[llvm-branch-commits] [flang] release/20.x: [flang] Exempt construct entities from SAVE check for PURE (#131383) (PR #137752)

[via llvm-branch-commits]

https://github.com/llvmbot updated https://github.com/llvm/llvm-project/pull/137752

>From 8272e451613d8f929e3d9d0d28c3ca1b225b0000 Mon Sep 17 00:00:00 2001
From: Peter Klausler <pklausler at nvidia.com>
Date: Wed, 19 Mar 2025 12:01:18 -0700
Subject: [PATCH] [flang] Exempt construct entities from SAVE check for PURE
 (#131383)

A PURE subprogram can't have a local variable with the SAVE attribute.
An ASSOCIATE or SELECT TYPE construct entity whose selector is a
variable will return true from IsSave(); exclude them from the local
variable check.

Fixes https://github.com/llvm/llvm-project/issues/131356.

(cherry picked from commit b99dab25879449cb89c1ebd7b4088163543918e3)
---
 flang/lib/Semantics/check-declarations.cpp | 5 ++++-
 flang/test/Semantics/call10.f90            | 4 ++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/flang/lib/Semantics/check-declarations.cpp b/flang/lib/Semantics/check-declarations.cpp
index 5c26469b9fa24..8da9252133bdc 100644
--- a/flang/lib/Semantics/check-declarations.cpp
+++ b/flang/lib/Semantics/check-declarations.cpp
@@ -359,7 +359,10 @@ void CheckHelper::Check(const Symbol &symbol) {
       // are not pertinent to the characteristics of the procedure.
       // Restrictions on entities in pure procedure interfaces don't need
       // enforcement.
-    } else if (!FindCommonBlockContaining(symbol) && IsSaved(symbol)) {
+    } else if (symbol.has<AssocEntityDetails>() ||
+        FindCommonBlockContaining(symbol)) {
+      // can look like they have SAVE but are fine in PURE
+    } else if (IsSaved(symbol)) {
       if (IsInitialized(symbol)) {
         messages_.Say(
             "A pure subprogram may not initialize a variable"_err_en_US);
diff --git a/flang/test/Semantics/call10.f90 b/flang/test/Semantics/call10.f90
index 2d2f57934cd8a..1e186f7b4048a 100644
--- a/flang/test/Semantics/call10.f90
+++ b/flang/test/Semantics/call10.f90
@@ -36,6 +36,8 @@ pure subroutine s05a
     end subroutine
   end interface
 
+  real :: moduleVar = 1.
+
  contains
 
   subroutine impure(x)
@@ -117,6 +119,8 @@ pure subroutine s05 ! C1589
     !ERROR: A pure subprogram may not initialize a variable
       real :: v6 = 0.
     end block
+    associate (x => moduleVar) ! ok
+    end associate
   end subroutine
   pure subroutine s06 ! C1589
     !ERROR: A pure subprogram may not have a variable with the VOLATILE attribute