)
+  !ERROR: Substrings are not allowed on AFFINITY clause
+  !$omp task affinity(iterator(i = 1:n) : a(i)(2:4))
+    a(1) = "abcdefg"
+  !$omp end task
+end subroutine
+
+subroutine affinity_section_component(n)
+  integer, intent(in) :: n
+  type t
+    integer :: x
+  end type
+  type(t) :: a(n)
+  !ERROR: Structure components are not allowed in an AFFINITY clause
+  !$omp task affinity(a(1:n)%x)
+    a(1)%x = 1
+  !$omp end task
+end subroutine
+
+subroutine affinity_iterator_component(n)
+  integer, intent(in) :: n
+  integer :: i
+  type t
+    integer :: x
+  end type
+  type(t) :: a(n)
+  !ERROR: Structure components are not allowed in an AFFINITY clause
+  !$omp task affinity(iterator(i = 1:n) : a(i)%x)
+    a(1)%x = 1
+  !$omp end task
+end subroutine
+
+subroutine affinity_iterator_section_component(n)
+  integer, intent(in) :: n
+  integer :: i
+  type t
+    integer :: x
+  end type
+  type(t) :: a(n)
+  !ERROR: Structure components are not allowed in an AFFINITY clause
+  !$omp task affinity(iterator(i = 1:n) : a(i:i+1)%x)
+    a(1)%x = 1
+  !$omp end task
+end subroutine