[flang-commits] [flang] [flang] fix scoping of cray pointer declarations and add check for initialization (PR #136776)

[Andre Kuhlenschmidt via flang-commits]

https://github.com/akuhlens created https://github.com/llvm/llvm-project/pull/136776

This PR:
- makes Cray pointer declarations shadow previous bindings instead of modifying them,
- errors when the pointee of a cray pointee has the SAVE attribute, and
- adds a missing newline after dumping the list of cray pointers in a scope.

Closes #135579

>From f0fd6587cbb6a680430cc91a24c21bd916470bfb Mon Sep 17 00:00:00 2001
From: Andre Kuhlenschmidt <akuhlenschmi at nvidia.com>
Date: Tue, 22 Apr 2025 14:59:37 -0700
Subject: [PATCH] initial commit

---
 flang/lib/Semantics/check-declarations.cpp  | 12 +++++++++++-
 flang/lib/Semantics/resolve-names.cpp       |  2 +-
 flang/lib/Semantics/semantics.cpp           |  1 +
 flang/test/Lower/OpenMP/cray-pointers01.f90 |  2 +-
 flang/test/Semantics/declarations08.f90     |  6 ++++++
 5 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/flang/lib/Semantics/check-declarations.cpp b/flang/lib/Semantics/check-declarations.cpp
index 8d5e034f8624b..6cc4665532385 100644
--- a/flang/lib/Semantics/check-declarations.cpp
+++ b/flang/lib/Semantics/check-declarations.cpp
@@ -963,7 +963,17 @@ void CheckHelper::CheckObjectEntity(
         "'%s' is a data object and may not be EXTERNAL"_err_en_US,
         symbol.name());
   }
-
+  if (symbol.test(Symbol::Flag::CrayPointee)) {
+    // NB, IsSaved was too smart here.
+    if (details.init()) {
+      messages_.Say(
+          "Cray pointee '%s' may not be initialized"_err_en_US, symbol.name());
+    } else if (symbol.attrs().test(Attr::SAVE) ||
+        symbol.implicitAttrs().test(Attr::SAVE)) {
+      messages_.Say(
+          "Cray pointee '%s' may not be SAVE"_err_en_US, symbol.name());
+    }
+  }
   if (derived) {
     bool isUnsavedLocal{
         isLocalVariable && !IsAllocatable(symbol) && !IsSaved(symbol)};
diff --git a/flang/lib/Semantics/resolve-names.cpp b/flang/lib/Semantics/resolve-names.cpp
index f1d2ba4078236..e0550b3724bef 100644
--- a/flang/lib/Semantics/resolve-names.cpp
+++ b/flang/lib/Semantics/resolve-names.cpp
@@ -6650,7 +6650,7 @@ bool DeclarationVisitor::Pre(const parser::BasedPointer &) {
 
 void DeclarationVisitor::Post(const parser::BasedPointer &bp) {
   const parser::ObjectName &pointerName{std::get<0>(bp.t)};
-  auto *pointer{FindSymbol(pointerName)};
+  auto *pointer{FindInScope(pointerName)};
   if (!pointer) {
     pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
   } else if (!ConvertToObjectEntity(*pointer)) {
diff --git a/flang/lib/Semantics/semantics.cpp b/flang/lib/Semantics/semantics.cpp
index 10a01039ea0ae..e07054f8ec564 100644
--- a/flang/lib/Semantics/semantics.cpp
+++ b/flang/lib/Semantics/semantics.cpp
@@ -731,6 +731,7 @@ void DoDumpSymbols(llvm::raw_ostream &os, const Scope &scope, int indent) {
     for (const auto &[pointee, pointer] : scope.crayPointers()) {
       os << " (" << pointer->name() << ',' << pointee << ')';
     }
+    os << '\n';
   }
   for (const auto &pair : scope.commonBlocks()) {
     const auto &symbol{*pair.second};
diff --git a/flang/test/Lower/OpenMP/cray-pointers01.f90 b/flang/test/Lower/OpenMP/cray-pointers01.f90
index 87692ccbadfe3..d3a5a3cdd39a3 100644
--- a/flang/test/Lower/OpenMP/cray-pointers01.f90
+++ b/flang/test/Lower/OpenMP/cray-pointers01.f90
@@ -33,7 +33,7 @@ subroutine set_cray_pointer
 end module
 
 program test_cray_pointers_01
-  real*8, save :: var(*)
+  real*8 :: var(*)
   ! CHECK: %[[BOX_ALLOCA:.*]] = fir.alloca !fir.box<!fir.ptr<!fir.array<?xf64>>>
   ! CHECK: %[[IVAR_ALLOCA:.*]] = fir.alloca i64 {bindc_name = "ivar", uniq_name = "_QFEivar"}
   ! CHECK: %[[IVAR_DECL_01:.*]]:2 = hlfir.declare %[[IVAR_ALLOCA]] {uniq_name = "_QFEivar"} : (!fir.ref<i64>) -> (!fir.ref<i64>, !fir.ref<i64>)
diff --git a/flang/test/Semantics/declarations08.f90 b/flang/test/Semantics/declarations08.f90
index bd14131b33c28..140ff710228c1 100644
--- a/flang/test/Semantics/declarations08.f90
+++ b/flang/test/Semantics/declarations08.f90
@@ -5,4 +5,10 @@
 !ERROR: Cray pointee 'x' may not be a member of a COMMON block
 common x
 equivalence(y,z)
+!ERROR: Cray pointee 'v' may not be initialized
+real :: v = 42.0
+pointer(p,v)
+!ERROR: Cray pointee 'u' may not be SAVE
+save u
+pointer(p, u)
 end